High-temperature phase relationships for YxNd1–xBa2Cu3Oy(0.7 ≤ x ≤ 1.0) superconductors via containerless processing

Drop-tube experiments have been performed on YxNd1–xBa2Cu3Oy (0.7 ≤ x ≤ 1.0) to understand the effects of partial substitutions of Nd for Y on the phase relationships in these systems at elevated temperatures. Powders 50–100 μm in diameter were processed in pure O2 at furnace temperatures of 1575–1800 °C, every 25 °C. The resulting samples were examined microstructurally by scanning electron microscopy, energy dispersive spectroscopy, and optical microscopy. Powder x-ray diffraction was performed for phase identification. It was found that Nd substitution alters phase selection by introducing at least one new phase and allowing for solidification of the superconducting composition directly from the melt via undercooling to below the peritectic transformation temperature. A decreasing trend in the overall melting temperature with increasing Nd was also identified.