On phase transitions in the NaH3(SeO3)2 crystal

Abstract

Experimental studies of elastic, anelastic, dielectric, polarization and thermal properties of sodium trihydrogen selenite NaN3(SeO3)2 crystal in the temperature range of 5–210 K. Above the ferroelectric Curie temperature, an intermediate ferroelastic β′-phase was detected between the paraelectric α-phase and the ferroelectric β-phase. The phase transition from α- to β′–phase at 195 K is classified as a first-order transition, accompanied by the occurrence of spontaneous deformation x 6s. When the temperature decreases, in addition to the previously known transition from the β-phase to the γ-phase, a new phase transition from the γ-phase to the nonpolar η-phase at a temperature of 112.4 K was detected.