title: Optical and magnetic properties of manganese-doped zinc sulfide nanoclusters.
abstract: We report the synthesis of fixed-size ZnS nanoclusters approximately 24 A in diameter with varying manganese concentrations. Various samples of Zn1-x MnxS, with x = 0, 0.02, 0.055, 0.09, and 0.13, have been prepared and characterized using X-ray diffraction, energy-dispersive analysis of X-rays, UV absorption, fluorescence emission and excitation, electron paramagnetic resonance (EPR), and magnetic susceptibility measurements. The manganese ions are found to substitute Zn randomly without giving rise to any clustering of Mn sites, as seen from EPR and magnetic susceptibility results. Our studies reveal that the band gap of the doped nanoclusters passes through a maximum as the manganese concentration is varied. Also, we observe orange emission from Mn2+ ions in the doped ZnS nanoclusters, apart from the blue emission characteristic of the ZnS defect states. The relative intensity of the orange emission compared with the blue varies with the manganese concentration in a nonmonotonic way. The inverse of susceptibility temperature plots can be plotted onto a universal curve by simple multiplicative constants, thus showing that the magnetic interactions between Mn2+ ions are weak.
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Sameer
authors.initials: S
authors.lastname: Sapra
authors.forename: J
authors.initials: J
authors.lastname: Nanda
authors.forename: A
authors.initials: A
authors.lastname: Anand
authors.forename: S V
authors.initials: SV
authors.lastname: Bhat
authors.forename: D D
authors.initials: DD
authors.lastname: Sarma
mesh_terms: D003460:Crystallization / Q000379:methods*; D008280:Magnetics / Q000295:instrumentation*; D008345:Manganese / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods*; D008968:Molecular Conformation; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D043942:Nanotubes / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D055095:Optics and Photonics / Q000295:instrumentation*; D012666:Semiconductors; D013440:Sulfides / Q000737:chemistry* / Q000528:radiation effects; D013499:Surface Properties; D014466:Ultraviolet Rays; D017967:Zinc Compounds / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D013440:Sulfides; D017967:Zinc Compounds; D008345:Manganese; C031238:zinc sulfide