Phase transitions in typical fluorite-type ferroelectrics

Abstract

While ferroelectric hafnia ($\mathrm{Hf}{\mathrm{O}}_2$) has become a technically important material for microelectronics, the physical origin of its ferroelectricity remains poorly understood. The tetragonal $P{4}_2/nmc$ phase is commonly assigned as its paraelectric mother phase but has no soft mode at the Brillouin zone center. In this work, we propose that the paraelectric-ferroelectric transition in hafnia-like $Pca{2}_1$ ferroelectric family can be described by a $Pcca$-$Pca{2}_1$ transition, where the $Pcca$ mother phase will evolve into either the $Pca{2}_1$ ferroelectric phase or the centrosymmetric $P{2}_1/c$ monoclinic phase, depending on the strain conditions. The $Pcca$ phase is directly linked to both phases in the context of continuous phase transition. Hafnia is regarded as a special case of this family, in that it has accidental atomic degeneracy because all anions are oxygen. The theory is also correlated to the seven-coordination theory that explains the ferroelectricity in hafnia from a chemical perspective. In addition, the strain conditions to promote the ferroelectric phase in hafnia are discussed.

12 pages, 4 figures

References in corpus (6)

• An approximation to density functional theory for an accurate calculation of band-gaps of semiconductors
• Improved self-energy correction method for accurate and efficient band structure calculation
• Structural Polymorphism Kinetics Promoted by Charged Oxygen Vacancies in HfO${}_2$
• Stabilization of competing ferroelectric phases of HfO${}_2$ under epitaxial strain
• Trilinear coupling driven ferroelectricity in HfO${}_2$
• Ferroelectricity in $\mathrm{Hf}{\mathrm{O}}_2$ from a chemical perspective

Cited by in corpus (1)

• Anharmonic thermodynamics redefines metastability and parent phases in ferroelectric HfO2