A ceria-zirconia composite oxide includes at least one of lanthanum, yttrium, and praseodymium. A rate of a total content of the at least one rare earth element to a total content of cerium and zirconium is 0.1 at % to 4.0 at %. A content of the rare earth element present in near-surface regions, which are at a distance of less than 50 nm from surfaces of primary particles of the ceria-zirconia composite oxide, accounts for 90 at % or more of the total content of the rare earth element. An average particle size of the primary particles of the ceria-zirconia composite oxide is 2.2 m to 4.5 m. After a predetermined durability test, the intensity ratio I(14/29) of a diffraction line at 2=14.5 to a diffraction line at 2=29 and the intensity ratio I(28/29) of a diffraction line at 2=28.5 to the diffraction line at 2=29 respectively satisfy the following conditions:
I(14/29)0.02, and
I(28/29)0.08.

There is provided an oxide semiconductor that is capable of achieving p-type semiconductor properties in the oxide semiconductor and has excellent transparency, mobility and weather resistance. The oxide semiconductor is achieved by an oxide composite having a pyrochlore structure that contains Sn and Nb whose composition ratio Sn/Nb is 0.81Sn/Nb<1.0. The oxide semiconductor has a wide bandgap of 2.2 eV, indicating that the oxide semiconductor has transparency in a visible spectrum and is a p-type semiconductor with high mobility. When Sn is less than a stoichiometric composition ratio in a composition formula of Sn.sub.2Nb.sub.2O.sub.7, that is, when Sn/Nb<1, p-type semiconductor properties can be achieved by generation of a structural defect V.sub.Sn, and when the composition ratio Sn/Nb is greater than or equal to 0.81, the pyrochlore structure is obtained.

A ceria-zirconia-based composite oxide containing a composite oxide of ceria and zirconia is provided, in which primary particles having a particle diameter of 1.5 to 4.5 m account for, on a particle number basis, at least 50% of all primary particles in the ceria-zirconia-based composite oxide, and the molar ratio of cerium to zirconium in the ceria-zirconia-based composite oxide is between 43:57 and 55:45.

Provided is a polycrystalline oxide having a chemical formula such as the following A.sub.1xB.sub.1yM.sub.yO.sub.3 and having an improved grain boundary proton conductivity as an oxide having a perovskite structure. Through the present invention, the conductivity and chemical stability of proton conducting oxide may be improved.

A ceria-zirconia-based composite oxide containing a composite oxide of ceria and zirconia is provided, in which primary particles having a particle diameter of 1.5 to 4.5 m account for, on a particle number basis, at least 50% of all primary particles in the ceria-zirconia-based composite oxide, and the molar ratio of cerium to zirconium in the ceria-zirconia-based composite oxide is between 43:57 and 55:45.

The object of the present invention is to provide an exhaust gas purifying catalyst that can achieve high purification performance while suppressing H.sub.2S emissions. The object is solved by an exhaust gas purifying catalyst in which the lower layer of the catalyst coating layer comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % in relation to the total cation amount, and the molar ratio of (cerium+additional element):(zirconium) is within the range from 43:57 to 48:52.

Provided is a cerium-zirconium-based composite oxide having an excellent OSC, high catalytic activity, and excellent heat resistance, and also provided is a method for producing the same. The cerium-zirconium-based composite oxide comprises cerium, zirconium, and a third element other than these elements. The third element is (a) a transition metal element or (b) at least one or more elements selected from the group consisting of rare earth elements and alkaline earth metal elements. After a heat treatment at 1,000 C. to 1,100 C. for 3 hours, (1) the composite oxide has a crystal structure containing a pyrochlore phase, (2) a value of {I111/(I111+I222)}100 is 1 or more, and (3) the composite oxide has an oxygen storage capacity at 600 C. of 0.05 mmol/g or more, and an oxygen storage capacity at 750 C. of 0.3 mmol/g or more.

The present invention relates to high-entropy rare earth zirconates. The high-entropy rare earth zirconate structure of the present invention has a single phase, and, compared to the conventional rare earth zirconate, lattice distortion increases and oxygen vacancies are increased to suppress heat transfer, so it can be confirmed that it has an excellent heat barrier effect as a heat shield coating material. It can maintain a stable single phase without phase change even in a high temperature environment of 1000 C. or higher.

A core-shell support, comprising: a core which comprises at least one oxygen storage/release material selected from the group consisting of ceria-zirconia based solid solutions and alumina-doped ceria-zirconia based solid solutions; and a shell which comprises a rare earth-zirconia based composite oxide represented by a composition formula: (Re.sub.1-xCe.sub.x).sub.2Zr.sub.2O.sub.7+x (where Re represents a rare earth element, and x represents a number of 0.0 to 0.8) and with which an outside of the core is coated, the rare earth-zirconia based composite oxide comprising crystal particles having a pyrochlore structure, and the rare earth-zirconia based composite oxide having an average crystallite diameter of 3 to 9 nm.

The instant disclosure sets forth multiphase lithium-stuffed garnet electrolytes having secondary phase inclusions, wherein these secondary phase inclusions are material(s) which is/are not a cubic phase lithium-stuffed garnet, but which is/are entrapped or enclosed within a lithium-stuffed garnet. When the secondary phase inclusions described herein are included in a lithium-stuffed garnet at 30-0.1 volume %, the inclusions stabilize the multiphase matrix and allow for improved sintering of the lithium-stuffed garnet. The electrolytes described herein, which include lithium-stuffed garnet with secondary phase inclusions, have an improved sinterability and density compared to phase pure cubic lithium-stuffed garnet having the formula Li.sub.7La.sub.3Zr.sub.2O.sub.12.