On the barocaloric properties of non-magnetic materials: application to K ₂ TaF ₇ and AgI

Abstract

In this paper, we theoretically discuss the effect of thermal expansion on the entropy change and the barocaloric properties of non-magnetic materials. For this purpose, we use a microscopic model Hamiltonian that takes into account the lattice vibrations beyond the harmonic approximation. The model was applied to calculate the entropy change and the barocaloric quantities ∆Siso and ∆Tad in the compounds K2TaF7 and AgI.

Chemical pressure as an effective tool for tuning the structural disordering and barocaloric efficiency of complex fluorides (NH4)3MF7 (M: Sn, Ti, Ge, Si)

“…etc) can be considered as an interdisciplinary one, combining the interests of solid state physics and chemistry, as well as materials science. The study of these phenomena is very informative and useful from fundamental and practical points of view, since it is connected, in the first case, with the development of understanding of the relationship between the chemical composition, symmetry, order/disorder of structure and the physical properties of solids under various external conditions, and, in the second case, with the search and design of effective solid refrigerants for alternative cooling technologies [1][2][3][4][5][6].…”

“…(∂T/∂p) S = (∂V/∂S) p = (∂V/∂T) p (∂T/∂S) p , (2) the extensive and intensive components of BCE represent reversible changes in entropy, ∆S BCE , and temperature, ∆T AD , under the influence of hydrostatic pressure under isothermal and adiabatic conditions, respectively, and largely depend on the thermal expansion of the material. This point reveals that, firstly, BCE can be realized in solids of different physical origin and, secondly, their largest values can be realized in the region of phase transitions, where the derivative (∂V/∂T) p demonstrates anomalous behavior.…”