Adiabatic small polaron hopping in K₂O-WO₃-Nb₂O₅-P₂O₅ glasses

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• 作者：Isaias Oliva ; Atsunobu Masuno ; Hiroyuki Inoue ; Motohiro Sakamoto ; Kazuki Morita
• 关键词：Alkali tungsten phosphate glasses ; Heat treatment ; Electronic conductivity ; Ionic conductivity ; Mixed conductor
• 刊名：Solid State Ionics
• 出版年：1 February, 2014
• 年：2014
• 卷：255
• 期：Complete
• 页码：56-59
• 全文大小：372 K

文摘

The electrical conductivity of 45xKO_1/2-45(1 鈭?#xA0;x)WO₃-25NbO_5/2-30PO_5/2 (x = 0.5, 0.6, and 0.7) glasses was investigated. Heat treatment of the sample under a CO atmosphere at temperatures below the glass-transition temperature introduced electrons into the glass as carriers, following which W^6 + was reduced to W^5 +. The electrical conductivity increased by four orders of magnitude for the x = 0.5 glass and by two orders of magnitude for the x = 0.6 glass, whereas it only doubled for the x = 0.7 glass. The results suggested that the increase in the electrical conductivity of the glasses for which x = 0.5 and 0.6 was caused by hopping of small polarons, which were generated by nearby W^5 +, in an adiabatic process. However, the adiabatic small polaron theory could not be applied to the x = 0.7 glass, which we attributed to the change in the K⁺-ion conductivity in the case of the x = 0.7 glass, where the K⁺ ions contributed substantially to the electrical conductivity even before the heat treatment under a CO atmosphere.