MATERIALS WITH LAYERED STRUCTURES .8. SUBSOLIDUS PHASE-DIAGRAM OF THE SYSTEM MNIN2S4-MNIN2SE4 AND CHARACTERIZATION OF THE LAYERED MATERIALS MNIN2SXSE4-X BY ELECTRICAL MEASUREMENTS AND DIFFUSE-REFLECTANCE SPECTROSCOPY

In the quasibinary system MnIn2S4-MnIn2Se4 a series of solid solutions of general formula MnIn2SxSe4-x exists for 2.4 ≥ x ≥ 0.2 with the layered MgAl2S4 structure. The samples have been characterized by X-ray powder diffraction and investigated by electrical measurements and diffuse reflectance spectroscopy. The compounds are semiconductors with optical band gaps varying between 1.6 and 1.2 eV depending on x. From Arrhenius plots of the conductivity data at least two different activation energies Ea can be obtained: in the temperature interval from 50 to 200°C we find Ea = 0.5 eV, independent of the composition of the samples, while in the high temperature region from 200 to 400°C, Ea varies with x from 1.35 to 0.56 eV. © 1993 Academic Press, Inc.