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  • 更新日期:2018-09-12
  • Temperature independent low loss dielectrics based on quaternary pyrochlore oxides
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2018-06-15
    Gabriella Giampaoli, Theeranun Siritanon, Blake Day, Jun Li, M.A. Subramanian
    更新日期:2018-07-12
  • Synthesis and application of nano-structured metal nitrides and carbides: A review
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2018-05-17
    Sefiu Abolaji Rasaki, Bingxue Zhang, Kousika Anbalgam, Tiju Thomas, Minghui Yang

    Transition metal nitride and carbide have several similarities in their preparatory methods, properties, and applications. Synthetic parameters have remained the main factors that determine the effectiveness of nitrides and carbides in electrochemical storage devices, photocatalysis, environmental remediation, gas sensing and medicinal agents. This review addresses aspects of relevance to electronic structure and chemical bonding, and recent advances made in the synthesis approaches. The syntheses approaches that are particularly relevant for reducing (i) production cost, (ii) energy consumption, and (iii) synthesis time for these materials systems are discussed in detail. Furthermore some of the recent techniques like solid-solid state separation, carbothermal, gas-phase, electrochemical, sonochemical, solvothermal, sol-gel reaction and solid state reaction that offer new avenues for researchers (including a sustainability-oriented exploration) are mentioned. We discuss synthetically tunable properties (morphology, electronic characteristics, energy storage capacity, corrosion resistance, catalytic ability and gas sensing properties), heat treatment aspects, and relevant applications of these systems. We expect this review to be useful to the ever growing community of researchers that are interested in nitrides and carbides, and their applications.

    更新日期:2018-07-12
  • Low field magnetoelectric studies on sol–gel grown nanostructured YMnO3 manganites
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-12-22
    Zalak Joshi, Davit Dhruv, K.N. Rathod, Hetal Boricha, Keval Gadani, D.D. Pandya, A.D. Joshi, P.S. Solanki, N.A. Shah

    Single phasic nanostructured YMnO3 manganites were successfully synthesized by employing acetate precursor based modified sol–gel technique followed by their sintering at different temperatures. Structural studies were carried out by performing X–ray diffraction (XRD) measurement and Rietveld analysis on raw data of XRD. Particle size and shape were studied using transmission electron microscopy (TEM) while size distribution was investigated by performing particle size analyzer. Nanostructured samples were studied for their electrical properties under low applied magnetic field of 1.2T. Frequency and magnetic field dependent dielectric behavior has been understood on the basis of boundaries between the particles and inverse Dzyaloshinskii–Moriya (DM) interaction. Nanostructured YMnO3 manganites exhibit positive magnetodielectric (MD) effect. Universal dielectric response (UDR) model and relaxation mechanism have been employed for dielectric behavior of the samples understudy. Role of particle morphology and magnetic disorder have been discussed for the understanding of impedance and negative magnetoimpedance (MI) of the samples. Frequency and magnetic field dependent variation in conductivity has been explained using boundary and magnetic disorders and free charge carriers in the samples. All nanostructured YMnO3 show positive Magnetoconductivity (MC) throughout the frequency and magnetic field range studied. Variation in voltage dependent hysteretic capacitance and estimated built–in potential have been discussed in the context of the role of defects, vacancies, disorder and free charge carriers in the samples sintered at different temperatures.

    更新日期:2018-07-12
  • Mass spectrometry drives stoichiometric GaAs formation from single-source precursors
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-10-18
    Anatoliy Sokolov, Bruce Gerhart, Robert J. Wright, Anna M. Zink, George L. Athens, Steve Rozeveld, Arkady L. Krasovskiy, Liam P. Spencer, Robert Froese, Peter Nickias, James C. Stevens

    Evolved gas analysis (EGA) mass-spectrometry (MS) is used to characterize the solid state pyrolysis decomposition pathways of air- and moisture-sensitive organometallic compounds. In this study, the single-source GaAs compounds (Et2AsGaEt2)3 (1), (t-Bu2AsGaEt2)2 (2), and [t-Bu(H)AsGaEt2]2 (3) were heated in capillary tubes under inert condition and the volatile products were analyzed by MS. In addition, the relative ratios of evolved gases were characterized using gas chromatography (GC), while the solid state pyrolysis products were analyzed by EDS, 1H NMR and XRD. Pyrolysis of GaAs single-source materials in the solid state reveals chemical information on the stability of the GaAs bond, an observation masked in gas-phase analysis of single-source materials during chemical vapor deposition. Information on GaAs bond stability may be elucidated due to the volatility of the by-products formed during Ga-As precursor pyrolysis. Loss of GaAs bond integrity in materials with alkyl substitution on Ga and As leads to formation of mobile and volatile alkyl diarsine species, as was observed for the pyrolysis of 1. An in-situ method to monitor solid-state pyrolysis by mass spectrometry identified the loss of a tetraalkyl-diarsine as the critical factor that drives formation of sub-stoichiometric GaAs products from single-source precursors. Replacing a single alkyl group on the As atom with a H (precursor 3) leads to the loss of an alkane instead of tetraalkyl-diarsine formation. Solid-state pyrolysis precursor 3 results in the formation of polycrystalline GaAs in up to 58% yield with a 52:48 Ga:As stoichiometry.

    更新日期:2018-07-12
  • Molecular structure of Se-rich amorphous films
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-10-20
    V.I. Mikla, J.M. Turovci, V.V. Mikla, N. Mehta

    Structure and its transformation are examined for amorphous Se-rich AsxSe1-x (0 ≤ x ≤ 0.2) alloys by employment of diffraction and non-diffraction structural probes. It is shown that the molecular structure of amorphous Se (a-Se) on the scale of short-range order is close to that of crystalline phase, while medium-range order differs from the structure of most inorganic glasses and may be placed between three-dimensional network glasses and polymeric ones. Further experiments show the existence of successive phases in laser-induced glass-crystalline transition with pronounced threshold behavior. Below the energy density threshold, Eth, only small changes in the local structure of the system can be detected. Above Eth, the changes were attributed to crystallization transformation. The corresponding Raman spectra reveal transformation of the system from amorphous into the crystalline phase under laser irradiation. In the binary AsxSe1-x glass system, a change of structural regime takes place near the composition x ≈ 0.04. The presence of this topological threshold is established by direct and indirect evidence, such as peculiarities in the composition dependence of the basic parameters for electron diffraction and Raman vibration modes. The peculiarities are caused by the transition from a chain-ring-like structure to preferentially a chain-like structure. Experiments described in this section have shown that Raman technique is a particularly sensitive method to determine the presence of microcrystal's in the glassy matrix. Room-temperature polarized Raman scattering spectra of model glass have been collected. Low-frequency peaks were observed in the spectra. A model is proposed for explanation of their appearance. It is shown clearly that the low-frequency Raman spectra allow determining the conditions at the boundaries, sizes as well as concentration of micro-heterogeneities in non-crystalline materials. It was established earlier that for all amorphous (glassy) materials a low-frequency peak, observed in the corresponding spectral region of Raman scattering and called boson peak, is inherent. This peak is absent in crystals of the same chemical composition and is associated with space correlations on the scale of medium-range order Rc ≈ 10 Å. On the contrary, less known is that a boson peak can give important information about the presence of microcrystalline inclusions and heterogeneities in the low-frequency Raman spectra of glasses irrespective to their chemical composition.

