Thermal expansion coefficients of high-T_c superconductor substrate NdGaO₃ single crystal

We report the temperature dependence of lattice constants for a NdGaO ₃ single crystal grown by the Czochralski method and thermal expansion coefficients which were obtained for the first time. Lattice mismatch between the NdGaO₃ substrate and YBa₂Cu₃O _x superconducting film is 0.27% at elevated temperatures and the appropriate expansivities are similar. The crystalline quality of deposited YBa₂Cu₃O_x films on NdGaO₃ by the laser ablation method was extremely good. NdGaO₃ is, therefore, an excellent candidate for epitaxial high-T_c superconducting films.