Crystal structure and ab initio calculations of CaZrO3

Calcium zirconate (CaZrO3), because of its high melting point, low thermal expansion coefficient, high strength and excellent corrosion resistance against alkali oxides, is a good candidate for a novel refractory material. CaZrO3 is mostly synthesized by the reaction in the solid state but the material obtained in such a way often suffers low bulk density, high porosity and other defects which lower its potential application value. To overcome these obstacles a novel synthesis method by an electric arc melting technique was proposed. The crystal structure of melted CaZrO3 was compared with a conventionally synthesized material. According to X-ray measurements the obtained material has an orthorhombic perovskite-like structure. Its stoichiometry was confirmed by the scanning electron microscope and EDS analysis. The material is almost poreless with its density close to theoretical. The estimated crystal structure parameters were used to calculate the electronic structure of CaZrO3 using the full potential linear augmented plane wave (FLAPW) method. It has been found that CaZrO3 is an insulator with the energy band gap of 4.1 eV. The Ca-O bond is typically ionic while Zr-O bond is of a significant covalent character.