V. N. Voronov

Barocaloric effect near the structural phase transition in the Rb2KTiOF5 oxyfluoride

The barocaloric effect (BCE) in the oxyfluoride Rb2KTiOF5 has been studied in the vicinity of the structural phase transition at a temperature of 215 K in the pressure range 0—0.6 GPa. It has been established that the extensive and intensive barocaloric effects are ΔSBCE ∼ −46 J/kg K and ΔTAD ∼ 18 K, respectively, over a wide temperature range 215—280 K. The studies performed have shown that the external hydrostatic pressure is a very effective tool for changing the entropy and temperature of the crystals which undergo structural phase transitions accompanied by a large change in the entropy.

Heat capacity, p-T phase diagram, and structure of Rb2KTiOF5

AbstractElpasolite Rb2KTiOF5 (space group, Fm

Lattice dynamics and hydrostatic-pressure-induced phase transitions in ScF3

\bar 3

Thermodynamic properties and structure of oxyfluorides Rb2KMoO3F3 and K2NaMoO3F3

m, Z = 4) was synthesized using a solid-phase reaction method. The temperature dependences of the heat capacity, the unit cell parameters, the structure, the permittivity, the response to an external pressure, and the Raman spectra were studied. A nonferroelectric phase transition was revealed at T0 = 215 K; the transition is accompanied by a tetragonal distortion of the unit cell (space group I4/m, Z = 10) and a change in the entropy (ΔS0 = Rln8), which is anomalously large for perovskite-like oxyfluorides with atomic cations. The specific features of the mechanism of structure distortion are discussed in combination with the previous experimental data obtained for cryolite (NH4)3TiOF5 and elpasolite Rb2KGaF6.

A Raman Study of Hydrostatic Pressure Induced Phase Transitions in Rb 2 KInF 6 Crystals

AbstractA new chemical compound, (NH4)2KWO3F3, was synthesized. The Rietveld-refined crystal structure was found to be cubic at room temperature and to belong to the elpasolite family (space group

Structures of distorted phases and critical and noncritical atomic displacements of elpasolite Rb2KInF6 during phase transitions

Fm\bar 3m