Elastic properties and superconductivity of V 3 Si at high pressure

The pressure derivatives of the single crystal elastic constants of V 3 Si have been measured at 77 and 298 °K, and the pressure derivative of the shear modulus c s = ( c 11 – c 12 )/2 has been measured between 37 and 298 °K. The V 3 Si crystal was of the kind which undergoes the Batterman‐Barrett low temperature structural transformation. The results differ significantly from those for nontransforming V 3 Si in that for transforming crystals (∂ c /∂ p ) T shows a negative minimum at about 80 °K and is positive below about 50 °K. This is in semiquantitative agreement with the negative pressure coefficient for the structural transformation measured by Chu. From the elastic data the elastic Grüneisen parameters and the pressure coefficients (∂ T c /∂ p ) of the superconducting transition temperature were calculated in the anisotropic Debye approximation. For nontransforming V 3 Si the calculated value of (∂ T c /∂ p ) shows the correct sign, but is two and one‐half times larger than the experimental value. The calculated (∂ T c /∂ p ) is for transforming V 3 Si considerably smaller than for nontransforming samples.