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AssigneeNGK Insulators, Ltd.
InventorsMasahiro Abe, Tsutomu Nanataki, Shinsuke Yano
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A dielectric ceramic composition is disclosed which consists essentially of: a main ceramic composition containing barium oxide, titanium oxide, rare earth oxide and bismuth oxide as major components, which composition is represented by xBaO.multidot.yTiO.sub.2 .multidot.z[(1-a)RE.sub.2 O.sub.3 .multidot.aBi.sub.2 O.sub.3 ] where RE represents at least one rare earth metal, 0.10.ltoreq.x.ltoreq.0.20, 0.60.ltoreq.y.ltoreq.0.75, 0.10 .ltoreq.z.ltoreq.0.25, x+y+z=1 and 0<a.ltoreq.0.3; and a glass composition composed of ZnO, B.sub.2 O.sub.3 and SiO.sub.2, which is represented by k(wt. %)ZnO.multidot.m(wt. %)B.sub.2 O.sub.3 .multidot.n(wt. %)SiO2 where 30 .ltoreq.k.ltoreq.85, 5.ltoreq.m.ltoreq.50, 2.ltoreq.n.ltoreq.40, k+m+n=100. The glass composition is contained in an amount of at least 0.1 part by weight, but not more than (18-62.5a) parts by weight (where 0<a.ltoreq.0.2) or not more than 5.5 parts by weight (where 0.2<a.ltoreq.0.3), per 100 parts by weight of the main ceramic composition. The main ceramic composition may have another combination of major components. Also disclosed are a method of preparing the dielectric ceramic composition as described above, a dielectric resonator and filter using such a dielectric ceramic composition, and a method of producing such a dielectric resonator or filter.
A dielectric filter including a plurality of dielectric resonators, each dielectric resonator comprising (a) a dielectric ceramic obtained by firing a dielectric ceramic composition which consists essentially of (i) a main ceramic composition containing barium oxide, titanium oxide, rare earth oxide and bismuth oxide as major components, which composition is represented by xBaO.multidot.yTiO.sub.2 .multidot.z((1-a) RE.sub.2 O.sub.3 .multidot.aBi.sub.2 O.sub.3), wherein RE represents at least one rare earth metal, 0.10.ltoreq.x.ltoreq.0.20, 0.60.ltoreq.y.ltoreq.0.75, 0.10.ltoreq.z.ltoreq.0.25, x+y+z=1 and 0<a.ltoreq.0.3, and (ii) a glass composition comprised of ZnO, B.sub.2 O.sub.3 and SiO.sub.2, which is represented by k.(wt. %) ZnO.multidot.m (wt. %) B.sub.2 O.sub.3 .multidot.n(wt. %)SiO.sub.2 where 30.ltoreq.k.ltoreq.85, 5.ltoreq.m.ltoreq.50, 2.ltoreq.n.ltoreq.40, k+m+n=100, said glass composition being contained in an amount of at least 0.1 parts by weight, but not more than (18-62.5a) parts by weight (where 0<a.ltoreq.0.2) or not more than 5.5 parts weight (where 0.2<a.ltoreq.0.3), per 100 parts by weight of said main ceramic composition;
A dielectric filter including a plurality of dielectric resonators, each dielectric resonator comprising (a) a dielectric ceramic obtained by firing a dielectric ceramic composition which consists essentially of (i) a main ceramic composition containing barium oxide, titanium oxide and rare earth oxide as major components, which composition is represented by xBaO.multidot.yTiO.sub.2 .multidot.zRE.sub.2 O.sub.3, wherein RE represents at least one rare earth metal, 0.10.ltoreq.x.ltoreq.0.20, 0.60.ltoreq.y.ltoreq.0.75, 0.10.ltoreq.z.ltoreq.0.25, and x+y+z=1, and (ii) a glass composition comprised of ZnO, B.sub.2 O.sub.3 and SiO.sub.2, which is represented by k(wt. %)ZnO.multidot.m(wt. %)B.sub.2 O.sub.3 .multidot.n(wt. %)SiO.sub.2 where 30.ltoreq.k.ltoreq.85, 5.ltoreq.m.ltoreq.50, 2.ltoreq.n.ltoreq.40, k+m+n=100, said glass composition being contained in an amount of 0.1.about.18 parts by weight per 100 parts by weight of said main ceramic composition;
