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  • A noninvasive precise treatment strategy for implant-related infections based on X-ray-induced luminescent/photodynamic therapeutic multilayered device surface materials
    J. Lumin. (IF 2.961) Pub Date : 2020-02-22
    Xin Wang; Yunqian Li; Henry H.Y. Tong; Peng Yuan; Ka-Leung Wong; Yanmin Yang

    Conventional prophylaxis and treatment of implant-related infections via devices’ surface biofilm elimination include extensive non-targeting antibiotics prescription, invasive surgical intervention, and periodic implant replacement, with their inevitable relapses being lifelong guaranteed leading to financial burdens and drug resistance risks for patients. Herein, we propose a novel, sustainable modality of noninvasive precise treatment strategy based on potential theranostic, multilayered Gd3+ (UV), Eu3+ (red) and Tb3+ (green) doped Y(PO3)3 X-ray-induced luminescent matrix surface materials cum a nanolayer coating of titanium dioxide with pH indicators on implantable medical devices, which simultaneously integrate X-ray-initiated pH-sensitive NIR luminescence for location detection of biofilm infection, and X-ray-excited, UV-triggered deep-tissue-localized antimicrobial photodynamic therapy. The Y(PO3)3 crystal composite structures allow doping of rare earth ions at rarely high concentrations and produce high emission intensity even under less-detrimental low-dose X-ray radiation. The feasibility of such precise treatment strategy has been substantiated through various pH and inactivation experiments. With the growing aging population, this work aims to provide a potentially new, patient-friendly, (i.e. surgery/antibiotics-free and lower-cost) proof-of-principle theranostic resolution for the increasing incidence of orthopaedic implant-related biofilm infections, from preventive device maintenance to precise curative eradication.

    更新日期:2020-02-23
  • Comparative study of optical and luminescence properties of Sm3+-ions doped Li2O–Gd2O3–PbO–SiO2 and Li2O-GdF3-PbO–SiO2 glasses for orange emission solid state device application
    J. Lumin. (IF 2.961) Pub Date : 2020-02-22
    I. Khan; G. Rooh; R. Rajaramakrishna; N. Sirsittipokakun; S.H.J. Kim; S. Kothan; J. Kaewkhao; K. Kirdsiri
    更新日期:2020-02-23
  • Effect of thermal annealing and sp-d exchange interaction in the optical properties of Mn2+-doped PbS nanocrystals embedded in a glass matrix
    J. Lumin. (IF 2.961) Pub Date : 2020-02-21
    Lara R. Rastrello; Eder V. Guimarães; Marco A.T. da Silva; Noelio O. Dantas; Nilo F. Cano; Sidney A. Lourenço; Ricardo S. da Silva

    Semimagnetic chalcogeneide Pb1-xMnxS nanocrystals were grown in borosilicate glass host and their optical, structural and magnetic properties were investigated. Transmission electron microscopy images confirms the growth of the Pb1-xMnxS nanocrystals. Uv–Vis-Nir spectroscopy measurements of these nanocrystals revealed band-gap shifting from 0.94 eV (1307 nm) to 1.12 eV (1111 nm), which was attributed to the incorporation content (x) of Mn2+ ions in the typical PbS rock salt crystal structure. EPR data shows the six hyperfine lines assigned to the Mn2+ ions incorporated into the host crystal structure of PbS nanocrystals. The Photoluminescence obtained at 20k was analyzed and shows an anomalous increase in emission efficiency considering carrier transfer for Pb1-xMnxS nanocrystals with different sizes.

    更新日期:2020-02-21
  • Controllable synthesis of all inorganic lead halide perovskite nanocrystals and white light-emitting diodes based on CsPbBr3 nanocrystals
    J. Lumin. (IF 2.961) Pub Date : 2020-02-21
    Yan Xu; Sunqi Lou; Chao Xia; Tongtong Xuan; Huili Li

    The colloidal cesium lead halide perovskite nanocrystals (NCs) have attracted much attention over the past five years as a promising class of material with potential application in wide-color-gamut backlight display because of their high photoluminescence quantum yield (PLQY) and narrow-band emission (full-width at half-maximum, FWHM < 35 nm). To controllably synthesize perovskite NCs, the effects of reaction temperature and reaction time on structure, morphology, particle size and photoluminescence (PL) properties of the NCs were systematically investigated inthis article. Based on these results, the formation kinetics of the perovskite NCs was analyzed and disclosed in further. Finally, a white light-emitting diode (WLED) was prepared by using synthesized CsPbBr3 NCs and K2SiF6:Mn4+ phosphors as the color converters. The WLED exhibits the bright white emission with a CIE chromaticity coordinate of (0.389, 0.376) and a wide color gamut of 123% of NTSC, indicating a potential application in the field of wide color gamut displays in the future.

    更新日期:2020-02-21
  • Er3+/Yb3+ co-doped TeO2–ZnO–ZnF2–La2O3 glass with a high fluorescence intensity ratio for an all-fiber temperature sensor
    J. Lumin. (IF 2.961) Pub Date : 2020-02-21
    Kai Yang; Rui Xu; Qingyang Meng; Liang Chen; Shilong Zhao; Yang Shen; Shiqing Xu

    Er3+/Yb3+ co-doped TeO2–ZnO–ZnF2–La2O3 (TZZL) glasses with different concentrations of Er3+ ions were fabricated. Strong green upconversion emission bands centered at 523 and 545 nm induced by 980 nm excitation were observed. The maximum emission intensity of the TZZL glasses was obtained at the Er3+ ion concentration of 0.2 mol%. High-temperature difference (ΔT = 131.8 °C) between the transition and onset crystallization temperatures was confirmed by differential thermal analysis curve. The relationship between fluorescence intensity ratio value and temperature was examined within 303–560 K. The maximum absolute sensitivity (Sa) and the maximum relative sensitivity (Sr) was 0.006 K−1 at 560 K and 0.012 K−1 at 303 K, respectively. A prototype of an all-fiber temperature sensor was designed, and its temperature-sensing performance within 293–383 K was evaluated. Results showed that the absolute errors were within ±1 K, and the largest value of relative standard deviation was approximately 0.2%, suggesting that Er3+/Yb3+ co-doped TZZL glasses have potential applications in optical-fiber temperature sensors.

    更新日期:2020-02-21
  • Phase transition and fluorescence regulation of BaAl2Si2O8:Eu using Ba source
    J. Lumin. (IF 2.961) Pub Date : 2020-02-21
    Lanlan Sun; Qingling Wang; Xinxin Zhang; Zhijie Yang; Jing Cheng; Aierken Sidike; Jiuyang He
    更新日期:2020-02-21
  • Probing traps in the persistent phosphor SrAl2O4:Eu2+,Dy3+,B3+ - A wavelength, temperature and sample dependent thermoluminescence investigation
    J. Lumin. (IF 2.961) Pub Date : 2020-02-14
    Jakob Bierwagen; Teresa Delgado; Guillaume Jiranek; Songhak Yoon; Nando Gartmann; Bernhard Walfort; Markus Pollnau; Hans Hagemann
    更新日期:2020-02-20
  • Effect of Ba2+ doping on the photoluminescence of YVO4: Eu3+ phosphor and first principles calculations
    J. Lumin. (IF 2.961) Pub Date : 2020-02-14
    Tianxiang Zhao; Nan Chen; Guoping Du; Changshuang Jiang

    In this work, YVO4: Eu3+ phosphors with and without Ba2+ doping (having the formula of Y1-x-y (EuxBay)VO4) were prepared by the high-temperature solid-state reaction method, and their photoluminescence and relevant physical mechanism were studied. A large enhancement in the photoluminescence of the YVO4: Eu3+ phosphors by Ba2+ doping has been observed. When the Ba2+ doping concentration is at 3 at%, the YVO4: Eu3+ phosphors have the strongest photoluminescence. It has been found that the Ba2+ doping extends the luminescence decay lifetimes of YVO4: Eu3+. In addition, the Ba2+ doping also makes the charge transfer state absorption band of VO43− blue shifted and widens the 5D0→7F2 emission of Eu3+. The underlying mechanism for these results has been investigated using the first principles calculations. It has been shown that the Ba2+ doping increases the bandgap value of YVO4 and causes the energy level of the Eu-d orbit to split, and the individual atomic orbitals move toward higher energy after Ba2+ doping. A higher energy transfer efficiency from VO43− to Eu3+ has been predicted by the first principles calculations. The theoretical calculation results explain the photoluminescence enhancement of YVO4: Eu3+ by Ba2+ doping, and the mechanism has been revealed.

