Bulk Diffusion of Gold in Single-Crystal Iridium

摘要

The method of secondary-ion mass spectrometry was used to measure coefficients of bulk diffusion of gold in a temperature range of 1300-2000K (0.48-0.75 T_m) in single-crystal iridium annealed in an ultrahigh vacuum. The parameters of the Arrhenius plots of these diffusion coefficients were found to be as follows: the enthalpy of activation Q =423.2 +- 4.6 kJ/mol and the preexponential factor D_0 = (4.92 +- 0.2) X 10~(-5) m~2/s. It was shown, using the linear dependence of the enthalpy of activation of self-diffusion Q_(SD) of d transition metals on the universal homologous temperature V = 0.3 T_m +0.7 #theta#, that the available parameters of bulk self-diffusion of iridium (1) agree completely with the linear dependence Q_(SD)(V) for the d transition metals and that the corrected value is (Q_(SD))_(Ir) = 449 kJ/mol. The difference of the enthalpies of activation of the bulk diffusion of gold and of self-diffusion in iridium qualitatively agrees with the available charge dependences of such differences for the bulk diffusion of isocoric impurities in single crystals of tungsten and gold (2-8).