    更新日期:2018-07-12
  • CO2 reduction using oxynitrides and nitrides under visible light
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-11-22
    Kazuhiko Maeda

    Reduction of CO2 using a heterogeneous photocatalyst under visible light has been studied as a potential means to address the problems of global warming and the depletion of fossil fuels. Recently, hybrid photocatalysts constructed with a metal complex and a particulate semiconductor are of particular interest because of the excellent electrochemical (and/or photocatalytic) ability of the metal complexes for CO2 reduction and the high efficiency of the semiconductors for oxidation reactions, where the ultimate target of oxidation reaction is water oxidation to form molecular O2. This review article highlights our recent progress in the development of metal-complex/semiconductor hybrid materials for visible-light CO2 reduction with a focus on oxynitride and nitride materials as the semiconductor component.

    更新日期:2018-07-12
  • Nitride and oxynitride phosphors for white LEDs: Synthesis, new phosphor discovery, crystal structure
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-11-14
    Takashi Takeda, Rong-Jun Xie, Takayuki Suehiro, Naoto Hirosaki

    Si,Al containing nitride and oxynitride phosphors have been applied to white LEDs. Phosphors play important roles to produce high color rendering in lighting and wide color gamut in display. Si,Al containing nitrides and oxynitrides have been studied as high-temperature materials with high strength and thermal shock resistance. The inherited high temperature property is utilized as low thermal quenching in luminescence. The increased covalent bonding character compared to oxide phosphors contributes to high efficiency in blue excitation. The crystal structure (especially the coordination sphere around luminescent center) dominates the luminescent property of phosphor. Wide variety of crystal structure in Si,Al containing nitride and oxynitride leads to multiplicity of luminescent property. In this contribution, Si,Al containing nitride and oxynitride phosphors are reviewed from viewpoints of synthesis, new phosphor discovery, and crystal structure.

    更新日期:2018-07-12
  • Synthetic approaches in oxynitride chemistry
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-11-03
    Amparo Fuertes

    Mixed anion oxides are emerging materials showing a variety of physical and chemical properties. Among them oxynitrides are widely investigated because of notable photocatalytic, dielectric, luminescent and electronic properties. Nitrides show more positive free energies of formation than oxides because of the higher stability of N2 molecule with respect to O2 and the unfavourable electron affinity of nitrogen compared to oxygen. However the stability of oxynitrides is higher than for nitrides, and they easily form from oxides in presence of reactive gases as NH3. In addition to ammonolysis several synthetic strategies have been developed in the last years leading to the stabilization of relevant materials with a variety of structures. In this review we will discuss recent progress in the synthesis of oxynitrides emphasizing the importance of kinetic factors and the influence of preparative parameters on the structure types and oxidation states of the cations, and the consequences on physical properties.

    更新日期:2018-07-12
  • Sodium flux synthesis of nitrides
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-09-14
    Hisanori Yamane, Francis J. DiSalvo

    Studies of the synthesis of solid state nitrides using a Na flux are reviewed. The role and effect of Na is to solubilize polyatomic species containing nitrogen, and to lower the crystal growth temperature below the decomposition temperature of the obtained product(s). Many new ternary and quaternary nitrides have been synthesized in single crystal forms with sizes at least large enough (or larger) than is needed for structure analysis by X-ray diffraction. Isolated and extended anionic groups typically containing N and Si, Ge, Ga, and/or some transition metal elements are typical. These are usually surrounded by alkaline-earth atoms and are the most common of such nitrides. Compounds composed of nitridometallate anions and Zintl polyanions are also obtained. The structural features of each of these compounds are described.

    更新日期:2018-07-12
  • Remarkable effects of local structure in tantalum and niobium oxynitrides
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-08-24
    Shinichi Kikkawa, Akira Hosono, Yuji Masubuchi

    Compounds that contain two types of anion are attracting attention as a new field of solid state chemistry. The nitride anion is similar to the oxide anion in size and nature. They coordinate together to cations in oxynitrides to form characteristic local structures around them in a certain way. Special properties induced by the specific local structure have been observed in oxynitrides. Ferroelectricity was identified in oxynitride perovskites, especially those of tantalum, because the oxide and nitride anions form a polar ordered local crystal structure around Ta5+ in the 5d0 electron configuration. The critical current density in superconductivity was enhanced by the formation of clusters in niobium oxynitrides with the rocksalt-type structure. Main group elements doped into the niobium oxynitrides, especially silicon, are coordinated mainly by oxides with some amount of nitrides to form silicon oxide-like clusters. The niobium in the oxynitride has some 4d electrons to maintain the superconductivity in the niobium oxynitride host. Here, the preparation, crystal structure and properties of oxynitrides formed with tantalum and niobium are reviewed.

    更新日期:2018-07-12
  • Magnetic iron nitrides inspired by historic research on α″-Fe16N2
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-06-06
    Shinichi Kikkawa, Yuji Masubuchi

    Strong ferromagnetic materials at room temperature are of interest for various magnetic applications such as magnetic recording, sensors, and motors. Gigantic magnetism expected for α″-Fe16N2 thin films had been attracted much attention in terms of its large magnetization per weight in comparison to rare earth iron nitrides R2Fe17N3 because these films are made of only iron and nitrogen. It developed much straggling on iron nitride thin film research but inconsistent results were obtained using different preparation methods. A powdered α″-Fe16N2-like compound was prepared by the ammonolysis of fine α-Fe powder in low temperature below 200 °C to clarify the confusion; the magnetism was not large in α″-Fe16N2 itself but was increased in the intermediate ammonolysis dual-phase mixture product of the α″-Fe16N2-like compound and residual α-Fe. A way to control the magnetic coercivity was subsequently investigated to utilize the larger magnetization in the α″-Fe16N2-like compound mixture as magnetic materials similarly to Sm2Fe17N3 bonded magnet. Iron nitrides, zinc blende type γ″-FeN and rock-salt type γ‴-FeN, also decompose at around 500 °C. Thermal decomposition was a disadvantage in the preparation of the iron nitrides; however, iron nanoparticles dispersed composites in AlN matrix were derived from the iron nitrides (Fe,Al)N by thermal treatment including laser heating. Iron nitrides are thus promising magnetic materials for their potential applications in science and technology.