    更新日期:2020-02-20
  • Tunable white light emission through energy transfer processes between silver species in Ag-doped zinc phosphate glass
    J. Lumin. (IF 2.961) Pub Date : 2020-02-13
    H. Félix-Quintero; E.V. Mejía-Uriarte; C. Falcony; D. Acosta; J. Hernández A; C. Flores J; E. Camarillo G; H. Murrieta S

    Silver doped zinc phosphate glass was successfully synthesized at different molar concentrations of AgCl from 1% up to 20%. Zinc phosphate glass shows a high capacity to hold silver impurities without loss of optical quality. This material shows two different centers able to emit blue and green-red light, the first one from isolated Ag+ ions and the latter from Ag+ pairs. The intensity of each emission can be tuned by varying the composition of silver in the matrix, reaching the white light emission at 12 and 14% molar AgCl. Two energy transfer mechanisms were detected: charge transfer from zinc phosphate glass matrix to isolated Ag+ ions (that can improve the forbidden blue emission) and energy transfer from Ag+ single ions to Ag+ pairs.

    更新日期:2020-02-20
  • Tunable white light emission in zinc phosphate glasses activated with Agmn+ clusters and Sm3+
    J. Lumin. (IF 2.961) Pub Date : 2020-02-13
    O. Soriano-Romero; R.L. Flores-Cruz; R. Lozada-Morales; U. Caldiño; C. Falcony; S. Cármona-Téllez; I. Camarillo; A. Méndez-Blas; A.N. Meza-Rocha

    Zinc phosphate glasses, activated with Agmn+ clusters and Sm3+, were prepared by the conventional melt-quenching method. The X-ray diffraction patterns revealed that the samples remain amorphous for Ag and Sm3+ contents up to 3.0 and 1.0 mol%, respectively. The Raman and FTIR spectra showed that the main vibrational modes are associated with P–O bonds. The absorption coefficient spectrum of the Ag singly doped glass sample displayed a broad band centered at 318 nm, related to Agmn+ clusters, whereas those co-doped with Sm3+ showed, in addition to the Agmn+ cluster absorption, the well-known Sm3+ absorptions at 343, 360, 374, 401, 415, 438, 465 and 477 nm. The photoluminescence excitation spectrum of the Ag singly doped glass sample exhibited a broadband from 3 to 6 eV (207–413 nm), assigned to superposition of the Ag+: 4 d10 → 4d95s and Agmn+ cluster: S0 → S1 transitions, being the excitation into the Agmn+ clusters attractive for W-LEDs applications. The photoluminescence emission spectra of the Ag singly doped glass sample, upon Agmn+ cluster excitations at 340, 350 and 360 nm, displayed cold white light tonality, with (0.279, 0.300) CIE1931 chromaticity coordinates of 9453 K and bluish-white light tonality with (0.264, 0.276) and (0.259, 0.270) CIE1931 chromaticity coordinates and correlated color temperature values of 12901 and 14201 K, respectively. The global emission of the Ag and Sm3+ co-doped glass samples was, upon 340, 350 and 360 nm excitations, gradually tuned from the bluish and cold white region to the warm white one, as the Sm3+ content was increased, with correlated color temperatures in the 14201-2691 K range. The Sm.3+ emission bands, under excitations at 340 and 350 nm, were attained at expense of radiative and non-radiative energy transfer from the Agmn+ clusters, as revealed respectively by the sinks mounted on the Agmn+ cluster emission bands and the emission decay profile shortening in presence of Sm3+. Analysis of the Agmn+ cluster emission intensity and decay profiles, with the Dexter and Burstein models, showed that Agmn+ cluster cross-relaxation and/or non-radiative energy transfer to Sm3+ might be dominated by an electric quadrupole-quadrupole interaction.

    更新日期:2020-02-20
  • Radiative and non-radiative losses by voltage-dependent in-situ photoluminescence in perovskite solar cell current-voltage curves
    J. Lumin. (IF 2.961) Pub Date : 2020-02-13
    Chris Dreessen; Daniel Pérez-del-Rey; Pablo P. Boix; Henk J. Bolink

    The rapid development of perovskite solar cells has been based on improvements in materials and device architectures, yet further progress towards their theoretical limit will require a detailed study of the main physical processes determining the photovoltaic performance. Luminescence can be a key parameter for this purpose, as it directly assesses radiative recombination. We present steady-state absolute photoluminescence of an operating device at varying voltages as a tool to study the loss mechanisms in perovskite devices. The calibration to absolute photon numbers gives access to the variation of the relative radiative/non-radiative recombination weighted along the measured potentials, and allows identifying charge extraction deficits not only at short-circuit conditions but at each point of the current-voltage curve, which we show on a vacuum-deposited solar cell. These measurements can be crucial to characterize the nature of the charge losses, a step to develop approaches to improve this photovoltaic technology.

    更新日期:2020-02-20
  • Development of fluorescent aptasensing system for ultrasensitive analysis of kanamycin
    J. Lumin. (IF 2.961) Pub Date : 2020-02-14
    Yangyang Zhou; Lixiang Zuo; Yanli Wei; Chuan Dong
    更新日期:2020-02-20
  • Realizing bright blue-red color-tunable emissions from Gd2GeO5:Bi3+,Eu3+ phosphors through energy transfer toward light-emitting diodes
    J. Lumin. (IF 2.961) Pub Date : 2020-02-14
    Qi Sun; Thangavel Sakthivel; Balaji Devakumar; Shaoying Wang; Liangling Sun; Jia Liang; Sanjay J. Dhoble; Xiaoyong Huang
    更新日期:2020-02-20
  • One- and two-photon electron-transfer induced uncaging of coumarin from cinnamate-capped CdSe quantum dots
    J. Lumin. (IF 2.961) Pub Date : 2020-02-20
    Aravind Baride; David Hawkinson; Daniel Engebretson; P. Stanley May
    更新日期:2020-02-20
  • Enhanced red light emission from dense Si quantum dot-based silicon oxynitride light-emitting diodes with reduced efficiency droop
    J. Lumin. (IF 2.961) Pub Date : 2020-02-20
    Zewen Lin; Yanqing Guo; Zhenxu Lin; Jie Song; Yi Zhang; Chao Song; Rui Huang

    Strong red light emission from silicon oxynitride-based (SiOxNy-based) light-emitting diodes (LEDs) was investigated. The introduction of dense Si quantum dots (Si QDs) into SiOxNy not only increases carrier injection efficiency but also results in a significant enhancement of more than 300% in the light emission efficiency compared with SiOxNy-based LEDs without Si QDs. Moreover, the efficiency droop phenomenon is remarkably suppressed in the SiOxNy-based LED containing dense Si QDs. Analysis of the dominant recombination process indicates that the improved performance of the SiOxNy-based LEDs results from the increased bimolecular radiative recombination probability .

