%0 Journal Article
%T Synthesis and Optical Characterization of Mg1-xNixO Nanostructures
%A Nageswararao Budiredla
%A Ashok Kumar
%A Subhash Thota
%A Jitendra Kumar
%J ISRN Nanomaterials
%D 2012
%R 10.5402/2012/865373
%X An attempt has been made here to synthesize nano-powders via sol-gel process. These powders are shown to possess an f.c.c. (NaCl-type) structure with a typical lattice parameter of £¿£¿ for when decomposition of dried oxalate gel product is carried out at 600¡ãC for 2£¿h in air. Moreover, they exhibit (i) clusters/agglomerates of nanosize particles and (ii) high BET specific surface area (123.0¨C135.5£¿m2/g). Also, the infrared absorption spectra reveal their strong affinity to water. The UV-Vis absorption peaks appearing at ~202£¿nm, 296£¿nm, and 379£¿nm are associated with oxygen defect centres and correspond to the electronic transitions (i) ( , , or ), (ii) ( , or ) and (iii) ( ), respectively. The incorporation of Ni2+ ions causes some modifications in the energy levels and the optical absorbance characteristics. The suppression of a strong broad emission peak at 440£¿nm and improvement of a weak band at 400£¿nm in the photoluminescence (PL) spectrum arise due to decrease in population density of centres (or F+ dimmers) and emergence of additional F+ centres, respectively with increase in nickel content. 1. Introduction Magnesium oxide (MgO) exhibits an f.c.c. (NaCl-type) crystal structure, high thermal stability, predominantly ionic nature, and insulating behaviour [1]. MgO has been extensively used in catalysis, toxic waste remediation, antibacterial materials, refractories, paints, and superconductors due to its unique optical, electronic, magnetic, thermal, mechanical, and chemical properties [2¨C8]. Recently, it has found promising application in plasma display panels [9]. Of particular interest is MgO nanopowder because of inherent size effects, for example, large surface area-to-volume ratio [10]. Various investigations have been undertaken earlier on its optical and electrical properties [2, 8, 11]. Surface anions with low coordination, considered to be chemically active sites, form excitons and give rise to specific optical transitions in the UV range [5, 8]. The processes usually used to synthesize MgO nanopowders include thermal evaporation, flame spray pyrolysis, laser vaporization, chemical gas phase deposition, combustion, aqueous wet chemical, vapor-phase transport, sol-gel, and hydrothermal reaction [5, 8, 12¨C15]. The incorporation of another element into a parent phase (i.e., oxide matrix) leads to crystal defects (e.g., vacancies, interstitials, and antisites) which, in turn, can modify the useful characteristics [16, 17]. Recently, interest arose in transition metal and rare earth-doped oxides mainly due to their excellent luminescence
%U http://www.hindawi.com/journals/isrn.nanomaterials/2012/865373/