Ngk Spark Plug Company, Limited

Ngk Spark Co., Ltd.

Hirofumi Ozeki

Hiroshi Katagiri

Masahiko Okuyama

Hidetoshi Mizutani

Hideo Sobue

Takashi Yamamoto

Tsutomu Tsunooka

Kanji Ohya

Masanori Takase

Koji Ogura

Tokiomi Kato

Tokiomi Katoh

Noritaka Yoshida

Composition for producing low sintering temperature ceramic dielectrics and method of manufacturing such dielectrics

Powders of BaCO.sub.3, TiO.sub.2, ZnO, etc. are mixed to each other at a predetermined ratio of quantity, calcined in an atmospheric air at 90.degree.-120.degree. C., and pulverized to obtain a calcined powder having an average grain size from 1 to 3 .mu. m. 0.1 to 20 parts-by weight of a powder having an average grain size from 0.1 to 1.5 .mu.m comprising a glass having a transition point of not higher than 450.degree. C. obtained by mixing powders of Pb.sub.3 O.sub.4, SiO.sub.2, Na.sub.2 O, etc. to each other, melting and then pouring into water and pulverizing the thus obtained glass is admixed to the calcined powder. The mixture is dried, pelleted by adding a resin and the pellet powder is molded into a cylindrical shape, applied with CIP (Cold isotactic press), and the molding product after the treatment is sintered in an atmospheric air at 850.degree. to 1000.degree. C. to obtain a dielectric ceramic sintered at low temperature. The resultant dielectric ceramic has high denseness and high unloaded Q value while maintaining .tau.f within a practical range.

Composition for producing low sintering temperature ceramic dielectrics

The present invention provides a microwave dielectric ceramic composition in which .epsilon.r, Qu and .tau.f are generally controlled within a practical characteristic range and each of the characteristics is maintained in a well balanced state. A ceramic composition of the present invention comprises a composition represented by xBi.sub.2 O.sub.3 -(1-x) (yNb.sub.2 O.sub.5 -(1-y)Ta.sub.2 O.sub.5) in which 0.45.ltoreq.x.ltoreq.0.55 and 0.1.ltoreq.y&lt;1.0 as a main ingredient, to which not more than 0.8 parts by weight of V.sub.2 O.sub.5 is added and incorporated. An another ceramic composition comprises a composition represented by Bi(NbxTa1-x)O.sub.4 in which 0&lt;x.ltoreq.0.96 as a main ingredient, to which not more than 5 wt % of V.sub.2 O.sub.5 and not more than 2 wt % of PbO are added and incorporated. An another ceramic composition comprises the main ingredient as described above to which not more than 5 wt % of V.sub.2 O.sub.5 and not more than 2 wt % of MnO.sub.2 are added and incorporated. An another ceramic composition comprises the main ingredient as described above to which not more than 2 wt % of V.sub.2 O.sub.5 and not more than 1 wt % of TiO.sub.2 are added and incorporated. An another ceramic composition comprises the main ingredient as described above, to which not more than 2 wt % of V.sub.2 O.sub.5, not more than 2 wt % of MnO.sub.2 and not more than 0.7 wt % of TiO.sub.2 are added and incorporated. Instead of TiO.sub.2 described above, not more than 0.5 wt % (particularly not more than 0.4 wt %) of PbO can be added and incorporated.

Microwave dielectric ceramic composition

A ceramic composition having a high value .epsilon.r while maintaining Qu and .tau.f each in a range of practical characteristic. The present invention is applicable to dielectric resonators and impedance matching of various kinds of microwave circuits. The ceramic composition comprises Ba.sub.1-x Sr.sub.x (Zn.sub.1/3 Nb.sub.2/3)O.sub.3 (in which 0.6.ltoreq..times..ltoreq.1.0) as the main ingredient, to which TiO.sub.2 is incorporated by 0.01 to 1 parts by weight based on 100 parts by weight of the main ingredient. The ceramic composition may have a Qu value of 2000 to 2900 (at 4.5 GHz), relative dielectric constant of 39 to 42, and a temperature constant of resonance frequency (.tau.f) in the range of -8 to +10 ppm/.degree.C. The ceramic composition may not contain Sr.sub.5 Nb.sub.4 O.sub.15 or Ba.sub.4 Nb.sub.2 O.sub.9. It may index for the regularity of the B site ingredient of 7-9.times.10.sup.-2. The ceramic composition may be prepared by calcination, sintering, and an annealing treatment after sintering. A calcination atmosphere and a sintering atmosphere may be ZnO atmosphere.

