Ba3−xSrxTb3−xCexO9 (x = 1 and 1.5) ceramics (BSTC) with a relative density of 93% and a grain size distribution of 0.2–3 µm were prepared by the mixed-oxides reaction route. The crystalline structures, microstructures, valence states, and electrical properties of two ceramics were analyzed using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and electrical measurements. Rietveld analyses of XRPD patterns show that BSTC1 is indexed as a trigonal structure with the space group R-3c, and BSTC3/2 is indexed as an orthorhombic perovskite structure with the space group Pmcn. The EPR, XPS, and electrical conductivity results confirm that Ce and Tb ions in BSTC exist as Ce4+ and mixed-valence states of Tb4+/Tb3+, respectively. At room temperature, the two BSTC ceramics exhibit a similar semiconducting behavior. The relationships between electrical conductivity and temperature/frequency are provided. The defect chemistry is discussed.

中文翻译：

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新型致密陶瓷 Ba3−xSrxTb3−xCexO9（x = 1 和 1.5）钙钛矿的表征和 Rietveld 改进

巴3−X锶X结核病3−X铈X○9(X= 1 和 1.5) 陶瓷 (BSTC)，相对密度为 93%，粒度分布为 0.2–3微米m 由混合氧化物反应路线制备。使用 X 射线粉末衍射 (XRPD)、扫描电子显微镜 (SEM)、X 射线光电子能谱 (XPS)、电子顺磁共振 (EPR)、和电气测量。Rietveld 对 XRPD 模式的分析表明，BSTC1 被索引为具有空间群的三角结构R-3C, 并且 BSTC3/2 被索引为具有空间群的正交钙钛矿结构pmcn. EPR、XPS 和电导率结果证实 BSTC 中的 Ce 和 Tb 离子以 Ce 形式存在4+Tb 和混合价态4+/Tb3+， 分别。在室温下，两种 BSTC 陶瓷表现出相似的半导体行为。提供了电导率和温度/频率之间的关系。讨论了缺陷化学。