Title

Color Bleaching and Oxygen Diffusion in a Niobium Phosphate Glass

Abstract

The color of niobium phosphate glasses ranges from clear to deep blue depending on their thermal history. In this study, a glass with the nominal composition (mole %) 23K2O·40Nb2O5·37P2O5 was treated in oxidizing and reducing atmospheres at temperatures around Tg (730 °C) and the color at room temperature was analyzed using optical spectroscopy. Electron spin resonance (ESR) spectroscopy shows that the blue color is associated with the presence of Nb4+ ions, which oxidize to Nb5+ in the clear glasses. Bleaching kinetics were determined from a series of heat treatments below Tg in flowing oxygen, and analyzed with an diffusion model that indicated an activation energy of 150 ± 31 kJ/mol.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Color; Diffusion; ESR; Niobium; Phosphate

International Standard Serial Number (ISSN)

0022-3093

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2014 Elsevier B.V., All rights reserved.

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