Ceria-Doped Yttria Crystals, Their Structure and Electrical Conductivity

Y₂O₃ and ceria-doped yttria crystals were prepared by the oriented crystallization in a cold container in order to modify the quality of crystals, their structure and electrical properties. Ceria addition results in an increased phase stability of the melt and also the solid phase. The crystals of ceria-doped yttria have a rod-shaped character in comparison with the mosaic structure of undoped yttria. The distribution and valence of cerium ions in the crystals are inhomogeneous. The addition of ceria results in the increase of electrical conductivity of yttria. An anomaly observed in the Arrhenius dependences of conductivity versus temperature could be explained by the excess vacancies formed by dislocations created during the crystallization of mosaic blocks or rods. The behaviour of electrical conductivity is in a good agreement with that of microhardness.