Investigation of Solid-Solid Transition in Ti and Zr at High Pressure by Electrical Resistivity

The group IV metals Ti and Zr are isoelectronic and crystallize in a hexagonal closed packed structure at ambient conditions. Herein, the electrical resistivity of Ti and Zr at room temperature with increasing pressure up to 20 GPa is reported using a 4-wire resistivity method. The slope of their resistivity against pressure changes value at various pressures. At 10 GPa, resistivity of Ti increases with pressure whereas Zr resistivity decreases with pressure. The opposite behavior is interpreted to be due to incoherent scattering in Ti versus coherent scattering in Zr, as both undergo solid alpha -> omega transition. By comparing the Zr result with a previous study that combined in situ X-ray synchrotron with compressional and shear wave velocity measurement, the boundaries of the region of alpha -> omega phase coexistence are constrained in Zr to be 4-8 GPa. The Ti result will be valuable for constraining its boundary when such in situ velocity measurement becomes available for Ti as well.