Partial and integral molar thermodynamic properties of Ni xTe 1− x(s, x = 0.595 to 0.630) alloys

Abstract

The vapour pressure of tellurium over non-stoichiometric Ni x Te 1− x ( x = 0.595, p) and ( x = 0.610, p 1) have been measured between 981 to 1150 K using a Knudsen-effusion mass-loss technique and can be represented by the equations: log 10 ( p kPa )±0.062 = 8.050 − 11706( K T ) , and log 10 ( p 1 kPa )±0.017 = 7.569−11944( K T ) . Using the vapour pressures of tellurium over tellurium metal the relative chemical potentials of Te in the two alloys were calculated. The molar Gibbs free energy of formation of the nickel-rich alloy Ni 0.630Te 0.370 was obtained by measuring tellurium pressures p 2 over biphasic (Ni + nickel-rich alloy) in the temperature range 1071 to 1188 K. The vapour pressures are given by the equation: log 10 ( p 2 kPa )±0.057 = 7.399 − 12303( K T ) , from which the standard molar Gibbs free energy of formation of the nickel-rich alloy was calculated to be Δ f G m o ( Ni 0.63Te 0.37, s , T)/ ( kJ·mol −1 )±0.21 = −22.29±0.00198( T K ) .