A composite sintered body is a ceramic composite sintered body which includes metal oxide which is a main phase, and silicon carbide which is a sub-phase, in which crystal grains of the silicon carbide are dispersed in crystal grains of the metal oxide and at crystal grain boundaries of the metal oxide, and a proportion of the crystal grains of the silicon carbide dispersed in the crystal grains of the metal oxide is 25% or more in an area ratio with respect to a total crystal grains of the silicon carbide.

In an exemplary embodiment, a piezoelectric ceramic composition is an alkali niobate-based piezoelectric ceramic composition whose primary component is a compound expressed by the general formula Li.sub.xNa.sub.yK.sub.1xyNbO.sub.3 (where 0<x<1, 0<y<1, and x+y<1), and which contains 100 ppm or more but less than 1000 ppm of fluorine by mass. The alkali niobate-based piezoelectric ceramic composition demonstrates good properties even when sintered at low temperature.

A method for recovering valuable metals and simultaneously preparing ceramsite by roasting cyanide tailing belongs to the area of comprehensive recovery and high value utilization of metallurgical waste residue. In this method, cyanide tailings, bentonite, calcium chloride, coal powder and albite are mixed by ball milling according to certain weight ratio to get a mixture. After drying and roasting twice, dust is collected from the roasted ash, the obtained polymetallic ash is collected and treated. The secondary calcined material is cooled to obtain ceramsite. The invention volatilizes and recovers the valuable metal in the roasting and sintering process of cyanide tailings and directly prepares the ceramsite through reasonable batching, which achieves the effect of recycling cyanide tailings and high-value utilization, can create good economic and environmental benefits, and has significant effect of energy saving and consumption reduction.

To provide at least one of: a powder composition from which a calcined body with similar processability can be produced without requiring the application of different forming conditions and calcination conditions for each composition; a method for producing the powder composition; a calcined body produced from the powder composition; a method for producing the calcined body; and uses thereof.

A powder composition including: two or more types of zirconia in which a lanthanoid rare-earth element is dissolved; a transition metal element other than zirconium and hafnium; and a remainder composed of zirconia stabilized only by one or more selected from the group consisting of yttrium, calcium and magnesium, wherein a different lanthanoid rare-earth element is dissolved in each zirconia in which the lanthanoid rare-earth element is dissolved, and a transition metal element content is 1500 ppm or less.

The method for manufacturing a ceramic component, in particular component containing zirconia and/or alumina, for a timepiece or a jewelry piece, is characterised in that it includes a step (E3) of depositing at least one additional element or compound on a ceramic powder, optionally bound, by atomic layer deposition (ALD).

Disclosed is a fused grain having the following chemical composition, expressed in percentages by mass on the basis of the oxides: ZrO.sub.2+HfO.sub.2: 2% to 13%; elements other than ZrO.sub.2, HfO.sub.2, Y.sub.2O; and Al.sub.2O.sub.3: 2%. Y.sub.2O.sub.3+Al.sub.2O.sub.3: made up to 100%; with 0.0065Y.sub.2O;/(ZrO.sub.2+HfO.sub.2)0.1300.

In an exemplary embodiment, a piezoelectric ceramic composition is an alkali niobate-based piezoelectric ceramic composition whose primary component is a compound expressed by the general formula Li.sub.xNa.sub.yK.sub.1-x-yNbO.sub.3 (where 0<x<1, 0<y<1, and x+y<1), and which contains 100 ppm or more but less than 1000 ppm of fluorine by mass. The alkali niobate-based piezoelectric ceramic composition demonstrates good properties even when sintered at low temperature.

A fused grain is essentially composed of a matrix of a magnesium aluminum oxide of MgAl.sub.2O.sub.4 spinel structure and/or of the MgOMgAl.sub.2O.sub.4 eutectic structure, and of inclusions essentially composed of magnesium oxide. The grain has the following overall chemical composition, as percentages by weight, expressed in the form of oxides: more than 5.0% and less than 19.9% of Al.sub.2O.sub.3, Al.sub.2O.sub.3 and MgO together represent more than 95.0% of the weight of the grain. The cumulative content of CaO and of ZrO.sub.2 is less than 4000 ppm, by weight.

It is difficult for a CrSi-based sintered body composed of chromium silicide (CrSi.sub.2) and silicon (Si) to have high strength. Provided is a CrSi-based sintered body including Cr (chromium) and silicon (Si), in which the crystal structure attributed by X-ray diffraction is composed of chromium silicide (CrSi.sub.2) and silicon (Si), a CrSi.sub.2 phase is present at 60 wt % or more in a bulk, a density of the sintered body is 95% or more, and an average grain size of the CrSi.sub.2 phase is 60 ?m or less.

A solid electrolyte body for a gas sensor element constituted by solid electrolyte particles made of zirconia containing a stabilizer has a solid electrolyte phase in which a large number of the solid electrolyte particles are aggregated, and, in the solid electrolyte phase, pairs of the solid electrolyte particles adjoining each other do not have a particle interface impurity layer between their particle interfaces, and the particle interfaces directly contact with each other.