50聽mol%indium substituted BaTiO₃: Characterization of structure and conductivity

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• 作者：S.M.H. Rahman^a ; ^{habibur@chalmers.se} ; ^{smhabib92@yahoo.com} ; C.S. Knee^b ; I. Ahmed^a ; ^c ; ¹ ; S.G. Eriksson^a ; R. Haugsrud^d
• 关键词：Barium titanate ; Perovskite ; Brownmillerite ; Proton conductivity ; X-ray diffraction ; Impedance spectroscopy
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 期刊代码：42_03603199
• 类别：ch
• 出版时间：May, 2012
• 卷：37
• 期：9
• 页码：7975-7982
• 文件大小：1113 K

摘要

BaTi_0.5In_0.5O_3鈭?em>未 was prepared by solid state reaction at 1400聽掳C. Rietveld analysis of high resolution X-ray powder diffraction data indicated phase pure as-prepared material that adopts a cubic perovskite structure with a聽=聽4.1536(1)聽脜. Thermogravimetric analysis revealed the presence of significant levels of protons in the as-prepared material and 57%of the theoretically achievable protonation was attained on exposure to a humid environment at 185聽掳C. After hydration the cell parameter increased to 4.1623(1)聽脜. Electrical conductivity was measured both with fixed and variable frequency ac impedance methods as a function of temperature, oxygen-, water vapour- and heavy water vapour partial pressures. In the temperature range 400-800聽掳C a slight increase in the total conductivity with increasing oxygen partial pressure is encountered, characteristic of a contribution from p-type charge carriers. The effect of the water vapour pressure on conductivity below 600聽掳C is much more prominent indicative of dominant proton conduction. At 300聽掳C the total conductivity in wet O₂ was estimated to be 9.30聽脳聽10^鈭?聽S/cm. At T聽>聽800聽掳C the material is a pure oxide ion conductor.