Nonaqueous synthesis of colloidal ZnGa₂O₄ nanocrystals and their photoluminescence properties

Highly photoluminescent ZnGa₂O₄ nanocrystals were synthesized by using the nonaqueous sol-gel method in the absence of surfactants or ligands. The sizes and shapes of the nanocrystals are found to be uniform and there are almost no agglomerates existing in the samples. The transparent colloidal solution in chloroform shows an intense blue emission under a UV lamp, which is not found for the nanopowders and nanofilms. The emission spectrum of nanocrystals show a peak position at 427 nm with excitation at 330 nm. The results show that the good dispersibility of the nanocrystals in chloroform is due to their surface properties that are direct consequence of the nonaqueous sol-gel procedure. The presence of organic ligands is found to positively influence the particle size and redispersibility of the nanocrystals.