Impact of point defects on the elastic properties of BaZrO3: Comprehensive insight from experiments and ab initio calculations
Impact of point defects on the elastic properties of BaZrO3: Comprehensive insight from experiments and ab initio calculations
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DOI：
10.1016/j.actamat.2018.08.042
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发表时间：
2018-11-01
期刊：
影响因子：
9.4
通讯作者：
Maier, J.
中科院分区：
文献类型：
--
作者：
Hoedl, M. F.;Makagon, E.;Maier, J.
受主掺杂的BaZrO 3是质子传导钙钛矿的原型，其作为中温燃料电池的电解质具有强烈的兴趣。使用超声飞行时间（TOF）测量，并补充从头计算，允许不同的贡献进行分析的弹性性能的干燥和水合Y掺杂的BaZrO 3（1.5-17摩尔% Y）。实验和理论研究结果是一致的，并揭示了一个强烈的减少的杨氏模量，剪切模量和体积模量时，增加掺杂剂浓度。这种降低归因于以下因素的组合效应：（i）主要由不同离子半径引起的宏观晶格化学膨胀，和（ii）局部削弱钙钛矿结构中的化学键的点缺陷如受体Acc '（Zr）（具有降低的阳离子电荷）、氧空位V-O（中心点中心点）和质子缺陷OHO中心点（氧化物离子位点上的氢氧根离子）的存在。相对于Acc ′（Zr）、V-O（中心点）、OHO中心点削弱化学键所引起的模量降低，晶格参数的改变对模量的影响较小。脱水和水合样品之间的弹性模量仅略有不同。随着受主和氧空位浓度的增加，弹性模量的降低在Y掺杂的BaZrO 3中（每摩尔%空位在Y：BaZrO 3中为-5.8%）比在Gd掺杂的CeO 2中（在Gd：CeO 2中为-2%）的类似早期研究强得多。这一结果表明，与具有强烈弯曲的M-O-M键的萤石相比，氧空位对具有线性B-O-B键的ABO（3）钙钛矿的弹性性质的影响更大。(C)2018 Acta Materialia Inc.由Elsevier Ltd.出版。保留所有权利。
Acceptor doped BaZrO3 is the prototype of proton conducting perovskites which are of strong interest as electrolytes for intermediate temperature fuel cells. Elastic properties of both dry and hydrated Y-doped BaZrO3 (1.5-17 mol% Y) were determined using ultrasound time of flight (TOF) measurements, and complemented by ab initio calculations which allow for an analysis of the different contributions. The experimental and theoretical findings are consistent and reveal a strong decrease of the Young's, shear and bulk moduli upon increasing dopant concentration. This decrease is attributed to a combined effect of (i) macroscopic lattice chemical expansion mainly caused by differing ionic radii, and (ii) presence of point defects such as acceptors Acc'(Zr) (with decreased cation charge), oxygen vacancies V-O(center dot center dot), and protonic defects OHO center dot (hydroxide ions on oxide ion sites) that locally weaken the chemical bonds in the perovskite structure. The effect from modified lattice parameter is minor relative to the decrease in moduli caused by Acc'(Zr), V-O(center dot center dot), OHO center dot weakening the chemical bonds. The elastic moduli differ only slightly between the dehydrated and hydrated samples. The decrease in the elastic moduli with increasing acceptor and oxygen vacancy concentrations is much stronger in Y-doped BaZrO3 (-5.8% in Y:BaZrO3 per mol% of vacancies) compared to similar earlier investigations on Gd-doped CeO2 (-2% in Gd:CeO2). This result indicates a greater effect of oxygen vacancies on the elastic properties in ABO(3) perovskites with the linear B-O-B bonds as compared to fluorites with strongly bent M-O-M bonds. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.