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)(3)O-y (0 less than or equal to x less than or equal to 4%) with a high-resolution dilatometer using the three terminal capacitance technique. The present setup kis sensitive enough to detect changes in alpha of about 10(-8) K-1. Results indicate that the jump Deltaalpha in the coefficient of linear thermal expansion decreases with an increase in Zn content. For x = 1%, Deltaalpha 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 alpha for compounds with high Zn concentration depend on the conditions of sample growth.