A solid ion conductor compound including Li, Ho, and a halogen element, wherein the compound has diffraction peaks at 30?2? to 33?2?, 33?2? to 36?2?, 40?2? to 44?2?, and 48?2? to 52?28?, when analyzed using CuK? radiation, and wherein a full width at half maximum of at least one peak at 40?2? to 44?2? is 0.3?2? or greater.

A solid electrolyte material has a pair of surfaces which face each other and includes at least one of a predetermined halide-based solid electrolyte or a predetermined sulfide-based solid electrolyte, in which a surface ten-point average roughness Rz.sub.JIS of at least one of the pair of surfaces falls in the range from 20 nm or more and 1500 nm or less.

A method for producing a halide includes heat-treating a mixed material in an inert gas atmosphere, the mixed material being a mixture of M.sub.2O.sub.3, NH.sub.4X, and LiZ. The M includes at least one element selected from the group consisting of Y, a lanthanoid, and Sc. The X is at least one element selected from the group consisting of CI, Br, I, and F. The Z is at least one element selected from the group consisting of CI, Br, I, and F.

A method for producing a halide includes heat-treating a mixed material in an inert gas atmosphere, the mixed material being a mixture of M.sub.2O.sub.3, NH.sub.4X, and LiZ. The M includes at least one element selected from the group consisting of Y, a lanthanoid, and Sc. The X is at least one element selected from the group consisting of CI, Br, I, and F. The Z is at least one element selected from the group consisting of CI, Br, I, and F.

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.

The present invention provides a lanthanide-doped fluoride nanocomposite, which comprises: a core layer, is consisting of a first compound, wherein the first compound has a sodium fluoride compound with a base material, a first lanthanide metal and a second lanthanide metal; a middle layer covering the core layer, is consisting of a second compound, wherein the second compound has a sodium fluoride compound with the base material and the first lanthanide metal; and an outer shell layer covering the middle layer, is consisting of a third compound, wherein the third compound has a sodium fluoride compound with the base material and the first lanthanide metal or a third lanthanide metal.

Synthesizing upconverting nanoparticles includes heating a precursor solution comprising one or more rare earth salts, an alkali metal salt or alkaline earth salt, and a solvent comprising a plasticizer in a microwave reactor to yield a product mixture, and cooling the product mixture to yield the upconverting nanoparticles. Core-shell upconverting nanoparticles are synthesized by combining the upconverting nanoparticles with a precursor solution comprising one or more rare earth salts, an alkali metal salt or alkaline earth salt, and a solvent comprising a plasticizer to yield a nanoparticle mixture, heating the nanoparticle mixture in a microwave reactor to yield a product mixture, and cooling the product mixture to yield the core-shell upconverting nanoparticles.

Synthesizing upconverting nanoparticles includes heating a precursor solution comprising one or more rare earth salts, an alkali metal salt or alkaline earth salt, and a solvent comprising a plasticizer in a microwave reactor to yield a product mixture, and cooling the product mixture to yield the upconverting nanoparticles. Core-shell upconverting nanoparticles are synthesized by combining the upconverting nanoparticles with a precursor solution comprising one or more rare earth salts, an alkali metal salt or alkaline earth salt, and a solvent comprising a plasticizer to yield a nanoparticle mixture, heating the nanoparticle mixture in a microwave reactor to yield a product mixture, and cooling the product mixture to yield the core-shell upconverting nanoparticles.

The present disclosure provides a solid electrolyte material having high lithium ion conductivity. The solid electrolyte material of the present disclosure includes Li, M1, M2 and X, and has a spinel structure. M1 is at least one element selected from the group consisting of Mg and Zn. M2 is at least one element selected from the group consisting of Al, Ga, Y, In and Bi. X is at least one element selected from the group consisting of F, Cl, Br and I.

Disclosed is a lithium metal halide-based solid electrolyte having a novel crystal structure and excellent lithium ion conductivity.