Review
Structural relaxation and viscosity of Al2O3 doped magnesium phosphate glasses

https://doi.org/10.1016/j.jnoncrysol.2020.120323Get rights and content

Abstract

Thermomechanical analysis and differential scanning calorimetry were used to study the viscosity and relaxation behavior of the Al2O3-doped magnesium phosphate glasses. Viscosity in the range (107 - 1011) Pa•s was described by the nowadays top performing multiparametric models. A fixed extrapolation of high-temperature viscosity according to the Eyring theory was applied with the exception of the Arrhenius equation. The activation energies of viscous flow were very close to the activation energy of enthalpy relaxation determined in terms of the Tool-Narayanaswamy-Moynihan model. On the contrary, the activation energy of volume relaxation was found to be much lower in comparison with the viscous flow activation energy. In general, the increase of the Al2O3 content leads to the increases of the viscosity, of the activation energies of viscous flow and structural relaxation (as well as of the kinetic fragilities calculated from these quantities), and of the temperatures characterizing the glass transition during the viscosity, volume, and enthalpy measurements. The phosphate chains interconnecting effect of the Al3+ ions was found to be much stronger than the influence of the MgO modifying oxide. However, the enthalpy changes during the relaxation processes seem to be primarily influenced by the MgO/P2O5 ratio. Consistence of the compositional interpretation of the obtained results indicates the benefits of the utilization of the correlation coefficients for attributing the structural units responsible for the changes of physico-chemical quantities.

Introduction

Amorphous magnesium phosphate (AMP) is an important material for various bio-applications, mostly used as a biomaterial for bioresorbable orthopedic implants. In [1] the AMP was studied with respect to the utilization for bone void filling applications. The mineralization of AMP was shown to mimic the hydroxyapatite-type characteristic morphology on the substrate surface, and to promote the proliferation and differentiation of the osteoblast-like cells. Recently, a biodegradable, non-exothermic, self-setting orthopedic cement based on AMP was developed [2] by incorporation of the water soluble biocompatible polymer (polyvinyl alcohol, PVA), which enables a controlled growth of the final phase via the biomimetic process. The cement composition with 15% of PVA in aqueous medium exhibited clinically relevant setting times, mechanical properties and biodegradability. In another application, the composite film of nanostructured amorphous magnesium phosphate and polylactic acid was spin-coated on the surface of the biodegradable AZ31 magnesium alloy [3], significantly improving corrosion resistance and biomineralization capability. This indicates the great potential of the AMP composites in the protective and bioactive coating applications on biodegradable orthopedic magnesium alloys.

Understanding the structural relaxation processes and viscosity behavior is the key factor for the successful practical application of all glassy materials. These processes not only determine the long-term stability of the materials’ mechanical properties, but they are also closely related to the glass-forming tendency and manufacturing procedures. Unfortunately, since these properties can be tedious to measure, literature usually lacks the data needed for considering the manufacturing/processing side of the novel biomaterials. In the present study, the relaxation and viscosity behaviors of the Al2O3-doped magnesium phosphate glasses will be reported, where the Al2O3 component was added in order to improve the chemical resistivity and anti-corrosive properties (it is well known that the tetrahedral Al ions cross-link with the neighboring phosphor chains by the formation of AlPO4 species that strengthen the glass network [4, 5]). In addition, the utilization of the correlation coefficients between the composition and various physical quantities will be demonstrated, showing the strengths and also the possible weaknesses of this approach.

Section snippets

Experimental

Magnesium phosphate glasses doped with Al2O3 were prepared by the common melt-quenching procedure. The glasses were prepared by melting the p.a. ammonium dihydrogen phosphate (NH4H2PO4) and magnesium carbonate (MgCO3) in alumina crucibles [6]. Appropriate quantities of these compounds were mixed in an agate mortar and placed into alumina crucible. In the first step, the crucible was heated up to 700 °C in an electrical furnace at slow heating rate to remove the water, ammonia and carbon dioxide

Results

The Raman spectra were recorded in the range of (100 – 1500) cm−1; the data were corrected by the Böse-Einstein population factor [10] (see Eq. (1)) after the baseline subtraction:Icor=Lexpvv031−exp[−hcv/kT](v0−v)4 where Iexp and Icor are the observed and corrected Raman intensities, respectively, ν and ν0 are the Raman shift ant the wavenumber of the excitation laser, respectively, and h, k, c, and T represent Planck's constant, Boltzmann's constant, the speed of light, and thermodynamic

