Application of the method of secondary-ion mass spectroscopy to the study of heterodiffusion in alkali-halide crystals

The present paper gives the results of investigations of the high-temperature diffusion of Na and Mg ions into single crystals of potassium bromide by the method of secondary-ion mass spectrometry (SIMS). It is demonstrated that the diffusion profiles are nonelementary in character, and the diffusion in the near-surface layer is decelerated. To determine the volume diffusion coefficient, the diffusion profiles must be approximated for depths ≥1 μm. The efficiency of the procedure for determining the diffusion coefficient is confirmed by a comparison of the diffusion coefficients for Na ions determined in the present work with their values obtained by other methods having high reliability and measurement accuracy. The diffusion coefficients of the magnesium impurity are determined for various initial chemical states.