Multiorder and structural mechanism of the LiRh₂O₄ tetragonal phase formation

Abstract

The results of the group-theoretical analysis of phase transitions in the LiRh2O4 are presented. It is found that the critical irreducible representation inducing phase transitions and multiorder in this substance is the eight-dimensional representation \(~{{k}_{{11}}}{{{\text{\tau }}}_{5}} + {{k}_{{10}}}{{{\text{\tau }}}_{2}}\). It is shown that the multiorder and the structural mechanism of formation of the tetragonal phase of lithium rhodonite are related to the displacements of oxygen atoms, the tilts of the [RhO]6 octahedra, and the ordering of the rhodium t2g orbitals.