Nanocrystallization of Vanadium Borophosphate Glass for Improving the Electrical and Catalytic Properties

Abstract

75V2O5‐10P2O5‐15B2O3 ternary‐system glasses were prepared and nanocrystallized to examine the catalytic effect and the variations in their structural and electrical properties. These glasses were annealed in a graphite mold above the glass transition temperature for 2 h and heat‐treated at the crystallization temperature for 1, 3, and 5 h. Fourier transform infrared spectroscopy (FTIR) was used to analyze the structural changes in the B‐O bonds after nanocrystallization, while X‐ray photoelectron spectroscopy (XPS) analysis showed a decrease in V5+ and an increase in V4+. X‐ray diffraction (XRD) analysis of the structure array (BO3 + V2O5 ↔ BO4 + 2VO2) verified these inferred changes. Structural changes induced by the heat treatment were confirmed by analyzing the molecular volume determined from the sample density. Conductivity and catalytic effects were discussed based on the migration of vanadate ions with different valence states due to the increase in VO2 nanocrystallinity at 275°C. Both conductance and the catalytic effect were higher after nanocrystallization at 275°C for 1 h compared to the annealed sample. Furthermore, compared to the sample heat‐treated for 1 h, the conductance and catalytic effect were increased and decreased, respectively, for samples nanocrystallized at 275°C for 3 and 5 h.