Provided are enhanced MXene materials made from MAX-phase precursors that comprise an excess of metal A. The resultant enhanced MXenes exhibit improved stability over periods of days and months, particularly when stored in aqueous media.

Preparing MAX phase structures includes forming a gel including a transition metal M, a Group 3A or Group 4A metal or semimetal A, and an acidic chelating agent or gelling agent X. X includes one or both of carbon and nitrogen. Preparing the MAX phase structures further includes shaping the gel to yield a shaped gel and heating the shaped gel to yield carbonaceous MAX phase structures with a composition represented by M.sub.n+1AX.sub.n, wherein n is 1, 2, 3, or 4. The MAX phase structures can be thick films, microspheres, or microwires.

The present invention provides a system and method for purifying and preparing vanadium pentoxide powder. Industrial grade vanadium pentoxide is converted to vanadium oxytrichloride by low temperature fluidizing chlorination, wherein chlorinating gas is preheated via heat exchange between fluidizing gas and chlorination flue gas, and an appropriate amount of air is added to enable a part of carbon powder to combust so as to achieve a balanced heat supply during the chlorination, thereby increasing the efficiency of chlorination and ensuring good selectivity in low temperature chlorination. The vanadium oxytrichloride is purified by rectification, and then subjected to fluidized gas phase ammonification, thereby obtaining ammonium metavanadate, and further obtaining a high-purity vanadium pentoxide powder product through fluidized calcination. The system and method have advantages of favorable adaptability to a raw material, no discharge of contaminated wastewater, low energy consumption and chlorine consumption in production, stable product quality and so on.

The present invention relates to a method for producing a metal nitride, which is a method for synthesizing a metal nitride by igniting a raw material powder containing a metal powder housed in a reaction vessel (2) under a nitrogen atmosphere and propagating nitriding combustion heat of the metal powder to the whole of the housed raw material powder, characterized in that the raw material powder is housed in the reaction vessel (2) as a molded body (1B) having a void ratio of 40 to 70%. According to the present invention, it is possible to provide a method for producing a metal nitride capable of suppressing the occurrence of powder scattering and improving the recovery rate of the metal nitride.

Compositions and devices comprising MXene materials, suitable for use as selective and/or tunable infrared emitters and/or absorbers, and methods of making coatings with low thermal emissivities using coatings comprising MXene materials.

In a general aspect, a ceramic thin film with nanotwinned regions at a tunable volume fraction is manufactured. In some aspects, a method for manufacturing a ceramic thin film on a surface of a substrate in an evacuated chamber is disclosed. The ceramic thin film includes crystalline grains; and each of the crystalline grains includes one or more nanotwinned regions. The one or more nanotwinned regions have a volume fraction in a range of 30-80% of the ceramic thin film. The ceramic thin film comprises titanium, nitrogen, and boron. A plurality of targets including a plurality of sputtering materials is prepared. A gas atmosphere in the evacuated chamber is formed. Electric power is supplied to the plurality of targets to cause co-sputtering of the plurality of sputtering materials to form the ceramic thin film with the one or more nanotwinned regions.

The present disclosure describes a crumpled form of MXene materials, and methods of making and using these novel compositions.

Phosphors include a CaAlSiN.sub.3 family crystal phase, wherein the CaAlSiN.sub.3 family crystal phase comprises at least one element selected from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb.

Proposed are a layered Group III-V compound having ferroelectric properties, a Group III-V compound nanosheet that may be prepared using the same, and an electrical device including the materials. Proposed is a layered compound represented by [Formula 1] M.sub.x−mA.sub.yB.sub.z (M is at least one of Group I or Group II elements, A is at least one of Group III elements, B is at least one of Group V elements, x, y, and z are positive numbers which are determined according to stoichiometric ratios to ensure charge balance when m is 0, and 0<m<x), and having ferroelectric-like properties.

Provided are methods of stabilizing MXene compositions using polyanionic salts so as to reduce the oxidation of the MXenes. Also provided are stabilized MXene compositions.