Electrical and magnetic properties of strontium substituted lanthanum manganate perovskite crystals prepared using fused salt electrolysis
Electrical and magnetic properties of strontium substituted lanthanum manganate perovskite crystals prepared using fused salt electrolysis
复制标题
熔盐电解制备锶取代锰酸镧钙钛矿晶体的电学和磁学性能
DOI：
10.1006/jssc.1999.8224
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发表时间：
1999
影响因子：
5.4
通讯作者：
M. Greenblatt
中科院分区：
文献类型：
--
作者：
W. Mccarroll;K. Ramanujachary;I. Fawcett;M. Greenblatt
在稳定的氧化锆坩埚中使用 Cs{sub 2}-MoO{sub 4}-MoO{sub 3} 溶剂通过熔盐电解生长含有 7--34 摩尔% Sr 的 Sr 掺杂钙钛矿锰酸盐晶体。菱形晶体以类似立方体的习性生长，通常在边缘具有 0.25--4 mm{sup 2} 的面面积，平均面面积随着 Sr 含量的增加而减小。所有测量的 Sr 含量在 11.7 至 33.6 摩尔% SR 之间的晶体都经历了从顺磁绝缘体到铁磁金属态的转变，其 {Tc} 和 T{sub IM} 值在 325 至 > 400 K 之间（对于 T{sub IM}），该值随着 Sr 含量的增加而增加。对于组成为 Sr{sub 0.336}La{sub 0.661}Mn{sub 0.997}O{sub 3} 的晶体，在 375 K 下观察到约 45% 的磁阻。对于如此低 Sr 含量的样品，Sr{sub 0.117}La{sub 0.844}Mn{sub 0.990}O{sub 3} 的异常高 {Tc} = 325 K 可以解释为 A 阳离子位点上的高空位水平，这稳定了菱面体钙钛矿结构，否则可能被认为是斜方晶系 1 型。具有斜方2型结构的掺杂Sr的锰酸镧钙钛矿在阴极的形成可以用静电辅助空气氧化机制来解释。 42 条参考文献，4 个图，2 个更多 » 标签。« 更少
Crystals of Sr-doped perovskite lanthanum manganates, containing 7--34 mole percent Sr have been grown by fused salt electrolysis using Cs{sub 2}-MoO{sub 4}-MoO{sub 3} solvents in stabilized zirconia crucibles. The rhombohedral crystals grow with cubic-like habits typically with facial areas 0.25--4 mm{sup 2} on edge with the average facial area decreasing with increasing Sr content. All measured crystals with Sr contents between 11.7 and 33.6 mole percent SR underwent transitions from a paramagnetic-insulator to a ferromagnetic-metallic state with values of {Tc} and T{sub IM} between 325 and > 400 K (for T{sub IM}), the values increasing with Sr content. A magnetoresistance of approximately 45% at 375 K was observed for a crystal of composition Sr{sub 0.336}La{sub 0.661}Mn{sub 0.997}O{sub 3}. The anomalously high {Tc} = 325 K for Sr{sub 0.117}La{sub 0.844}Mn{sub 0.990}O{sub 3} for a sample of such low Sr content is interpreted in terms of a high vacancy level on the A cation site which stabilizes the rhombohedral perovskite structure, which otherwise might have been expected to be orthorhombic type-1. The formation of Sr-doped lanthanum manganate perovskite at the cathode with the orthorhombic type-2 structure is interpreted in terms of an electrostatically assisted air oxidation mechanism. 42 refs., 4 figs., 2more » tabs.« less