    更新日期:2018-07-12
  • Itinerant nitrides and salt-like guanidinates – The diversity of solid-state nitrogen chemistry
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-04-05
    Tanja Scholz, Arno L. Görne, Richard Dronskowski

    Recent advances in the chemistry of two peculiar nitrogen-based materials, that is, ternary itinerant iron nitrides and unsubstituted guanidinate salts, are reviewed. Key to their synthesis is the versatile tool ammonia, either as a gas or as a liquid. For metallic nitrides MxFe4−xN including transition-metal and main-group elements M, it is of paramount importance to follow an improved ammonolytic reaction for achieving both stable and metastable compounds; in addition, there is a magnetic effect acting on the crystal structure of GaxFe4−xN, and one also finds spin-glass behavior in main-group nitrides (M = Ga, Ge, Sn). The guanidinate review features an oxidation-controlled low-temperature synthesis of Yb salts, the first magnetic guanidinates, and the doubly-deprotonated guanidinates; the latter represent the all-nitrogen analogues of the ubiquitous carbonates. The covered guanidinates adopt the compositions MCN3H4, M(CN3H4)2, M(CN3H4)3 and MC(NH)3 (M = Li–Cs, Sr, Eu, Yb). We also cover the application of first-principles calculations at all levels to gain a deeper understanding of the studied materials.

    更新日期:2018-07-12
  • Stereochemistry and ab initio topology analyses of electron lone pair triplets and twins in interhalogen compounds and halogen suboxides
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-06-16
    Samir F. Matar, Guillaume Couegnat, Jean Galy

    The paper reports a thorough investigation of little inspected two classes of group VIIA based crystals: interhalogen compounds ClF, ClF3, BrF3 and IF3 on one hand and halogen suboxides F2O, Cl2O and Br2O on the other hand, as well as rare gas fluorides (here exemplarily XeF4), all exhibiting peculiar stereochemistry of electron (non-bonding) lone pairs merging in forms of twins and triplets. Particularly with respect to the well known VSEPR (Valence Shell Electron Pair Repulsion) model we present original approach merging crystal chemistry and density functional theory (DFT) electron localization function (ELF) to provide accurate topologic analyses and precise metrics of electron lone pairs geometries. In this context we rewrite the chemical formulae above by adjoining E designing the lone pair (LP) and M* formulating the LP-bearing element: ClF{E3}, M*2OE2{E3}2 (M* = F, Cl, Br), M*F3E2 (M* = Cl, Br, I) and XeF4E2. Then in ClF{E3} and M*2OE2{E3}2 (M* = F, Cl, Br) family an original stereochemistry is developed with LP concentration in E triplets which generate electronic torus revolving around Cl and M* which in the neighborhood of largely electronegative F, exhibit cationic-like behavior. E around Cl in ClF and then around M* of the series under consideration exhibits an ellipsoidic shape with an equivalent sphere of influence radius (rE) increasing along with the atomic number Z, i.e. rE_F = 0.52 Å, rE_Cl = 0.65 Å and rE_Br = 0.70 Å. From selected sections in ELF data we obtained precise topology and metrics details of these tori. For M*2OE2{E3}2 family the E twins attached to O have also been localized, their size remaining constant with rE_O = 0.68 Å in all studied compounds. The lone pair twins in the series M*F3E2 (M* = Cl, Br, I; M* trivalent oxidation state) as well as in noble gas tetrafluoride XeF4E2 provide remarkable examples: rE evolution versus Z, rE_Cl = 0.77 Å (Z = 17), rE_Br = 0.85 Å (Z = Br) and rE_I = 0.90 Å (Z = 53), follow a linear expansion while in the xenon case with a close ZXe = 54 but with tetravalent oxidation state, Xe exhibits a radius rE_Xe = 0.95 Å, indicating the important influence of the charge magnitude on E volume. The interaction of cations with E centroïd: Ec -defined as the electronic volume attached to the lone pair- of neighboring molecules is plausible in explaining unusually short distances between cations. Even surrounded by E torus the cations obviously exert attractive influence through its vortex axis. Based on combined stereochemistry and ab initio topology analyses the paper endeavors showing the unavoidable necessity to accurately account for electron lone pairs: – position of their centroïd, – their shape, – their size, – and their deformation (knowing that the electron cloud which accompanies them exhibits a certain plasticity), in order to fully understand their remarkable influence on crystal networks.

    更新日期:2018-06-03
  • Carboxylated fullerenes: Physico-chemical properties and potential applications
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-09-22
    Konstantin N. Semenov, Elena V. Andrusenko, Nikolai A. Charykov, Elena V. Litasova, Gayane G. Panova, Anastasia V. Penkova, Igor V. Murin, Levon B. Piotrovskiy

    Carboxylated fullerenes may have wide applications in science and technology. Therefore, there is particular interest in investigating the physico-chemical and biological properties and the applications of these compounds. This review systematizes the current literature data on the synthesis, physico-chemical properties and application of carboxylated fullerenes as nanomodifiers of polyelectrolytes as well as their use in medicine and agriculture. Presented experimental and theoretical data gives a comprehensive overview of these substances and can be valuable to specialists in the fields of nanotechnology, nanomaterials and bionanomedicine.

    更新日期:2018-06-03
  • The applications of graphene-based materials in pollutant control and disinfection
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2017-02-22
    Chi Him A. Tsang, H.Y.H. Kwok, Zhanjun Cheng, D.Y.C. Leung

    Due to their extra-large surface area and porosity, high compression power, hydrophobicity, and strong activity characteristics, there have been increasing interests in applying graphene-based materials for pollutant control and disinfection. The topics covered from photocatalytic reactions in the dye removal and organic conversions in liquid or gas phase, disinfection, oil absorption, and pollutant adsorption. In this manuscript, the characteristics of the photocatalytic reactions for toxins and pollutants like toxic hydrocarbons, carbon dioxides, and dye wastewater, removal of pollutants like oil and heavy metal ions via absorption/adsorption, and disinfection by different graphene-based materials via adsorption inactivation or photocatalytic inactivation will be emphasized. The challenges in pollutant removal research by graphene-based materials, such as the deactivation of graphene-based materials in photocatalytic pollutant removal reactions which was discovered recently and solutions to the corresponding weaknesses were discussed.

