Predicting phase transitions in PbTi O3 using zentropy through quasiharmonic phonon calculations

Nigel Lee En Hew, Shunli Shang, Zi Kui Liu

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

According to x-ray diffraction (XRD) measurements, PbTiO3 undergoes a phase transition from a tetragonal ferroelectric (FE) phase to a cubic paraelectric phase at 763 K. However, x-ray absorption fine-structure (XAFS) measurements indicate that PbTiO3 is locally tetragonal even after the phase transition. The difference in these results is because XAFS measurements can probe local features of a structure, while XRD averages over such local features. For both measurements to be consistent, PbTiO3 is macroscopically cubic but locally tetragonal after the phase transition. Despite this, most models, such as the Landau-Ginsburg-Devonshire theory and effective Hamiltonians, are still unable to explain this phenomenon. Moreover, these methods involve model parameters fitted to experimental or theoretical data and do not consider other tetragonal configurations, such as domain walls, to predict the phase transition. In our previous study, we used our zentropy approach to predict the phase transition by considering the tetragonal FE ground-state configuration and the tetragonal 90 ° and 180 ° domain wall configurations with their total energies at 0 K. In this paper, the Helmholtz energies of the three configurations are obtained from density functional theory calculations through energy-volume curves and phonon calculations. The predicted phase transition temperature using the meta-GGA r2SCAN and revised multiplicities of configurations is 716 K, showing good agreement with the experimental value of 763 K.

Original languageEnglish (US)
Article number184103
JournalPhysical Review B
Volume110
Issue number18
DOIs
StatePublished - Nov 1 2024

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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