Refractometry of Rb2ZnCl4 crystals under uniaxial pressure

Abstract

The influence of uniaxial pressures applied along the main crystallophysical directions on the dispersion and temperature dependences of the refractive index n_i of Rb₂ZnCl₄ crystals has been investigated. The n_i value is found to be rather sensitive to uniaxial pressures, whereas uniaxial stress does not change the character of the dispersion and temperature dependences of n_i. The pressure-induced changes in electronic polarizability α_і, refraction R, and the parameters of UV oscillators are studied for mechanically deformed Rb₂ZnCl₄ crystals. The contributions of the UV and IR oscillators to the changes in n_i at different temperatures, in different spectral regions, and under different mechanical stresses are estimated. The points of paraelectric–incommensurate–commensurate phase transitions (PTs) are found to undergo a significant pressure-induced shift to different temperature regions, depending on the pressure-application direction.