Synthesis of high-purity YbBa2Cu3O7−d and LuBa2Cu3O7−d superconductors by polymerizable complex method

Polycrystalline samples of YbBa2Cu3O71d and LuBa2Cu3O71d were prepared by polymerizable complex method. The combined results of both X-ray diffraction and Raman scattering analyses indicated that YbBa2Cu3O71d sample was of single phase when the samples were sintered in a low oxygen partial pressure (1%) at relatively low temperature (845°C). On the other hand, LuBa2Cu3O71d sample was only slightly contaminated with a very small amount of Lu2BaCuO5 and BaCuO2 impurities when the sample was prepared under the same condition as YbBa2Cu3O71d. Ac complex magnetic susceptibility measurements exhibited that a transition into the superconducting state for YbBa2Cu3O71d and LuBa2Cu3O71d samples was sharp and smooth, implying that both of the samples were of “superconducting” single phase. The Tc onset values of the YbBa2Cu3O71d and LuBa2Cu3O71d, were 93.4 and 92.3K, respectively.