The crystal structure of Rb_2SeO_4 at high temperature

摘要

The crystal structure of Rb_2SeO_4 in its high-temperature phase is reported for the first time. Powder diffraction data collected at T=898K show that it is hexagonal (a = 6.3428(1)A, c = 8.5445(l)A, V= 297.71(1) A3, space group P6_3lmmc (194), Z = 2) and is isostructural to Tl_2SeO_4, thus belonging to the alpha-K_2SO_4 structure type. DSC measurements indicate that the phase transition occurs at T=818 K.