Methods to fabricate tightly packed arrays of nanoparticles are disclosed, without relying on organic ligands or a substrate. In some variations, a method of assembling particles into an array comprises dispersing particles in a liquid solution; introducing a triggerable pH-control substance capable of generating an acid or a base; and triggering the pH-control substance to generate an acid or a base within the liquid solution, thereby titrating the pH. During pH titration, the particle-surface charge magnitude is reduced, causing the particles to assemble into a particle array. Other variations provide a device for assembling particles into particle arrays, comprising a droplet-generating microfluidic region; a first-fluid inlet port; a second-fluid inlet port; a reaction microfluidic region, disposed in fluid communication with the droplet-generating microfluidic region; and a trigger source configured to trigger generation of an acid or a base from at least one pH-control substance contained within the reaction microfluidic region.

The invention provides an organic solvent dispersion of titanium oxide particles in a content of 10% by weight or more in an organic solvent except methanol and ethanol,

wherein the titanium oxide particles are surface-treated with a surface treating agent comprising a silane coupling agent having the general formula (I)

(RO).sub.nSiX.sub.4-n (I)

wherein R is an alkyl group having carbon atoms of 1-4, n is 2 or 3, X is an alkyl, a fluoroalkyl, a vinyl or a (meth)acryloyloxyalkyl group, and 12-hydroxystearic acid, and

wherein the titanium oxide particles in the organic solvent have a D50 in a range of 1 to 30 nm, and

wherein the organic solvent dispersion has a transmittance of 2% or more at a wavelength of 500 nm and a transmittance of 70% or more at a wavelength of 800 nm, a viscosity of 10 mPa.Math.s or less at a temperature of 25 C. immediately after production while the increase in the viscosity is 40 mPa.Math.s or less seven days after production as compared to that of the dispersion immediately after production.

Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

A method of fabricating titanium oxide having a hexagonal column shape is provided. The fabricating method includes preparing a first mixture solution containing oxalic acid and sodium dodecylbenzenesulfonate (SDBS), and adding a second mixture solution including titanium to the first mixture solution to fabricate titanium oxide having a hexagonal column shape.

The invention relates to O3/P2 mixed-phase sodium-containing doped layered oxide materials which comprise a mixture of a first phase with an O3-type structure and a second phase with a P2-type structure; wherein the O3:P2 mixed-phase sodium-containing doped layered oxide material has the general formula: Na.sub.aA.sub.bM.sup.1.sub.c M.sup.2 M.sup.3.sub.eM.sup.4.sub.f M.sup.5 O.sub.2. The invention also provides a process for making such O3/P2 mixed-phase sodium-containing doped layered oxide materials, and use applications therefor.

The present invention relates to a facile synthetic method to synthesize novel hexagonal phase CuCo (HCuCo) PBAs with high crystallinity, as well as extended synthesis of doping PBAs with hexagonal phase: Fe.sub.0.1CuCo, Fe.sub.0.2CuCo, Co.sub.0.1CuCo, Ni.sub.0.1CuCo, and Zn.sub.0.1CuCo. The hexagonal phase HCuCo PBAs and the doping sequence of PBAs with hexagonal phase exhibit superior crystallinity and significantly higher intrinsic specific surface area. Meanwhile, HCuCo PBAs show great potential for gas adsorption and have a positive impact on the development of PBAs for other applications.