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<p>Bismuth-doped molybdenum vanadium-phosphate glasses of composition xBi<sub>2</sub>O<sub>3</sub>–(1–x) (0.35MoO₃-0.35&#xa0;V₂O₅-0.30P₂O₅) where x = 0.05, 0.15, 0.25, and 0.35 were prepared by a conventional melt quenching process. The addition of Bi<sub>2</sub>O<sub>3</sub> increases the glass samples’ density from (4.05–5.27&#xa0;g/cm<sup>3</sup>). Several elastic moduli were theoretically determined using both the bond compression model and the Makishima and Mackenzie model. Obtained bulk modulus (decreased from 36.88 to 35.46 GPa), longitudinal modulus (decreased from 69.97 to 66.08 GPa), shear modulus (decreased from 24.89 to 23.03 GPa), and Young’s modulus (decreased from 59.98 to 56.79 GPa), which alter with the Bi<sub>2</sub>O<sub>3</sub> incorporation. As the Bi₂O₃ content rises, the bulk, longitudinal, shear, and Young’s moduli decrease progressively, indicating a reduction in cross-link density and a decrease in average bond strength due to structural depolymerisation. Dielectric studies across a broad frequency (25&#xa0;Hz–5&#xa0;MHz) and temperature (383–533&#xa0;K) range show strong frequency dispersion and thermally activated polarization, primarily driven by Maxwell–Wagner interfacial effects and hopping conduction. Electrical modulus analysis reveals non-Debye relaxation, accurately modelled by the Bergman-modified Kohlrausch–Williams–Watts equation, where relaxation times follow Arrhenius behaviour linked to small-polaron hopping between mixed-valence V⁴⁺/V⁵⁺ and Mo⁵⁺/Mo⁶⁺ sites. These findings highlight robust structure–property relationships, with targeted Bi₂O₃ doping effectively tuning mechanical strength, thermal stability, and dielectric performance in phosphate-vanadate-molybdate glasses, positioning them as strong contenders for dielectric, optoelectronic, and energy storage applications.</p>

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Compositional tuning of thermal stability, elastic moduli, and dielectric relaxation in Bi₂O₃-doped molybdenum-vanadium phosphate glasses

  • 期刊论文

  • 发表日期：

    2026年3月23日

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  • Dipankar Biswas,
  • Arpan Mandal,
  • Souvik Brahma Hota,
  • Atul Babbar,
  • Aparna Sharma,
  • Debabrata Pramanik,
  • Rohit Kumar Singh Gautam,
  • Arnab Das Sarma,
  • Nipu Modak,
  • Rittwick Mondal

摘要

Bismuth-doped molybdenum vanadium-phosphate glasses of composition xBi2O3–(1–x) (0.35MoO₃-0.35 V₂O₅-0.30P₂O₅) where x = 0.05, 0.15, 0.25, and 0.35 were prepared by a conventional melt quenching process. The addition of Bi2O3 increases the glass samples’ density from (4.05–5.27 g/cm3). Several elastic moduli were theoretically determined using both the bond compression model and the Makishima and Mackenzie model. Obtained bulk modulus (decreased from 36.88 to 35.46 GPa), longitudinal modulus (decreased from 69.97 to 66.08 GPa), shear modulus (decreased from 24.89 to 23.03 GPa), and Young’s modulus (decreased from 59.98 to 56.79 GPa), which alter with the Bi2O3 incorporation. As the Bi₂O₃ content rises, the bulk, longitudinal, shear, and Young’s moduli decrease progressively, indicating a reduction in cross-link density and a decrease in average bond strength due to structural depolymerisation. Dielectric studies across a broad frequency (25 Hz–5 MHz) and temperature (383–533 K) range show strong frequency dispersion and thermally activated polarization, primarily driven by Maxwell–Wagner interfacial effects and hopping conduction. Electrical modulus analysis reveals non-Debye relaxation, accurately modelled by the Bergman-modified Kohlrausch–Williams–Watts equation, where relaxation times follow Arrhenius behaviour linked to small-polaron hopping between mixed-valence V⁴⁺/V⁵⁺ and Mo⁵⁺/Mo⁶⁺ sites. These findings highlight robust structure–property relationships, with targeted Bi₂O₃ doping effectively tuning mechanical strength, thermal stability, and dielectric performance in phosphate-vanadate-molybdate glasses, positioning them as strong contenders for dielectric, optoelectronic, and energy storage applications.