The invention relates to perovskite compounds which have surprisingly good emission properties, particularly photoluminescent emission properties, in the blue region of the visible spectrum. These perovskites contain a mixture of cations or a mixture of halides, or both. The invention also relates to a photoactive material containing the perovskite species of the invention; to an optoelectronic device containing the photoactive material of the invention; to a method of producing blue light; and to the use of the photoactive material of the invention to emit blue light or as a phosphor.

Processes for producing a disubstituted oxalate are disclosed. The process includes contacting a cesium salt with one or more alcohols and carbon dioxide (CO.sub.2) under reaction conditions sufficient to produce a composition comprising a disubstituted oxalate.

A nanoparticle used in 3D printing is disclosed herein. In an example, the nanoparticle can comprise: at least one metal oxide, which absorbs infrared light in a range of from about 780 nm to about 2300 nm and is shown in formula (1):

M.sub.mM′O.sub.n  (1)

wherein M is an alkali metal, m is greater than 0 and less than 1, M′ is any metal, and n is greater than 0 and less than or equal to 4; and a bilayer-forming surfactant encapsulating at least a portion of the metal oxide, wherein the nanoparticle has a diameter of from about 0.1 nm to about 500 nm.

A luminescent composite material and a preparation method therefor. The luminescent composite material is prepared by mixing a precursor of a quantum dot and an oxide or a precursor thereof followed by high-temperature calcination. Compared with traditional methods, the method provided herein is a simple and low-cost synthesis process without using solvents, and is suitable for large-scale production. The luminescent composite material has high quantum efficiency, luminous intensity and luminous color purity and good photothermal stability, which can provide basis for theoretical research and applications of the luminescent composite material in high-performance photoluminescence devices, lasers and nonlinear optical devices.

A luminescent composite material and a preparation method therefor. The luminescent composite material is prepared by mixing a precursor of a quantum dot and an oxide or a precursor thereof followed by high-temperature calcination. Compared with traditional methods, the method provided herein is a simple and low-cost synthesis process without using solvents, and is suitable for large-scale production. The luminescent composite material has high quantum efficiency, luminous intensity and luminous color purity and good photothermal stability, which can provide basis for theoretical research and applications of the luminescent composite material in high-performance photoluminescence devices, lasers and nonlinear optical devices.

The present invention relates to a method for separating cesium and technetium from radioactive waste, which method comprises the sublimation of cesium pertechnetate, and an apparatus for carrying out this method. The separation includes the steps of obtaining the two elements cesium and technetium together from the waste and subsequently separating the two elements from each other. The aim of the present invention is to significantly reduce the activity of radioactive solid waste and to use the obtained radionuclides in an economical and technical manner. Additionally, the method allows elements of cesium and technetium to be separated directly from the operation of a vitrification, sintering, drying, combustion, cementing, or calcinating plant, thus obviating additional problems when carrying out the process.

The present invention relates to a method for separating cesium and technetium from radioactive waste, which method comprises the sublimation of cesium pertechnetate, and an apparatus for carrying out this method. The separation includes the steps of obtaining the two elements cesium and technetium together from the waste and subsequently separating the two elements from each other. The aim of the present invention is to significantly reduce the activity of radioactive solid waste and to use the obtained radionuclides in an economical and technical manner. Additionally, the method allows elements of cesium and technetium to be separated directly from the operation of a vitrification, sintering, drying, combustion, cementing, or calcinating plant, thus obviating additional problems when carrying out the process.

The present invention relates to a method for removing cesium in a clay mineral using hydrogen peroxide. According to the present invention, cesium in a clay mineral is removed using hydrogen peroxide, which serves to induce interlayer expansion of the clay mineral to allow a cation to easily enter an interlayer of the clay mineral, and thus cesium desorption efficiency can be further improved. Also, the method according to the present invention can be efficiently used to restore soil in residential areas widely contaminated with a radionuclide when a major accident such as Fukushima nuclear accident occurs as well as various sites of atomic energy facilities contaminated with a radionuclide. Also, since radiation-contaminated soil is treated with only hydrogen peroxide and cations, secondary environmental pollution caused by wastes can be significantly reduce and the waste disposing cost can also be saved.

The present invention relates to a method for removing cesium in a clay mineral using hydrogen peroxide. According to the present invention, cesium in a clay mineral is removed using hydrogen peroxide, which serves to induce interlayer expansion of the clay mineral to allow a cation to easily enter an interlayer of the clay mineral, and thus cesium desorption efficiency can be further improved. Also, the method according to the present invention can be efficiently used to restore soil in residential areas widely contaminated with a radionuclide when a major accident such as Fukushima nuclear accident occurs as well as various sites of atomic energy facilities contaminated with a radionuclide. Also, since radiation-contaminated soil is treated with only hydrogen peroxide and cations, secondary environmental pollution caused by wastes can be significantly reduce and the waste disposing cost can also be saved.

A light valve containing ABX.sub.3 perovskite particles (200) suspended in a liquid suspension (300) that can control light transmittance is provided. The preferable ABX.sub.3 perovskite particles (200) are halide ABX.sub.3 perovskite particles wherein A is at least one of Cs.sup.+, CH.sub.3NH.sub.3.sup.+, and Rb.sup.+, B is at least one of Pb.sup.2+, Ge.sup.2+, and Sn.sup.2+, and X is at least one of Cl.sup., Br.sup., and I.sup.. Use of the light valve in the manufacture of a light control device and a method of controlling light transmittance by using the light valve are also provided.