    更新日期:2020-02-20
  • Scintillation and dosimetric properties of Ce-doped MgAl2O4 single crystals
    J. Lumin. (IF 2.961) Pub Date : 2020-02-20
    Yuma Takebuchi; Hiroyuki Fukushima; Daisuke Nakauchi; Takumi Kato; Noriaki Kawaguchi; Takayuki Yanagida

    The undoped and Ce-doped MgAl2O4 single crystals were synthesized by the floating zone method equipped with four xenon arc lamps, and the photoluminescence (PL), scintillation, and dosimetric properties were investigated. The Ce-doped crystals showed PL emission peaks at around 420 and 740 nm, which were ascribed to the 5d-4f transition of Ce3+ ion and Mg deficiency, respectively. The PL decay time profiles of the Ce-doped crystals exhibited the fast decay, and the decay time constants were the typical value of others Ce-doped materials. Thus, the decay time constants were attributed to the 5d-4f transitions of Ce3+ ion. In addition, optically-stimulated luminescence (OSL) signals could be detected in all the crystals when the stimulation wavelength was 470 nm. The OSL dose response functions showed linearly proportional relationship from 10 to 10,000 mGy in all the Ce-doped crystals. The thermally-stimulated luminescence (TSL) glow curves exhibit three peaks due to antisite of Al3+ ion, V center and antisite of Mg2+ ion. All the Ce-doped crystals showed improved TSL intensity and dose response sensitivity compared the undoped crystal. The 0.2 and 1% Ce-doped crystals showed linearly response at the dose range of the 0.1–1000 mGy.

    更新日期:2020-02-20
  • A newly developed OSL dosimeter based on beryllium oxide: BeO:Na,Dy,Er
    J. Lumin. (IF 2.961) Pub Date : 2020-02-20
    V. Altunal; V. Guckan; Y. Yu; A. Dicker; Z. Yegingil

    This study aims to develop a high sensitivity Optically Stimulated Luminescence (OSL) dosimeter based on tissue-equivalent BeO:Na,Dy, Er ceramic (Zeff = 7.31) using the precipitation method. The material structure was confirmed by performing X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDS) analyses. Thermoluminescence (TL), OSL, and X-ray luminescence (XL) techniques were used for the investigation of the luminescence properties. BeO:Na,Dy, Er has two TL peaks located at ∼170 and 350 °C (at a heating rate of 2 °C/s) found to be associated with the OSL signals using the step annealing procedure. The OSL signals of newly developed BeO:Na,Dy, Er pellets were found highly sensitive to beta radiation and almost linear with a linearity coefficient of 1.03, i.e., described by a relation y=a+bx1.03at a range of 0.1–50 Gy. We investigated that the sensitivity of OSL from BeO:Na,Dy, Er pellets is the same after repeated exposure and reprocessing. Except for instability in short storage times, negligible long-term OSL signal fading was observed for up to three months at ambient temperature, in dark. In XL analyses, a broad band emission from 200 nm to 500 nm was observed at different dopant concentrations. The OSL characteristics of this material were found to be very encouraging and convenient for personal and medical dosimetry applications.

    更新日期:2020-02-20
  • Investigation of thermoluminescence processes during linear and isothermal heating of dosimetric materials
    J. Lumin. (IF 2.961) Pub Date : 2020-02-20
    George S. Polymeris; Vasilis Pagonis; George Kitis

    During experiments involving heating of dosimetric materials, trapped electrons are thermally excited and subsequently recombine with holes, producing a thermally stimulated luminescence signal. Thermal stimulation can take place either at a constant elevated temperature giving rise to a isothermal decay signal (PID), or with a constant heating rate which gives rise to a thermoluminescence (TL) signal. The recombination pathways during thermal stimulation stage (also called the readout stage), can be either of a delocalized nature involving the conduction band, or of a localized nature involving an excited state of the trapped electrons. The present work investigates the experimental conditions which can distinguish between delocalized and localized transitions during the readout stage. The dosimetric materials used in this study are LiF:Mg,Ti, BeO, a natural apatite and artificial porcelain. The results show that during the readout stage with a constant heating rate, the prevalent recombination mechanism in all these materials involves delocalized transitions. However, the results show that during an isothermal decay experiment, the recombination mechanism in LiF:Mg,Ti and BeO involves delocalized transitions, whereas in the case of apatite and artificial porcelain the recombination takes place through localized transitions.

    更新日期:2020-02-20
  • Structure, valence change, and optical properties of BaMgSiO4:Eu phosphor
    J. Lumin. (IF 2.961) Pub Date : 2020-02-19
    W.B. Dai; K. Huang; Y.M. Fan; H. Li; M. Xu
    更新日期:2020-02-20
  • Highly luminescent copper-doped ultrathin CdSe nanoplatelets for white-light generation
    J. Lumin. (IF 2.961) Pub Date : 2020-02-19
    Bedil M. Saidzhonov; Vladimir B. Zaytsev; Mikhail V. Berekchiian; Roman B. Vasiliev
    更新日期:2020-02-20
  • Photoluminescence of trivalent rare-earth ions codoped in ZnO thin films: Competing site occupation by Eu3+ and Er3+ ions
    J. Lumin. (IF 2.961) Pub Date : 2020-02-19
    Housei Akazawa

    The effect of codoping two kinds of trivalent rare-earth ions in ZnO thin films was investigated in terms of photoluminescence (PL) intensities relative to those of singly doped ones. ZnO films codoped with 1 at.% of Eu3+ and a variable concentration of Er3+ were deposited on Si(100) and SiO2 substrates. With preference to securing emission signals from Eu3+, the deposition was carried out under flow of H2O vapor gas. After the samples were post annealed at various temperatures, their PL spectra upon bandgap excitation at 325 nm were monitored. It was found that the Eu3+ emission signal at 612 nm became steeply attenuated as the Er3+ concentration increased, whereas the Er3+ emission signal was absent from the films deposited on Si(100) substrate. The necessary conditions for Er3+ emission signal at 665 nm to appear were (i) deposition on SiO2 substrate at low H2O pressure, (ii) high Er content close to 3 at.%, and (iii) post annealing above 700 °C. Conditions (i) and (iii) correspond to minimizing the influence of hydrogen-containing (OH and H) species. Thus, the emissions from Eu3+ and Er3+ do not appear together because Eu3+ emission requires a hydrogenated ZnO host crystal, whereas Er3+ emission prefers a hydrogen-free environment. The observation of Er3+ emissions from films on SiO2 but not from films on Si reflected the stiffness of the Si crystal and the flexibility of the SiO2 network. Strain in the ZnO host crystal, which was caused by rare-earth ions substituting at Zn2+ sites, would have been relieved by slightly deforming the amorphous SiO2 network. The concentration quenching for codoping with Eu3+ and Er3+ was greater than that for single doping with Eu3+ or Er3+. We propose an occupation-site-competing model wherein only limited numbers of emission-active Zn2+ sites are available for substitution by Eu3+ and Er3+

    更新日期:2020-02-20
  • The photoluminescence and thermoluminescence characteristics of the Eu3+ doped CaMoO4: Detailed kinetic analysis of TL glow curves
    J. Lumin. (IF 2.961) Pub Date : 2020-02-18
    Fatih Mehmet Emen; Vural Emir Kafadar; Nurettin Korozlu; Ruken Esra Demirdogen
    更新日期:2020-02-20
  • Significant improvement of luminescence efficiency and thermal stability of NaZr2(PO4)3:Eu2+ phosphors induced by Na+-Sc3+ substitution
    J. Lumin. (IF 2.961) Pub Date : 2020-02-17
    Zehua Liu; Chao Yang; Hua Tian; Jingjing Chen; Yang Zhao; Dajian Wang; Zhiyong Mao

    In this work, the luminescence efficiency and thermal stability of NaZr2(PO4)3:Eu2+ phosphors were significantly improved through Na+-Sc3+ ions substitution for Zr4+ ions. The evolutions of crystal structure and luminescent performances induced by Na+-Sc3+ ions substitution were investigated in details for Na1+xZr2-xScx(PO4)3:Eu2+ phosphors. The extra Na+ ions occupied the interstitial sites in NaZr2(PO4)3 lattice accompanied with the replacement of Zr4+ ions by Sc3+ ions, resulting in the increase of crystal structure density of materials. As a result, the displacement (ΔR) between the ground state and excited state of Eu2+ activators in the configuration coordinate diagram was decreased because of the increased crystal structure density induced by Na+-Sc3+ ions substitution, then leading to the significant improvement of luminescence efficiency and thermal stability. The presented study revealed that crystal structure density might be used a useful proxy in screening higher performance phosphors.

    更新日期:2020-02-20
  • An effective strategy to boost 3D perovskite light-emitting diode performance via solvent mixing strategy
    J. Lumin. (IF 2.961) Pub Date : 2020-02-15
    Zhe Liu; Fangru He; Wei Guan; Wenwei Tang; Xiaofei Gu; Zhengjian Qi; Lintao Hou
    更新日期:2020-02-20
  • DFT/TD-DFT investigation on the photoinduced electron transfer of diruthenium and viologen complexes
    J. Lumin. (IF 2.961) Pub Date : 2020-02-15
    Malinee Promkatkaew; Songwut Suramitr; Thitinun Karpkird; Masahiro Ehara; Supa Hannongbua
    更新日期:2020-02-20
  • Dysprosium activated strontium aluminate phosphor: A potential candidate for WLED applications
    J. Lumin. (IF 2.961) Pub Date : 2020-02-14
    K. Ganesh Kumar; P. Balaji Bhargav; K. Aravinth; Raja Arumugam; P. Ramasamy

    A series of dysprosium activated strontium aluminate phosphors (SrAl2O4:xDy3+: x = 0.1, 0.2, 0.3, 0.4 and 0.5%) are prepared by conventional solid state reaction method. The structure of the prepared phosphors is analyzed by XRD, results confirm that the crystallinity of the synthesized phosphors is monoclinic phase with space group P21. Morphology and microstructure of the synthesized phosphors is analyzed using FESEM and TEM analysis respectively. Optical properties are analyzed by using Raman and PL spectra. The characteristic peak observed at 465 cm−1 corresponds to bending mode of O–Al–O bonds in corners sharing with [AlO4]5- tetrahedral. The strongest PL emission band observed at 470 nm is assigned to 4F9/2 - 6H15/2 transition in blue region under the ultraviolet excitation wavelength of 347 nm. White light is formed by combination of these three colors and is confirmed by CIE chromatic coordinate graph and possible responsible mechanism is explained in detail.

    更新日期:2020-02-20
  • Synthesis, characterization, photophysical and intramolecular energy transfer properties of oxy-naphthylchalcone appended cyclotriphosphazene cores
    J. Lumin. (IF 2.961) Pub Date : 2020-02-14
    Hanife Ibişoğlu; Zafer Kiliç; Fatma Yuksel; Süreyya Oğuz Tümay
    更新日期:2020-02-20
  • Effects of rapid thermal annealing in InGaN/GaN quantum disk-in-GaN nanowire arrays
    J. Lumin. (IF 2.961) Pub Date : 2020-02-14
    Mahitosh Biswas; Ravinder Kumar; Arka Chatterjee; Yuanpeng Wu; Zetain Mi; Pallab Bhattacharya; Samir Kumar Pal; Subhananda Chakrabarti

    The effects of rapid thermal annealing on the structural and optical properties of InGaN/GaN quantum disk-in-nanowire heterostructure arrays have been investigated. Temperature-dependent and time-resolved photoluminescence measurements were complemented by x-ray photoemission spectroscopy. It was observed that annealing, in general, increased the non-radiative recombination rate in the InGaN quantum disk regions and consequently lowered the internal quantum efficiency and reduced the average carrier lifetime. These are due to an increase in the density of surface states associated with –O and –OH bonds in the disk region and possible enhancement of non-radiative recombination due to In segregation.

    更新日期:2020-02-20
  • 更新日期:2020-02-12
  • Broadband excited Nd3+ NIR emission in Sr5(PO4)3Cl:Eu2+, Nd3+ phosphor for solar spectral modification
    J. Lumin. (IF 2.961) Pub Date : 2020-02-12
    Rupesh A. Talewar; Sk Mahamuda; A.S. Rao; Vishwajit M. Gaikwad; P.D. Belsare; S.V. Moharil
    更新日期:2020-02-12
  • Engineering near-infrared emitting scintillators with efficient Eu2+ → Sm2+ energy transfer
    J. Lumin. (IF 2.961) Pub Date : 2020-02-12
    W. Wolszczak; K.W. Krämer; P. Dorenbos

    Recently, we proposed a concept for a new class of near infrared (NIR) scintillators by employing efficient Eu2+ → Sm2+ energy transfer. In this article we investigate the optical spectroscopy of Sm2+ in BaBrI, CsSrI3, and CsBa2I5 halide hosts. A criterion was derived for fast Sm2+ 5d → 4f emission and a list of new potential NIR scintillators is proposed.

    更新日期:2020-02-12
  • Photoluminescence properties of the material based on SiO2–Y2O3:Eu3+,Tb3+ under different in situ temperature prepared by the sol-gel process
    J. Lumin. (IF 2.961) Pub Date : 2020-02-12
    Lorena Laize Santos Alves; Renata C. de Lima; Marco Antônio Schiavon; Rogéria Rocha Gonçalves; Helliomar P. Barbosa; Jefferson Luis Ferrari

    The codoped SiO2–Y2O3:Tb3+,Eu3+ (xTb: 1.0 mol%; xEu: 0.1; 0.2; 0.5; 0.7 and 1.0 mol%) nanomaterials were prepared at room temperature by sol-gel method and heat treated at 900 and 1000 °C during 4 h, in air atmosphere. The materials were characterized by X-ray powder diffraction (XRD) and UV excited photoluminescence. The material exhibits Y2O3 cubic, one peak positioned around 26° assigned to the cristobalite SiO2 phase and amorphous SiO2 phases due to the Y2O3 and SiO2 presences. The emission bands observed in the emission spectra under excitation at 301 are assigned to the Tb3+ and Eu3+ ions, with clear evidence of energy transfer from Tb3+ to Eu3+. The line assigned to the 5D0→7F2 transition (Eu3+) increase the intensity as a function of Eu3+ concentration. The sensibility under controlled temperature variation was investigate. The Eu3+: 0.5 mol% doped material (annealed @900 °C) exhibited higher thermic sensitivity (with maximum relative sensitivity 0.294% K−1 in 303 K). Under excitation at 395 nm, the red color emission increases the intensity due the thermal treatment. Furthermore, CIE parameters and the color correlated temperature (CCT) are discussed in order to characterize the greenish color emission. Based on the results, these luminescence materials may be potential candidates for optical thermometry diodes, solid-state lighting and nano in vivo biological system.

