Powder of particles, more than 95% by number of said particles exhibiting a circularity greater than or equal to 0.85, wherein said powder contains more than 99.8% of a rare earth oxide and/or of hafnium oxide and/or of yttrium aluminum oxide, as percentage by weight relative to the oxides, and has: a median particle size D 50 of between 10 and 40 microns and a size dispersion index (D 90D 10)/D 50 of less than 3; a percentage by number of particles having a size less than or equal to 5 m which is less than 5%; an apparent-density dispersion index (P<50P)/P of less than 0.2, the cumulative specific volume of the pores which have a radius of less than 1 m being less than 10% of the apparent volume of the powder, in which the percentiles Dn of the powder are the particle sizes corresponding to the percentages, by number, of n %, on the curve of cumulative distribution of the particle size of the powder, the particle sizes being classified in increasing order, the density P<50 being the apparent density of the fraction of particles having a size less than or equal to D50, and the density P being the apparent density of the powder.

Nanowires useful as heterogeneous catalysts are provided. The nanowire catalysts are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to ethylene. Related methods for use and manufacture of the same are also disclosed.

A method for producing a metal oxide nanocrystals according to the embodiment of the present invention comprises continuously flowing a nanocrystal precursor solution comprising a nanocrystal precursor into a continuous flow path and heating the nanocrystal precursor solution in the continuous flow path to create nanocrystals, comprising: providing a nanocrystal precursor solution supply unit that is connected to the continuous flow path and comprises a first vessel and a second vessel; delivering a nanocrystal precursor solution in the second vessel to the continuous low path; and creating a nanocrystal precursor solution in the first vessel as a different batch from the nanocrystal precursor solution in the second vessel.

Terbium-based Faraday rotators, optical isolators incorporating the Faraday rotators, and methods for forming the Faraday rotators are described. Formation methods include hydrothermal growth methods for forming monolithic single crystals of TbO(OH) as Faraday rotator materials. TbO(OH) can also be used as a starting material in a hydrothermal growth method to form monolithic single crystals of Tb.sub.xYb.sub.(2-x)O.sub.3, in which x is between about 0.05 and about 1 or terbium aluminum garnet TAG for use as a Faraday rotator in an optical isolator.

The present invention relates to a porous formed article comprising an organic polymer resin and an inorganic ion adsorbent and having the most frequent pore size of 0.08 to 0.70 m measured with a mercury porosimeter.

The present invention also relates to a method for producing a porous formed article and a production apparatus for a porous formed article.

A method for producing metal oxide nanocrystals, according to the embodiment of the present invention, includes: continuously flowing, into a continuous flow path, one or a plurality of nanocrystal precursor solutions each comprising one or more nanocrystal precursors dissolved in a non-polar solvent; directing a segmenting gas into the continuous flow path to create a segmented reaction flow; flowing the segmented reaction flow into a thermal processor; heating the segmented reaction flow in the thermal processor to create a product flow; and collecting metal oxide nanocrystals from the product flow.

The present invention relates to a novel method for preparing a water-insoluble metal hydroxide, and a use thereof. The water-insoluble metal hydroxide of the present invention is conveniently and efficiently prepared s through the high-temperature heat treatment step two times and the washing step, and thus contains a small amount of an alkali metal and has a high crystallinity and a phase purity. The water-insoluble metal hydroxide of the present invention or metal oxide therefrom exhibits an absorption wavelength at a low wavelength range (for example, 490 nm or less) and a light emitting wavelength at a high wavelength range (for example, from 500 nm or more to less than 1,100 nm). Accordingly, the water-insoluble metal hydroxide of the present invention may be efficiently used in various applications such as a fire retardant, an antacid, an adsorbent and so forth, and may also be doped with another metal ion to be utilized as a raw material for fabricating a catalyst, a fluorescent material, an electrode material, a secondary battery material and the like.

The object of the present invention is to provide a high-performance exhaust gas purifying catalyst that can achieve oxygen absorption/release capacity and NOx purification performance. The object is solved by an exhaust gas purifying catalyst, which comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure in the upstream part of the catalyst coating layer, 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 % of the total cation amount, and has a molar ratio of (cerium+the additional element):(zirconium) of 43:57 to 48:52.

Disclosed is a method and system for recovering at least rare earth elements from within an object A consisting of at least one first rare earth portion or a mixture of rare earth elements and a second metal portion. The method includes a solvothermal treatment step that places the object in contact with a fluid for causing at least one rare earth portion and/or mixture of rare earth elements and the metal portion to oxidize in order to separate same, the value of the reaction temperature Tr is selected according to the nature of the object, the reaction following a R-M.fwdarw.R(X)x+M(X)y scheme, where R is the rare earth element or a mixture of rare earth elements, M is the transition metal, and (X) is a group which depends on the fluid used.

A gas sensor capable of detecting carbon dioxide and having high stability is provided. A carbon dioxide gas sensor comprising an insulating substrate 3 and a gas sensing layer 1 formed on one major surface of the insulating substrate 3 via electrodes 2, wherein the gas sensing layer 1 comprises: (a) one or more rare earth metal oxycarbonates represented by Ln.sub.2O.sub.2CO.sub.3, Ln being at least one rare earth metal element selected from Sc, Y, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Pr, Yb and Lu, the rare earth metal oxycarbonate containing a hexagonal rare earth metal oxycarbonate as a main component; or (b) monoclinic samarium dioxycarbonate,
a production method of the gas sensor, and a method of selectively producing crystal polymorphism of lanthanum dioxycarbonate represented by La.sub.2O.sub.2CO.sub.3 are provided.