Non-Destructive Method of Diffusion Parameters Determination in Solids

Abstract

Diffusion of nitrogen implanted in tungsten and molybdenum single crystals has been investigated at temperature about 0.3 Tm (Tm is the melting point). Existence of several dopant atom fluxes is found in subsurface region of the ion implanted material. The diffusion coefficients of the nitrogen connected with the radiation damages and that with the bulk diffusion mechanism are determined. Change of the nitrogen surface concentration has been measured by Auger electron spectroscopy. Initial distribution of the nitrogen and diffusion profiles for various annealing time have been determined by secondary-ion mass-spectroscopy technique. Transmission electron microscopy and X-ray diffraction investigations were used to study the microstructure and phase state of the implanted samples.

Diffusion Parameters Determination by a Non-Destructive Technique with an Assumption of Mass Exchange on the Surface

“…It should be also mentioned that the reference data were obtained within higher temperature ranges. Accounting of the nitrogen vaporization gives about twice lower values for D as compared with those obtained in [1] where the boundary supposed to be fully reflective. High value of the k coefficient is the evidence of intensive nitrogen desorption from the surface of tungsten samples.…”

“…Results on the nitrogen surface concentration which change during the annealing of the ionimplanted tungsten samples are presented in [1]. Tungsten belongs to the metals with an endothermic nitrogen solution [3].…”

“…The first maximum is associated with the diffusion by the radiation damages. The second one is connected with the bulk diffusion mechanism [1]. Assuming that the fluxes with different diffusivities are independent, nitrogen surface concentration was determined as a sum of concentrations delivered by each flux:…”

“…In the reference [1] non-destructive technique for the diffusion constant determination is presented. To carry out this technique it is necessary to form initial dopant concentration profile in the sample's sub-surface layer with a maximum at a definite depth.…”