The objective of this work was to produce an ordered array of size-controlled gallium nitride (GaN) nanoparticles. The synthesis was performed by the in situ formulation and subsequent decomposition of cyclotrigallazane in a polystyrene (PS)-b-poly(4-vinylpyridine) (b-P4VP) block copolymer matrix. The matrix served as a templating medium to constrain the particle size and to allow the control of particle morphology, spacing and packing arrangement. The size and spacing of nanoparticles were controlled by the molecular weight of the entire polymer chain (81 000 g mol(-1)), and the particle morphology and packing arrangement were controlled by the ratio of the sequestering block to the matrix block (21 wt% P4VP to 79 wt% PS by elemental analysis). High-resolution and analytical transmission electron microscopy revealed the amorphous nanoparticles to be composed mainly of gallium and nitrogen (with oxygen detected in some particles) about 10 nm in diameter with an average interparticle distance of 60 nm and organized in a regular hexagonal packing arrangement. The impact of this synthesis technique is to afford the means to investigate systematically the effect of quantum confinement and quantum coupling on the optical properties of small GaN particles.

Indium oxide powders were reacted in flowing ammonia at various temperatures and times to form indium nitride (InN), and the kinetics of the oxide- to- nitride reaction was quantitatively determined by X-ray diffraction analysis. The quantity of the InN phase formed increased expectedly at higher temperatures and longer times showing a stretched-out exponential dependence. The reaction rate constant at a given temperature was determined using the Avrami equation. The activation energy for the reaction was calculated to be 164.5 KJ mol−1 in the temperature range of 580–650°C and the Avrami constant varied between 1.56 and 2.8.

Controlled oxidation of GaN powders was performed inside xerogel cavities with the objective of demonstrating formation of composites of GaN nanoparticles embedded in a silicate matrix. A 60% reduction in GaN particle size was observed due to the oxidation of bulk particles dispersed inside the xerogel. The microstructure and phase chemistry of the nano-GaN in xerogel composite were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD).