A heat ray shielding fine particle dispersion body and a heat ray shielding laminated transparent substrate that as well as exhibit heat ray shielding properties and suppressing a scorching sensation on the skin when used in structures such as window materials and the like, also enable usage of communication devices, imaging devices, sensors and the like that use near-infrared light interposing the heat ray shielding film or the heat ray shielding glass, containing a transparent thermoplastic resin, and wherein heat ray shielding fine particles are dispersed in the transparent thermoplastic resin, the heat ray shielding fine particles having elements L, M, tungsten, and oxygen, and a hexagonal crystal structure represented by a general formula (L.sub.AM.sub.B) W.sub.CO.sub.D, wherein the element L is an element selected from K, Rb, Cs, and the element M is one or more elements selected from K, Rb, and Cs and is different from the element L.

A method for manufacturing an environmental-friendly heat shielding film using a non-radioactive stable isotope includes: a substrate layer providing step of providing a substrate layer; and a heat shielding layer forming step of, after the substrate layer providing step, forming, on one surface of the substrate layer, a heat shielding layer containing a non-radioactive stable isotope tungsten bronze compound that does not emit radiation.

An LTCC microwave dielectric material, including the following components: a Ba.sub.5Si.sub.8O.sub.21+(1−a) (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4+Ba—B—Si glass; wherein 0.4≤a≤0.8, 0≤x≤1, 0≤y≤1, 0≤z≤1. By adjusting the amounts of Ba.sub.5Si.sub.8O.sub.21 and (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4, the temperature coefficient of resonance frequency can be adjusted to nearly zero. The material is suitable for the fields of high-frequency communication and radiofrequency. Also disclosed is a method for preparing the LTCC microwave dielectric material.

Provided is a method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries, the method including: a mixing step of obtaining a W-containing mixture of Li metal composite oxide particles represented by the formula: Li.sub.zNi.sub.1-x-yCO.sub.xM.sub.yO.sub.2 and composed of primary particles and secondary particles formed by aggregation of the primary particles, 2 mass % or more of water with respect to the oxide particles, and a W compound or a W compound and a Li compound, the W-containing mixture having a molar ratio of the total amount of Li contained in water and the solid W compound or the W compound and the Li compound of 3 to 5 with respect to the amount of W contained therein; and a heat treatment step of heating the W-containing mixture to form lithium tungstate on the surface of the primary particles of the Li metal composite oxide particles.

Provided is a method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries, the method including: a mixing step of obtaining a W-containing mixture of Li metal composite oxide particles represented by the formula: Li.sub.zNi.sub.1-x-yCO.sub.xM.sub.yO.sub.2 and composed of primary particles and secondary particles formed by aggregation of the primary particles, 2 mass % or more of water with respect to the oxide particles, and a W compound or a W compound and a Li compound, the W-containing mixture having a molar ratio of the total amount of Li contained in water and the solid W compound or the W compound and the Li compound of 3 to 5 with respect to the amount of W contained therein; and a heat treatment step of heating the W-containing mixture to form lithium tungstate on the surface of the primary particles of the Li metal composite oxide particles.

A method for synthesizing two-dimensional (2D) nanosheets comprises heating a bulk material in a solvent. The process is scalable and can be used to produce solution-processable 2D nanosheets with uniform properties in large volumes.

A method for synthesizing two-dimensional (2D) nanosheets comprises heating a bulk material in a solvent. The process is scalable and can be used to produce solution-processable 2D nanosheets with uniform properties in large volumes.

A preparation method of phosphotungstic acid includes mixing a mixed solution containing tungsten, phosphorus and an inorganic acid with an organic-alcohol-containing oil phase for extraction, stripping the obtained supported organic phase and distilled water according to an oil phase:aqueous phase volume ratio of 3:1 to 10:1 to obtain a stripping solution; and carrying out thermal evaporation crystallization or spray drying on the stripping solution to obtain a phosphotungstic acid crystal, wherein the organic alcohol is a C7-C20 alcohol. The inventors have found out that the addition of an inorganic acid to a solution of phosphorus or tungsten and the use of an organic alcohol as an extractant can achieve simultaneous and efficient extraction of phosphotungstic acid. It has also been found that the organic-alcohol-containing oil phase has excellent selectivity for phosphotungstic acid molecules in the mixed solution.

A preparation method of phosphotungstic acid includes mixing a mixed solution containing tungsten, phosphorus and an inorganic acid with an organic-alcohol-containing oil phase for extraction, stripping the obtained supported organic phase and distilled water according to an oil phase:aqueous phase volume ratio of 3:1 to 10:1 to obtain a stripping solution; and carrying out thermal evaporation crystallization or spray drying on the stripping solution to obtain a phosphotungstic acid crystal, wherein the organic alcohol is a C7-C20 alcohol. The inventors have found out that the addition of an inorganic acid to a solution of phosphorus or tungsten and the use of an organic alcohol as an extractant can achieve simultaneous and efficient extraction of phosphotungstic acid. It has also been found that the organic-alcohol-containing oil phase has excellent selectivity for phosphotungstic acid molecules in the mixed solution.

The present invention relates to a process for preparing ammonium metatungstate using a reverse osmosis cell, and to a device for performing the process according to the invention.