The present invention relates to a ferrite particle, containing a crystal phase component containing a perovskite crystal represented by the compositional formula:

RZrO.sub.3 (provided that R represents an alkaline earth metal element), and having an apparent density in a range represented by the following formula:

1.90≤Y≤2.45

provided that Y in the formula is the apparent density (g/cm.sup.3) of the ferrite particle.

There is provided a piezoelectric stack, including: a substrate; an oxide film on the substrate, containing zinc and oxygen as main elements; an electrode film on the oxide film; and a piezoelectric film on the electrode film, being an alkali niobium oxide film containing potassium, sodium, niobium, and oxygen and having a perovskite structure.

Compositions comprise a perovskite and a non-perovskite. Perovskites comprise A.sub.xA′.sub.yA″.sub.(1−x−y)BX.sub.3, and non-perovskites may comprise A″, B and X, where A is a first cation, A′ is a second cation, A″ is a third cation, B is a fourth cation, X is an anion. In some instances, A, A′, and A″ are each independently (NH.sub.2).sub.2CH.sup.+, CH.sub.3NH.sub.3.sup.+, Cs.sup.+, Rb.sup.+, or (NH.sub.2).sub.2(C═NH.sub.2).sup.+, with the proviso that A, A′, and A″ are each different. The perovskite may have a first crystal structure in which the anion is corner-sharing, the non-perovskite may have a second crystal structure comprising at least one of an orthorhombic structure, a hexagonal structure, or a perovskite-like structure, and 1−x−y may be greater than about 0.15.

The present disclosure pertains to a color filter for a display device, which has at least one color filter element for generating a predefined color in response to incident light, wherein the at least one color filter element includes a Perovskite material.

A powder of melted particles, more than 95% by number of the particles exhibiting a circularity of greater than or equal to 0.85. The powder including more than 99.8% of a rare earth metal oxide and/or of hafnium oxide and/or of an aluminum oxide, as percentage by mass based on the oxides. The powder has a median particle size D.sub.50 of less than 15 μm, a 90 percentile of the particle sizes, D.sub.90, of less than 30 μm, and a size dispersion index (D.sub.90−D.sub.10)/D.sub.10 of less than 2, and a relative density of greater than 90%. The D.sub.n percentiles of the powder are the particle sizes corresponding to the percentages, by number, of n %, on the cumulative distribution curve of the size of the particles in the powder and the particle sizes are classified by increasing order.

Disclosed are processes for preparing hybrid perovskite quantum dots and the resulting hybrid perovskite quantum dots and uses thereof. Such quantum dots are useful as semiconductors in devices such as solar cells and light-emitting diodes.

Provided is a method for producing a near infrared-reflective black pigment containing at least the element calcium, the element titanium, and the element manganese, wherein the method produces a pigment that exhibits little of the elution of the element calcium and the element manganese that is caused by contact with acid. At least a calcium compound, a titanium compound, and a manganese compound are mixed by a wet grinding method and are calcined to provide a BET specific surface area of at least 1.0 m.sup.2/g and less than 3.0 m.sup.2/g. In another method, the element bismuth and/or the element aluminum is incorporated in a near infrared-reflective black pigment containing at least the element calcium, the element titanium, and the element manganese.

The present invention refers to a gas sensor comprising a hybrid material of perovskite and graphene, to the method for obtaining said sensor and to the gas detection method using said sensor.

A piezoelectric composition containing: at least one or more elements selected from alkali metal elements; at least one or more elements selected from a group consisting of vanadium, niobium, and tantalum; copper or copper and germanium; and oxygen. The piezoelectric composition has a main phase, and a high Cu-concentration phase in which a content ratio of copper is higher than the main phase, and when a content ratio of oxygen in the high Cu-concentration phase is set as O.sub.g, and a content ratio of copper is set as Cu.sub.g, O.sub.g and Cu.sub.g satisfy relationships of 51≤O.sub.g≤60 and 2.0≤Cu.sub.g≤15.

A compound has a perovskite type crystal structure containing A which is a monovalent cation, B which is a metal ion, and X which is a halide ion as components. The perovskite type crystal structure has a unit cell volume of 0.2000 nm.sup.3 or more and 0.2150 nm.sup.3 or less, an ionic radius of B of 0.7 Å or more and 1.4 Å or less, and an ionic radius of X of 0.5 Å or more and 2.5 Å or less.