Pressure-Induced Insulator-to-Metal Transition in TbBaCo₂O_5.48

TbBaCo₂O_5.48 has been studied by high-pressure synchrotron x-ray diffraction together with resistivity measurements as a function of temperature and pressure. It was found that under pressure a structural phase transition takes place corroborating with a sluggish insulator-to-metal transition. An onset of the metallic state was deduced from a gradual drop of resistivity at the range 3–10 GPa culminating into the change in sign of dR/dT, from negative to positive, at P≥10  GPa; at the same pressure range there is a change of lattice strain components calculated from the unit cell dimensions. The changes in structural and transport properties are very similar to those found on heating at ambient pressure implying a common mechanism.