    更新日期:2018-06-03
  • 更新日期:2018-06-03
  • Colored oxides with hibonite structure: A potential route to non-cobalt blue pigments
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-11-15
    Jun Li, Elena A. Medina, Judith K. Stalick, Arthur W. Sleight, M.A. Subramanian

    The crystal structure of hibonite with an ideal formula CaAl12O19 is hexagonal P63/mmc, isostructural with magnetoplumbite. Natural and synthetic hibonites have been widely studied for their formation, compositions, crystal structures, properties and applications. Recent increasing interest in its coloration has led to the search of inorganic pigments based on the hibonite structure. We present here the syntheses and characterization of hibonite compounds with a general formula of AAl12−xMxO19 (A = Ca, Sr, RE (rare earths) or any combination thereof; and M = Ni or Ni coupled with one of the following: Ti, Sn, Ge, Nb, Ta, Sb). Bright sky-blue to royal-blue colors are induced in these oxides prepared by conventional solid state reactions, as demonstrated in the solid solutions of CaAl12−2xNixTixO19 (x = 0–1) and Ca1−xLaxAl12−xNixO19 (x = 0–1). The values of color coordinates L*a*b* range from 64.5, −5.3, −18.5 to 57, −11.33, −30.38. Structure refinements of neutron powder diffraction data reveal that Ni preferably occupies the tetrahedral site in the hibonite structure, and magnetic susceptibility analysis confirms that this Ni is Ni2+. Optical measurements further verify that the observed blue color is due to d-d transitions of tetrahedral Ni2+. The preference of Ni2+ for the tetrahedral site is unusual because Ni2+ prefers the octahedral site in the spinel NiAl2O4. We attribute this unexpected behavior to the unusually large Al−O distances for the tetrahedral site in the hibonite structure. These blue hibonites exhibit excellent thermal stability, superior acid/base durability and better near-infrared reflectance than that of the commercial cobalt blue pigment. Our results suggest a potential route to the development of inexpensive, enduring and cobalt-free blue pigments. Synthesis and characterization methods are briefly reviewed for hibonite type of oxides, especially those with blue colors.

    更新日期:2018-06-03
  • Ceramic combinatorial syntheses exploring the chemical diversity of metal oxides
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-11-17
    M. Iranmanesh, J. Hulliger

    A ceramic combinatorial method to investigate the phase space of e.g. metal oxides by a single sample is reviewed along with its application to cuprate superconductors. The main idea behind this method is to use a large number N of starting materials (micrometer size grains) to generate local reaction centers producing possible compounds at the reaction temperature. Mathematical calculations using also empirical data on the occurrence of compounds in phase systems allow to conclude that in 1 cm3 of a sample, there are enough grains to populate all local reaction centers in order to obtain in principle what the N starting materials can produce. A variety of characterization technics have been applied to such libraries to identify e.g. cuprate superconductors. Finally the success of the concept will depend on analytical tools allowing for a simultaneous analysis of the composition and physical properties. Here, we have applied for the first time scanning SQUID microscopy to reveal local superconductivity in inhomogeneous ceramic samples.

    更新日期:2018-06-03
  • Recent developments on the optical properties of thin films of chalcogenide glasses
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-11-15
    Pankaj Sharma, Neha Sharma, Sunanda Sharda, S.C. Katyal, Vineet Sharma

    Chalcogenide glasses (ChG) has emerged as important materials due to their potential applications in infrared optics for communication, imaging, limiting, remote sensing and laser power delivery etc. Examining ChG for their various applications, different properties of these were under immense investigation by various researchers from nearly every part of the world. Study of ChG for optical properties like optical band gap and refractive index are the backbone while considering them for applications. The present review focuses on the optical properties of various binary, ternary and quaternary chalcogenide systems. Subsequently applications and future prospects of ChG have been sketched. The attracting prospective applications have drive us to put the review on optical properties of chalcogenide thin films both comprehensive and expedient to new as well as established researchers in this area.

    更新日期:2018-06-03
  • Proton exchange reactions in SiOx-based resistive switching memory: Review and insights from impedance spectroscopy
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-07-29
    Yao-Feng Chang, Burt Fowler, Ying-Chen Chen, Jack C. Lee

    In this work, the AC admittance and conductance of non-polar SiOx-based resistive switching memory devices is measured as a function of temperature to investigate charge transport and potential switching mechanisms. After electroforming using a forward/backward voltage scan, devices were measured over the frequency range of 1 k–1 MHz and the temperature range of 200–400 K. For temperature (T) > 300 K, AC conductance follows σ(ω) = Aωs, where s is linearly dependent on temperature and close to, but less than, unity. For T < 300 K, σ(ω) is almost temperature-independent with s ∼ 1. A classical hopping model and AC impedance spectroscopy measurements are found to provide reasonable explanations of the experimental data. Defect concentration is estimated to be 1–5 × 1019 cm−3 and independent of device resistive state when modeling charge transport using a polaron hopping characteristic. The energy barrier to electron hopping is estimated to change from 0.1 eV to 0.6 eV and the average hopping distance varies from 1 nm to 6 nm when the device is switched between low- and high-resistance states, respectively. Device switching mechanisms are modeled by simple proton exchange reactions that both activate and deactivate the defects involved in change transport. The impedance spectroscopy results supporting hole-like polaron hopping and the values obtained for the physical parameters provide additional insights into the fundamental mechanisms of SiOx-based resistive memory. Uniform switching performance with robust high temperature reliability and fast operating speed demonstrate good potential for future nonvolatile memory applications.

    更新日期:2018-06-03
  • Review of functional titanium oxides. I: TiO2 and its modifications
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-08-03
    Nazanin Rahimi, Randolph A. Pax, Evan MacA. Gray

    An extensive and wide-ranging literature about the polymorphs of titanium dioxide (TiO2) has accumulated during the last few decades, providing a very large resource of data on its properties, functionality and many present and potential industrial uses. This review focuses on the structural, kinetic, thermodynamic and electrical properties of TiO2 from the viewpoint of the relationship between the crystal structure and its present or potential useful functionality, via the electronic structure. The reason for this focus is the fundamental relationship between the electronic band structure of this wide band-gap semiconductor and its interaction with light and chemical species. Intense interest in the photoactivity of TiO2 followed the demonstration by Fujishima and Honda in 1972 of its ability to dissociate water using sunlight. Approaches to band gap engineering via chemical modifications are surveyed and correlated with band-structure calculations using Density Functional Theory and Hartree Fock methods. In the last section, progress in TiO2 applications and prospects for new applications of this material are summarised.

