ACTIVATION-ENERGY OF SINGLE VACANCY FORMATION IN PLATINUM

The formation energy of single vacancies in platinum (purity 5 N) has been measured resistometrically in thin wires, quenched exponentially from temperatures 650 ÷ 1150 °C. Attention has been paid to the establishment of the effective temperature, corresponding to the total concentration of vacancies. In pure samples, the influence of this correction on EF is rather small, whereas the uneven distribution of temperature along the specimen length is of greater importance. The size-effect correction partially improves the curvature of the Arrhenius plot at low temperatures. The quenching rate in helium gas was high enough to retain almost all vacancies present in the solid solution. For evalution of experimental data the method of least squares was used, taking into account the changing scale of the Arrhenius plot. The most probable value of formation energy EF is 1·31±0·05 eV; it is compared with results of other authors and the reason of large spread of experimentally found formation energies is discussed. © 1979 ACADEMIA, Publishing House of the Czechoslovak Academy of Sciences.