Study of impurities in alpha-Al2O3 powders and crystals using EPR spectroscopy

This paper presents the results of electron paramagnetic resonance spectroscopy studies on Al2O3, in powders, granules and crystal form. The EPR investigations were carried out to identify impurities in the studied materials. The Al2O3 powders and granules were supplied by different manufacturers and crystals were grown by a micro-pulling down (MPD) method. The results of the EPR measurements revealed the presence of a small amount of iron and chromium ions in the nominally pure feed materials as well as in the grown crystals. Analysis of the EPR line intensity showed that the concentration of iron ions is much higher as compared to chromium ion concentration.