A ceramic contains, in mass percent: Si.sub.3N.sub.4: 20.0 to 60.0%, ZrO.sub.2: 25.0 to 70.0%, and one or more oxides selected from MgO, Y.sub.2O.sub.3, CeO.sub.2, CaO, HfO.sub.2, TiO.sub.2, Al.sub.2O.sub.3, SiO.sub.2, MoO.sub.3, CrO, CoO, ZnO, Ga.sub.2O.sub.3, Ta.sub.2O.sub.5, NiO, and V.sub.2O.sub.5: 5.0 to 15.0%. The ceramic has a coefficient of thermal expansion as high as that of silicon and an excellent mechanical strength, allows fine machining with high precision, and prevents particles from being produced.

Disclosed is a polycrystalline ceramic dielectric comprising: crystal grain bulks made of a barium titanate-based ceramic; and grain boundaries comprising interfaces between the crystal grain bulks, wherein the composition of the grain boundaries is controlled using dopants. By controlling the grain boundary composition using dopants so that the dopants are distributed across a width of 5 nm or less and using a nano-sized, fine-grained barium titanate-based ceramic precursor, the grain boundary structure within the polycrystals may maintain electroneutrality, and their ferroelectricity may be controlled, thereby allowing for smoother polarization reaction. Accordingly, the present disclosure provides polycrystalline ceramic dielectrics that have dielectric properties such as high permittivity and low dielectric losses in a wide frequency range, a small amount of reduction in electric field-dependent relative permittivity, high temperature stability, non-reducibility under a reduction sintering condition, and resulting high insulation resistance, and a preparation method therefor.

This disclosure relates to a polycrystalline diamond (PCD) body comprising a PCD material formed of intergrown diamond grains forming a diamond network, and an iron-containing binder.

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.

A ceramic composition contains Fe, Cu, Ni, Zn, Co, and Cr. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and when a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by mole, the ceramic composition contains 45.00 to 49.70 parts by mole Fe in terms of Fe.sub.2O.sub.3, 2.00 to 8.00 parts by mole Cu in terms of CuO, 19.40 to 45.40 parts by mole Ni in terms of NiO, and 1.00 to 27.00 parts by mole Zn in terms of ZnO. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and when a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by weight, the ceramic composition contains 5 to 100 ppm Co in terms of CoO and 10 to 400 ppm Cr in terms of Cr.sub.2O.sub.3.

A ceramic composition contains Fe, Cu, Ni, Zn, Co, and Cr. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by mole, the ceramic composition contains from 48.20 to 49.85 parts by mole Fe in terms of Fe.sub.2O.sub.3, from 2.00 parts to 8.00 parts by mole Cu in terms of CuO, from 11.90 to 18.70 parts by mole Ni in terms of NiO, and from 27.00 to 33.50 parts by mole Zn in terms of ZnO. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by weight, the ceramic composition contains from 5 to 100 ppm Co in terms of CoO and from 10 to 400 ppm in terms of Cr.sub.2O.sub.3.

A superconducting composition of matter including overlapping first and second regions. The regions comprise unit cells of a solid, the first region comprises an electrical insulator or semiconductor, and the second region comprises a metallic electrical conductor. The second region extends through the solid and a subset of said second region comprise surface metal unit cells that are adjacent to at least one unit cell from the first region. The ratio of the number of said surface metal unit cells to the total number of unit cells in the second region being at least 20 percent.

A dielectric composition includes a main ingredient having a perovskite structure represented by ABO.sub.3, where A is at least one of Ba, Sr, and Ca and B is at least one of Ti, Zr, and Hf, and a first accessory ingredient. The first accessory ingredient comprises 0.1 mole or more of a rare earth element, 0.02 mole or more of Nb, and 0.25 mole or more and 0.9 mole or less of Mg, a sum of contents of the rare earth element and Nb is 1.5 mole or less.

This invention relates to a ceramic module for assembly into a therapeutic device for treating a human or animal body with irradiation of far infrared. More specifically, said ceramic module can simultaneously emit blackbody-like thermal radiation and stimulated FIR-photons radiation in 3-16 μm wavelength spectrum, while the overall radiation in 8-14 μm wavelength range is measured to be an approximated blackbody radiation at a temperature that is at least 1 °K. (or 1 °C.) higher than the actual body temperature of said ceramic module, signifying an effective emissivity greater than 1.0. Said ceramic module may be used alone or serve as components of a therapeutic device for increasing physiologic performance, immune competence, health, and mean lifespan of human or animal.

When the porous ceramic structure contains Co together with Fe or Mn, the Co content is higher than or equal to 0.1 mass % and lower than or equal to 3.0 mass % in terms of Co.sub.3O.sub.4, and when the porous ceramic structure contains Co without containing Fe and Mn, the Co content is higher than or equal to 0.2 mass % and lower than or equal to 6.0 mass % in terms of Co.sub.3O.sub.4. The ratio of the sum of the Fe content in terms of Fe.sub.2O.sub.3, the Mn content in terms of Mn.sub.2O.sub.3, and the Co content in terms of Co.sub.3O.sub.4 to the Ce content in terms of CeO.sub.2 is higher than or equal to 0.8 and lower than or equal to 9.5.