Vanadium Ions in Sol-Gel Silica Studied by Electron Spin Resonance, UV-Visible Absorption, Diffuse Reflectance, and Photoluminescence Spectroscopies.

DOI Web Site Web Site 26 References
  • KAWASHIMA Michiyo
    Department of Industrial Chemistry, College of Engineering, Kanto Gakuin University
  • ODA Nobuhiro
    Department of Industrial Chemistry, College of Engineering, Kanto Gakuin University
  • UCHIDA Yoshikuni
    Department of Industrial Chemistry, College of Engineering, Kanto Gakuin University
  • MATSUI Kazunori
    Department of Industrial Chemistry, College of Engineering, Kanto Gakuin University

Bibliographic Information

Other Title
  • ESR, 紫外-可視吸収, 拡散反射, ホトルミネッセンス分光法によるゾル-ゲルシリカ中のバナジウムイオンの研究

Search this article

Abstract

Valence states and structures of vanadium species supported on silica, which were synthesized by a sol-gel method, were studied by Electron Spin Resonance (ESR), UV-visible absorption, diffuse reflectance, and photoluminescence spectroscopies for various stages of the process (sols, xerogels and heated xerogels). ESR measurements revealed that V4+ ions were present as [VO(H2O)5]2+ in sols and xerogels for a lower vanadium concentration, whereas a higher vanadium concentration led to the aggregation of V4+ ions in the drying stage of the sol-gel process. Upon calcinations at a higher temperature of. 873K, the V4+ ions were oxidized to V5+ which, for a lower vanadium concentration, were located in isolated pseudotetrahedral silica sites, and with an increase in the vanadium content, were aggregated so that V2O5 was finally formed. Changes of pseudotetrahedral structure to octahedral one by the coordination of water molecules in the atmosphere were observed, especially when. the xerogels was heated at a lower temperature of 973K.

Journal

References(26)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top