The fracture behaviour of Chromium- and Titanium-doped sapphire monocrystals

The influence of chromium and titanium on the fracture behaviour of sapphire crystals was analysed by means of crack indentation pattern, and the critical stress intensity factors for the easiest spalling planes of the sapphire were measured from the crack lengths at the indents. Together with information on the room temperature plasticity of sapphire the results allow conclusions on the influence of the dopants on crystallographic and glass-like fracture features, respectively.