Tomoki Suzuki

Growth of Y-Ca-Ba-La-Cu-O Tetragonal Superconductors by Liquid-Phase Epitaxy

Thick films with a tetragonal structure were grown on NdGaO3 (110) substrates by the liquid-phase epitaxy technique using a mixture of Y0.4Ca0.6Ba1.4La0.6Cu3Ox and BaCuO2–CuO flux. The Ca and La concentrations in the films were found to be about 1/9 and 1/2 of those in the solute, respectively. The films showed a sharp superconducting transition with Tc(zero)=79.4 K and a transition width of 0.8 K. The growth of the films changed from a c-axis orientation to an a-axis orientation with an increase in the growth temperature and the holding time of the molten solution.

Annealing effect on ErBa2Cu3Ox films grown by liquid-phase epitaxy

Annealing characteristics of ErBa2Cu3Ox (ErBCO) films grown by a liquid-phase epitaxy technique using BaZrO3 crucibles were studied. Annealing in a mixed gas of O2 and N2 with an oxygen concentration of 1% at 800°C after oxygen annealing at 400–500°C for 300 h increased the critical temperature (Tc) of the ErBCO films. The ErBCO films also showed the highest Tc (zero) of 94 K by annealing in the mixed gas at 800°C for 12 h after oxygen annealing at 500°C for 24 h. No change in lattice constants was observed for the ErBCO films after annealing in the mixed gas.

Crystal Growth of CaLaBaCu3Ox Tetragonal Superconductors

The crystal growth of the tetragonal CaBaLaCu3Ox from the molten solution prepared by the mixture of CaBaLaCu3Ox and BaCuO2-CuO flux was investigated. The tetragonal films with the lattice constants of a=3.88A and c=l 1.64A were grown on NdGaO3 (110) (NGO) by liquid phase epitaxy. The change from c-axis orientation to a-axis orientation was observed with increasing the time of keeping the temperature of the solution constant. Single crystals were also grown by the self-flux technique.