    更新日期:2020-02-12
  • Eu3+-induced multicolor luminescence properties and enhanced thermal stability in the novel phosphors of Li0.1Na0.9Gd0.5Tb0.5-xEux(MoO4)2
    J. Lumin. (IF 2.961) Pub Date : 2020-02-12
    Huan Chen; Shenghao Ai; Chengli Dong; Heng Wang; Zhanglei Ning; Mengjiao Liu; Jian Bi; Yan Zhao; Xin Lai; Daojiang Gao
    更新日期:2020-02-12
  • Structures and exciton dynamics of aggregated lutein and zeaxanthin in aqueous media
    J. Lumin. (IF 2.961) Pub Date : 2020-02-12
    Liping Lu; Yujie Liu; Liangshu Wei; Fang Wu; Zhigang Xu
    更新日期:2020-02-12
  • Energy localization vs. charge funneling in aggregates of CsPBr3 perovskite nanocrystals
    J. Lumin. (IF 2.961) Pub Date : 2020-02-12
    Dharmendar Kumar Sharma; Shuzo Hirata; Martin Vacha

    We studied photoluminescence (PL) and electroluminescence (EL) on single aggregates composed of tens to hundreds of nanocrystals (NCs) of the halide perovskite CsPbBr3. Energy landscape of the aggregate caused by size distribution of the NCs leads to funneling of charges towards and EL from the largest NC. This phenomenon results in pronounced blinking of the aggregate EL. In PL, on the other hand, the absorbed light energy is localized and reemitted on individual NCs, without significant redistribution by energy/exciton transfer. As a result the PL of individual aggregates does not show any blinking. We further investigated the effect of externally applied dc voltage on PL of the aggregates in a capacitance-like device and observed an intriguing phenomenon of large oscillations of PL intensity that occur with a period of seconds and are correlated between different aggregates across micrometer distances.

    更新日期:2020-02-12
  • Structure, tunable luminescence and thermal stability in Tb3+ and Eu3+ co-doped novel KBaIn2(PO4)3 phosphors
    J. Lumin. (IF 2.961) Pub Date : 2020-02-11
    M.J. Xu; J.Y. Si; G.H. Li; Y.J. Liu; G.M. Cai; J. Zhang
    更新日期:2020-02-12
  • Choice of low thermal quenching phosphors based on high lattice energy for light-emitting application
    J. Lumin. (IF 2.961) Pub Date : 2020-02-11
    Zhen Sun; Mochen Jia; Fang Lin; Bofei Hou; Zuoling Fu; Xin Yang
    更新日期:2020-02-11
  • Efficient chemiluminescent ZnO nanoparticles for cellular imaging
    J. Lumin. (IF 2.961) Pub Date : 2020-02-11
    Zhi-Yu Liu; Cheng-Long Shen; Qing Lou; Wen-Bo Zhao; Jian-Yong Wei; Kai-Kai Liu; Jin-Hao Zang; Lin Dong; Chong-Xin Shan

    Chemiluminescence (CL) induced by peroxalate fuel and hydrogen peroxide has been widely applied in chemical detection and bioimaging. Nevertheless, the chemiluminescent emitters in the CL are focused on organic small-molecular dyes, most of which encounter serious obstacles in practical application due to their potential biotoxicity and low photostability. Here, bright blue CL is observed when biocompatible zinc oxide nanoparticles (ZnO NPs) with yellow photoluminescence (PL) are added into peroxalate and hydrogen peroxide solution, which is originated from the interaction between the zinc interstitial of ZnO NPs and the energy-rich intermediate produced in the CL process. With the modification of silane coupler, the CL quantum yield of ZnO NPs presents two orders of magnitude increase from 6.2× 10−6 to record 3.7 × 10−4 E⋅mol−1 for inorganic NPs owing to the protective effect from silicon oxide shell layer. By virtual of excellent CL ability, ZnO NPs have been firstly used as CL probes in bioimaging, which opens the way to a new design freedom for biosensor or bioimaging in the future.

    更新日期:2020-02-11
  • Tailoring the 3F4 level lifetime in Tm3+: Y3Al5O12 by Eu3+ co-doping for signal processing application
    J. Lumin. (IF 2.961) Pub Date : 2020-02-10
    Zhonghan Zhang; Anne Louchet-Chauvet; Loïc Morvan; Perrine Berger; Philippe Goldner; Alban Ferrier

    Tm3+: Y3Al5O12 (Tm:YAG) crystal is a promising material for high-resolution spectral analysis of broadband radio-frequency (RF) signals, where the absorption spectrum is modified via spectral hole burning. In Tm:YAG, the efficiency of the spectral tailoring is limited by the long-lived metastable level 3F4, acting as a bottleneck for the optical pumping mechanism. We demonstrate that co-doping Tm:YAG with Eu3+ ions can significantly shorten the optical lifetime of 3F4 state, while that of 3H4 is essentially conserved. We show with a model that these modified lifetimes allow faster tailoring of the absorption profile. Because of their low cost and easiness of processing, we use Tm3+ and Eu3+ co-doped Y3Al5O12 ceramics to probe the energy transfer efficiency and find the optimal cation co-doping concentration. Furthermore, we show that Eu3+ co-doping increases the inhomogeneous broadening on the Tm3+ optical transition, hence the spectral analysis bandwidth. Finally, we confirm these results on a single crystal grown by the Czochralski method.

    更新日期:2020-02-10
  • Theoretical investigation of intermolecular hydrogen bond induces fluorescence quenching phenomenon for Coumarin-1
    J. Lumin. (IF 2.961) Pub Date : 2020-02-10
    You Li; Chaofan Sun; Jianhui Han; Qiao Zhou; Bifa Cao; Hang Yin; Ying Shi
    更新日期:2020-02-10
  • Synthesis, characterization and photoluminescence studies of samarium doped zinc sulfide nanophosphors
    J. Lumin. (IF 2.961) Pub Date : 2020-02-08
    K. Ashwini; C. Pandurangappa; K. Avinash; S. Srinivasan; E. Stefanakos

    Nanoparticles of zinc sulfide doped with samarium ions of different molar concentrations from 1 to 5 mol% were synthesized by co-precipitation method. Various metrological tools were used to characterize the as-synthesized nanoparticles for their structural, nanostructural, chemical, optical and photoluminescence characteristics. The results of powder x-ray diffraction pattern and high-resolution transmission electron microscopic images revealed the presence of samarium inside the zinc sulfide nanoparticles, with particle size between 3 and 7 nm. The purity of the ZnS:Sm nanoparticles were obtained from Fourier transform infrared spectral profiles. Large agglomeration of fine particles was shown by the scanning electron microscope images. The UV–Vis diffuse reflectance spectroscopy was used to study the optical absorption properties of the as-prepared ZnS:Sm sample. Photoluminescence studies of samarium doped zinc sulfide nanoparticles showed two major emission peaks when excited at 365 nm, one in the orange region (603 nm) and the other one in the red region (701 nm) due to f-f transitions of the Sm3+ in the 4f5configuration.

