A heat-resistant member (1) according to the present disclosure contains alumina as a main component, and magnesium aluminate and boron. The content percentage of the magnesium aluminate at the surface is higher than the content percentage of the magnesium aluminate in a surface layer section located directly below the surface.

A heat-resistant member (1) according to the present disclosure contains alumina as a main component, and magnesium aluminate and boron. The content percentage of the magnesium aluminate at the surface is higher than the content percentage of the magnesium aluminate in a surface layer section located directly below the surface.

The invention provides for a method of making a magnesium aluminate spinel including an alumina compound and a magnesium compound, the method including the steps of; dispersing the alumina compound by dispersing it in a aqueous solution, to form an alumina dispersion, the aqueous solution having a pH of between 2 and 5; preferably between 2 and 4, flocculating the alumina by increasing the pH of the alumina dispersion to a pH of between 8 and 10 by adding a base; adding the alumina dispersion to an aqueous dispersion of the magnesium compound to form a slurry; drying the slurry to produce a dried spinel precursor; and calcining the dried spinel precursor to produce the magnesium aluminate spinel. Dispersing at such a low pH results in a conversion to spinel as well as allows for the control of the surface area of the spinel.

A positive electrode active material that has high capacity and excellent charge and discharge cycle performance for a secondary battery is provided. The positive electrode active material includes a group of particles including a first group of particles and a second group of particles. The group of particles includes lithium, cobalt, nickel, aluminum, magnesium, oxygen, and fluorine. When the number of cobalt atoms included in the group of particles is taken as 100, the number of nickel atoms is greater than or equal to 0.05 and less than or equal to 2, the number of aluminum atoms is greater than or equal to 0.05 and less than or equal to 2, and the number of magnesium atoms is greater than or equal to 0.1 and less than or equal to 6. When particle size distribution in the group of particles is measured by a laser diffraction and scattering method, the first group of particles has a first peak and the second group of particles has a second peak; the first peak has a local maximum value at longer than or equal to 2 μm and shorter than or equal to 4 μm, and the second peak has a local maximum value at longer than or equal to 9 μm and shorter than or equal to 25 μm.

A positive electrode active material that has high capacity and excellent charge and discharge cycle performance for a secondary battery is provided. The positive electrode active material includes a group of particles including a first group of particles and a second group of particles. The group of particles includes lithium, cobalt, nickel, aluminum, magnesium, oxygen, and fluorine. When the number of cobalt atoms included in the group of particles is taken as 100, the number of nickel atoms is greater than or equal to 0.05 and less than or equal to 2, the number of aluminum atoms is greater than or equal to 0.05 and less than or equal to 2, and the number of magnesium atoms is greater than or equal to 0.1 and less than or equal to 6. When particle size distribution in the group of particles is measured by a laser diffraction and scattering method, the first group of particles has a first peak and the second group of particles has a second peak; the first peak has a local maximum value at longer than or equal to 2 μm and shorter than or equal to 4 μm, and the second peak has a local maximum value at longer than or equal to 9 μm and shorter than or equal to 25 μm.

A double capsule assembly includes an outer capsule and an inner capsule configured to be positioned within the outer capsule. The inner capsule is configured to have a sample positioned therein. The double capsule assembly is configured to be placed in a solid media assembly to analyze or synthesize the sample.

A double capsule assembly includes an outer capsule and an inner capsule configured to be positioned within the outer capsule. The inner capsule is configured to have a sample positioned therein. The double capsule assembly is configured to be placed in a solid media assembly to analyze or synthesize the sample.

A solid electrolyte includes an ion conductor represented by at least one of Formulae 1 to 3,
Li.sub.1+3xM1.sub.1−xO.sub.2  Formula 1
wherein, in Formula 1, M1 is a trivalent element, and 0<x<1,
L.sub.1−yM2O.sub.2−yX.sub.y  Formula 2
wherein, in Formula 2, M2 is a trivalent element, X is at least one of a halogen atom or a pseudohalogen, and 0<y<1,
Li.sub.1−z(a−3)M3.sub.1−zD.sub.zO.sub.2  Formula 3
wherein, in Formula 3, M3 is a trivalent element, D is at least one of a monovalent element to a hexavalent element, and 0<z<1.

A solid electrolyte includes an ion conductor represented by at least one of Formulae 1 to 3,
Li.sub.1+3xM1.sub.1−xO.sub.2  Formula 1
wherein, in Formula 1, M1 is a trivalent element, and 0<x<1,
L.sub.1−yM2O.sub.2−yX.sub.y  Formula 2
wherein, in Formula 2, M2 is a trivalent element, X is at least one of a halogen atom or a pseudohalogen, and 0<y<1,
Li.sub.1−z(a−3)M3.sub.1−zD.sub.zO.sub.2  Formula 3
wherein, in Formula 3, M3 is a trivalent element, D is at least one of a monovalent element to a hexavalent element, and 0<z<1.

Provided is a layered double hydroxide oriented membrane in which layered double hydroxide plate-like particles are highly oriented in the approximately perpendicular direction and which is also suitable for densification. The layered double hydroxide oriented membrane of the present invention is composed of a layered double hydroxide represented by the general formula: M.sup.2+.sub.1-xM.sup.3+.sub.x(OH).sub.2A.sup.n−.sub.x/n.mH.sub.2O wherein M.sup.2+ is a divalent cation, M.sup.3+ is a trivalent cation, A.sup.n− is an anion having a valency of n, n is an integer of 1 or greater, x is 0.1 to 0.4, and m is 0 or greater, wherein when a surface of the oriented membrane is measured by X-ray diffractometry, a peak of a (003) plane is not substantially detected or is detected to be smaller than a peak of a (012) plane.