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 around x=1% and then increases for higher Fe concentrations. The oxygen content per unit formula is almost constant up to x=1% and then increases rapidly with x. It has also been observed that the anomalous behaviour of α around 260 K observed by Meingast et al  for Fe concentration x=5% is due to inadequate annealing of the sample.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)