Structural properties of sulfur copper (CuS) nanocrystals grown by chemical bath deposition

Abstract

In this paper, we present preliminary results in the synthesis of copper sulfide (CuS) nanocrystals, applying the Chemical Bath Deposit technique and subsequent thermal treatment at 1000 °C in air atmosphere. The crystalline growth is systematically performed at two different reaction temperatures of 20 °C and 90 °C. The powders are investigated by applying the techniques of Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and differential scanning calorimetry (DSC). SEM images showed morphology with crystalline conglomerates on the surfaces, and energy dispersive spectrometry (EDX) spectra shows of Cu, S and O elements. The materials show surface morphological differences associated with the temperature of the crystalline growth and the effect of temperature thermal treatment on texture, grain size, and grain boundaries. XRD identifies a hexagonal phase in CuS20 and CuS90 samples, as well as the transition to CuS(s)→CuO(s). The grain for size for the 20 °C and 90 °C is ∼3.7-5.7 nm, and ∼14.2–35.2 nm respectively. The FTIR analysis shows bands identified with the CO32- and OH− ions located at range ∼1000−2000 cm-1 which was generated by thiourea hydrolysis. These bands decrease with thermal treatment up to disappear completely. The DSC plots show the changes associated with the structural transition of CuS(s)→ CuO(s). This structural behavior is associated with the thermal stability properties of the CuS and CuO.