Perovskite LaPbMSbO{sub 6} (M=Co, Ni): Structural distortion, magnetic and dielectric properties

• Published in: Journal of solid state chemistry 2014-09, Vol.217
• Main Authors: Bai, Yijia, Chemical Engineering College, Inner Mongolia University of Technology, 49 Aimin Street, Hohhot 010051, Han, Lin, University of Chinese Academy of Sciences, Beijing 10049, Liu, Xiaojuan, Deng, Xiaolong, Wu, Xiaojie, Yao, Chuangang, Liang, Qingshuang, Meng, Junling, Meng, Jian
• Format: Article
• Language: English
• Subjects: ANTIFERROMAGNETISM; ANTIMONY IONS; BOND ANGLE; COBALT IONS; DEFORMATION; DIELECTRIC MATERIALS; ELECTRONIC STRUCTURE; GELS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LEAD IONS; MAGNETIC PROPERTIES; OXIDES; PERMITTIVITY; PEROVSKITE; SOLS; SPIN; TEMPERATURE DEPENDENCE; X-RAY DIFFRACTION
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/J.JSSC.2014.05.013

The B-site ordered double perovskite oxides LaPbMSbO{sub 6} (M=Co, Ni) have been synthesized via the modified Sol–Gel precursor two-step route. Rietveld refinements reveal strong abnormal structural distortion and BO{sub 6} octahedral deformation appearing along the ab plane. Owing to the cooperative Jahn–Teller effect of Co{sup 2+} and Pb{sup 2+} ions, the Co-related compound exhibits almost complete Co{sup 2+}–Sb{sup 5+} order. For magnetic properties, spin-canted antiferromagnetic state with high extent of magnetic frustration is confirmed. The Ni-related compound presents heavier magnetic frustration for introducing tiny disorder on site occupation accompanied with valence state and further enhancing the complexity of magnetic competition. Dielectric measurements present a considerable temperature dependent dielectric relaxation with great dc-like loss feature in the LaPbCoSbO{sub 6}. For LaPbNiSbO{sub 6}, however, the permittivity with low dielectric loss is shown to be insensitive to either temperature or frequency. The corresponding electronic active energy manifests that the weakly bounded 3d-electron is prone to hop in a more distorted Co–Sb sublattice. - Graphical abstract: XRD Rietveld refinement result of LaPbCoSbO{sub 6} presented a large BO{sub 6} octahedral distortion along the ab plane. Based upon the variations from Co–O–Sb bond angles, a fierce competition from many extended magnetic coupling routes (M–O–O–M) would induce a considerably large magnetic frustration and electron hopping restriction. - Highlights: • Highly ordered LaPbMSbO{sub 6} (M=Co, Ni) were synthesized. • Abnormal structural distortion appeared in the ab plane. • Strong magnetic frustration was confirmed via M{sup 2+}–O–O–M{sup 2+} route. • Dielectric measurements presented a large difference between Co and Ni samples. • 3d-electronic structure determines lattice distortion and physical properties.