    更新日期:2018-06-03
  • Tl(I) to Po(IV) 6s2 lone pairs in tetrahedral, triangular bipyramidal, square pyramidal, octahedral and hexahedral geometries: Crystal chemistry and ab initio visualizations and analyses
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-04-26
    Jean Galy, Samir F. Matar

    The stereochemistry of 6s2 (E) lone pair LP characterizing TlI, PbII, BiIII, and PoIV (M∗) in fluorides and oxides as well as in mixed valence compounds is examined within a coherent crystal chemistry and ab initio visualizations and analyses. Besides square planar environments, large coverage of tetrahedral, triangular bipyramidal, square pyramidal, octahedral and hexahedral geometries is presented and addressed. In our formal image ns2 lone pair is considered as a free electron doublet concentrated in a centroïd, called Ec, which generates around it an electronic cloud, detected in the crystal network as an empty volume, attached to M∗, opposite to bonding coordination and where physical condensation (pressure) can eventually distort but not compress. Finally the lone pair E is defined by a sphere of influence found to occupy a volume close to oxygen or fluorine anions. Only crystal network by its architecture more or less dense can really modify M∗–E eventually to m*–E = 0 coalescence of the center of volume of influence E with the cation center transforming M∗ in a large cation [M∗E]n+ comparable to K+, Cs+ or Ba2+. The crystal chemistry analyses combined with electron localization function ELF from density functional theory DFT based calculations allow defining E volume and plasticity, M∗–E directions and distances of the different extended case studies. Original features highlighted with ELF and electronic densities of states and chemical bonding plots characterize the mixed valence compounds containing both LP-bearing (ex. TlI, PbII, BiIII) and non LP bearing (TlIII, PbIV, BiV) ions.

    更新日期:2018-06-03
  • Fullerenols: Physicochemical properties and applications
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-05-03
    K.N. Semenov, N.A. Charykov, V.N. Postnov, V.V. Sharoyko, I.V. Vorotyntsev, M.M. Galagudza, I.V. Murin

    Fullerenols may find the widest application in science and technology. This causes particular interest in developing available and simple methods for the synthesis of water-soluble polyhydroxylated fullerene derivatives on an industrial scale as well as investigating the physicochemical and biological properties and principles of their application. This study systematizes the current literature data on the synthesis, physicochemical properties, and application of polyhydroxylated fullerenes (fullerenols), a class of water-soluble fullerene derivatives. The experimental and theoretical data presented in this study provide a comprehensive overview of these substances and can be valuable to specialists in the fields of nanotechnology, nanomaterials, and nanobiomedicine.

    更新日期:2018-06-03
  • Synthesis, functionalization, and applications of morphology-controllable silica-based nanostructures: A review
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-01-11
    Bin Sun, Guowei Zhou, Huaijin Zhang

    Morphology-controllable silica-based nanostructures (MC SiO2Ns) have been comprehensively studied because of their potential practical applications in various fields, such as biological chemistry. The superior properties of these nanostructures, including low density, biocompatibility, thermal stability, and high mechanical strength, have been the focus of research to improve their current performance. In this review, experimental parameters, morphology, and formation mechanism of MC SiO2Ns (including vesicle-like mesoporous silica, rod-like mesoporous silica, and silica mesoporous nanospheres) are discussed. Moreover, current progress in functionalization and performance improvement of MC SiO2Ns is presented. Applications of MC SiO2Ns in immobilization techniques, biological catalysis, and drug delivery are also provided.

    更新日期:2018-06-03
  • Hydrogen-modified superconductors: A review
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2016-02-12
    Hasnain M. Syed, C.J. Webb, E. MacA. Gray

    We present an overview of hydrogen-containing superconductors, including metallic, cuprate, pnictide and carbon-based materials. Particularly in BCS-like superconductors, hydrogen introduces new phonon modes and these may lead to better or worse superconducting properties, with anharmonicity of the H potential being a decisive factor. The availability of the deuterium isotope, in addition to protium, makes hydrogen an extremely useful extra probe of mechanisms of superconductivity. While hydrogen modification has not so far led to any confirmed remarkable improvement in already existing metallic superconductors, hydrogen plays an important role in the synthesis of novel iron-based superconductors and as a substitutional impurity appears to increase the transition temperature. Most recently, a new record for the superconducting transition temperature of 203 K has been claimed for a metallic hydride under high pressure, H2S. We survey elemental hydrides and superconductors, discuss techniques for introducing hydrogen into materials, then review and summarise published knowledge about hydrogen-containing superconductors.

    更新日期:2018-06-03
  • Recent advances in perovskites: Processing and properties
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2015-10-08
    Carlos Moure, Octavio Peña

    The perovskite structure is one of the most wonderful to exist in nature. It obeys to a quite simple chemical formula, ABX3, in which A and B are metallic cations and X, an anion, usually oxygen. The anion packing is rather compact and leaves interstices for large A and small B cations. The A cation can be mono, di or trivalent, whereas B can be a di, tri, tetra, penta or hexavalent cation. This gives an extraordinary possibility of different combinations and partial or total substitutions, resulting in an incredible large number of compounds. Their physical and chemical properties strongly depend on the nature and oxidation states of cations, on the anionic and cationic stoichiometry, on the crystalline structure and elaboration techniques, etc. In this work, we review the different and most usual crystalline representations of perovskites, from high (cubic) to low (triclinic) symmetries, some well-known preparation methods, insisting for instance, in quite novel and original techniques such as the mechanosynthesis processing. Physical properties are reviewed, emphasizing the electrical (proton, ionic or mixed conductors) and catalytic properties of Mn- and Co-based perovskites; a thorough view on the ferroelectric properties is presented, including piezoelectricity, thermistors or pyroelectric characteristics, just to mention some of them; relaxors, microwave and optical features are also discussed, to end up with magnetism, superconductivity and multiferroïsme. Some materials discussed herein have already accomplished their way but others have promising horizons in both fundamental and applied research. To our knowledge, no much work exists to relate the crystalline nature of the different perovskite-type compounds with their properties and synthesis procedures, in particular with the most recent and newest processes such as the mechanosynthesis approach. Although this is not intended to be a full review of all existing perovskite materials, this report offers a good compilation of the main compounds, their structure and microstructure, processing and relationships between these features.

    更新日期:2018-06-03
  • Water's phase diagram: From the notion of thermodynamics to hydrogen-bond cooperativity
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2015-04-01
    Xi Zhang, Peng Sun, Tingting Yan, Yongli Huang, Zengsheng Ma, Bo Zou, Weitao Zheng, Ji Zhou, Yinyan Gong, Chang Q. Sun
    更新日期:2018-06-03
  • Coherent view of crystal chemistry and ab initio analyses of Pb(II) and Bi(III) lone pair in square planar coordination
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2015-05-16
    Samir F. Matar, Jean Galy

