Negative thermal expansion in electron doped PbVO3-xFx

Abstract

PbVO3 with a large polar tetragonal distortion is a candidate for a negative thermal expansion (NTE) material because it shows a transition to cubic phase accompanied by 10.6% volume shrinkage under pressure. Here, we demonstrate a giant NTE in fluorine substituted PbVO3-xFx. Tetragonal-to-cubic transition was observed at x ∼ 0.20. Temperature induced transition was observed for PbVO2.79F0.21, giving rise to a volume shrinkage on heating with a dilatometric linear coefficient of thermal expansion ∼-358 ppm K-1. The volume difference of 10.8% between the tetragonal and the cubic phases is the largest among the NTE materials.