    更新日期:2020-02-10
  • Correlation between growth interruption and indium segregation in InGaN MQWs
    J. Lumin. (IF 2.961) Pub Date : 2020-02-08
    M. Dmukauskas; J. Mickevičius; D. Dobrovolskas; A. Kadys; S. Nargelas; G. Tamulaitis

    InGaN/GaN multiple quantum wells (MQWs) with the same indium content and QW widths were grown by metalorganic chemical vapor deposition using metal precursor flow interruptions of different length. The influence of the growth interruption length on photoluminescence (PL) properties was studied by combining temperature-dependent and spatially-resolved PL spectroscopy. The PL band variations are attributed to the transformation of localizing potential: growth interruptions change the density of indium clusters, which modifies the density of localized states. The optimized localizing potential in the structure grown using 9 s-long growth interruptions facilitated an increase in PL intensity by a factor of up to 2.

    更新日期:2020-02-10
  • Novel highly luminescent double-perovskite Ca2GdSbO6:Eu3+ red phosphors with high color purity for white LEDs: Synthesis, crystal structure, and photoluminescence properties
    J. Lumin. (IF 2.961) Pub Date : 2020-02-08
    Zongjie Zhang; Liangling Sun; Balaji Devakumar; Jia Liang; Shaoying Wang; Qi Sun; Sanjay J. Dhoble; Xiaoyong Huang
    更新日期:2020-02-10
  • A novel Al3+ modified Li6CaLa2Sb2O12:Mn4+ far-red-emitting phosphor with garnet structure for plant cultivation
    J. Lumin. (IF 2.961) Pub Date : 2020-02-07
    Ya-jie Han; Shuang Wang; Han Liu; Lei Shi; Xiang-zun Dong; Rong-rong Fan; Chang Liu; Zhi-yong Mao; Da-jian Wang; Zhi-wei Zhang; Ying Zhao

    A novel-far red emission Li6CaLa2Sb2O12 (LCLSO):Mn4+ phosphor was prepared by traditional high temperature solid state reaction method. The morphology, spectral characteristics and luminescence properties of the phosphors were all studied systematically. Based on the results, when x = 0.0045 (x represents the doping concentration of Mn4+), the emission intensity of LCLSO:xMn4+ phosphor reaches the maximum, and the concentration quenching occurs after the Mn4+ doping concentration exceeds 0.0045. In addition, the effect of Al3+-doped on the luminescent properties of the materials was also studied. The optimum doping concentration of Al3+ is y = 0.009 (y represents the doping concentration of Al3+), and the luminescence intensity of Mn4+ can be increased about 4 times. Moreover, the integrated luminescence intensity, the thermal activation energy, and decay time can be obtained via calculation. In summary, LCLSO:Mn4+, Al3+ phosphor exhibits good luminescence efficiency and thermal stability, and possesses the latent application foreground in plant growth lighting.

    更新日期:2020-02-07
  • Cobalt and iron co-doped ZnSe nanocrystals:Mid-IR luminescence at room temperature
    J. Lumin. (IF 2.961) Pub Date : 2020-02-07
    Huawei Shi; Xiaoxia Cui; Xusheng Xiao; Yantao Xu; Chao Liu; Chaoqi Hou; Haitao Guo

    Fe:Co:ZnSe nanocrystals with different co-doping ratios of Fe2+/Co2+ ions were fabricated by hydrothermal synthesis. The facile method used in the present work avoids the mid-infrared quench effect induced by the organic molecular introduced in the past preparation process. These nanocrystals are spherical in shape and exhibit a cubic sphalerite structure with an average grain size of about 15 nm. Through the energy conversion between Co2+ and Fe2+ ions, mid-infrared fluorescences at 3.3 μm and 4.4 μm were detected under 1550 nm laser excitation at room temperature. The fluorescence band of 4.4 μm in the Fe:Co:ZnSe nanocrystals is thought to be an overlapping emission involving the peak centered at 4648 nm corresponding to the Co2+:4T1 (F) → 4T2 (F) energy transition and the peak centered at 4273 nm corresponding to Fe2+:5T2 (D) → 5E (D) energy transition. These high-quality optically active nanomaterials show potential applications in mid-infrared devices such as composite fiber-amplifiers and lasers materials.

    更新日期:2020-02-07
  • Modification of halloysite nanotubes (HNTs) with xanthene dyes and their application in luminescent polymer nanocomposites
    J. Lumin. (IF 2.961) Pub Date : 2020-02-07
    Qadeer Alam; Piotr Bartczak; Hanna Paananen; Mika Suvanto; Tuula T. Pakkanen

    In this study, halloysite nanotubes (HNTs) were modified with three xanthene dyes and subsequently utilized for the fabrication of luminescent polymer nanocomposites. Two different sets of dyes (rhodamine B, rhodamine 6G, and fluorescein) were chosen because of their ability to interact differently with HNTs. Rhodamines B and 6G were adsorbed on the negatively charged external surface of HNTs due to their cationic nature, while fluorescein was infiltrated into the positively charged nano-size lumen of HNTs. The influence of the HNTs substrate on photoluminescence (PL) of the dyes in the polystyrene matrix was investigated. An enhancement in the PL intensity of fluorescein by a factor of 8 was observed upon its encapsulation into lumens of HNTs. On the other hand, the adsorption of rhodamines on HNTs led to a decrease in their PL intensity. A homogenous dispersion of the dye molecules achieved at nanoscale introduced luminescence properties in the polymer nanocomposites. The robust protocol for the modification of halloysites with organic chromophores provides a straightforward way to distribute the dye molecules in a polymer matrix and to incorporate luminescent properties into different polymer matrices.

    更新日期:2020-02-07
  • Tunable emission and selective luminescence sensing for nitro- pollutants and metal ions based on bifunctional lanthanide metal-organic frameworks
    J. Lumin. (IF 2.961) Pub Date : 2020-02-06
    Xiaofei Cheng; Jinsong Hu; Jiaxin Li; Mingdao Zhang

    Series of Eu/Tb bifunctional metal-organic frameworks (MOFs) [EuxTb1-x(L)(H2O)3]n (1-EuxTb1-x) (H4L+·Cl− = 1, 3-bis (3, 5-dicarboxyphenyl) imidazolium chloride) were synthesized successfully by solvothermal reaction. In these complexes, the adjacent Tb3+ or Eu3+ are linked by L3− to form two-dimensional sheet, and then forming three-dimensional frameworks by various H-bondings. All of complexes have wonderful selectivities and sensitivities for detecting 4-nitrophenol (4-NP) and Fe3+, comparatively speaking, the mixed [Eu0.5Tb0.5(L)(H2O)3]n (1-Eu0.5Tb0.5) has better sensing performance than isolate [Eu(L)(H2O)3]n (1-Eu) or [Tb(L)(H2O)3]n (1-Tb) for 4-NP; while 1-Tb has better sensing performance for Fe3+, the highest quenching constants Ksv for 4-NP and Fe3+ reach to 7.5 × 106 M−1 and 9.6 × 105 M−1. The variable temperature XRD and regenerated experiments prove the good thermal and structural stabilities of 1-EuxTb1-x. Furthermore, the sensing mechanisms of complexes as bifunctional sensors have been explored detail based on experiments and calculations.

