A zirconium nitride powder which has a specific surface area of 20 to 90 m.sup.2/g as measured by a BET method, has a peak corresponding to zirconium nitride but does not have a peak corresponding to zirconium dioxide, a peak for lower zirconium oxide or a peak corresponding to lower zirconium oxynitride in an X-ray diffraction profile, and the light transmittance X at 370 nm is at least 18%, the light transmittance Y at 550 nm is 12% or less and the ratio (X/Y) of the light transmittance X at 370 nm to the light transmittance Y at 550 nm is 2.5 or more in the transmission spectra of a dispersion that contains the powder at a concentration of 50 ppm.

A zirconium nitride powder which has a specific surface area of 20 to 90 m.sup.2/g as measured by a BET method, has a peak corresponding to zirconium nitride but does not have a peak corresponding to zirconium dioxide, a peak for lower zirconium oxide or a peak corresponding to lower zirconium oxynitride in an X-ray diffraction profile, and the light transmittance X at 370 nm is at least 18%, the light transmittance Y at 550 nm is 12% or less and the ratio (X/Y) of the light transmittance X at 370 nm to the light transmittance Y at 550 nm is 2.5 or more in the transmission spectra of a dispersion that contains the powder at a concentration of 50 ppm.

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.

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.

Asymmetric porous films, methods of making, and devices. An asymmetric porous film may have a surface layer, which may be an isoporous surface layer, disposed on a substructure, which may be a graded porous substructure that may have mesopores throughout. An asymmetric porous film may be a hybrid asymmetric porous film comprising one or more precursor(s). An asymmetric porous film may include one or more carbon material(s), one or more metalloid oxide(s), one or more metal(s), one or more metal oxide(s), one or more metal nitride(s), one or more metal oxynitride(s), one or more metal carbide(s), one or more metal carbonitrides, or a combination thereof. A method of making an asymmetric porous film may comprise formation of an asymmetric porous film using CA a mixture comprising a multiblock copolymer that can self-assemble and one or more precursor(s).

Provided are: composite particles having excellent oxidation resistance; and a method for producing composite particles. The composite particles are obtained by forming a composite of TiN and at least one of Al, Cr, and Nb. In the method for producing composite particles, a titanium powder and a powder of at least one of Al, Cr, and Nb are used as raw material powders and composite particles are produced using a gas phase method.

A black material of the present invention consists of a zirconium nitride powder containing yttrium. The amount of the yttrium is 1.0% by mass to 12.0% by mass with respect to a total 100% by mass of the zirconium nitride powder and the yttrium. In a transmission spectrum obtained from a dispersion in which the concentration of the zirconium nitride powder containing yttrium is 50 ppm, assuming that the light transmittance at a wavelength of 550 nm is denoted by X.sub.1, and the light transmittance at a wavelength of 365 nm is denoted by X.sub.2, X.sub.1 is 7.5% or less, X.sub.2 is 25% or more, and X.sub.2/X.sub.1 is 3.5 or more.

Provided is a piezoelectric thin film device containing: a first electrode layer; and a piezoelectric thin film. The first electrode layer contains a metal Me having a crystal structure. The piezoelectric thin film contains aluminum nitride having a wurtzite structure. The aluminum nitride contains a divalent metal element Md and a tetravalent metal element Mt. [Al] is an amount of Al contained in the aluminum nitride, [Md] is an amount of Md contained in the aluminum nitride, [Mt] is an amount of Mt contained in the aluminum nitride, ([Md]+[Mt])/([Al]+[Md]+[Mt]) is 36 to 70 atom %. L.sub.ALN is a lattice length of the aluminum nitride in a direction that is approximately parallel to a surface of the first electrode layer with which the piezoelectric thin film is in contact, L.sub.METAL is a lattice length of Me in a direction, and L.sub.ALN is longer than L.sub.METAL.

Provided is a piezoelectric thin film device containing: a first electrode layer; and a piezoelectric thin film. The first electrode layer contains a metal Me having a crystal structure. The piezoelectric thin film contains aluminum nitride having a wurtzite structure. The aluminum nitride contains a divalent metal element Md and a tetravalent metal element Mt. [Al] is an amount of Al contained in the aluminum nitride, [Md] is an amount of Md contained in the aluminum nitride, [Mt] is an amount of Mt contained in the aluminum nitride, ([Md]+[Mt])/([Al]+[Md]+[Mt]) is 36 to 70 atom %. L.sub.ALN is a lattice length of the aluminum nitride in a direction that is approximately parallel to a surface of the first electrode layer with which the piezoelectric thin film is in contact, L.sub.METAL is a lattice length of Me in a direction, and L.sub.ALN is longer than L.sub.METAL.

Provided are a method of producing a titanium-containing rare earth-iron-nitrogen anisotropic magnetic powder having good magnetic properties, and secondary particles for a titanium-containing anisotropic magnetic powder. The method includes: obtaining a first precipitate containing R, iron, and titanium by mixing a first precipitating agent with a solution containing R, iron, and titanium, wherein R is at least one selected from Sc, Y, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu; obtaining a second precipitate containing R and iron by mixing, in the presence of the first precipitate, a second precipitating agent with a solution containing R and iron; obtaining an oxide containing R, iron, and titanium by calcining the second precipitate; obtaining a partial oxide by heat treating the oxide in a reducing gas atmosphere; obtaining alloy particles by reducing the partial oxide; and obtaining an anisotropic magnetic powder by nitriding the alloy particles.