Effect of Fe substitution on the thermal expansion of the highT c superconductor Y1Ba2Cu3O y |
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Authors: | Ashok Rao Om Prakash S N Das P N Dheer |
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Affiliation: | (1) Department of Physics and Astrophysics, University of Delhi, 110 007 Delhi, India |
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Abstract: | Thermal expansion measurements have been carried out on Fe substituted superconducting compounds Y1Ba2(Cu1−x Fe x )3O y (0<x<4%) using a high resolution dilatometer employing the three terminal capacitance technique. The experimental set up is sensitive enough to detect changes in α of less than 10−8K−1. Results show that the jump Δα in the coefficient of linear thermal expansion at the superconducting transition temperature,T c, increases almost linearly with Fe concentration. The normal state thermal expansion coefficient α first decreases, attains a minimum value aroundx=1% and then increases for higher Fe concentrations. The oxygen content per unit formula is almost constant up tox=1% and then increases rapidly withx. It has also been observed that the anomalous behaviour of α around 260 K observed by Meingastet al [22] for Fe concentrationx=5% is due to inadequate annealing of the sample. |
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Keywords: | Thermal expansion high temperature superconductors discontinuity in α iodometric titrations |
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