Elasticity of ω-phase zirconium

Compressional (V(P)) and shear wave (V(S)) velocities as well as unit-cell volumes of the omega phase of Zr have been measured at high pressure (6.9-10.9 GPa) at room temperature using ultrasonic interferometry in conjunction with synchrotron x radiation. Both V(P) and V(S) as well as the adiabatic bulk (K(S)) and shear (G) moduli exhibit monotonic increase with increasing pressure. Using a finite strain equation of state approach, the elastic bulk and shear moduli and their pressure derivatives are derived from the directly measured velocities and densities, yielding K(S0)=104.0 (16) GPa, G(0)=45.1 (9) GPa, K(S0)(')=2.8 (2), and G(0)(')=0.6 (1) independent of pressure calibration. The low pressure dependence of K(S0) and G(0) may be attributed to the pressure-induced progressive s-d electron transfer in the omega-Zr as suggested by previous Raman studies as well as static compressions at high pressure.