Influence of Zn doping on the thermal expansion of the high Tc superconductor Y1Ba2Cu3Oy

Thermal expansion measurements have been carried out for the Zn-substituted compounds Y1Ba2(Cu1-xZnx)3Oy (0 ≤ x ≤ 4%) with a high-resolution dilatometer using the three terminal capacitance technique. The present setup is sensitive enough to detect changes in α of about 10-8 K-1. Results indicate that the jump Δα in the coefficient of linear thermal expansion decreases with an increase in Zn content. For x = 1%, Δα decreases by a factor of about five whereas the oxygen content and transition temperature do not change appreciably. There is strong evidence that the temperature dependences of α for compounds with high Zn concentration depend on the conditions of sample growth