Synthesis and Optical Characterization of Mg1-xNixO Nanostructures

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  Å for when decomposition of dried oxalate gel product is carried out at 600°C for 2 h in air. Moreover, they exhibit (i) clusters/agglomerates of nanosize particles and (ii) high BET specific surface area (123.0–135.5 m 2 /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 Ni 2+ 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.