Discussion

The relation between the relaxation motions and the viscous flow process has been the subject of debate for a long time – see e.g. [34], [35], [36]. In general, the activation energies of these phenomena are often considered close or even similar. In the present work, we have tested this hypothesis for the three Al2O3-doped magnesium phosphate glasses. The activation energies of viscous flow Eη, volume structural relaxation Δh*V and enthalpy structural relaxation Δh*H are for the studied

Conclusions

The structural relaxation and viscosity behaviors were studied using TMA and DSC for the Al2O3-doped magnesium phosphate glasses. Volume relaxation behavior (measured via cyclic TMA experiments performed in the glass transition region) was described by the TNM and TNMa models in combination with the viscous creep equation. Cyclic enthalpy relaxation measurements were evaluated in terms of the TNM model. The viscosity was described by the MYEGA, AM and VFT models in the (107 - 1011) Pa•s range.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by The Slovak Grant Agency for Science under grant No. VEGA 2/0091/20, VEGA 1/0064/18, APVV SK-PL-18-0062 and the project centre for Functional and Surface Functionalized Glass (CEGLASS), ITMS code is 313011R453, operational program Research and innovation, co-funded from European Regional Development Fund.

References (37)

  • B.A. Shakhmatkin et al.

    The thermodynamic properties of oxide glasses and glass-forming liquids amd their chemical structure

    J. Non-Cryst. Sol.

    (1994)
  • I. Avramov et al.

    Effect of disorder on diffusion and viscosity in condensed systems

    J. Non-Cryst. Solids

    (1988)
  • I.M. Hodge

    Adam-Gibbs formulation of nonlinear enthalpy relaxation

    J. Non-Cryst. Sol.

    (1991)
  • C.A. Angell

    Relaxation in liquids, polymers and plastic crystals – strong fragile patterns and problems

    J. Non-Cryst. Sol.

    (1991)
  • N. Ostrowski et al.

    Synthesis, osteoblast and osteoklast viability of amorphous and crystalline tri-magnesium phosphate

    ACS Biomater. Sci. Eng.

    (2015)
  • E. Babaie et al.

    Evaluation of amorphous magnesium phosphate (AMP) based non-exothermic cements

    Biomed. Mater.

    (2016)
  • J. Urbánek et al.

    Thermomechanical properties of mullitic materials

    Process. Appl. Ceramics

    (2017)
  • B. Hruška et al.

    Thermodynamic model and Raman spectra of MgO-P2O5 glasses

    J. Therm. Anal. Calorim.

    (2019)

    • Cited by (5)

    • Thermokinetic behavior of the Al<inf>2</inf>O<inf>3</inf>-PbO-B<inf>2</inf>O<inf>3</inf> glasses

      2022, Journal of Non-Crystalline Solids
      Citation Excerpt :

      % Al2O3) to the formation of the original boron oxide phases. However, further substitution of PbO by Al2O3 most probably leads to almost full interbonding of the glassy matrix, where the surplus Al2O3 gets phase-separated to form the Al4O12 anorthic crystallites (akin behavior was observed e.g. in [25,26]). The remaining small crystallization peak (corresponding to the original pre-peak at 3 mol.

    • Role of modifiers in the structural interpretation of the glass transition behavior in MgO/BaO-Al<inf>2</inf>O<inf>3</inf>-P<inf>2</inf>O<inf>5</inf> glasses

      2021, Journal of Non-Crystalline Solids
      Citation Excerpt :

      Hence, the Ba/MgO-Al2O3-P2O5 glasses belong among the materials with broad spectrum of applicability - optics and telecommunications [12-14], production of thermal glasses [15] and radiation shielding materials [16-20], synthesis of biodegradable self-setting orthopedic cements [21-23]. The present work will combine some of our previous results on the phosphate glasses [24,25] with the new data In addition, we will introduce several new approaches for describing and interpreting the glass transition behavior with regard to the involved structural arrangement, focusing primarily on the role of the modifying oxides. The Ba/MgO-Al2O3-P2O5 phosphate glasses were synthesized via the melt-quench process.

    • Structural Relaxation Rate and Aging in Amorphous Solids

      2023, Journal of Physical Chemistry C

    • Structural relaxation in chalcogenide glasses

      2023, Journal of the American Ceramic Society

    • Heterogeneous UV disinfection aided by ZnO/Al<inf>2</inf>O<inf>3</inf> composites for inhibiting antibiotic resistant bacteria photoreactivation and gene recovery

      2022, Environmental Science: Nano
    View full text
    © 2020 Elsevier B.V. All rights reserved.