A process of isolating samarium from a hydrophilic composition comprises nitrate ions, europium and samarium, by reducing europium(III) to europium(II) in this hydrophilic composition, and by extracting the samarium with a water-immiscible organic phase comprising an ionic liquid comprising nitrate anions.

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 disclosure provides for compositions, methods of making compositions, and methods of using the composition. In an aspect, the composition can be a reactive material that can be used to split a gas such as water or carbon dioxide.

The present invention is to provide an electron or hydride ion intake/release material comprising a lanthanoid oxyhydride represented by the formula Ln(HO) (in the formula, Ln represents a lanthanoid element) or an electron or hydride ion intake/release composition comprising at least one kind of lanthanoid oxyhydride; a transition metal-supported material wherein a transition metal is supported by the above electron or hydride ion intake/release material or electron or hydride ion intake/release composition; and a catalyst comprising the transition metal-supported material. The electron or hydride ion intake/release material or electron or hydride ion intake/release composition according to the present invention has a higher ability for intake/release of electron or hydride ion than that of a conventional hydride-containing compound, and can be used effectively as a catalyst such as a catalyst having excellent ammonia synthesis activity by supporting a transition metal thereon.

The present invention is to provide an electron or hydride ion intake/release material comprising a lanthanoid oxyhydride represented by the formula Ln(HO) (in the formula, Ln represents a lanthanoid element) or an electron or hydride ion intake/release composition comprising at least one kind of lanthanoid oxyhydride; a transition metal-supported material wherein a transition metal is supported by the above electron or hydride ion intake/release material or electron or hydride ion intake/release composition; and a catalyst comprising the transition metal-supported material. The electron or hydride ion intake/release material or electron or hydride ion intake/release composition according to the present invention has a higher ability for intake/release of electron or hydride ion than that of a conventional hydride-containing compound, and can be used effectively as a catalyst such as a catalyst having excellent ammonia synthesis activity by supporting a transition metal thereon.

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.

A highly stable gas sensor capable of detecting carbon dioxide is provided. A carbon dioxide gas sensor includes an insulating substrate and a gas sensing layer formed on one major surface of the insulating substrate via electrodes, in which the gas sensing layer comprises one or more rare earth oxides represented by Ln.sub.2O.sub.3, Ln being at least one rare earth metal element selected from Sc, Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Pr, Yb and Lu, and a method for producing the gas sensor are provided.

There is provided a lithium-iron-manganese-based composite oxide capable of providing a lithium-ion secondary battery which has a high capacity retention rate in charge/discharge cycles and in which the generation of a gas caused by charge/discharge cycles is suppressed. A lithium-iron-manganese-based composite oxide having a layered rock-salt structure, wherein at least a part of the surface of a lithium-iron-manganese-based composite oxide represented by the following formula is coated with an oxide of at least one metal selected from the group consisting of La, Pr, Nd, Sm and Eu:
Li.sub.xM.sup.1.sub.(y-p)Mn.sub.pM.sup.2.sub.(z-q)Fe.sub.qO.sub.(2-) wherein 1.05x1.32, 0.33y0.63, 0.06z0.50, 0<p0.63, 0.06q0.50, 00.80, yp, and zq; M.sup.1 is at least one element selected from Ti and Zr; and M.sup.2 is at least one element selected from the group consisting of Co, Ni and Mn.

A process for separating rare earth elements (REE) from Ca, Mg and other non-REE elements comprises raising the pH of an acidic aqueous solution of REE to pH 8 to pH 11; adding nano- or micro (NoM) particles having a silica or titanium oxide surface; agitating the suspension for 6 h to 48 h to provide for adherent crystallization of REE hydroxide on the particles; separating the particles from the solution; releasing REE by treatment with aqueous acid to form an aqueous solution of REE salt; separating them from the aqueous solution of REE salt formed. The acidic aqueous solution comprising REE is preferably provided by leaching of an REE mineral with aqueous acid; adding a base to bring the pH to from pH 4.0 to pH 6.5; separating precipitated non-REE hydroxide from the solution.

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.