STRUCTURAL AND PHYSICAL CHARACTERIZATION OF BI2CA1-XLNXSR2CU2O8+DELTA(LN=DY OR Y) GLASSES

Glasses of Bi2Ca1-xLnxSr2Cu2O8+delta prepared by the melt quenching of oxides have been studied for their physical and structural properties . With increasing rare earth concentration, it is found that the cryst allinity increases in the as-prepared glass when observed by X-ray and electron diffraction. Multiple crystallization temperatures are obser ved in the differential scanning calorimetry studies, indicating co-ex istence of different crystalline phases. The capacitance measurements show a large anomaly at the glass crystallization temperature. The mag netic studies on the as-prepared glasses containing no magnetic rare e arth ions show a sizeable paramagnetic contribution which is supported by the electron spin resonance studies. This is attributed to the loc alized 3d electrons of copper 2+ ions, which follow a Curie-Weiss beha viour up to the glass crystallization temperature, beyond which the ma terial irreversibly transforms into a Pauli paramagnet and shows super conductivity at low temperatures.