![]() ![]() A strong rectification characteristic of Au/MO/n-Si heterojunction was obtained from the current density–voltage measurements under dark condition. An allowed indirect optical transition was observed for MO and the band gap was found to be thickness independent and equal to 2.02 eV. The optical properties of MO films were investigated by UV–vis spectrophotometry which was analyzed to obtain the electronic transition, optical band gap (Eg) and Urbach energy (E0). This dependence was found to be typical for p-type semiconductor which was correlated with the MO molecular structure. The temperature dependence of dark electrical conductivity (σ) and Seebeck's coefficient (S) for MO thin films in the temperature range of 300–450 K have been investigated for different thicknesses in the range 300–700 nm. The crystalline structure of MO powder and films were studied by using X-ray diffraction (XRD) and their lattice parameters were found to be the same. The surface morphology of thin films was studied by using scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed for studying the thermal stability of MO. The low expansion characteristics along c appear to be controlled by the linkages between the (CuS 3 + BiS 2) sheets perpendicular to c being relatively inflexible.Thin films of methyl orange (MO) were successfully prepared using thermal evaporation technique from their powder. The Debye-Waller factor for the first shell of S atoms surrounding Cu in end member CuSbS 2 tends to be slightly smaller than for the intermediate solid solutions, suggesting that the tetrahedral Cu environments in the intermediate composition samples is somewhat more disordered than in the end-member. The local structure and co-ordination of Cu in the samples were studied by EXAFS analysis of the Cu- K edge but no significant variation occurs in the local Cu environment. No evidence of this decomposition was observed when the amount of the CuSbS 2 component was >30%. ![]() With the addition of 10% CuSbS 2 to CuBiS 2, the decomposition temperature increases and the endothermic peak is broadened but the energy remains essentially the same (2.53 kJ/mol.). ![]() ![]() DSC experiments on CuBiS 2 show an endothermic heat effect (2.45 kJ/mol.) at 472☌ due to the breakdown reaction to Cu 3BiS 3 (wittichenite) plus Bi 2S 3 (bismuthinite). All members of the series are orthorhombic (space group Pnma) and show smoothly increasing a and b cell parameters with substitution of Bi for Sb the c cell parameter increases up to 50% CuBiS 2 substitution and then becomes constant. Seven compositions with the general formula Cu(Sb xBi 1– x)S 2 have been synthesized using dry methods at 310☌. Sulphosalts in the system CuSbS 2-CuBiS 2 (chalcostibite-emplectite) form a complete solid solution series. ![]()
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