The crystal structure, TG-MS, IR, and hydration thermodynamic parameters of the inherently oxygen-deficient Ba₇In_6–xY_xAl₂O₁₉ system have been investigated. X-ray diffraction analysis showed that the Ba₇In_6–xY_xAl₂O₁₉ (0 ≤ x ≤ 0.25) are hexagonal perovskites belonging to the P6₃/mmc space group. The hydrated materials exhibited the same structure with larger cell parameters. IR spectroscopy of the hydrated specimens confirmed the existence of three types of hydroxyl groups involved in different hydrogen bonds. The dissolution of water was measured by using thermogravimetric (TG) analysis. The TG measurements showed the water uptake growth with increase of x. Dehydration upon heating is a three-stage process, namely, two close effects in the temperature range 200–600 °C and a small high-temperature effect near 800 °C. A defect chemical model was developed to derive hydration thermodynamic parameters based on TG data. A thermodynamic approach to the hydration process showed that the increase in the Y³⁺ content was accompanied by a decrease in the enthalpy of hydration due to the enlargement in the basicity of the phases. The strategy of introducing an isovalent dopant with a larger size and lower electronegativity turned out to be favorable in terms of increasing the proton concentration and decreasing the enthalpy of hydration.

中文翻译：

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质子导电六方钙钛矿 Ba7In6–xYxAl2O19 的水合过程


已经研究了固有缺氧 Ba₇In_6–xY_xAl₂O₁₉ 系统的晶体结构、TG-MS、IR 和水合热力学参数。X 射线衍射分析表明，Ba₇In_6–xY_xAl₂O₁₉ （0 ≤ x ≤ 0.25） 是属于 P6₃/mmc 空间群的六方钙钛矿。水合材料表现出相同的结构，具有更大的细胞参数。水合样品的红外光谱证实存在三种类型的羟基，这些羟基涉及不同的氢键。使用热重 （TG） 分析测量水的溶出度。TG 测量显示吸水率随 x 的增加而增长。加热脱水是一个三个阶段的过程，即在 200-600 °C 的温度范围内有两个紧密效应，在 800 °C 附近有一个较小的高温效应。 开发了一个缺陷化学模型，以基于 TG 数据推导出水合热力学参数。水合过程的热力学方法表明，由于相碱性的扩大，Y³⁺ 含量的增加伴随着水合焓的降低。事实证明，引入具有更大尺寸和更低电负性的等价掺杂剂的策略在增加质子浓度和降低水合焓方面是有利的。