Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, AP 70360 México DF 04510, México.
Inorg Chem. 2011 Sep 5;50(17):8340-7. doi: 10.1021/ic2008864. Epub 2011 Jul 25.
In this work, the sol-gel synthesis, structural characterization, and transport properties of a new solid solution of the general formula La(x)Bi(1-x)Fe(0.5)Cr(0.5)O(3) (0.4 ≤ x ≤ 1) are presented. The solubility limit x has been determined and variation of the lattice parameters measured through profile fitting. The cell parameters, space group, and atomic positions, as obtained by the Rietveld refinement of X-ray diffraction data, are reported. This analysis and electron diffraction studies as well do not reveal any evidence of Fe/Cr ordering. Regarding the transport properties, magnetic and electric characterizations are described. The electrical response with the temperature and frequency has been studied, and a "positive temperature coefficient" for the resistivity has been found for temperatures between 270 and 400 °C. The magnetic behavior is striking because, for all materials studied, zero-field-cooling curves appear above field-cooling ones, an anomalous feature that is interpreted as being due to complex ferromagnetic/antiferromagnetic interactions in the B perovskite sublattice.
在这项工作中，介绍了通式 La(x)Bi(1-x)Fe(0.5)Cr(0.5)O(3)（0.4 ≤ x ≤ 1）的新型固溶体的溶胶-凝胶合成、结构表征和输运性质。确定了溶解度极限 x，并通过轮廓拟合测量了晶格参数的变化。报道了通过 X 射线衍射数据的 Rietveld 精修得到的晶胞参数、空间群和原子位置。该分析和电子衍射研究也没有发现 Fe/Cr 有序的任何证据。关于输运性质，描述了磁性和电性特征。研究了温度和频率对电阻的影响，发现电阻在 270 到 400°C 之间呈现“正温度系数”。磁行为引人注目，因为对于所有研究的材料，零场冷却曲线出现在磁场冷却曲线之上，这种异常现象被解释为是由于 B 钙钛矿亚晶格中复杂的铁磁/反铁磁相互作用所致。
