Electrocaloric effect (ECE) has the potential applications in solid-state refrigeration with the features of high efficiency and environmentally friendly. Large adiabatic temperature change in a wide temperature range is needed for electrocaloric effect to meet the requirement of commercially application. In this work, giant electrocaloric effect is found in PbTiO3 nanoparticle with double-vortex domain structure in a wide temperature range by using phase field method, which the lowest and highest adiabatic temperature change (ΔT) is 7.2 K and 16.5 K, respectively. The influence of misfit strain on the ECE of PbTiO3 nanoparticle with the double-vortex domain structure is investigated, and results show that the compress misfit strain can enhance the ECE, but the tensile misfit strain reduces the ECE. This work reveals a way to obtain giant ECE of ferroelectric materials by domain engineering and strain engineering in a wide temperature range.

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β-Ga2O3 based solar-blind photodetectors have strong radiation hardness and great potential applications in Earth's space environment due to the large bandgap and high bond energy. In this work, we investigated the photoelectric properties influence of β-Ga2O3 photodetector irradiated by 100 MeV high-energy protons which are the primary components in the inner belt of the Van Allen radiation belts where solar-blind photodetectors mainly worked. After proton irradiation, due to the formation of more oxygen vacancies and their migration driven by bias at the metal/semiconductor interface, transportation of carriers transforms with electron tunneling conduction for low-resistance state and thermionic emission for high resistance state. As a result, the current–voltage curves of β-Ga2O3 solar-blind photodetectors exhibit apparent hysteresis loops. The photoresponsivity of β-Ga2O3 photodetectors slightly increases from 1.2 × 103 to 1.4 × 103 A/W after irradiation, and the photoresponse speed becomes faster at a negative voltage while slower at positive voltage. The results reveal the effects of high-energy proton irradiation on β-Ga2O3 solar-blind photodetectors and provide a basis for the study of their use in a radiation harsh environment.

The elastocaloric effect in the Bi4Ti3O12(BIT) ferroelectric nanoparticle with vortex domain structure was studied using a phase field simulation in this work. A transformation from the negative elastocaloric effect to positive elastocaloric effect which is associated with vortex domain structure is found under the uniaxial stress in the BIT nanoparticle. In addition, the negative adiabatic temperature change is found under the biaxial compressive stress, and the positive adiabatic temperature change is found under the biaxial tensile stress. The results of this study provide an explanation of the mechanism of the negative/positive elastocaloric effect in the low-dimensional ferroelectrics from the viewpoint of the domain structure.

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