Synthesis and structural, optical, and magnetic properties of Mn-doped CdS quantum dots prepared by chemical precipitation method

Mn-doped CdS nanoparticles were successfully prepared by the chemical precipitation method. The effect of Mn doping on the structure, optical, and magnetic properties of the prepared samples was studied. Cubic CdS is indicated by XRD investigation and no change in CdS crystal structure was noted by Mn doping due to the low concentration of Mn doping. The morphology of the pure and 0.07% doped samples was investigated by a high-resolution transmission electron microscope (TEM). TEM images revealed mosaic-shaped grains with a size range of 7-8 nm. The thermal behavior and stability of the pure sample were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) in the argon atmosphere. The whole weight loss over the temperature range of 25-700 degrees C was about 17.4% which reveals the thermal stability of the prepared compound. The optical properties of the prepared samples were studied through diffuse reflection (DR). The transition energy increases only by the initial addition of Mn and then did not get affected by more Mn. The impact of doping on the energy bandgap, refractive index, and dielectric constant was discussed. Magnetic properties of Mn-doped CdS were investigated by a vibrating-sample magnetometer at room temperature. The results indicated an anti-ferromagnetic property with weak ferromagnetic behavior with no saturation.