    The stereochemistry of 6s2 (E) lone pair of divalent Pb and trivalent Bi (PbII and BiIII designated by M∗) in structurally related PbO, PbFX (X = Cl, Br, I), BiOX (X = F, Cl, Br, I) and Bi2NbO5F is rationalized. The lone pair LP presence determined by its sphere of influence E, equal to those of oxygen or fluorine anions, was settled by its center then giving M∗–E directions and distances. Detailed description of structural features of both elements in the above cited compounds characterized by [PbEO]n and [BiEO]n layers allowed to show the evolution of M∗–E distance versus the changes with the square pyramidal SP coordination polyhedra. All are different, in red PbO one finds {PbEO4E4} square antiprism, a {[Bi.E]O4X4Xapical} monocapped square antiprism in PbFX and BiOX and {BiEO4F4}square antiprism in Bi2NbO5F. To analyze the crystal chemistry results, the electronic structures of these compounds were calculated within density functional theory DFT. Real space analyses of electron localization illustrate a full volume development of the lone pair on Pb(II) within {PbEO4E4} in PbOE, {PbEF4X4} in PbFXE and Bi(III) within {BiEO4X4} square antiprisms, contrary to Bi(III) within {[Bi.E]O4F4Fapical} monocapped square antiprism. Larger hardness (larger bulk modules B0) and band gap characterize BiOF versus PbO due to the presence of fluorine which brings antibonding Bi–F interactions oppositely to mainly bonding Bi–O. In PbFX and BiOX series there is a systematic decrease of B0 with the increasing volume following the nature and size of X which is decreasingly electronegative and increasingly large. The electronic densities of states mirror these effects through the relative energy position and relative electronegativities of F/X and O/X leading to decrease the band gap.

    更新日期:2018-06-03
  • Chemistry of one dimensional silicon carbide materials: Principle, production, application and future prospects
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2015-07-03
    Jyoti Prakash, Ramani Venugopalan, B.M. Tripathi, S.K. Ghosh, J.K. Chakravartty, A.K. Tyagi
    更新日期:2018-06-03
  • A2B′B″O6 perovskites: A review
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-09-06
    Sami Vasala, Maarit Karppinen

    The B-site substituted perovskite oxides A2B′B″O6 have in the recent decades gained an increasing amount of interest due to their various interesting properties and possible applications. Here we survey the literature for ca. one thousand A2B′B″O6 perovskite compounds. Crystal structures and the various crystal chemistry features such as ordering and valence mixing of the B cations characteristic to these compounds are reviewed, together with their electronic and magnetic properties. Most importantly, the thorough examination of the research so far carried out allows us to make predictions for a number of new A2B′B″O6 compounds yet to be synthesized and reveal exciting but not yet fully explored puzzles related to this family of functional oxide materials.

    更新日期:2018-06-03
  • Structure–property relationships of YbFe2O4– and Yb2Fe3O7–type layered oxides: A bird's eye view
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-09-23
    Rosa Grajczyk, M.A. Subramanian

    This work surveys the structural and physical properties of layered hexagonal (A3+M3+O3)(M2+O) and (A3+M3+O3)2(M2+O) phases where A3+ = In, Lu, Y, Yb, M3+ = Fe, Ga and M2+ = Cu, Mg, Zn. This family of compounds is of recent interest because of the trigonal bipyramid coordination that is rarely observed in transition metal oxides. The lattice parameters for a number of the (A3+M3+O3)(M2+O) and (A3+M3+O3)2(M2+O) compositions are provided herein, in addition to the bond lengths and atomic positions of selected compositions. The triangular geometry of the cations in the trigonal bipyramidal layers adds a component of frustration into the system, specifically with the magnetic properties. The work summarized in this review has used cation substitutions into the trigonal bipyramidal site of YbFe2O4-type compounds to further understand how the rare crystallographic coordination dictates the observed physical properties.

    更新日期:2018-06-03
  • Structural instability of the rutile compounds and its relevance to the metal–insulator transition of VO2
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2015-03-03
    Zenji Hiroi

    The metal–insulator transition (MIT) of VO2 is discussed with particular emphasis on the structural instability of the rutile compounds toward dimerization. Ti substitution experiments reveal that the MIT is robust up to 20% Ti substitutions and occurs even in extremely thin V-rich lamellas in spinodally decomposed TiO2–VO2 composites, indicating that the MIT is insensitive to hole doping and essentially takes on a local character. These observations suggest that either electron correlation in the Mott–Hubbard sense or Peierls (Fermi-surface) instability plays a minor role on the MIT. Through a broad perspective of crystal chemistry on the rutile-related compounds, it is noted that VO2 and another MIT compound NbO2 in the family eventually lie just near the borderline between the two structural groups with the regular rutile structure and the distorted structures characterized by the formation of dimers with direct metal–metal bonding. It is also shown that the two compounds of the rutile form do not follow the general trends in structure observed for the other rutile compounds, giving clear evidence of an inherent structural instability present in the two compounds. The MITs of VO2 and NbO2 are natural consequences of structural transitions between the two groups, as all the d electrons are trapped in the bonding molecular orbitals of dimers at low temperatures. Such dimer crystals are ubiquitously found in early transition metal compounds having chain-like structures, such as MoBr3, NbCl4, Ti4O7, and V4O7, the latter two of which also exhibit MITs probably of the same origin. In a broader sense, the dimer crystal is a kind of “molecular orbital crystals” in which virtual molecules made of transition metal atoms with partially-filled t2g shells, such as dimers, trimers or larger ones, are generated by metal–metal bonding and are embedded into edge- or face-sharing octahedron networks of various kinds. The molecular orbital crystallization opens a natural route to stabilization of unpaired t2g electrons in crystals.

    更新日期:2018-06-03
  • Electrolytes for lithium and lithium ion batteries: From synthesis of novel lithium borates and ionic liquids to development of novel measurement methods
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-21
    M. Amereller, T. Schedlbauer, D. Moosbauer, C. Schreiner, C. Stock, F. Wudy, S. Zugmann, H. Hammer, A. Maurer, R.M. Gschwind, H.-D. Wiemhöfer, M. Winter, H.J. Gores

    This review covers various aspects of electrolyte investigations. The first section reports on synthesis and characterization of lithium salts and ionic liquids, including some unpublished recent work. The next part is devoted to transference number measurements of lithium ions. It contains recently published work and new results on this rarely investigated but important topic. Studies of anodic aluminum dissolution with our novel fast impedance scanning electrochemical quartz microbalance (FIS-EQCM) follow next. After a short introduction to the method, some recently published results are reviewed along with some yet unpublished material. We have also shown that the solubility of solids and gases in liquids can be measured with this equipment, including the solubility of lithium salts in ionic liquids. First results of FIS-EQCM studies show that electroplating and corrosion of lithium and subsequent dissolution of the SEI can be studied as well. The last parts of this manuscript are dedicated to the investigation of miscellaneous topics that are of interest for studies of electrolytes for LIBs.

