Relationship between the nature of dopants and charging or mechanical properties of ceramics

The effect of doping elements in alumina should be a function of the different characteristics of the elements such as size, charge and electronegativity. For understanding this effect, we have studied, (i) the diffusion of different metallic elements (chromium, silver, copper) in alumina single crystals, (ii) the evolution of electrical and mechanical properties of different doped samples. The results show that the dissolution of silver, copper and chromium in sapphire decreases the mechanical toughness and increases the charge capacity. However, a high chromium concentration resulting in Cr₂O₃ cluster formation decreases the trapping energy and increases the alumina toughness