| 摘要 |
PURPOSE:To sense the presence of about 1% oxygen in the case of an electric furnace, facilities using explosive materials, etc., where the presence of oxygen is disliked by using one or >=2 kinds of yttrium, lanthanum, etc., as a rare earth element RE and specifying the substitution quantity X of Ca to a 0<=X<=1.0 range. CONSTITUTION:The rare earth element RE is one or >=2 kinds of the yttrium, lanthanum, etc., and the substitution quantity X of Ca is in the 0<=X<=1.0 range. The crystal structure of the ceramics, compsn. expressed by compsn. formula Pb2Ba2(RE1-xCax)Cu3Oy has a laminar perovskite structure of an oxygen lack type and exhibits a semiconductor-like electrical conductivity when the substitution quantity X of Ca is in the 0.5<=X<=1.0 range. This ceramics compsn. is rapidly changed to the perovskite structure having BaPbO3 in the basic structure when the temp. is raised to about >=600 deg.C in the presence of the oxygen. Further, this change is reversible. The compsn. BaPbO3 has a semimetallic band structure and the electrical conductivity thereof is large. |
