ELECTRONIC-PROPERTIES OF SRMNO3-X

Hexagonal four-layered (4L) and perovskite-like SrMnO3-x were prepared from equilibrium states at 1200 similar to 1600 degrees C by quenching in water. Reoxidized specimens were also made by heating hexagonal 4L SrMnO3-x in air at 900 degrees C for 24 hr and perovskite-like ones at 300 degrees C for 0.5 hr. Dielectric properties and de conductivities of quenched and reoxidized specimens were measured as a function of temperature. There is a distinct difference in conductivity between hexagonal 4L and perovskite-like SrMnO3-x. The conductivity of hexagonal 4L SrMnO3-x does not change very much even if it is reoxidized, while the conductivity of cubic perovskite SrMnO3 transformed from perovskite-like SrMnO3-x by reoxidation increases remarkably from conductivity before reoxidation. Dielectric relaxation peaks appear in the loss tangent in quenched specimens, but disappear in reoxidized specimens. The dielectric constants are greatly increased by reoxidation. These results are discussed based on crystal structures of SrMnO3-x. (C) 1995 Academic Press, Inc.