Abstract
Effects of open shell cations on magnetic, optical and carrier transport properties were examined for layered wide bandgap semiconductors MCuF Ch ( M=Sr, Eu, Ch=S, Se). Single-phase MCuF Ch powder and ceramic samples were synthesized by solid-state reactions. The crystal structures refined by the Rietveld analyzes revealed that all the materials have the space group P 4 / nmm , indicating that the samples have the same crystal structure as that of layered oxychalcogenides LaCuO Ch, and cation vacancies of several percent were present for Cu + and Eu 2+ sites in EuCuF Ch. Thermopower measurements revealed that both SrCuF Ch and EuCuF Ch were p-type semiconductors. Degenerate conduction was observed for EuCuF Ch with conductivities >1 S cm −1, whereas SrCuF Ch exhibited thermally activated behavior. The optical band gaps of SrCuFS and SrCuFSe estimated were approximately 3.0 and 2.7 eV, respectively, and those of EuCuF Ch were ∼2 eV. Temperature dependence of magnetic susceptibilities of EuCuF Ch followed the Curie–Weiss law down to 5 K and the samples did not show any transition to a magnetic ordering phase.
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