Diffusion of Cobalt Ions into Crystals of Non-Stoichiometric Magnesium-Aluminate Spinel MgO•xAl2O3

Magnesium-aluminate spinel crystals MgO center dot xAl(2)O(3) have been grown by the horizontal directed crystallization method. The structure, phase and element composition of crystals were investigated using X-ray diffraction and scanning electron microscopy with a microanalysis system. The obtained MgO center dot xAl(2)O(3) crystals have a spinel structure with 1 <= x < 2. The temperature stability of the spinel phase for different stoichiometry was established. Diffusion doping of magnesium-aluminate spinel crystals with cobalt ions through the gas phase using cobalt oxide as a diffusion source has been studied under the temperature treatment of 1300-1500 degrees C. It was found that the penetration depth of the cobalt ions into the crystal body significantly increases with the increase of x. The diffusion coefficients of cobalt into MgO center dot xAl(2)O(3) (x = 1.00) at 1300-1500 degrees C and the efficient activation energy were estimated.