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Enhanced diffusion in sapphire during microwave heating
- JANNEY, M. A, KIMREY, H. D, ALLEN, W. R, KIGGANS, J. O
- Journal of materials science 1997 v.32 no.5 pp. 1347-1355
- activation energy, furnaces, microwave treatment, oxygen, stable isotopes, wafers
- The diffusion of oxygen in sapphire was accelerated by heating in a 28 GHz microwave furnace as compared with heating in a conventional furnace. Tracer diffusion experiments were conducted using 18O. Single crystal sapphire wafers with a (1 0 1 2) rhombohedral planar orientation were used as the substrate. Concentration depth profiling was done by proton activation analysis using a 5 MeV Van de Graaff accelerator. The diffusion of 18O was greatly enhanced by microwave heating as compared with conventional heating in the 1500–1800°C range. The apparent activation energy for 18O bulk diffusion was determined to be 390 kJ mol-1 with microwave heating and 650 kJ mol-1 with conventional heating.