Provided is a vanadium oxide film which shows substantially no hysteresis of resistivity changes due to temperature rising/falling, has a low resistivity at room temperature, has a large absolute value of the temperature coefficient of resistance, and shows semiconductor-like resistance changes in a wide temperature range. In the vanadium oxide film, a portion of the vanadium has been replaced by aluminum and copper, and the amount of substance of aluminum is 10 mol % based on the sum total of the amount of substance of vanadium, the amount of substance of aluminum, and the amount of substance of copper. This vanadium oxide film has a low resistivity, has a large absolute value of the temperature coefficient of resistance, and shows substantially no hysteresis of resistivity changes due to temperature rising/falling. This vanadium oxide film is produced by applying a mixture solution containing a vanadium organic compound, an aluminum organic compound, and a copper organic compound to a substrate, calcining the substrate at a temperature lower than the temperature at which the substrate decomposes, and irradiating the surface of the substrate onto which the mixture solution has been applied with ultraviolet light.

Provided is a vanadium oxide film which shows substantially no hysteresis of resistivity changes due to temperature rising/falling, has a low resistivity at room temperature, has a large absolute value of the temperature coefficient of resistance, and shows semiconductor-like resistance changes in a wide temperature range. In the vanadium oxide film, a portion of the vanadium has been replaced by aluminum and copper, and the amount of substance of aluminum is 10 mol % based on the sum total of the amount of substance of vanadium, the amount of substance of aluminum, and the amount of substance of copper. This vanadium oxide film has a low resistivity, has a large absolute value of the temperature coefficient of resistance, and shows substantially no hysteresis of resistivity changes due to temperature rising/falling. This vanadium oxide film is produced by applying a mixture solution containing a vanadium organic compound, an aluminum organic compound, and a copper organic compound to a substrate, calcining the substrate at a temperature lower than the temperature at which the substrate decomposes, and irradiating the surface of the substrate onto which the mixture solution has been applied with ultraviolet light.

The invention provides a method for producing composite nanoparticles, the method using a first compound capable of transitioning from a monoclinic to a tetragonal rutile crystal state upon heating, and having the steps of subjecting the first compound to a hydrothermal synthesis to create anisotropic crystals of the compound; encapsulating the first compound with a second compound to create a core-shell construct; and annealing the construct as needed. Also provided is a device for continuously synthesizing composite nanoparticles, the device having a first precursor supply and a second precursor supply; a mixer to homogeneously combine the first precursor and second precursor to create a liquor; a first microreactor to subject the liquor to hydrothermic conditions to create an\isotropic particles in a continuous operation mode; and a second microreactor for coating the particles with a third precursor to create a core-shell construct.

An object of the present invention is to provide vanadium oxide-containing particles each having a core-shell structure, which are excellent in thermochromic property and durability.

The vanadium oxide-containing particles each having a core-shell structure (1) each has (2) a core layer, which contains vanadium dioxide as a major component, and (4) a shell layer, which contains vanadium oxide containing vanadium having a valency number other than four as a major component.

VO.sub.2 and V.sub.2O.sub.5 nano- or micro-materials. The VO.sub.2 nano-materials and micro-materials have an M1 phase structure and oxygen stoichiometry that deviates 2% or less from theoretical stoichiometry. The VO.sub.2 nano-materials and micro-materials may doped with cation dopants and/or anion dopants. The VO.sub.2 and V.sub.2O.sub.5 nano- or micro-materials can be made by hydrothermal methods starting with V.sub.3O.sub.7.H.sub.2O nano- or micro-material. The VO.sub.2 and V.sub.2O.sub.5 nano- or micro-materials can be used as, for example, thermochromic window coatings.

VO.sub.2 and V.sub.2O.sub.5 nano- or micro-materials. The VO.sub.2 nano-materials and micro-materials have an M1 phase structure and oxygen stoichiometry that deviates 2% or less from theoretical stoichiometry. The VO.sub.2 nano-materials and micro-materials may doped with cation dopants and/or anion dopants. The VO.sub.2 and V.sub.2O.sub.5 nano- or micro-materials can be made by hydrothermal methods starting with V.sub.3O.sub.7.H.sub.2O nano- or micro-material. The VO.sub.2 and V.sub.2O.sub.5 nano- or micro-materials can be used as, for example, thermochromic window coatings.

Methods for producing ethylene using nanowires as heterogeneous catalysts are provided. The method includes, for example, an oxidative coupling of methane catalyzed by nanowires to provide ethylene.

Methods for producing ethylene using nanowires as heterogeneous catalysts are provided. The method includes, for example, an oxidative coupling of methane catalyzed by nanowires to provide ethylene.

A magnesium electrochemical cell having a positive electrode containing as an active ingredient, a material of formula [V.sub.2O.sub.5].sub.c [M.sub.aO.sub.b].sub.d and/or a material of formula [V.sub.2O.sub.5].sub.c[M.sub.aO.sub.b].sub.d[MgX.sub.e].sub.g in a metastable structural and morphological phase is provided. In the formulas M is an element selected from the group consisting of P, B, Si, Ge and Mo; and X is O or a halide.

A magnesium electrochemical cell having a positive electrode containing as an active ingredient, a material of formula [V.sub.2O.sub.5].sub.c [M.sub.aO.sub.b].sub.d and/or a material of formula [V.sub.2O.sub.5].sub.c[M.sub.aO.sub.b].sub.d[MgX.sub.e].sub.g in a metastable structural and morphological phase is provided. In the formulas M is an element selected from the group consisting of P, B, Si, Ge and Mo; and X is O or a halide.