Crystal growth, structure, and properties of KLa(CrO4)2

Abstract

The crystal growth and structure of KLa(CrO₄)₂, its spectroscopic properties, and thermal decomposition are reported. Crystals of KLa(CrO₄)₂ were obtained from an aqueous solution of K₂Cr₂O₇+ La₂O₃(3:1), maintained at 150 °C for 1 month: space group P2₁/c, Z= 4, with a= 8.729(2), b= 7.4752(7), c= 11.049(6)Å, and β= 92.42(1)°. They consist of parallel layers of [La(CrO₄)₂]_n^n– perpendicular to the a axis, the K⁺ being situated between these layers. Of the possible 36 absorption bands, 16 were observed in the i.r. and Raman spectra, which were analysed using factor-group analysis. The thermal decomposition proceeds in one step at 720–760°C according to KLa(CrO₄)₂→ LaCrO₃+ KCrO₂+O₂.