    更新日期:2020-02-07
  • Sr2LaSbO6:Mn4+ far-red phosphor for plant cultivation: Synthesis, luminescence properties and emission enhancement by Al3+ ions
    J. Lumin. (IF 2.961) Pub Date : 2020-02-05
    Lei Shi; Shuang Wang; Ya-jie Han; Zhi-xin Ji; Di Ma; Zhong-fei Mu; Zhi-yong Mao; Da-jian Wang; Zhi-wei Zhang; Lu Liu

    A series of novel Mn4+-activated double perovskite antimonate Sr2LaSbO6 (SLSO) far-red emitting phosphors were successfully synthesized by a high-temperature solid-state method. X-ray diffraction (XRD), photoluminescence excitation (PLE) and emission (PL) spectra, temperature-dependent photoluminescence spectra, CIE chromaticity coordinates, as well as internal quantum efficiency (IQE) were used to analyze these phosphor samples. Under 334 nm excitation, the SLSO:Mn4+ phosphors emit far red emission peaking around 694 nm due to the Mn4+: 2Eg→4A2g transition. The optimal doping concentration of Mn4+ was 0.8 mol%, moreover, the critical distance (Rc) was 40.89 Å. The dipole-quadrupole interaction may be responsible for the concentration quenching mechanism of Mn4+ ions in the SLSO:Mn4+ phosphors. Furthermore, various Al3+ improved SLSO:0.008Mn4+ phosphors are investigated. When Al3+ is doped with 0.8%, the PL intensity increased by 2.92 times. In addition, the IQE of SLSO:0.008Mn4+ and SLSO:0.008Mn4+, 0.008Al3+ were found to be as high as 35.2% and 38.1%, respectively. Impressively, all chromaticity coordinates of samples located in far-red region. Therefore, these superior luminescence properties of SLSO:Mn4+ sample demonstrated its potential applications in plant cultivation and growth light-emitting diodes (LEDs).

    更新日期:2020-02-06
  • Interpretation of the photoluminescence decay kinetics in metal halide perovskite nanocrystals and thin polycrystalline films
    J. Lumin. (IF 2.961) Pub Date : 2020-02-05
    Vladimir S. Chirvony; Kairolla S. Sekerbayev; Hamid Pashaei Adl; Isaac Suárez; Yerzhan T. Taurbayev; Andrés F. Gualdrón-Reyes; Iván Mora-Seró; Juan P. Martínez-Pastor

    In this paper we present critical analysis of different points of view on interpretation of the photoluminescence (PL) decay kinetics in lead halide perovskites prepared in the form of well passivated nanocrystals (PNCs) or thin polycrystalline layers. In addition to the literature data, our own measurements are also considered. For PNCs, a strong dependence of the PL lifetimes on the type of passivating ligand was observed with a consistently high PL quantum yield. It is shown that such ligand effects, as well as a decrease in the PL lifetime with decreasing temperature, are well qualitatively explained by the phenomenological model of thermally activated delayed luminescence, in which the extension of the PL decay time with temperature occurs due to the population of lower-lying shallow non-quenching traps. In the case of thin perovskite layers, we conclude that the PL kinetics under sufficiently low excitation intensity is determined by the excitation quenching on the layer surfaces. We demonstrate that a large variety of possible PL decay kinetics for thin polycrystalline perovskite films can be modelled by means of one-dimensional diffusion equation with use of the diffusion coefficient D and surface recombination velocity S as parameters and conclude that long-lived PL kinetics are formed in case of low D and/or S values.

    更新日期:2020-02-06
  • Non-contact fluorescence intensity ratio optical thermometer based on Yb3+/Nd3+ codoped Bi4Ti3O12 microcrystals
    J. Lumin. (IF 2.961) Pub Date : 2020-02-04
    Hao Chen; Gongxun Bai; Qinghua Yang; Youjie Hua; Shiqing Xu; Liang Chen

    Optical thermometer based on the non-contact fluorescence intensity ratio technique of two thermally-couple levels has huge potential applications in many fields, such as the electric power industry and in-situ physiological measurements. In the paper, the Yb3+/Nd3+ codoped Bi4Ti3O12 nanocrystal ratio thermometer has prepared by solid-phase sintering. The two thermally-couple levels are Nd3+:4F7/2 (emission peak around 753 nm) and Nd3+:4F5/2 (emission peak at 805 nm), respectively. The optical thermometer has based on the upconversion in near-infrared luminescence under 980 nm excitation with low power of 1.87 W/cm2. Due to the relatively low pump power, the effect of the excitation heat effect on the material is reduced. This resulted in a relatively high relative sensitivity (SR = 1% K−1) in the temperature range of 323–573 K. In addition to the characteristics, the excellent repeatability (σ = 1.5%) of the fluorescence intensity ratio between the two Nd3+ emission peaks makes Yb3+/Nd3+ codoped Bi4Ti3O12 microcrystals a promising non-contact near-infrared ratio thermometer.

    更新日期:2020-02-04
  • Enhanced 2.7 μm continuous-wave emission of Er,Pr:Lu2O3 crystal
    J. Lumin. (IF 2.961) Pub Date : 2020-02-04
    Wentao Hou; Hengyu Zhao; Na Li; Yanyan Xue; Qingguo Wang; Xiaodong Xu; Jun Xu

    The high optical quality Er:Lu2O3 and Er,Pr:Lu2O3 crystals were grown by Floating zone method. The spectral properties of Er:Lu2O3 and Er,Pr:Lu2O3 crystals were investigated. After co-doping small concentration of Pr3+, the depopulated influence of Pr3+ to the NIR emission was much stronger than the MIR emission. The near-infrared and up-conversion fluorescence were significantly quenched. Moreover, the fluorescence lifetime of 4I13/2 abviously decreases from 4.02 ms to 1.71 ms in 7% Er, 0.05% Pr: Lu2O3 crystal, and the lifetime ratio is 1.63 with large fluorescence lifetime of 4I11/2 which is desirable lifetime ratio in these crystals. Thus, the spectral performance was significantly improved by co-doping 0.05 at.% of Pr3+. The high laser performance at 2.7 μm of 7% Er, 0.05% Pr: Lu2O3 crystal is expectable.

    更新日期:2020-02-04
  • Observation of optical gain in Er-Doped GaN epilayers
    J. Lumin. (IF 2.961) Pub Date : 2020-02-01
    V.X. Ho; Y. Wang; B. Ryan; L. Patrick; H.X. Jiang; J.Y. Lin; N.Q. Vinh

    Rare-earth based lasing action in GaN semiconductor at the telecommunication wavelength of 1.5 μm has been demonstrated at room temperature. We have reported the stimulated emission under the above bandgap excitation from Er doped GaN epilayers prepared by metal-organic chemical vapor deposition. Using the variable stripe technique, the observation of the stimulated emission has been demonstrated through characteristic features of threshold behavior of emission intensity as functions of pump intensity, excitation length, and spectral linewidth narrowing. Using the variable stripe setup, the optical gain up to 75 cm−1 has been obtained in the GaN:Er epilayers. The near infrared lasing from GaN semiconductor opens up new possibilities for extended functionalities and integration capabilities for optoelectronic devices.

    更新日期:2020-02-03
  • Kinetic properties of YAG: Eu3+ emission upon electron beam excitation
    J. Lumin. (IF 2.961) Pub Date : 2020-02-01
    Grigorii A. Gusev; Kseniia N. Orekhova; Vlad A. Kravets; Anton I. Isakov; Alexander N. Trofimov; Maria V. Zamoryanskaya

    Luminescent properties of yttrium-aluminum garnet activated by different amount of europium (YAG:Eu3+) single crystals were studied by local cathodoluminescence (CL) technique. Samples were grown by flux method. CL spectra were obtained in the range from 400 to 800 nm with spectral resolution of 0.1 nm. The rise and decay kinetics of various CL bands were investigated. The concentration dependencies of CL intensity and decay times of transitions were plotted. The concentration quenching for 5D1-7F2 Eu3+ transition was observed at about 3.5 at.% of Eu by Y, and for 5D2-7F1 and 5D3-7F3 transitions – at about 2.5–3 at.% of Eu by Y. For transition 5D0-7F1 no concentration quenching was observed. The high-energy excitation capture efficiency by different energy levels of Eu3+ in YAG was estimated based on the dependence of the CL rise rate of these levels on the electron beam current density. It was found that 5D1 energy level excitation capture efficiency is about three times higher than that of the 5D0, 5D2 and 5D3 energy levels.

