Experimental research on residual carbon of Y211 inclusions in a melt-textured Y123/Y211 composite

The inherent doping of residual carbon during the preparation of Y2BaCuO5 (Y211) inclusions would degrade the physical and mechanical performance of the Y1Ba2Cu3O7-x (Y123) superconducting matrix. Y211 precursor powders were prepared by the oxalate coprecipitation process in this study. Residual carbon contents of Y211 powders under different heat treatment processes were studied by the highfrequency combustion infrared absorption method. The residual carbon content of Y211 reached the current best level similar to 0.012% when calcined in O-2 flow at 950 degrees C for 20 h. Y211 powders with the lowest carbon content were used to prepare a small batch of melt-textured Y123/Y211 composites. All samples were single-domain crystals without macro defects, which were usually caused by the emission of CO2. Among them, one sample (O27 mm x 14 mm) has a maximum levitation force of 71 N (77 K, 0.5 T), with critical current density J(c) of 3.2 x 10(8) A/m(2) (77 K, 0 T).