A silicon nitride sintered body includes a silicon nitride crystal grains and grain boundary phases. Further, when D stands for width of the silicon nitride sintered body before being subjected to surface processing, relations between an average grain diameter dA and an average aspect ratio rA of the silicon nitride crystal grain in a first region from an outermost surface to a depth of 0 to 0.01D and an average grain diameter dB and an average aspect ratio rB of the silicon nitride crystal grain in a second region inside the first region satisfy the inequalities:

0.8≤ dA/dB≤ 1.2; and

0.8≤ rA/rB≤ 1.2.

A composition and a solid material is especially suitable for the manufacture of an antenna adapted to operate in the very high frequency and ultra high frequency or V/UHF band. The composition has the formula Ni.sub.aZn.sub.bCu.sub.cCo.sub.dFe.sub.2-δO.sub.4, in which 2(a+b+c+d)+3(2−δ)=8, 0.05<b<0.5, e.g. 0.1<b<0.5, e.g. 0.1<b<0.4, e.g. 0.15<b<0.35, 0.10<c<0.25, preferably 0.15<c<0.25, alternatively c is 0.20, 0.04<d<0.25, preferably 0.06<d<0.25, and more preferably 0.07<d<0.25, and δ<0.05.

Provided is a dielectric composition containing: a main component expressed by {Ba.sub.xSr.sub.(1-x)}.sub.mTa.sub.4O.sub.12; and a first subcomponent, m satisfying a relationship of 1.95≤m≤2.40. The first subcomponent includes silicon and manganese. When the amount of the main component contained in the dielectric composition is set to 100 parts by mole, the amount of silicon contained in the dielectric composition is 5.0 to 20.0 parts by mole in terms of SiO.sub.2, and the amount of manganese contained in the dielectric composition is 1.0 to 4.5 parts by mole in terms of MnO.

Provided is a dielectric composition containing: a main component expressed by {Ba.sub.xSr.sub.(1-x)}.sub.mTa.sub.4O.sub.12; and a first subcomponent, m satisfying a relationship of 1.95≤m≤2.40. The first subcomponent includes silicon and manganese. When the amount of the main component contained in the dielectric composition is set to 100 parts by mole, the amount of silicon contained in the dielectric composition is 5.0 to 20.0 parts by mole in terms of SiO.sub.2, and the amount of manganese contained in the dielectric composition is 1.0 to 4.5 parts by mole in terms of MnO.

A lead-free piezoelectric ceramic sensor material and a preparation method thereof, and relates to the technical field of piezoelectric ceramic processing. The main raw materials of the lead-free piezoelectric ceramic sensor material disclosed in the present disclosure are a barium carbonate, a calcium carbonate, a zirconia, a titanium dioxide, a strontium carbonate, an oxidation bait, a bismuth oxide, a composite binder and a dispersant agent. The preparation method is prepared through the steps of preparing ingredients, ball milling, granulating and tableting, debinding, and sintering, and the lead-free piezoelectric ceramic sensor material can be made into a lead-free piezoelectric sensor through applying an electrode and electrode polarizing. The present disclosure has an excellent compactness and a good chemical stability. And the piezoelectric sensor made of the lead-free piezoelectric ceramic sensor material has a high sensitivity, a strong working stability, an excellent piezoelectric and has a high Curie temperature.

Set forth herein are processes and materials for making ceramic thin green tapes by casting ceramic source powders and precursor reactants, binders, and functional additives into unsintered thin green tapes in a non-reactive environment.

An extrusion system (100) includes at least one sensor (102, 104) to detect localized presence of oil (701) on an exterior surface (715) or skin of wet extrudate material (714 e.g., ceramic material having a honeycomb cross-sectional shape), and at least one infrared emitting device (106, 108) configured to impinge infrared emissions on at least a portion of the exterior surface responsive to one or more sensor signals. Localized impingement of infrared emissions may reduce presence of oil streaks (701) without undue differential drying of the extrudate skin (715), and avoid surface fissures that would otherwise result in fired ceramic bodies. Separately controllable infrared emitters (502), or at least one controllable infrared blocking or redirecting element (603), may be used to impinge infrared emissions on selected areas. A humidification section (120) arranged downstream of infrared emitters (106, 108) may be used to at least partially rehydrate the wet extrudate material, if necessary.

A paramagnetic garnet-type transparent ceramic characterized by being a sintered body of a terbium-containing composite oxide represented by formula (1) in which the linear transmittance at a wavelength of 1,064 nm at an optical path length of 15 mm is 83% or higher.
(Tb.sub.1-x-ySc.sub.xCe.sub.y).sub.3(Al.sub.1-zSc.sub.z).sub.5O.sub.12  (1)
(In the formula, 0<x<0.08, 0≤y≤0.01, 0.004<z<0.16.)

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 material which satisfies X9M characteristics and ensures operations over an extended period of time at 200° C. is provided.