Features of the Behavior of the Barocaloric Effect near Ferroelectric Phase Transition Close to the Tricritical Point

Abstract

A detailed study of the effect of temperature and pressure on heat capacity, entropy and hysteresis phenomena near the ferroelectric phase transition in ammonium sulfate (AS) was performed. An analysis of experimental results within the framework of the phenomenological theory showed that taking into account the temperature-dependent part of the anomalous entropy leads to a significant increase in the barocaloric effect (BCE). The maximum values of extensive and intensive BCE near the tricritical point are outstanding: Δ S B C E m a x ≈ 85 J/kgK, Δ T A D m a x ≈ 12 K and can be achieved at low pressure ∼0.5 GPa.

Keywords

• polymorphic phase transformation
• phase diagram
• order–disorder phenomena
• entropy
• barocaloric effect