Effect of A-site ionic disorder on the structure, magnetic, and magnetocaloric properties of La0.7-xNdxCa0.3-y(Ba,Sr)(y)MnO3
Effect of A-site ionic disorder on the structure, magnetic, and magnetocaloric properties of La0.7-xNdxCa0.3-y(Ba,Sr)(y)MnO3
复制标题
A位离子无序对La0.7-xNdxCa0.3-y(Ba,Sr)(y)MnO3结构、磁性和磁热性质的影响
DOI：
10.1063/1.5120740
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发表时间：
2020
影响因子：
3.2
通讯作者：
Wang Tao
中科院分区：
文献类型：
--
作者：
Chen Peiqi;He Wei;Xiao Guorui;Wen Jingxian;Yang Tonghan;Wu Xiaowei;Wang Tao
a位阳离子尺寸错配对恒定a位平均离子半径La0.7 - xNdxCa0.3 - y(Ba,Sr)(y)MnO3钙钛矿材料的影响= 1.2052埃。采用标准固相反应方法在高温下制备了多晶样品，并对其结构、磁性能和磁热效应（MCE）进行了详细研究。x射线衍射图表明，所有样品均为具有空间群Pnma的正交晶型结构。XPS分析证实，随着sigma(2)的变化，Mn3+/Mn4+的比值保持不变。同时，当σ(2)从0.0002增加到0.007时，居里温度（T-C）从254 K线性降低到108 K。基于M-H等温线，Arrott图和最大磁熵证明了随着σ(2)的增加一阶到二阶跃迁的交叉。西格玛(2)= 0.0002、0.001和0.003的样本呈现一阶转变，且mce比呈现二阶转变的样本大。
The effects of A-site cation size mismatch on La0.7 - xNdxCa0.3 - y(Ba,Sr)(y)MnO3 perovskite materials with a constant A-site average ionic radius ⟨r(A)⟩ = 1.2052 angstrom have been investigated. Polycrystalline samples have been prepared through the standard solid-state reaction method at high temperatures, and their structures, magnetic properties, and magnetocaloric effect (MCE) have been investigated in detail. X-ray diffraction patterns show that all of the samples crystallized in an orthorhombic structure with the space group Pnma. XPS analysis confirmed the Mn3+/Mn4+ ratio remained constant as sigma(2) was varied. Meanwhile, upon increasing sigma(2) from 0.0002 to 0.007, the Curie temperature (T-C) decreased linearly from 254 K to 108 K. Based on M-H isotherms, Arrott plots and the maximum magnetic entropy prove a crossover of first-to-second-order transition with increasing sigma(2). Samples with sigma(2) = 0.0002, 0.001, and 0.003 exhibited a first-order transition and had larger MCEs than those showing a second-order transition.