Journal of Inorganic Materials ›› 2022, Vol. 37 ›› Issue (7): 787-794.DOI: 10.15541/jim20210612

Special Issue: 【信息功能】电介质材料 【虚拟专辑】计算材料

• RESEARCH ARTICLE • Previous Articles     Next Articles

Pressure on the Structure and Thermal Properties of PbTiO3: First-principle Study

WEN Zhiqin(), HUANG Binrong, LU Taoyi, ZOU Zhengguang   

  1. School of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China
  • Received:2021-09-29 Revised:2021-11-27 Published:2022-07-20 Online:2021-12-16
  • About author:WEN Zhiqin (1987-), male, lecturer. E-mail: wenzhiqin@glut.edu.cn
  • Supported by:
    Guangxi Natural Science Foundation(2019GXNSFBA245092);Guangxi Natural Science Foundation(2019GXNSFGA245006);Science and Foundation of Guilin University of Technology(GUTQDJJ2019116)

Abstract:

PbTiO3 (PTO) is an important ferroelectric functional material, but its structure, stability, mechanical property, and thermodynamic property under pressure is still unknown, leading to restriction in applying in the field of electronic communication. Here, first-principles calculations based on density functional theory was performed to study the structure and thermal properties of pre-perovskite phase PbTiO3 (PP-PTO), ferroelectric tetragonal phase PbTiO3 (TP-PTO), and paraelectric cubic phase PbTiO3 (CP-PTO) under pressure. It is found that their compressibility in descending order is PP-PTO>TP-PTO>CP-PTO. Under considered pressure, three PTO phases have not undergone a phase transition analyzed by band structure and density of states, and their band gap gradually decreases with increasing pressure. Among them, the TP-PTO changes from an indirect to a direct band gap semiconductor at 20 GPa, while the others remain a direct band gap semiconductor. Those PTO phases are mechanically stable and anisotropy from 0 to 30 GPa. Furthermore, their comprehensive mechanical properties increase and anisotropy firstly decreases and then increases with increasing pressure. Analysis based on quasi- harmonic Debye approximation theory was performed to study the influence of temperature and pressure on Debye temperature, entropy and heat capacity. The results illuminate that Debye temperature decreases with temperature increase, nevertheless, pressure has the opposite effect, which elucidates that the order of covalent bond from strong to weak is CP-PTO>TP-PTO>PP-PTO. Entropy and heat capacity of PTO increase with rising temperature, but decrease with the increase of pressure.

Key words: PbTiO3, electronic structure, elastic mechanics, first-principles

CLC Number: