Effect of hydrostatic pressure on the structural phase transition in K2OsCl6:a35Cl nuclear quadrupole resonance

Abstract

The 35Cl nuclear quadrupole resonance frequency is reported in K2OsCl6 at temperatures in the vicinity of the structural phase transition for three externally applied hydrostatic pressures. The phase-transition temperature, Tc, decreases linearly with pressure, and the pressure coefficient, (dTc/dP), is measured to be −(2.2 ± 0.3) × 10−2 K∙MPa−1. This value is compared with that measured for K2ReCl6 and is consistent with the prediction of a calculation based on a modified rigid-sphere model. Measurements of (∂v/∂P)T show precursor behaviour as Tc is approached from the high-temperature cubic phase.