Tetrahedral rotations in alkaline-earth metal orthovanadates

• Main Authors: Saha, Amartyajyoti, Birol, Turan
• Format: Journal Article
• Language: English
• Published: 28-09-2023
• Subjects: Physics - Materials Science
• DOI: 10.48550/arxiv.2308.10342

Phys. Rev. Materials 7, 094407 (2023) The alkaline-earth orthovanadate Sr$_3$V$_2$O$_8$ with the palmierite
structure is reported to host a dielectric anomaly as well as a structural
phase transition above the room temperature. With V$^{5+}$ ions and tetrahedral
oxygen coordination, the crystal structure of this compound is not studied in
detail from first principles yet. In this work, we perform a detailed analysis
of the crystal structure and instabilities of M$_3$V$_2$O$_8$ ($\text{M} =
\text{Ca, Sr, Ba}$) orthovanadates with the palmierite structure using first
principles density functional theory. We find that as the M$^{2+}$ cation size
decreases, a significant structural distortion that changes the symmetry from
$R\bar{3}m$ to $C2/c$ emerges. This change is accompanied with a rotation of
the oxygen tetrahedra. Our calculations also indicate that the polar
instability in these compounds are suppressed by these tetrahedral rotations.