Pressure-induced disorder in Rb₂ZnCl₄

Abstract

Rb(2)ZnCl(4) in the normal phase (T = 308-313 K) has been studied under pressure by means of single-crystal x-ray diffraction up to 3.84 GPa and Raman spectroscopy up to 5.9 GPa. No pressure-induced phase transition has been observed but an orientational disorder of the tetrahedra is enhanced with the pressure. At the same time a partial one-dimensional correlation of some chlorine atoms might be favoured at high pressures. Raman spectra in the incommensurate phase (T = 293 K) were collected to higher pressure (24.2 GPa) varying the pressure-transmitting medium. The hydrostaticity during the compression is shown to affect drastically the broadness of the Raman peaks, leading to an amorphous-like spectrum in the least hydrostatic case.

Electronic band structure and related properties of Rb 2 ZnCl 4 crystals at different hydrostatic pressures

“…This decrease of electronic polarizability in the range 10-20 GPa in turn may indicate for the decrease of the averaged strength of interatomic bonding in the crystal. The latter peculiarity is in qualitative agreement with the hydrostatic pressure induced amorphization of Rb 2 ZnCl 4 communicated in the reference [10]. The result obtained (Fig.…”

“…Our results on the DFT-based hydrostatic pressure simulations of Rb 2 ZnCl 4 do not contradict to the experimental study of the crystal in the reference [10], where the pressure induced orientational disorder of ZnCl 4 tetrahedra was detected in the range 0-20 GPa.…”

“…Trying to obtain manifestations of the experimentally observed amorphization of Rb 2 ZnCl 4 induced by the hydrostatic pressure [10] in its electronic properties, we have performed the corresponding DFT-based calculations of the crystal under the applied pressure in the range 0-50 GPa. For these calculations, spatial symmetry of the crystal was not fixing during structure optimization (relaxation) at different hydrostatic pressures.…”

“…One of the interesting experimental results obtained with Rb 2 ZnCl 4 is the conclusion of the hydrostatic pressure induced amorphization of the crystal observed in the range 0-20 GPa at the normal phase (Pnam) [10]. X-ray diffraction and Raman spectroscopy techniques confirm that an orientational disordering of the ZnCl 4 tetrahedra is enhanced with increasing pressure.…”

Temperature–Pressure Phase Diagram for Rb2ZnCl4 Crystals

“…We know of a paper studying the effect of hydrostatic pressure on the Raman spectra [1] of RTCZ crystals [11]. The authors did not observe an effect from hydrostatic pressure on the position of the paraelectric -incommensurate phase transition, but they established orientational disordering of the tetrahedra upon application of pressure.…”