Orthorhombic symmetry and anisotropic properties of $\ensuremath{\beta}\ensuremath{-}{\mathrm{PbO}}_{2}$

Orthorhombic symmetry and anisotropic properties of $β - {PbO}_{2}$

Piotr Fabrykiewicz, Radosław Przeniosło, Nevill Gonzalez Szwacki, Izabela Sosnowska, Emmanuelle Suard, and François Fauth

Phys. Rev. B 103, 064109 – Published 26 February 2021

Abstract

The structural and electronic properties of the rutile-type oxide $β - Pb O_{2}$ (plattnerite) are studied by neutron and synchrotron radiation diffraction and first-principles density functional theory (DFT) calculations. Both diffraction measurements and DFT calculations show that $β - Pb O_{2}$ has a $Ca {Cl}_{2}$ -type orthorhombic structure (space group $P n n m$ ) instead of the widely accepted $β - Pb O_{2}$ rutile-type tetragonal structure (space group $P 4_{2} / m n m$ ). This symmetry lowering in $β - Pb O_{2}$ is a robust effect observed at ambient pressure at temperatures between 100 and 400 K. The orthorhombic symmetry rules out the possibility of a semimetallic symmetry-protected state in $β - Pb O_{2}$ . Both diffraction measurements and DFT calculations show an anisotropy of thermal expansion, atomic vibrations, and elastic constants of $β - Pb O_{2}$ along the [100] and [010] directions.