A positive electrode active material for a sodium ion battery includes a sodium complex oxide of the formula Na.sub.4(M.sup.1.sub.aM.sup.2.sub.1a).sub.2O.sub.5 having an orthorhombic crystal structure, wherein M.sup.1 and M.sup.2 are each independently Ti, Cr, Fe, Co, Ni, Mn, V, or a combination there of provided that M.sup.1 and M.sup.2 are different from each other; and 0a1.

Process for reducing hexavalent chromium in oxidic solids, which comprises the steps: a) heating of the oxidic solid containing Cr(VI) to a temperature of from 600 to 1400 C. in an atmosphere containing less than 0.1% by volume of an oxidizing gas and b) cooling of the reaction product obtained after step a) to a temperature below 100 C. in an atmosphere containing less than 0.1% by volume of an oxidizing gas,
characterized in that no reducing agent is added to the oxidic solid or to the atmosphere in step a) and b) in the process.

The present disclosure provides a metal compound. The metal compound is represented by a formula (I): Cu.sub.2A.sub.?B.sub.2-?O.sub.4-? (I). A contains at least one element selected from the groups 6 and 8 of the periodic table. B contains at least one element selected from the group 13 of the periodic table, 0<?<2, and 0<?<1.5. Polymer article containing the metal compound and method for preparing the polymer article as well as selective metallization of a surface of the polymer article are also provided. In addition, the present disclosure provides an ink composition and the selective metallization for a surface of the insulative substrate using the ink composition.

Shaded, zirconia ceramic materials are disclosed that are suitable for use in dental applications. Ceramic bodies are made from a zirconia-containing ceramic material and a coloring composition comprising a terbium (Tb)-containing component and a chromium (Cr)-containing component as a coloring agent. The pre-shaded ceramic body is machinable into a dental restoration either as a bisque body or sintered body. A pre-shaded machinable sintered ceramic body may obviate the need for further processing steps, such as shading or sintering, and may be suitable for use in chair-side machining applications, such as in a dentist's office, significantly reducing the time to create a custom finished product.

Shaded, zirconia ceramic materials are disclosed that are suitable for use in dental applications. Ceramic bodies are made from a zirconia-containing ceramic material and a coloring composition comprising a terbium (Tb)-containing component and a chromium (Cr)-containing component as a coloring agent. The pre-shaded ceramic body is machinable into a dental restoration either as a bisque body or sintered body. A pre-shaded machinable sintered ceramic body may obviate the need for further processing steps, such as shading or sintering, and may be suitable for use in chair-side machining applications, such as in a dentist's office, significantly reducing the time to create a custom finished product.

A magnetic hydrotalcite composite which is useful in fields such as wastewater treatment, ultraviolet absorption, electromagnetic wave absorption and acid gas absorption, and a production method thereof. The magnetic hydrotalcite composite comprises an inner layer and an outer layer, in which the inner layer is made of a hydrotalcite compound and the outer layer is made of a ferrite compound.

A cathode composition for a sodium-ion battery. The cathode composition may have the formula NaCr.sub.1-xM.sub.xO.sub.2, where M is one or more metal elements, and x is greater than 0 and less than or equal to 0.5.

Methods of forming spinel ferrite nanoparticles containing a chromium-substituted copper ferrite as well as properties (e.g. particle size, crystallite size, pore size, surface area) of these spinel ferrite nanoparticles are described. Methods of preventing or reducing microbe growth on a surface by applying these spinel ferrite nanoparticles onto the surface in the form of a suspension or an antimicrobial product are also described.

The present invention relates to a process for preparing chromium(III) oxide by reaction of alkali metal chromate with gaseous ammonia, subsequent hydrolysis, isolation of the hydrolysis product and calcination.

The present invention relates to a process for preparing chromium(III) oxide by reaction of alkali metal chromate with gaseous ammonia, subsequent hydrolysis, isolation of the hydrolysis product and calcination.