کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1480887 | 1510441 | 2014 | 5 صفحه PDF | دانلود رایگان |
• O2 diffusion resulting in Nb valence change for niobium phosphate glass below Tg
• Reversible color change in glass
• Diffusion coefficient calculated using optical spectroscopy
• Nb4 + gives blue color in phosphate glass.
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.
Journal: Journal of Non-Crystalline Solids - Volume 401, 1 October 2014, Pages 96–100