Microwave dielectric ceramic composition and preparing method thereof

Disclosed herein is a microwave dielectric ceramic composition which comprises as the main ingredient, a composition represented by xMgTiO.sub.3 .multidot.(1-x)CaTiO.sub.3 (0.93.ltoreq.x .ltoreq.0.95), to which 3-9 wt % of ZnO, 2-4 wt % of Ta.sub.2 O.sub.5, 1-6 wt % of Nb.sub.2 O.sub.5, 0.1-6 wt % of MnO.sub.2, 3-12 wt % of Al.sub.2 O.sub.3 or 3-12 wt % of Co.sub.2 O.sub.3 to xMgTiO.sub.3 .multidot.(1-x)CaTiO.sub.3. And the microwave dielectric ceramic compositions have a Qu value in the range of 3000 to 4600 (at 6 GHz), a temperature coefficient of the resonance frequency (.tau.f) in the range of -10 to +10 ppm/.degree.C. and relative dielectric constant (.epsilon..sub.r) in the range of 18 to 22. The dielectric ceramic compositions are capable of reducing .tau.f approximately to zero or optionally and stably controlling .tau.f to a desired value both to positive and negative sides around zero as the center while maintaining .epsilon..sub.r and Qu within practical characteristic ranges by controlling the addition (constitution) ratio of the specified oxides. Further, even if the sintering temperature is changed within a wide range, the sintering products of high density and high quality can be attained due to the addition of the specified oxides.

A dielectric ceramic composition which comprises a composition represented by xBaO.yNd.sub.2 O.sub.3.zTiO.sub.2 (where 8.5.ltoreq.x.ltoreq.20, 5.ltoreq.y.ltoreq.23, 62.ltoreq.z.ltoreq.85, and x+y+z=100), Y.sub.2 O.sub.3 in an amount not more than 15 wt % of the amount of said composition, and Al.sub.2 O.sub.3 in an amount not more than 2 wt % of the total amount of the principal components BaO, Nd.sub.2 O.sub.3, TiO.sub.2, and Y.sub.2 O.sub.3. And a relative permittivity .epsilon.r of the dielectric ceramic is not less than 59, its dielectric loss (tan .delta.) is 3.times.10.sup.-4 .about.8.times.10.sup.-4 (2.7 GHz), and its temperature coefficient of resonant frequency .tau.f may be -30.about.+10 ppm/.degree.C. This microwave ceramic dielectric will be used for dielectric resonators in the microwave frequency region, microwave IC substrates, and impedance matching of microwave circuits.

Disclosed herein is a ceramic composition which gives a microwave dielectric having a permittivity and unloaded Q in a practical range and a small temperature coefficient (.tau.f) in the neighborhood of zero of resonance frequency owing to the controlled amount of ZnO and Ta.sub.2 O.sub.5 added. The .tau.f value may be positive or negative in the neighborhood of zero according to need. The ceramic composition comprises a principal component represented by (BaO-3.7TiO.sub.2).xZnO, where x is in the range of 15.ltoreq.x.ltoreq.17 wt % and a secondary component containing 2-6 wt % Ta.sub.2 O.sub.5 and not more than 1 wt % MnO.sub.2 based on the amount of the principal component. The ceramic composition may also contain BaO-3.8TiO.sub.2, 12-16 wt % ZnO, and 2-6 wt % Ta.sub.2 O.sub.5, or contain BaO-3.6TiO.sub.2, 17-19 wt % ZnO, and 2-6 wt % Ta.sub.2 O.sub.5.

Ceramic composition for microwave dielectric

A particulate lead titanate ceramic obtained by calcining a mixture containing TiO.sub.2 and PbO at 1150.degree.-1300.degree. C., the proportion of the PbO being greater than 1 mole per mole of the TiO.sub.2. A composite material having the particulate lead titanate ceramic supported in an organic substrate exhibits improved piezoelectric properties and is useful as a piezoelectric element or pyroelectric element.

Particulate lead titanate ceramic and composite material containing same

A piezoelectric ceramic composite material useful for use in underwater transducers or hydrophones, including an elastic organic matrix, and piezoelectric ceramic powder dispersed in the substrate and having a composition:

Piezoelectric composite material

A piezoelectric ceramic composite material useful for use in underwater transducers or hydrophones, including an elastic organic matrix, and piezoelectric ceramic powder dispersed in the matrix and having the following chemical formula:

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Aichi, Japan

Hirofumi Ozeki