PHASE TRANSITION IN CuS NANOPARTICLES

Copper sulfide nanoparticles were synthesized by solvothermal method. The assynthesized nanoparticles annealed at 500 degrees C temperature was characterized by X ray diffraction, scanning electron microscopy and atomic force microscope to confirm the crystal structure, morphology and size. The DC electrical resistance was measured in the temperature range 310K-485K. Resistance measurements on copper sulfide nanoparticles shows a phase transition around 470 K, not previously reported. Resistance measurements made on copper sulfide nanoparticles prepared by precipitation method confirms this phase transition. A jump in electrical band gap energy was also observed in the two samples after phase transition. The band gap energies calculated from resistance measurements agree with the band gaps obtained from UV-VIS spectra, FTIR spectrum PL spectrum and previously reported values.