    更新日期:2018-06-03
  • A systematic solid state NMR spectroscopic study of the equiatomic lithium half-Heusler phases LiTX (T = Mg, Zn, Cd; X = P, As, Sb, Bi)
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-21
    Sven Dupke, Hellmut Eckert, Florian Winter, Rainer Pöttgen

    The equiatomic intermetallic lithium compounds LiTX (T = Mg, Zn, Cd; X = P, As, Sb, Bi) were synthesized by reacting the elements in sealed niobium tubes in muffle furnaces. The compounds crystallize with the cubic MgAgAs type structure, space group F 4 ¯ 3 m . The T and X atoms build up blende-type tetrahedral substructures in which the lithium atoms fill octahedral voids formed by the X atoms. Basic structural characterization of the samples was performed by powder X-ray diffraction. The charge distribution in these intermetallic compounds was investigated using metal ion (7Li, 25Mg and 113Cd) as well as pnictogen (31P, 75As, 121Sb) static and MAS-NMR. The metal ion chemical shifts are uniformly correlated with the pnictogen Pauling electronegativities, reflecting a systematic trend in the bonding characteristics in these phases. Furthermore, static temperature dependent 7Li wideline NMR spectra show motional narrowing effects on the NMR timescale, indicating lithium ionic mobility. Activation energies estimated from these data decrease systematically with decreasing difference of the electronegativities between the elements Li and X and between the elements T and X. These result can be rationalized in terms of shallower Coulomb potential wells in those compounds with lower ionic character.

    更新日期:2018-06-03
  • Investigations on novel electrolytes, solvents and SEI additives for use in lithium-ion batteries: Systematic electrochemical characterization and detailed analysis by spectroscopic methods
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-18
    Raphael W. Schmitz, Patrick Murmann, René Schmitz, Romek Müller, Lisa Krämer, Johannes Kasnatscheew, Philipp Isken, Philipp Niehoff, Sascha Nowak, Gerd-Volker Röschenthaler, Nikolai Ignatiev, Peter Sartori, Stefano Passerini, Miriam Kunze, Alexandra Lex-Balducci, Christian Schreiner, Isidora Cekic-Laskovic, Martin Winter

    Electrolyte solutions have vital function in lithium-ion batteries. Due to their modular composition, there is a broad variety of electrolyte component combinations. In this work, we present electrochemical results on newly investigated electrolyte solution components. The standard electrolyte salt in commercial batteries, LIPF6, was replaced by new imide and sulfonate anion based salts, with enhanced stability. The use of propylene carbonate was enabled by the application of new SEI forming electrolyte additives. Electrolyte solvents, such as adiponitrile and γ-butyrolactone were investigated in combination with LiBF4 as electrolyte salt. In order to evaluate these materials, various electrochemical techniques like galvanostatic cycling, conductivity and electrochemical stability window detection, cyclic voltammetry, etc. were applied. Furthermore, the electrode/electrolyte interfaces and interphases were studied via spectroscopic and spectrometric techniques.

    更新日期:2018-06-03
  • Synthesis and electrochemistry of polymer based electrolytes for lithium batteries
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-21
    Mariano Grünebaum, Martin M. Hiller, Sebastian Jankowsky, Steffen Jeschke, Benjamin Pohl, Thomas Schürmann, Preeya Vettikuzha, Ann-Christin Gentschev, Raphael Stolina, Romek Müller, Hans-Dieter Wiemhöfer

    An overview is presented on the development of improved polymer based electrolytes during the past years. The emphasis lies on new approaches regarding chemical concepts that achieve a higher total conductivity and lithium transference number as well as an increased electrochemical, mechanical and thermal stability. With respect to the polymer chemistry, the focus is laid on siloxane and phosphazene derived systems. Topics are the chemical modification of the polymeric, cyclic and low molecular derivates of these systems, the formation of stable membranes from these by suitable cross-linking strategies and an extensive electrochemical characterization in corresponding lithium cells. Recent trends towards composite and hybrid materials are illustrated with examples and newly developed hybrid electrolytes. A particular chance for improvements comes from the design and use of stable small molecular additives in combination with optimized and electrochemically stable polymer networks. Special compounds are introduced which may act themselves as novel solvents with increased electrochemical stabilities. The relevance of chosen lithium salts for polymer electrolytes is discussed, too, and a new family of pyrazolide anions is introduced. In all cases, the electrochemical performance has been characterized by standard experimental techniques.

    更新日期:2018-06-03
  • Substituted transition metal phospho olivines LiMM′PO4 (M = Mn, M′ = Fe, Co, Mg): Optimisation routes for LiMnPO4
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-05-14
    M. Köntje, M. Memm, P. Axmann, M. Wohlfahrt-Mehrens

    Since transition metal phospho olivines gain increasing interest as cathode materials for lithium ion batteries in the last decades lots of publications appeared. Various synthesis methods were in the focus of interest as well as structural investigations of the pure LiMPO4 and mixed Li (MM′)PO4 phases (M, M′ = Fe, Mn, Co, Ni, Mg, Zn, Al) and their structural changes during electrochemical conversion. Lithium insertion and exsertion mechanisms have been studied with the help of e.g. structural, optical and electronic, and electrochemical characterisation methods. Likewise many efforts have been done for material optimisation concerning synthesis procedure or substitution. We tend to give an overview about Li (MM′Mn)PO4 (M, M′ = Mg, Fe, Co) on the basis of our results. For the greater topic of enhancement of performance and energy density of LiMnPO4 we discuss different solution approaches concerning the raise of specific capacity, redox potential and optimisation of material characteristics. Thus we consider effects due to the intrinsic conductivity, structural stability of the charged phase as well as its chemical stability against the electrolyte and the dynamic stability of the interface between charged phase and discharged phase during electrochemical conversion. For this purpose in our experimental part we focus on three different approaches: substitution with an electrochemically active transition metal, substitution with an electrochemically inactive metal in case for the manipulation of unit cell volume alternation and the substitution with electrochemically inactive metals for the purpose of providing a “lithium reservoir”. This generated “lithium reservoir” is expected to be accessible for the utilisation of a new redox step. Phase transition in mixed transition metal phospho olivines Li(MnCo)PO4 has been investigated as example for the effect of substitution with an electrochemically active transition metal. Substitution with an electrochemically inactive metal leading to binary Li(MgMn)PO4 has been structurally and electrochemically investigated. Promising new electrochemical characteristics of binary Li(MgMn)PO4 phospho olivines are introduced for the first time. When charged to high potentials (>4.9 V) the activation of the Mn3+/Mn4+ step is reported.

