Abstract: A high frequency circuit elemental device comprising a casing and a dielectric ceramic mounted in said casing, such as oscillators, said dielectric ceramic being capable of undergoing order-disorder structural transformation, whereby the temperature coefficient of the resonant frequency of said elemental device can be compensated by heat-treatment of the dielectric ceramic.

Abstract: Dielectric ceramic and process of producing the same. A dielectric ceramic essentially consisting of a compound having a disordered perovskite-type complex crystal structure and having a composition represented by the general formula (I):Ba.sub.x A.sub.y B.sub.1-x-y O.sub.W (I)wherein A represents at least one element selected from the group consisting of Zn, Ni, Co and Mg, and the Mg content in the A is not more than 0.44y; B is at least one element selected from the group consisting of Ta and Nb; x and y are a number of 0.49.ltoreq.x.ltoreq.0.52 and 0.15.ltoreq.y.ltoreq.0.19, respectively. This dielectric ceramic has good dielectric properties, which are markedly small in variation, and can be produced by a process which is easy in control.

Abstract: A process for producing a dielectric ceramic comprising a firing step comprises the substeps of heating a calcined product rapidly up to a temperature of from 1,500.degree. to 1,700.degree. C. and thereafter sintering the product at the temperature, and heating the product thus heat-treated through said first heat-treating substep at about 1,200.degree. C. to 1,600.degree. C. for not less than 10 minutes. It is possible to prepare a dielectric ceramic with a desired temperature properties of the resonant frequency.

Abstract: A dielectric ceramic composition possessing a high dielectric constant and a high unloaded Q and exhibiting stable electric properties even in the high frequency range of 10 GHz contains BaO, ZnO, MgO, NiO, ZrO.sub.2 and Ta.sub.2 O.sub.5 in amounts of not less than 59.0 mol % and not more than 66.0 mol % of BaO, less than 10 mol % of ZnO, less than 10 mol % of MgO, less than 10 mol % of NiO, less than 10 mol % of ZrO.sub.2, and not less than 19.0 mol % and less than 24 mol % of Ta.sub.2 O.sub.5.

Abstract: A dielectric ceramic which has a composition represented by the following general formula (I) and having a substantially perovskite crystal structure:(Ba.sub.1-x Sr.sub.x) (Mg.sub.1-y-w Ni.sub.y Co.sub.w).sub.1-u (Ta.sub.1- Nb.sub.z).sub.u 0.sub.p (I)wherein x, y, z, u, w and p satisfy one selected from the following conditions: x=0, w=0, z=0, 0.001.ltoreq.y.ltoreq.0.088, 0.66.ltoreq.u<0.72, and p represents a number with which the charges of the cations of Ba, Mg, Ni and Ta are neutralized, whereby the entire composition is electrically neutralized; x=0, z=0, 0.001.ltoreq.y.ltoreq.0.40, 0.001.ltoreq.w.ltoreq.0.40, 0.61.ltoreq.u.ltoreq.0.72, 0.002.ltoreq.y+w.ltoreq.0.40 and p represents a number with which the charges of the cations of Ba, Mg, Ni, Co and Ta are neutralized, whereby the entire composition is electrically neutralized; x=0, w=0, 0.04.ltoreq.y.ltoreq.0.90, 0.10.ltoreq.z<0.96, 0.61.ltoreq.u.ltoreq.0.

Abstract: A dielectric ceramics comprises a complex oxide having a perovskite-type crystal structure, the complex oxide substantially having the composition represented by the following general formula (I)(Ba.sub.(1-x) Sr.sub.x){(Mg.sub.(1-y) Zn.sub.y).sub.1/3 ( -Ta.sub.(1-z) Nb.sub.z).sub.2/3 }O.sub.3 (I)wherein x, y and z are numbers represented respectively by the expressions 0<x<1, 0<y<1, and 0<x<1. The temperature coefficient of the resonant frequency of the ceramics can be freely changed by adjusting the x value.

Abstract: A dielectric ceramics possessing a high level of unloaded Q and low loss at high frequency beneficial for communications at high frequency is produced by a method which comprises heating a green compact of a composition represented by the general formula: xBaO.yMgO.zTa.sub.2 O.sub.5 (wherein x, y, and z satisfy 0.5.ltoreq.x.ltoreq.0.7, 0.15.ltoreq.y.ltoreq.0.25, 0.15.ltoreq.z.ltoreq.0.25, and x+y+z=1) to a temperature in the range of 1,500.degree. to 1,700.degree. C. at a temperature increasing rate of 100.degree. to 1,600.degree. C./minute and subsequently retaining the green compact at the temperature for not less than 30 minutes.

Abstract: Dielectric ceramics represented by the following general formula and substantially having the K.sub.2 NiF.sub.4 type crystal structure,aSrO.bCaO.cTiO.sub.2.dSnO.sub.2(wherein 0.39.ltoreq.a.ltoreq.0.70, 0.ltoreq.b.ltoreq.0.28, 0.27.ltoreq.c.ltoreq.0.35, 0.ltoreq.d.ltoreq.0.04, and a+b+c+d=1), have a high dielectric constant and an unloaded Q as high as 6000 and more in the high-frequency region of super high frequency band, and are therefore best suited for use in dielectric resonators, dielectric substrates for micro wave integrated circuit, and the like.