Synthesis, structural, optical, and magnetic properties of Co doped, Sm doped and Co+Sm co-doped ZnS nanoparticles

• Co, Sm and Co+Sm doped ZnS nanoparticles synthesized by hydrothermal method.
• The synthesized nanoparticles exhibited broad emission in the visible region.
• Co+Sm co-doped ZnS showed strong RTFM than Co and Sm doped ZnS nanoparticles.
• Co+Sm co-doped nanoparticles are potential materials for future spintronics.

The compositional, structural, optical and magnetic properties of ZnS, Zn0.98Co0.02S, Zn0.98Sm0.02S and Zn0.96Co0.02Sm0.02S nanoparticles synthesized by a hydrothermal method are presented and discussed. X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) studies revealed that all the samples exhibited cubic structure without any impurity phases. X-ray photoelectron spectroscopy (XPS) results revealed that the Co and Sm ions existed in +2 and +3 states in these samples. The photoluminescence (PL) spectra of all the samples exhibited a broad emission in the visible region. The room temperature magnetization versus applied magnetic field (M–H) curves demonstrated that the Sm+Co doped nanoparticles exhibited enhanced ferromagnetic behavior compare to Co and Sm individually doped ZnS nanoparticles, which is probably due to the exchange interaction between conductive electrons with local spin polarized electrons on the Co2+ or Sm3+ ions. This study intensifies the understanding of the novel performances of co-doped ZnS nanoparticles and also provides possibilities to fabricate future spintronic devices.