The pressure dependence of the electrical resistivity of potassium alloys

Abstract

Values of the residual resistivity, rho , and the volume derivative of the residual resistivity xrho (=(1/ rho )( delta rho / delta V)T) have been obtained for KRb, KCs, KNa and RbK alloys. The volume derivatives of the resistivity have also been obtained from values of the diffusion thermopower using a pseudopotential relation based on a nearly free electron model. In dilute KRb alloys the values of xrho from the resistivity and from the thermopower are -1.41+or-0.15 and -1.31+or-0.07 respectively, showing good agreement. The agreement is less satisfactory in RbK and KCs with xrho =-0.9+or-0.1 and -1.44+or-0.07 respectively in the former alloys and with xrho =-1.9+or-0.2 and -1.45+or-0.07 respectively in the latter alloys. In KNa there is an order of magnitude disagreement between xrho deduced for the resistivity (-0.07+or-0.02) and xrho deduced for the thermopower (-0.78+or-0.07). Calculations using an alternative set of pseudopotentials have been made in KRb, RbK and KNa. In this case the values of xrho deduced from the thermopower are higher by approximately 0.1 leaving the above conclusions unchanged. A number of possible reasons for the disagreement, particularly in KNa, are examined. Values of rho and xrho are also given for a number of concentrated KRb alloys.