Zur Messung von Diffusionskoeffizienten heterovalenter Zusätze in lonenkristallen

Abstract

An experimentally simple method is outlined which allows to measure chemical diffusion coefficients of heterovalent ions in ionic crystals with the help of resistivity measurements. After the deduction of the pertinent equations for an evaluation of the resistivity measurements, the chemical diffusion coefficients of Sr²⁺ in KCl and of Pb²⁺ in AgCl are determined. From these values the corresponding selfdiffusion coefficients are calculated. Results are: D⁰_Sr(KCl, 580°C) = 2,5 • 10^-8 cm²/sec and D⁰_Pb(AgCl, 270°C) = 4,0 • 10^-9 cm²/sec at the solubility limits of SrCl₂ and PbCl₂, respectively. The possibilities and limits of application of the proposed method for measuring chemical diffusion in ionic crystals are discussed.