Pressure derivatives of the elastic moduli of niobium and tantalum

Abstract
The pressure derivatives of the adiabatic elastic moduli of single‐crystal Nb and Ta have been measured ultrasonically at 25 °C. The results are in good agreement with shock compression data but differ, particularly for Nb, with previous ultrasonic work. Experimental evidence is presented which indicates that the discrepancy in results may be due to nonideal specimen‐transducer geometries which cause an apparent dependence of the observed pressure derivatives on the ultrasonic carrier frequency.