Exfoliation of copper hydroxysalt in water and the conversion of the exfoliated layers to cupric and cuprous oxide nanoparticles.

P-aminobenzoate-intercalated copper hydroxysalt was prepared by coprecipitation at high pH (∼12). As the pH was reduced to ∼7 on washing with water, the development of partial positive charge on the amine end of the intercalated anion caused repulsion between the layers leading to delamination and colloidal dispersion of monolayers of copper hydroxysalt in water. The dispersed copper hydroxysalt monolayers were used as precursors for the synthesis of copper(I)/(II) oxide nanoparticles at room temperature. While the hydroxysalt layers yielded spindle-shaped CuO particles when left to stand, they formed hollow spherical nanoparticles of Cu(2)O when treated with an alkaline solution of ascorbic acid.

Luminescence studies on low temperature synthesized ZnGa2O4:Ln3+ (Ln = Tb and Eu) nanoparticles.

ZnGa2O4 nanoparticles doped with lanthanide ions (Tb3+ and Eu3+) were prepared at a low temperature of 120 degrees C based on urea hydrolysis in ethylene glycol medium. X-ray diffraction studies have confirmed that strain associated with nanoparticles changes as Tb3+ gets incorporated in the ZnGa2O4 lattice. Based on steady state emission and excitation studies of ZnGa2O4:Tb nanoparticles, it has been inferred that ZnGa2O4 host is characterized by a broad emission around 427 nm and there exists energy transfer between the host and Tb3+ ions. Unlike this, for ZnGa2O4:Eu nanoparticles, very poor energy transfer between the host and Eu3+ ions is observed. These nanoparticles when coated with ligands like oleic acid results in their improved dispersion in organic solvents like chloroform and dichloromethane.