Correlation between structural and optical characteristics upon changing the composition ratio of CuS@MnS nanocomposites

Abstract

Nanocomposite (1 − x)CuS/(x)MnS samples (x = 0, 0.25, 0.5, 0.75, 1) were prepared by a simple thermolysis procedure at low temperature (250 °C). HighScor plus program and Rietveld profile method revealed that CuS crystallized in hexagonal phase, while MnS crystallized in hexagonal and cubic phases. The intermediate alloying ratios (x = 0.5, 0.75) have a cubic phase of MnS and a hexagonal phase of CuS, while sample with x = 0.25 has a hexagonal phase of CuS only. The phase percentage of MnS phase in the nanocomposite samples is always less than the nominal value proposed during the sample’s preparation. The MnS phase in the intermediate alloying ratios (x = 0.5, 0.75) has a larger crystallite size than the CuS phases. Composite samples (x = 0.5, 0.75) revealed two optical band gaps while sample with x = 0.25 showed only one optical band gap. The photoluminescence intensities for CuS@MnS nanocomposites were decreased as compared with either CuS or MnS samples. Nanocomposite (1 − x)CuS/(x)MnS samples emitted UV, violets, blue, green and yellow colors depended on the ratio between CuS and MnS mounts in the composite samples and the excitation wavelengths uses. The different kinds of defects in different samples were investigated also in detail.