Synthesis, crystal structure, thermal analysis and dielectric properties of two mixed trichlorocadmiates (II)

Bulletin of Materials Science

关键词: X-ray diffraction;    dielectric study;    phase transition;    DSC;    IR absorption;    Raman scattering.;   

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

K$_{0.57}$(NH$_4$)$_{0.43}$CdCl$_3$ and K$_{0.25}$(NH$_4$)$_{0.75}$CdCl$_3$ are orthorhombic, space group Pnma, $Z = 4$, with $a = 8.8760(4)$ $\AA$, $b = 3.9941(2)$ $\AA$, $c = 14.7004(7)$ $\AA$, and $Z = 4$, $a = 8.9567(9)$ $\AA$, $b = 3.9957(4)$ $\AA$, $c = 14.855(2)$ $\AA$, respectively. Final R values are 0.01 and 0.02 for 608 and 834 reflections, respectively. In both the materials, the crystal structure has been determined by X-ray single crystal analysis at room temperature (293 K). The compound structures consist of K$^+$ (or NH$^+_4$) cations and double chains of CdCl$_6$ octahedra sharing one edge extending along $b$-axis. The mixture of KA$^+$/NH$^+_4$ cations are located between the double chains ensuring the stability of the structure by ionic and hydrogen bonding contacts N/K–H$\ldots$ Cl. Spectroscopic, dielectric and differential scanning calorimetry(DSC) measurements were performed to discuss the mechanism of the phase transition. These studies show that these materials, K$_{0.57}$(NH$_4$)$_{0.43}$CdCl$_3$ and K$_{0.25}$(NH$_4$)$_{0.75}$CdCl$_3$, undergo a phase transition at 438 and 454 K, respectively.

【 授权许可】

CC BY