Influence of chromium and yttrium doping on transport phenomena in monocrystalline alpha-alumina
Abstract Electrical conductivity of single crystalline Al 2 O 3 doped with Cr 2 O 3 (800 and 8000 ppm) and Y 2 O 3 (1000 ppm) was measured as a function of temperature (1200°C up to 1700°C) and oxygen partial pressure (1 atm down to 10 −15 atm). The electrical conductivity is found to increase at both high and low oxygen partial pressure, these variations being more pronounced in the case of the yttrium-doped sample. Chemical diffusion coefficients in yttria-doped alpha-alumina single crystals have been deduced from electrical conductivity measurements performed during the equilibration of the gas-oxide system. The results obtained seem to indicate the precipitation of a second phase (yttrogarnet) at temperatures lower than 1650°C.