Coordination environment-induced ionic–electronic transport transition in LiVO3

Abstract

Lithium metavanadate (LiVO3) is a typical ionic conductor with a monoclinic pyroxene-type structure at ambient conditions. Here, we investigated the structural and electrical transport properties of LiVO3 under high pressures by combining in situ Raman scattering, x-ray diffraction, impedance spectroscopy measurements, and first-principles calculations. All experimental and theoretical results demonstrated that LiVO3 undergoes a structural transition from monoclinic to triclinic phase at around 5 GPa, during which partial VO4 tetrahedrons are transformed into a VO6 octahedron. The ion migration of LiVO3 was significantly suppressed above 5 GPa and an ionic–electronic transition was discovered at 10.7 GPa. The structural evolution involving coordination environment change results in an electron density rearrangement around Li and O atoms, which are responsible for the transformation of electrical transport mechanism in LiVO3 under high pressures. These results expand our understanding of the electrical and structural properties of LiVO3 under high pressures and provide insights into the pressure effects on ion migration in solid electrolytes.