Magnetization properties of Co incorporated ZnS nanocrystals synthesized at low temperature via chemical route

Co doped ZnS (Zn1-xCoxS) nanoparticles with a Co concentration of (x = 0.00, 0.05, 0.10 and 0.15) were prepared by straight forward chemical route at low temperature. The influence of Co ion concentration on optical, structural and magnetic properties was studied. The X-ray diffractograms revealed that asprepared Zni_ x Co x S nanoparticles were crystalline in nature with three (111), (220) and (311) intense peaks matched with primary cubic zinc blende phase. No peak was observed corresponding to elemental Co or its related oxides, demonstrating that Co ions were successfully incorporated into ZnS host without altering its pristine crystal structure. Furthermore, a weak signature of ZnS corresponding to hexagonal wurtzite phase is observed. Optical measurements exhibited a blue shift of 260 meV in the band gap as a result of the quantum size effect. Room temperature M - H measurement and thermomagnetic irreversibility in ZFC and FC magnetization measurements conclusively proved the presence of ferromagnetism at room temperature in pure and Co doped ZnS nanopowder within the scope of bound magnetic polaron formation. However, the features observed in M - H loops and ZFC and FC measurement of doped ZnS suggest the incorporation of higher Co content (x > 0.05) in ZnS lattice adversely effect the magnetic interaction without clustering of Co ions. (C) 2020 Elsevier B.V. All rights reserved.