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Solid solubility of silver in the superconducting YBa₂Cu₃O compound Zhang, Chongmin

Abstract

The solubility of silver in the YBa₂Cu₃Ox compound has been studied. Ceramic YBa₂Cu₃Ox pellets with added silver ranging from 0 to 10 wt% were prepared and characterized by X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), wavelength dispersive X-ray spectroscopy (WDX), and secondary ion mass spectrometry (SIMS). The lattice parameters were precisely determined by a rigorous X-ray diffraction method and by using a USGS computer program which uses an iterative least square solution to calculate the lattice parameters and the standard deviations. The final precisions are±0.0005Å for lattice parameters a and b, and ±0.001Å for the lattice parameter c. Silver appears to be present within the YBa2Cu3Ox grains. More intragranular silver was found inside quenched samples than slowly cooled samples. In both cases the silver solubility increased with the nominal silver concentration, which reached a constant level as the nominal silver concentration exceeded 2.5 wt%. The maximum silver solubilities are 0.41 and 0.37 wt% for samples quenched from 950°C and slowly cooled to room temperature, respectively. The intragranular silver concentrations were found to be much lower than the nominal silver concentrations added to the system. . . . [more text]

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