Room-temperature ferromagnetic and optical properties of Cr-doped CdS nanoparticles via a solvothermal preparation

Undoped and Cr doped CdS nanoparticles have been successfully prepared via a solvothermal route. X-ray diffraction measurements demonstrated that the undoped and Cr doped CdS nanoparticles had a hexagonal structure. Transmission electron microscopy images revealed that the morphologies of CdS with different amounts of chromium consisted of nanoparticles. The average particle size of Cd_1−xCr_xS (x = 0.0394) nanoparticles was in the range of 30–60 nm. This product, composed of Cr, Cd, and S, was observed by an energy dispersive spectrometer. UV–Vis absorption spectra was used to investigate the optical properties of Cr-doped CdS nanoparticles. Absorption spectra of Cr doped CdS nanoparticles showed that the absorption edge was slightly shifted towards the short wavelength when compared to undoped CdS. A vibrating sample magnetometer showed that the Cr-doped CdS nanoparticles exhibited increased ferromagnetism at room temperature, while pure CdS nanorods exhibited weak ferromagnetism. The saturation magnetization of the Cr-doped CdS nanoparticles increased with Cr concentration over the range of x = 0.0000–0394. The saturation magnetization of the Cd_1−xCr_xS (x = 0.0394) nanoparticles was 9.258 (10⁻³ emu/g). The origin of the ferromagnetism in the Cd_1−xCr_xS nanoparticles is attributed to be related to the Cr substitution in CdS lattice.