A zirconia composition, a zirconia semi-sintered body, a zirconia sintered body, and a dental product are provided. The zirconia sintered body contains 4 mol % to 7 mol % of yttria as stabilizer, and a shielding material. The zirconia sintered body comprises first region and second region having a higher content ratio of the shielding material than the first region. Difference between content ratio of yttria in the first region and that of yttria in the second region is 1 mol % or less.

A composite plate having a thickness of no more than 2 mm, and having laminated therein a zirconia sintered body, an adhesive layer, and a base material, the elasticity of the base material being no more than 100 GPa, and the apparent density of the composite plate being no more than 4.3 g/cm.sup.3.

A biocompatible material for bone repair is described. The bone repair composition includes a mixture of a type I collagen, a type I collagen-glycosaminoglycan coprecipitate, tricalcium phosphate; and bioactive glass. Methods of using the composition for bone repair, and a kit for the bone repair composition are also described.

A composite plate has a thickness of 2 mm or less, which is obtained by laminating and closely fixing a zirconia sintered body and a fiber-reinforced plastic with each other, and the thickness ratio of the zirconia sintered body to the fiber-reinforced plastic is 0.01 to 1, and the apparent density of the composite plate is 4.3 g/cm.sup.3 or less. A composite plate has a thickness of 2 mm or less, which is obtained by laminating and closely fixing a zirconia sintered body and a fiber-reinforced plastic with each other, and the maximum roughness depth of the surface of the zirconia sintered body is 50 m or less per 1 cm.sup.2.

The invention relates to a process for the preparation of a zirconia blank by introducing a zirconia suspension into a porous mould and demoulding the blank formed as well as the use of the optionally presintered blank formed for the preparation of a dental restoration using a very short dense-sintering process.

The invention relates to a process for the production of a dental restoration, in which an oxide ceramic material (a) is subjected to a first heat treatment, (b) is subjected to a second heat treatment and (c) is cooled,
wherein the heat treatment in step (a) is effected at lower pressure than the heat treatment in step (b).

An optical wavelength conversion member including a polycrystalline ceramic sintered body containing, as main components, Al.sub.2O.sub.3 crystal grains and crystal grains of a component represented by formula A.sub.3B.sub.5O.sub.12:Ce, wherein A is at least one element selected from Sc, Y and lanthanoids (except for Ce), and B is at least one element selected from Al and Ga. Further, the following relations are satisfied: 0%X25%, 9%Y45%, and 48%Z90%, wherein X represents a proportion corresponding to the ratio a/N, Y represents a proportion corresponding to the ratio b/N, and Z represents a proportion corresponding to the ratio c/N and a, b, c and N are as defined herein. Also disclosed is a light-emitting device including the optical wavelength conversion member.

A process for producing a process for producing a LnM.sub.2Cu.sub.3O.sub.x high-temperature superconductive powder, the process comprising: i) providing an aqueous solution of Ln, M and Cu and at least one mineral acid; ii) adding at least one sequestrating agent and, optionally, at least one dispersant to the solution to form a precipitate; iii) recovering the precipitate from the solution; and iv) heating the precipitate in a flow of oxygen to form the LnM.sub.2Cu.sub.3O.sub.x powder, wherein Ln is a rare earth element, preferably Y, Ce, Dy, Er, Gd, La, Nd, Pr, Sm, Sc, Yb, or a mixture of two or more thereof, and wherein M is selected from Ca, Sr, and Ba.

A wavelength converter 100 includes: a first phosphor 1 composed of an inorganic phosphor activated by Ce.sup.3+; and a second phosphor 2 composed of an inorganic phosphor activated by Ce.sup.3+ and different from the first phosphor. At least one of the first phosphor and the second phosphor is particulate. The first phosphor and the second phosphor are bonded to each other by at least one of a chemical reaction in a contact portion between the compound that constitutes the first phosphor and a compound that constitutes the second phosphor and of adhesion between the compound that constitutes the first phosphor and the compound that constitutes the second phosphor.

Provided are a black mixed oxide that contains chromium per se of any valency as a main component, and fails to contain cobalt as the main component material, and has a high safety, an excellent color tone and economical efficiency, and a method for producing the same, and various products using the black mixed oxide material. The mixed oxides comprise oxides containing La, Mn and Cu as main components but containing neither Cr nor Co as a main component, wherein the contents of La, Mn and Cu in the mixed oxides satisfy the following ratios, as oxide equivalent amount with respect to 100% by weight of the oxide equivalent amount: the La content as La.sub.2O.sub.3 being 35-70 wt %; the Mn content as MnO.sub.2 being 25-60 wt %; and the Cu content as CuO being 0.5-10 wt %.