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.

Keywords:

• Sodium trihydrogen selenite
• new phase transitions
• dielectric properties
• polarization
• internal friction

Additional information

Funding

This work was supported by the Ministry of Science and Higher Education of the Russian Federation in the framework of the state assignment (Project No. FZGM-2023-0006).