Disclosed is a ceramic sintered shaped body containing Y.sub.2O.sub.3-stabilized zirconia with a sintered density of at least 99% of the theoretical sintered density and having a mean grain size of <180 nm. The zirconia fraction of the sintered shaped body comprises tetragonal and cubic phases. Also disclosed is a process for the production of a ceramic sintered shaped body containing Y.sub.2O.sub.3-stabilized zirconia, which process comprises dispersion of a submicron powder and comminution of the dispersed submicron powder by means of grinding media having a diameter of less than or equal to 100 μm to a particle size d.sub.95 of <0.42 μm; shaping of the dispersion to form a body, and sintering of the body to form the sintered shaped body.

A zirconia sintered body, where when cross-sectional area of each zirconia crystal-grain is calculated in image of cross section of zirconia sintered body, converted crystal-grain size of each zirconia crystal-grain is calculated based on cross-sectional area where each zirconia crystal-grain has circular cross-sectional shape, zirconia crystal-grains are classified into class of <0.4 μm, class of ≧0.4 and <0.76 μm, and class of ≧0.76 μm based on converted crystal-grain size, total cross-sectional area of zirconia crystal-grains is calculated in each of classes, and rate of cross-sectional area to total cross-sectional area of all zirconia crystal-grains whose cross-sectional area has been calculated is calculated in each class, rate of cross-sectional area of zirconia crystal-grains in class of <0.4 μm is 4% to 35%, rate of cross-sectional area of zirconia crystal-grains in class of ≧0.4 and <0.76 μm is 24% to 57%, and rate of cross-sectional area of zirconia crystal-grains in class of ≧0.76 μm-is 16% to 62%.

A rare earth aluminate sintered compact including rare earth aluminate phosphor crystalline phases and voids, wherein an absolute maximum length of 90% or more by number of rare earth aluminate phosphor crystalline phases is in a range from 0.4 μm to 1.3 μm, and an absolute maximum length of 90% or more by number of voids is in a range from 0.1 μm to 1.2 μm.

Certain embodiments of the present disclosure relate to ceramic materials with high thermal shock resistance and high erosion resistance. In one embodiment, a ceramic material is formed from a composition comprising Al.sub.2O.sub.3, MgO, SiO.sub.2.

A light-emitting ceramic and a light-emitting device. The light-emitting ceramic comprises a YAG substrate and light-emitting centers and diffusion particles evenly dispersed in the YAG substrate. The light-emitting centers are lanthanide-doped YAG fluorescent powder particles of 10-20 μm in grain size. The particle size of the scattering particles is 20-50 nm. The YAG substrate is a lanthanide-doped YAG ceramic. Also, the grain size of the YAG substrate is less than the grain size of the YAG fluorescent powder particles.

A honeycomb structure according to at least one embodiment of the present invention includes: a honeycomb structure portion having: an outer peripheral wall; and a partition wall arranged inside the outer peripheral wall to define a plurality of cells each extending from a first end surface of the honeycomb structure portion to a second end surface thereof to form a flow path; and a pair of electrode portions arranged on an outer peripheral surface of the outer peripheral wall of the honeycomb structure portion. The electrode portions are each a porous body in which particles of silicon carbide are bound by a binding material, the silicon carbide contains α-type silicon carbide and β-type silicon carbide, and the silicon carbide has a D50 in a volume-based cumulative particle size distribution of 25 μm or less.

A semiconductor ceramic composition which is a BaTiO.sub.3 based semiconductor ceramic composition, wherein, part of Ba is replaced by at least A (at least one alkali metal element selected from Na and K), Bi and RE (at least one element selected from rare earth elements including Y), and part of Ti is replaced by at least TM (at least one element selected from the group including of V, Nb and Ta), the relationships of 0.7≦{(the content of Bi)/(the content of A)}≦1.43, 0.017≦{(the content of Bi)+(the content of A)}≦0.25, and 0<{(the content of RE)+(the content of TM)}≦0.01 are satisfied when the total content of Ti and TM is set as 1 mol, the grain sizes have a maximum peak in a grain size distribution in a range of 1.1 μm to 4.0 μm or less, and the distribution frequency of the peak is 20% or more.

A refractory article can include a body including a content of alumina of at least 60 wt %, a content of silica of not greater than 20 wt %, a content of zirconia of not greater than 20 wt % for a total weight of the body. In a particular embodiment, the body includes a third phase including composite grains including mullite and zirconia. The third phase including the composite grains can be present within a range including at least 1 wt % and not greater than 35 wt % for a total weight of the body.

There is provided a polycrystalline cubic boron nitride containing a cubic boron nitride at a content greater than or equal to 98.5% by volume, the polycrystalline cubic boron nitride having a dislocation density less than or equal to 8×10.sup.15/m.sup.2.

A sintered body containing polycrystalline grains of a metal oxynitride containing at least two metal elements, wherein Ba and at least one metal element of a crystal phase of the sintered body are contained in a triple point that is not a void between the polycrystalline grains. A method for producing the sintered body includes sintering a mixture of at least a metal oxynitride as a main component and a sintering aid containing cyanamide in an atmosphere containing nitrogen or a rare gas or in a reduced-pressure atmosphere of 10 Pa or less while applying a mechanical pressure with a retention time at a maximum heating temperature during the sintering set to 1 minute to 10 minutes.