1. Synthesis, structure and dielectric properties of new ordering perovskites LnPbMgSbO6 (Ln = La, Pr, Nd).
- Author
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Han, Lin, Bai, Yijia, Liu, Xiaojuan, Yao, Chuangang, Meng, Junling, Liang, Qingshuang, Wu, Xiaojie, and Meng, Jian
- Subjects
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PEROVSKITE synthesis , *DIELECTRIC properties , *LANTHANUM , *CRYSTAL structure , *OCTAHEDRAL molecules , *LOW temperatures , *PERMITTIVITY - Abstract
The synthesis, crystal structure, and dielectric properties of the titled compounds were described. The structural symmetry was determined to be monoclinic P 2 1 / n (No. 14) space group. Based on the highly ordered array of alternating MgO 6 and SbO 6 octahedra, these double perovskites exhibited significant octahedral tilting distortion according to the Glazer's notation system a − a − c + . As the result of substituting different rare earth ions from La 3+ to Nd 3+ , both the tolerance factor ( t ) and coordination number (CN) were reduced simultaneously and the B-site lattice distorted more heavily with the increase in chemical pressure by adopting smaller Ln 3+ ion. For the investigation of dielectric properties, all the samples consistently presented weak frequency dependent characteristic with relatively low dielectric constant ( ε ') and low tangent loss (tan δ ). With the shrinkage of the Ln 3+ ion size, the corresponding ε ' decreased remarkably and the dispersive tan δ peaks around 300 K shifted to low temperature, indicating that the space-charge-hopping mechanism dominated permittivity property can be tuned by controlling the degree of lattice distortion via substituting different Ln 3+ ions. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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