Search

Using the first‐principles approaches, we obtain a phase diagram of AgNbO3 as a function of in‐plane epitaxial strain, and two phase transitions (from Pm to Cm and from Cm to Amm2) were found throughout the whole range of strain. In particular, our study shows that the antiferrodistortion (AFD) is misfit‐dependent. Our results indicate that compressive in‐plane lattice strain can enhance the AFD instability of AgNbO3, which originates from the stronger coupling between the out‐of‐plane lattice strain and AFD than coupling with in‐plane lattice strain. In order to overcome the overestimation of rotational angle caused by the underestimation of lattice parameters, we construct a Gibbs free energy under a certain external pressure to obtain a reasonable angle, which is about 8.39°. We expect our results may offer some insights for designing and fabricating AgNbO3 thin films with excellent antiferroelectric properties by using compressive strain engineering. [ABSTRACT FROM AUTHOR]

Lead‐based antiferroelectric (AFE) ceramics have attracted increasing interest in pulse power systems owing to their high‐energy storage and power densities. However, the single AFE–ferroelectric (FE) phase transition in conventional AFE materials usually leads to premature polarization saturation and low breakdown strength, which are disadvantageous to energy storage performance. In this study, high energy storage performance was achieved in Pb0.94−xLa0.04Cax[Nb0.02(Zr0.99Ti0.01)0.975]O3 (PLCNZT) AFE ceramics by constructing electric‐field‐induced multiple phase transitions. A maximum recoverable energy storage density of 12.15 J/cm3 and a high energy efficiency of 85.4% were obtained for the PLCNZT ceramic with x = 0.03 at 420 kV/cm. These excellent properties are attributed to the AFE–FE Ⅰ‐FE Ⅱ multiple phase transitions induced by Ca2+ doping, which effectively enhances the breakdown strength. This result indicates that field‐induced multiple phase transitions significantly improve the energy storage of AFE materials. [ABSTRACT FROM AUTHOR]

Barocaloric effects in a layered hybrid organic–inorganic compound, (C10H21NH3)2MnCl4, that are reversible and colossal under pressure changes below 0.1 GPa are reported. This barocaloric performance originates in a phase transition characterized by different features: A strong disordering of the organic chains, a very large volume change, a very large sensitivity of the transition temperature to pressure and a small hysteresis. The obtained values are unprecedented among solid‐state cooling materials at such low pressure changes and demonstrate that colossal effects can be obtained in compounds other than plastic crystals. The temperature‐pressure phase diagram displays a triple point indicating enantiotropy at high pressure. [ABSTRACT FROM AUTHOR]