Misfit-Strain Phase Diagram, Electromechanical and Electrocaloric Responses in Epitaxial PIN-PMN-PT Thin Films

Yun Ou; Yingying Wu; Jinlin Peng

doi:10.3390/ma15217660

Misfit-Strain Phase Diagram, Electromechanical and Electrocaloric Responses in Epitaxial PIN-PMN-PT Thin Films

Materials (Basel). 2022 Oct 31;15(21):7660. doi: 10.3390/ma15217660.

Authors

Yun Ou^{1

2}, Yingying Wu², Jinlin Peng³

Affiliations

¹ Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment, Hunan University of Science and Technology, Xiangtan 411201, China.
² School of Materials Science and Engineering, Hunan University of Science and Technology, Xiangtan 411201, China.
³ All-Solid-State Energy Storage Materials and Devices Key Laboratory of Hunan Province, College of Information and Electronic Engineering, Hunan City University, Yiyang 413002, China.

Abstract

xPb(In_1/2Nb_1/2)O₃-(1-x-y)Pb(Mg_1/3Nb_2/3)O₃-yPbTiO₃ (PIN-PMN-PT) bulks possess excellent electromechanical coupling and dielectric properties, but the corresponding epitaxial PIN-PMN-PT thin films have not yet been explored. This paper adopts a nonlinear thermodynamics analysis to investigate the influences of misfit strains on the phase structures, electromechanical properties, and electrocaloric responses in epitaxial PIN-PMN-PT thin films. The misfit strain-temperature phase diagram was constructed. The results reveal that the PIN-PMN-PT thin films may exist in tetragonal c-, orthorhombic aa-, monoclinic M-, and paraelectric PE phases. It is also found that the c-M and aa-PE phase boundaries exhibit a superior dielectric constant ε11 which reached 1.979 × 10⁶ with u_m = -0.494%, as well as the c-M phase boundary showing a large piezoelectric response d₁₅ which reached 1.64 × 10⁵ pm/V. In comparison, the c-PE and M-aa phase boundaries exhibit a superior dielectric constant ε₃₃ over 1 × 10⁵ around um = 0.316% and the piezoelectric response d₃₃ reached 7235 pm/V. The large electrocaloric responses appear near the paraelectric- ferroelectric phase boundary. These insights offer a guidance for experiments in epitaxial PIN-PMN-PT thin films.

Keywords: PIN–PMN–PT; electrocaloric effect; ferroelectric thin films; misfit strain.

Grants and funding

This work was partially supported by the National Natural Science Foundation of China (11702092), and the project was supported by the Hunan Provincial Natural Science Foundation of China (2020JJ5182).