A dielectric filter including a plurality of dielectric resonators, each dielectric resonator comprising (a) a dielectric ceramic obtained by firing a dielectric ceramic composition which consists essentially of (i) a main ceramic composition containing barium oxide, strontium oxide, calcium oxide, titanium oxide, rare earth oxide and bismuth oxide as major components, which composition is represented by x((1-c-d)BaO.multidot.cSrO.multidot.dCaO).multidot.yTiO.sub.2 .multidot.z((1-e)RE.sub.2 O.sub.3 .multidot.eBi.sub.2 O.sub.3), wherein RE represents at least one rare earth metal, 0.10.ltoreq.x.ltoreq.0.20, 0.60.ltoreq.y<0.75, 0.10.ltoreq.z.ltoreq.0.25, x+y+z=1, 0 .ltoreq.c.ltoreq.0.40, 0.ltoreq.d.ltoreq.0.20, 0.ltoreq.e.ltoreq.0.30 and 0<c+d, and (ii) a glass composition comprised of ZnO, B.sub.2 O.sub.3 and SiO.sub.2, which is represented by k(wt. %)ZnO.multidot.m(wt. %)B.sub.2 O.sub.3 .multidot.n(wt. %)SiO.sub.2 where 30.ltoreq.k.ltoreq.85, 5.ltoreq.m.ltoreq.50, 2.ltoreq.n.ltoreq.40, k+m+n=100, said glass composition being contained in an amount of at least 0.1 parts by weight, but not more than (18-62.5e) parts by weight (where 0<e.ltoreq.0.2) or not more than 5.5 parts by weight (where 0.2<e<0.3), per 100 parts by weight of said main ceramic composition;
Dependencies are inferred from the claim text.
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Resonators of the waveguide type: dielectric resonators
Glass compositions containing a non-glass component, e.g. compositions containing fibres, filaments, whiskers, platelets, or the like, dispersed…:…
Based on titanium oxides or titanates: based on titanates
Based on titanates: based on alkaline earth metal titanates
Term ended 26 Dec 2012 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
Field of the Invention
The present invention relates in general to a dielectric ceramic composition suited for low temperature firing, and a method of preparing the same. In particular, the invention is concerned with a dielectric ceramic composition for microwave applications, which can be fired at a relatively low temperature, and which is suitably used for a dielectric resonator having internal conductive layers, of a stripline type filter, for example, and with a method of preparing such a dielectric ceramic composition. The present invention is also concerned with a dielectric resonator obtained by using such a dielectric ceramic composition, a dielectric filter including a plurality of such dielectric resonators, and with a method of producing the dielectric resonator or dielectric filter.
Discussion of the Prior Art
To further clarify the concept of the present invention, some examples of the invention will be described. It is to be understood that the invention is not limited to the details of the illustrated examples, but may be embodied with various alterations, modifications and improvements, which may occur to those skilled in the art, without departing from the scope of the invention defined in the appended claims.
Initially, highly pure barium carbonate, titanium oxide, neodymium oxide, samarium oxide, lanthanum oxide and bismuth oxide were weighed to give main ceramic compositions corresponding to samples No. 1 to No. 33 and represented by the formula: xBaO.multidot.yTiO.sub.2 .multidot.z[(1-a)RE.sub.2 O.sub.3 .multidot.aBi.sub.2 O.sub.3 ] wherein x, y, z, RE and a are as indicated in TABLES 1 and 2. The thus weighed materials, from which a given proportion of bismuth oxide to be added later was excluded, were wet-blended with some pure water in a polyethylene pot mill using alumina balls. The thus obtained mixture was taken out of the pot mill, dried, put into an alumina crucible (pot), and calcined in air for four hours at various temperatures between 900.degree. C. and 1270.degree. C. Then, the calcined mixture was roughly crushed, thrown back into the polyethylene pot mill with zirconia balls, and pulverized to achieve the average grain size of 0.4.about.1.0 .mu.m as measured by a laser diffraction abd scattering method. In this manner, calcined ceramic powders of respective compositions were obtained.
On the other hand, highly pure zinc oxide, boric oxide and silicon oxide were weighed in the proportion of 65% by weight of ZnO, 25% by weight of B.sub.2 O.sub.3 and 10% by weight of SiO.sub.2. These compounds were thrown with alumina balls into a polyethylene pot mill, and dry-blended. The thus obtained mixture was fused in a chamotte crucible, rapidly cooled off in water and thus vitrified. The glass obtained was thrown with alumina balls into an alumina pot mill, and pulverized in ethanol to achieve the average grain size of 4 .mu.m, to thereby provide a glass powder having a composition (G) as indicated in TABLE 3.