A method of manufacturing a dielectric for a capacitor and a dielectric for a capacitor manufactured thereby are provided. A dielectric for a capacitor is prepared by calcining a precursor mixture containing lead, lanthanum, zirconium, and titanium to produce calcined powder, adding additives including sodium, potassium, and the like to the powder, and sintering the mixture at a low temperature, whereby the dielectric has a high density and a large dielectric constant.

A dielectric composition is provided. The dielectric composition includes: a main component made of: a first complex oxide expressed by a chemical formula {K(Ba.sub.1-xSr.sub.x).sub.2Nb.sub.5O.sub.15}; and a second complex oxide expressed by a chemical formula that differs the chemical formula of the first complex oxide. The second complex oxide is a complex oxide expressed by one of chemical formulae: {(Ca.sub.1-ySr.sub.y)(Zr.sub.1-zTi.sub.z)O.sub.3}; {Ba(Ti.sub.1-uZr.sub.u)O.sub.3}; {(Ca.sub.1-vSr.sub.v)TiSiO.sub.5}; and {(Ba.sub.1-wRe.sub.2w/3)Nb.sub.2O.sub.6}, x satisfies 0.35≦x≦0.75, and a satisfies 0.25≦a≦0.75 when a molar ratio between the first and second complex oxides is defined by a:b in an order and a+b=1.00.

The disclosed technology relates to a ceramic composition and an article formed therefrom. A ceramic article for radio frequency applications is formed of a ceramic composite material comprising a matrix phase comprising aluminum oxide having a corundum crystal structure and a precipitate phase comprising ZnAl.sub.2O.sub.4 and Zn.sub.2TiO.sub.4 and having a spinel crystal structure.

Disclosed herein are methods for preparing a titanate compound powder comprising titanate compound particles having a controlled particle size and/or particle size distribution. The methods include mixing at least one first inorganic compound chosen from sources of a first metal or metal oxide, at least one second inorganic compound chosen from sources of titania, and at least one binder to form a mixture; calcining the mixture to form a polycrystalline material comprising a plurality of titanate compound grains and a plurality of micro-cracks; and breaking the polycrystalline material along at least a portion of the microcracks. Also disclosed are titanate compound powders having a controlled particle size distribution, ceramic batch compositions comprising the powders, and ceramic articles prepared from the batch compositions.

Heat treated alumina zirconia abrasive grains based on Al.sub.2O.sub.3 and ZrO.sub.2 may be fused in an electric arc furnace, and may have a weight content of: Al.sub.2O.sub.3 between 52% and 62% by weight; ZrO.sub.2 and HfO.sub.2 between 35% and 45% by weight, with at least 6% by weight based on the total weight content of ZrO.sub.2 being present in the tetragonal and/or cubic high temperature modifications of ZrO.sub.2; Si-compounds between 0.2% and 0.7% by weight expressed as SiO.sub.2; carbon between 0.03% and 0.5% by weight; additives between 0.5% and 10% by weight; and raw-material-based impurities of less than 3% by weight. The heat treated alumina zirconia abrasive grains may be heat treated in air between 350° C. and 700° C. for a time period of one to six hours using a rotary kiln.

A polycrystalline ceramic solid and a method for producing a polycrystalline ceramic solid are disclosed. In an embodiment a polycrystalline ceramic solid includes a main phase with a composition of the general formula: (1-y)Pb.sub.a(Mg.sub.bNb.sub.c)O.sub.3-e+yPb.sub.aTi.sub.dO.sub.3 with 0.055≤y≤0.065, 0.95≤a≤1.02, 0.29≤b≤0.36, 0.63≤c≤0.69, 0.9≤d≤1.1, and 0≤e≤0.1, and optionally one or more secondary phases, wherein, in each section through the solid, a proportion of the secondary phases relative to any given cross-sectional area through the solid is less than or equal to 0.5 percent, or wherein the solid is free of the secondary phases.

Disclosed herein are embodiments of materials having high thermal conductivity along with a high dielectric constants. In some embodiments, a two phase composite ceramic material can be formed having a contiguous aluminum oxide phase with a secondary phase embedded within the continuous phase. Example secondary phases include calcium titanate, strontium titanate, or titanium dioxide.

A lead-free piezoelectric ceramic composition mainly includes a first crystal phase (KNN phase) and a second crystal phase (NTK phase). In the first crystal phase (KNN phase), a plurality of crystal grains formed of an alkali niobate/tantalate perovskite oxide having piezoelectric characteristics is bound to each other in a deposited state. The second crystal phase (NTK phase) is formed of a compound containing titanium (Ti) and fills spaces between the crystal grains in the first crystal phase.

There is disclosed a plugged honeycomb structure. A plugged honeycomb structure includes a tubular honeycomb structure body having partition walls including a porous partition wall base material defining a plurality of cells which become through channels for a fluid and extend from a first end face to a second end face, and a porous trapping layer disposed on the surface of the partition wall base material; and plugging portions disposed in open ends of predetermined cells in the first end face and open ends of residual cells in the second end face, and the partition wall base material is constituted of a porous body including α-Al.sub.2O.sub.3 as a main phase and further including aluminum titanate and glass.

A piezoelectric material contains: a first component which is a rhombohedral crystal in a single composition, has a Curie temperature Tc1, and is a lead-free-system composite oxide having a perovskite-type structure; a second component which is a crystal other than a rhombohedral crystal in a single composition, has a Curie temperature Tc2 higher than Tc1, and is a lead-free-system composite oxide having a perovskite-type structure; and a third component which is a rhombohedral crystal in a single composition, has a Curie temperature Tc3 equal to or higher than Tc2, and is a lead-free-system composite oxide that has a perovskite-type structure and is different from the first component. When a molar ratio of the third component to the sum of the first component and the third component is α and α×Tc3+(1−α)×Tc1 is Tc4, |Tc4−Tc2| is 50° C. or lower.