A neutron diffraction study of Y 1 − xCa xBa 2Cu 4O 8

Abstract

Neutron and X-ray powder diffraction experiments on Y 0.93Ca 0.07Ba 2Cu 4O 8 were performed to study a structural phase transition suggested by specific-heat measurements on the Ca 2+ substituted systems. As a result, we found a discontinuity at around 150 K in the temperature dependence of the lattice parameters a and b. These may be caused by the structural phase transition, although no change in crystal symmetry is observed in these diffraction experiments.