    更新日期:2020-02-03
  • Up-conversion emission thermometry for semiconductor laser cooling
    J. Lumin. (IF 2.961) Pub Date : 2020-02-01
    Shubin Zhang; Zhuoming Zhang; Maksym Zhukovskyi; Boldizsár Jankó; Masaru Kuno

    The ability to precisely measure temperature is critical to eventually developing semiconductor-based optical refrigerators. Presently, a number of approaches exist for conducting contactless temperature measurements. They are mainly based on the temperature-dependent optical response of materials. A common approach called pump–probe luminescence thermometry (PPLT) uses temperature-dependent shifts of a material’s band edge emission energy to assess temperature. PPLT, however, cannot be reliably applied to materials such as CsPbBr3 nanocrystals, which exhibit temperature insensitive band gaps. To overcome this restriction, we have developed a new optical thermometry based on temperature-dependent changes to below gap-excited (anti-Stokes, ASPL) and above gap-excited (Stokes, PL) photoluminescence intensity ratios (i.e. IASPL/IPL). In it, IASPL/IPL can be used to assess local temperature due to the exponentially sensitive nature of emission up-conversion efficiencies. The developed thermometry is not unique to CsPbBr3 and can be applied other systems found suitable for demonstrating semiconductor-based laser cooling.

    更新日期:2020-02-03
  • Emission spectral change of CdSe/ZnS quantum dots caused by the dilution with organic solvents
    J. Lumin. (IF 2.961) Pub Date : 2020-02-01
    Takeshi Moriyasu; Asuka Kinan; Yuta Baba; Mitsutaka Kumakura

    The emission spectra of CdSe/ZnS core-shell type quantum dots were observed after the dilution of their toluene solution with organic solvents (acetone, diethyl ether, n-hexane, toluene, methanol, and ethanol). In addition to the well-known solvent dependence of the emission efficiency and peak wavelength, it was found that they change over several hours after the dilution, depending on the solvent and the number density of the quantum dot. Based on the solubility of the capping organic ligand to each solvent, the observed time variations were explained in terms of the elution of capping molecules from the dot surface and the resulting change of the number of charge traps.

    更新日期:2020-02-03
  • Thermo-optic and spectroscopic properties of Yb:GAGG, Nd:GAGG and Nd:GGG laser materials at cryogenic temperature
    J. Lumin. (IF 2.961) Pub Date : 2020-01-31
    Yanjie Song; Nan Zong; Zhimin Wang; Dafu Cui; Xiaojun Wang; Yong Bo; Qinjun Peng; Yanbin Li; Zhitai Jia; Xutang Tao; Zuyan Xu

    The solid-state lasers provide an attractive approach to enhance the laser performance benefitting from significant improvements in both thermo-optic and spectroscopic properties of the gain mediums under cryogenic temperature. Here, thermo-optic properties of Yb:Gd3(AlxGa1-x)5O12 (Yb:GAGG) and Nd:Gd3(AlxGa1-x)5O12 (Nd:GAGG) laser crystals, including thermal conductivity (κ), thermal expansion coefficient (α) and specific heat at constant pressure (Cp) were measured from 77 to 298 K. In addition, the thermal shock resistance parameters were also calculated. The spectroscopic properties and the fluorescence lifetimes of laser gain mediums Yb:GAGG, Nd:GAGG and Nd:Gd3Ga5O12 (Nd:GGG) were characterized at 77, 150, 298 K. The stimulated emission cross sections of these laser materials were determined by use of the Füchtbauer-Ladenburg (FL) formula at each temperature.

    更新日期:2020-02-03
  • Effects of Ca2+ doping on upconversion luminescence intensity and crystal field asymmetry of β-NaYF4:Yb3+/Er3+ microcrystals
    J. Lumin. (IF 2.961) Pub Date : 2020-01-31
    Hao Tang; Hua Zhou; Xianhua Cheng

    The green and red upconversion (UC) emissions of 35 mol% Ca2+ doped β-NaYF4:Yb3+/Er3+ microcrystals were improved to 102.8 and 43.1 times higher than those of Ca2+-free counterparts. X-ray powder diffraction spectra, scanning electron microscopy, Fourier transform infrared spectroscopy, upconversion luminescence (UCL) spectroscopy and Judd-Ofelt analysis were performed to investigate the mechanism of UCL intensity enhancement caused by Ca2+ doping. The hexagonal-to-cubic phase transition was observed when Ca2+ doping concentration exceeded 35 mol%. The incorporation of Ca2+ into hexagonal microcrystals lattice induced unit cell volume enhancement and microcrystals surface to volume ratio variation, which affected the UCL intensity by hindering the non-radiative energy loss process via Yb3+/Er3+ ions and changing the amount of surface quenchers adsorbed on the microcrystals surface. The hypersensitive transition related local crystal field asymmetry around Er3+ in the grown hexagonal microcrystals was also investigated by Judd-Ofelt analysis but unexpectedly found to be the less dominant factor for the UCL intensity variation. This study helps to realize the mechanism of impurity ion doping resulted UCL intensity enhancement, which is instructive for high-performance UC microcrystals synthesis.

    更新日期:2020-02-03
  • Surface plasmons enhanced band-edge emission in Ni nanoparticles decorated ZnO nanorods arrays architecture
    J. Lumin. (IF 2.961) Pub Date : 2020-01-30
    G. Jayalakshmi; K. Saravanan

    We report nickel (Ni) nanoparticles (NPs) surface plasmons assisted enhanced photoluminescence behaviour in Ni-decorated ZnO NRs arrays architecture. ZnO NRs arrays architecture was grown on the Si substrate by a conventional hydrothermal route, followed by Ni NPs were decorated on the surface of ZnO NRs arrays architecture by pulsed laser deposition technique. The XRD and Raman analyses confirm the grown nanostructure is in hexagonal wurtzite structure. On Ni NPs decoration, a more than 14-fold enhancement in the band-edge emission with simultaneous suppression in the visible emission is observed. The improved PL emission can be attributed to the resonant coupling between the exciton emission of ZnO NRs arrays and the surface plasmons of Ni NPs. The energy band diagram demonstrates the interfacial charge transfer that takes place from the trapping states of ZnO NRs arrays architecture to Ni NPs and its surface plasmons bands to the conduction band of ZnO NRs arrays architecture. Our experimental results reveal the decoration of Ni NPs on ZnO NRs arrays architecture is an effective means to tailor the optical properties of ZnO nanostructures.

    更新日期:2020-01-31
  • Yb:Ca9Gd(VO4)7, a potential ultrafast pulse laser crystal with promising spectral properties
    J. Lumin. (IF 2.961) Pub Date : 2020-01-30
    Fei Zheng; Shijia Sun; Yuanquan Feng; Huilin Kong; Chao Dou; Shakir Ullah; Jie Tang; Lingyun Li; Bing Teng; Degao Zhong
    更新日期:2020-01-31
  • Influence of Tb3+ doping on the structural and down-conversion luminescence behaviour of SrLaAlO4 nanophosphor
    J. Lumin. (IF 2.961) Pub Date : 2020-01-29
    Sushma Devi; Avni Khatkar; V.B. Taxak; Anju Hooda; Priyanka Sehrawat; Sonika Singh; S.P. Khatkar
    更新日期:2020-01-29
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