A similarity in structural changes in YBa2Cu4O8 by Ca doping and by high pressure

Abstract

A comparison of structural changes in YBa2Cu4O8 by cation dopants and high pressure is made. It is found that both, Ca doping and high pressure, which both enhance Tc, cause similar structural changes in the Cu(2)-O(1) bond length, the Cu(1)-O(1) bond length and the shape of the CuO2 plane, while Fe, Co and Ni, which decrease Tc, cause the opposite structural changes as compared to Ca doping and the high pressure effect. The similarity in the structural changes caused by Ca doping and by high pressure implies that the enhancement of Tc in YBa2Cu4O8 upon either Ca doping or due to pressure may have the same fundamental cause. © 1994.