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

K0.57(NH4) 0.43CdCl3 and K0.25(NH4) 0.75CdCl3 are orthorhombic, space group Pnma, Z = 4, with a = 8.8760(4) A, b = 3.9941(2) A, c = 14.7004(7) A, and Z = 4, a = 8.9567(9) A, b = 3.9957(4) A, c = 14.855 (2) A, 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 CdCl6 octahedra sharing one edge extending along b-axis. The mixture of K+/NH $_{{4}}^{{+}}$ cations are located between the double chains ensuring the stability of the structure by ionic and hydrogen bonding contacts N/K–H …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, K0.57(NH4)0.43CdCl3and K0.25(NH4)0.75CdCl3, undergo a phase transition at 438 and 454 K, respectively.