High-Tc superconductors synthesis using ferroelectric hosts: barium sodium niobate doped with copper and calcium

From the suggestion that ferroelectric host materials could be used in the search for the synthesis of new high-Tc superconductors, we have synthesized materials derived from barium sodium niobate. Measurements on magnetization, ac susceptibility and resistivity are reported. The materials change from weakly paramagnetic to weakly diamagnetic at low temperatures, when the time of oxygen annealing is reduced, but with high resistivity. With the increase of temperature, a strong decrease in resistivity (of the order of 10/sup 6/ /spl Omega/ cm), with diamagnetism, has been observed for temperatures above 1000 K.