Charge Compensation Mechanisms in La-Doped BaTiO3

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• 作者：Finlay D. Morrison ; Alison M. Coats ; Derek C. Sinclair and Anthony R. West
• 关键词：doping mechanisms ; defects ; phase equilibria ; conductivity ; impedance spectroscopy
• 刊名：Journal of Electroceramics
• 出版年：2001
• 出版时间：2001
• 年：2001
• 卷：6
• 期：3
• 页码：219-232
• 全文大小：223 KB

文摘

The mechanism of doping BaTiO₃ with La has been investigated by a combination of X-ray diffraction, electron probe microanalysis, scanning and transmission electron microscopy and impedance measurements. Phase diagram results confirm that the principal doping mechanism involves ionic compensation through the creation of titanium vacancies. All samples heated in oxygen at 1350–1400°C are electrical insulators, consistent with an ionic compensation mechanism. Samples heated in air or atmospheres of low oxygen partial pressure, at similar temperatures, lose a small amount of oxygen and this gives rise to a second, electronic compensation mechanism in addition to the main, ionic compensation mechanism; as a result, samples are dark-coloured and semiconducting. The change from insulating to semiconducting behaviour is reversible, by changing the atmosphere on heating at 1350–1400°C. We find no evidence for any changes in cationic composition of the BaTiO₃ solid solutions arising from changes in oxygen content.