    更新日期:2018-06-03
  • Influence of the technical process parameters on structural, mechanical and electrochemical properties of LiNi0.8Co0.15Al0.05O2 based electrodes – A review
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-18
    Hai Yen Tran, Corina Täubert, Magret Wohlfahrt-Mehrens

    The electrode manufacturing for lithium-ion batteries has been systematically evaluated. It has been shown that a proper tailoring of the electrodes can greatly improve both the electrochemical performance and the energy density of the battery. The pre-treatment of the electrode components, the degree of the electrode compacting and the mixing process have proven to have a strong impact on the electrochemical performance of the composite electrodes based on LiNi0.80Co0.15Al0.05O2. In addition, blending LiNi0.80Co0.15Al0.05O2 – NCA with lithium manganese oxide spinel (LiMn2O4, LMS) has exhibited beneficial effects on the discharge capacity of the blends, thus on the energy density and in the same time decreases the Mn dissolution from spinel structure. Moreover, the detailed study of the storage behaviour of LMS/NCA blend reveals that dissolved Mn from spinel structure is re-precipitable on NCA particles and so that less Mn2+ ions will be available in the electrolyte, which can migrate to the anode graphite and deposit thereof.

    更新日期:2018-06-03
  • 3d-Transition metal doped spinels as high-voltage cathode materials for rechargeable lithium-ion batteries
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-18
    Aiswarya Bhaskar, Daria Mikhailova, Nilüfer Kiziltas-Yavuz, Kristian Nikolowski, Steffen Oswald, Natalia N. Bramnik, Helmut Ehrenberg

    Finding appropriate positive electrode materials for Li-ion batteries is the next big step for their application in emerging fields like stationary energy storage and electromobility. Among the potential materials 3d-transition metal doped spinels exhibit a high operating voltage and, therefore, are highly promising cathode materials which could meet the requirements regarding energy and power density to make Li-ion batteries the system of choice for the above mentioned applications. The compounds considered here include substituted Mn-based spinels such as LiM0.5Mn1.5O4 (M = Ni, Co, Fe), LiCrMnO4 and LiCrTiO4. In this review, the recent researches conducted on these spinel materials are summarized. These include different routes of synthesis, structural studies, electrode preparation, electrochemical performance and mechanism of Li-extraction/insertion, thermal stability as well as degradation mechanisms. Note that even though the Ni-, Co-, and Fe-doped materials share the same chemical formula, the oxidation state distributions as well as the operating voltages are different among them. Furthermore, apart from the initial structural similarity, the Li-intercalation takes place through different mechanisms in different materials. In addition, this difference in mechanism is found to have considerable influence on the long-term cycling stability of the material. The routes to improve the electrochemical performance of some of the above candidates are discussed. Further emphasis is given to the parameters that limit their application in current technology, and strategies to overcome them are addressed.

    更新日期:2018-06-03
  • Lix(Al0.8Zn0.2) alloys as anode materials for rechargeable Li-ion batteries
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-21
    Ihor Chumak, Manuel Hinterstein, Helmut Ehrenberg

    The influence of the lithium content in the starting composition, depth of discharge, binder and electrolyte on the cycle stability was investigated. The structural changes in Lix(Al0.8Zn0.2) electrodes during electrochemical lithium extraction and reinsertion were studied by in situ synchrotron diffraction. The crystal structure of the new compound Li4Al3.42Zn11.58 was determined by single-crystal X-ray diffraction and can be described as combination of the CaCu5 and MgFe6Ge6 structure types. The phase equilibria at 150 °C in the Li–Al–Zn system were investigated on six alloys, prepared along the lithium extraction–insertion line.

    更新日期:2017-12-14
  • Influence of formulation method and related processes on structural, electrical and electrochemical properties of LMS/NCA-blend electrodes
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-18
    W. Haselrieder, S. Ivanov, H.Y. Tran, S. Theil, L. Froböse, B. Westphal, M. Wohlfahrt-Mehrens, A. Kwade

    The impact of different formulation methods, involving related process technologies, as well as the influence of dispersing intensity on the structural and electrical coating layer properties of LiMn2O4/LiNi0,80Co0,15Al0,05O2 (LMS/NCA) blends are studied. Findings are finally correlated with the electrochemical rate-capability in order to derive process-structure–property functions to facilitate systematical electrode development. LMS was found to be sensitive according mechanical stress but by processing LMS/NCA blend electrodes this problem can be avoided. In general carbon black (CB) agglomerate size and its distribution in the binder network were identified to be significant factors influencing rate-capability. Both were found to influence pore structure by utilizing representative low and high energy methods for the formulation of the suspensions. The specific pore volume in the pore size region of 10 μm ≥ dp ≥ 0.5 μm was discovered to strongly influence rate-capability. These highways for lithium-ion transport allow for higher mass of lithium-ions per unit time penetrating into the inner surface of the coating layer. Specific volume and thus rate-performance can either be increased by a binder solution based formulation method or by decreasing the specific energy input during dispersing process. Hence no superior formulation method exists. The adjustment of mixing intensity and therewith the achieved CB agglomerate size, referring to the formulation method used, is essential. Thus comparable electrochemical rate performance was found for the same specific volume of approximately 0.25 cc g−1 but for different dispersing intensities. Further, the pore size region of 1.5 μm > dp > 0.03 μm was identified to be characteristic for the CB agglomerate size and the corresponding CB treatment method used. Peakedness of the pore size distribution was found to follow electrode conductivity which was the largest for a distributive dry mixing method. For electrodes showing a good CB agglomerate distribution in the binder network rate-capability was found to be limited by the pore structure of the coating layer and, thus, preliminarily by the corresponding ion transport kinetic. Based on the findings a model concept on processes occurring during dispersing was proposed and discussed to describe viscosity evolution over dispersing time.

    更新日期:2017-12-14
  • A surface science approach to cathode/electrolyte interfaces in Li-ion batteries: Contact properties, charge transfer and reactions
    Prog. Solid State Chem. (IF 9.313) Pub Date : 2014-04-18
    René Hausbrand, Dirk Becker, Wolfram Jaegermann

    Reactions and charge transfer at cathode/electrolyte interfaces affect the performance and the stability of Li-ion cells. Corrosion of active electrode material and decomposition of electrolyte are intimately coupled to charge transfer reactions at the electrode/electrolyte interfaces, which in turn depend on energy barriers for electrons and ions. Principally, energy barriers arise from energy level alignment at the interface and space charge layers near the interface, caused by changes of inner electric (Galvani) potential due to interfacial dipoles and concentration profiles of electronic and ionic charge carriers. In this contribution, we introduce our surface science oriented approach using photoemission (XPS, UPS) to investigate cathode/electrolyte interfaces in Li-ion batteries. After an overview of the processes at cathode/electrolyte interfaces as well as currently employed analysis methods, we present the fundamentals of contact potential formation and energy level alignment (electrons and ions) at interfaces and their analysis with photoemission. Subsequently, we demonstrate how interface analysis can be employed in Li-ion battery research, yielding new and valuable insights, and discuss future benefits.

    更新日期:2017-12-14
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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