A process for producing a magnesium aluminate spinel comprising the steps of: i) preparing a magnesium suspension containing a magnesium compound; ii) preparing an aluminum suspension containing an aluminum compound; iii) feeding the magnesium suspension and aluminum suspension independently into a spray dryer nozzle to form a mixed magnesium, aluminum suspension; iv) feeding the mixed magnesium, aluminium suspension from the spray dryer nozzle into a spray dryer to form a mixed magnesium and aluminum compound; and v) calcining the mixed magnesium and aluminum compound to generate a magnesium aluminate spinel.

Provided is a zirconia sintered body that uses coloring of cerium oxide, the zirconia sintered body exhibiting a bright red color. The zirconia sintered body includes an oxide of cerium is an amount of 0.5% by mole or more and less than 4% by mole in terms of CeO.sub.2, yttria in an amount of 2% by mole or more and less than 6% by mole, an oxide of aluminum in an amount of 0.1% by weight or more and less than 2% by weight, and the balance being zirconia. The oxide of cerium contains trivalent cerium, and the zirconia has a crystal structure including a tetragonal phase.

Provided are a liquid-crystal-display protection plate that has a high strength, is produced at a reduced cost, and has a shape including a curved surface; and a method for producing the liquid-crystal-display protection plate. The liquid-crystal-display protection plate is formed of a spinel sintered body. The spinel sintered body has an average grain size of 10 m or more and 100 m or less. The liquid-crystal-display protection plate has a shape including a curved surface.

Particles for a monolithic refractory are made of a spinet porous sintered body which is represented by a chemical formula of MgAl.sub.2O.sub.4, wherein pores having a pore size of 0.01 m or more and less than 0.8 m occupy 10 vol % or more and 50 vol % or less with respect to a total volume of pores having a pore size of 10 m or less in the particles, and the particles for a monolithic refractory have grain size distribution in which particles having a particle size of less than 45 m occupy 60 vol % or less, particles having a particle size of 45 m or more and less than 100 m occupy 20 vol % or more and 60 vol % or less, and particles having a particle size of 100 m or more and 1000 m or less occupy 10 vol % or more and 50 vol % or less.

A process for preparing particles of a layered double hydroxide of the general formula

[M.sub.p.sup.z+M.sub.q.sup.y+(OH).sub.2].sup.a+(X.sup.n).sub.a/n.bH.sub.2O(I)

wherein M.sup.z+ and M.sup.y+ are metal cations or mixtures of metal cations, z=1 or 2; y=3 or 4; p+q=1; b=0 to 10, X.sup.n is an anion, n is 1 to 5 and a is determined by p, q, y and z such that a=zp+yq2, comprises (a) mixing, in aqueous solution, M.sup.z+ cations, M.sup.y+ cations and X.sup.n anions, with a base; and (b) allowing the layered double hydroxide of formula (I) to precipitate from the solution mixed in step (a).

Preferably, M is Li, Mg, Zn, Fe, Ni, Co, Cu, Ca, or a mixture of two or more. Preferably, y is 3, and M is Al, Ga, In, Fe or a mixture of two or more thereof. Also provided are particles obtainable by the process, especially wherein M is Ca, M is Al, and X.sup.n is NO.sub.3.sup.. Particles of a layered double hydroxide wherein the particles have a particle size of not greater than 2000 nm, preferably not greater than 300 nm and especially not greater than 100 nm, are also provided. The layered double hydroxides according to the invention are useful in certain applications, for example, as adsorbents, coatings and catalyst supports.

Spinel has conventionally been used as mentioned above in applications, such as gems, catalyst carriers, adsorbents, photocatalysts, optical materials, and heat-resistant insulating materials, and is not expected to be used in an application of an inorganic filler having thermal conductive properties. Accordingly, an object of the present invention is to provide spinel particles having excellent thermal conductive properties. A spinel particle having spinel containing a magnesium atom, an aluminum atom, and an oxygen atom, and molybdenum being existed on the surface of and/or in the inside of the spinel, wherein the crystallite diameter of the spinel at the [311] plane is 100 nm or more.

The present invention relates to a method for the passivation of MgAl.sub.2O.sub.4 (Mg-spinel) powders against hydrolysis exhibiting in aqueous media by coating the surfaces with Al.sub.2O.sub.3 during the synthesis via flame pyrolysis technique. Stable aqueous suspensions with high solid loading and low viscosity can be prepared from coated powders with a core/shell structure of MgO.nAl.sub.2O.sub.3 (0.65<n<4.10)/Al.sub.2O.sub.3. Such suspensions might not only ensure production of high quality granules, but also enable production of green bodies with high density and homogeneity through wet forming methods. Accordingly, precise microstructural control can be ensured during sintering. Al.sub.2O.sub.3 shell re-dissolves within the core during sintering at variable temperatures depending on the core stoichiometry (n value). The final stoichiometry might be altered by controlling the n value of the core, the shell thickness and particle size distribution.

The present invention relates to a method for the production of a support material for a nitrogen oxide storage component that is applicable in catalysts for treating exhaust gases from lean-burn engines and a support material made according to said process that is stable against the reaction with a Barium compound to form BaAl.sub.2O.sub.4.

Feed material comprising uniform solution precursor droplets is processed in a uniform melt state using microwave generated plasma. The plasma torch employed is capable of generating laminar gas flows and providing a uniform temperature profile within the plasma. Plasma exhaust products are quenched at high rates to yield amorphous products. Products of this process include spherical, highly porous and amorphous oxide ceramic particles such as magnesia-yttria (MgOY.sub.2O.sub.3). The present invention can also be used to produce amorphous non oxide ceramic particles comprised of Boron, Carbon, and Nitrogen which can be subsequently consolidated into super hard materials.

Separators, electrochemical cells and methods are provided, to improve operation of cells such as metal-ion batteries and fuel cells. Separators comprise a porous, ionically conductive film including layered double hydroxide(s) (LDHs), which are functional ceramic additives, removing potentially harmful anions from the electrolyte by incorporating them into the LDH structure of positively-charged sheets with intermediary anions. For example, anions which are electrolyte decomposition products or cathode dissolution products may be absorbed into the LDH to prevent them from causing damage to the cell and shortening the cell's life. LDHs may be incorporated in the separator structure, coated thereupon or otherwise associated therewith. Additional benefits include dimensional stability during thermal excursions, fire retardancy and impurity scavenging.