Ngk Spark Plug Company, Limited

Nkg Spark Plug Co., Ltd.

Takashi Oba

Kazuhisa Itakura

Akifumi Tosa

Masahiko Matsumiya

Manabu Sato

Jun Otsuka

Katsuya Yamagiwa

Takashi Kasashima

Kazushige Obayashi

Hisashi Koduka

A dielectric ceramic composition is provided which exhibits a high unloaded quality factor (Q) and permits regulation of the relative dielectric constant (&#x3b5;) and the temperature coefficient (&#x3c4;) of resonance frequency (f) within specific ranges in accordance with use or application of the composition. A dielectric resonator is also provided which includes a resonator main body formed from the composition. The dielectric ceramic composition contains, as metallic components, Ba, Zn, Nb, Ta, and Sb, and the amounts of the metallic components, as reduced to their oxides, satisfy the following relations expressed in mol %: 57.5&#x2266;BaO&#x2266;62.6; 16.0&#x2266;ZnO&#x2266;22.2; 0&#x3c;NbO&#x2266;20.6; 0&#x3c;TaO&#x2266;20.6; and 0&#x3c;SbO&#x2266;5.9.

Dielectric ceramic composition and dielectric resonator made from the composition

A dielectric ceramic material is represented by the following compositional formula, (100-a)[Ba{(ZnCoNb}O]-a[MTaO], where M represents at least one species selected from K, Na, and Li. In one method, the dielectric material is produced by mixing raw material powders such that proportions by mol of component metals simultaneously satisfy the relations, 0.5&#x2266;a&#x2266;25; 0.98&#x2266;u&#x2266;1.03; 0&#x2266;v&#x2266;1; 0.274&#x2266;w&#x2266;0.374; 0.646&#x2266;x&#x2266;0.696; 0.5&#x2266;y&#x2266;2.5; and 0.8&#x2266;z&#x2266;1.2. The method further includes subjecting the resultant mixture to primary pulverization; calcining the resultant powder at 1,100-1,300&#xb0; C., followed by wet secondary pulverization; drying the resultant paste; granulating; molding the resultant granules to thereby yield a compact; and firing the compact in air advantageously at 1,400-1,600&#xb0; C.

Dielectric ceramic material

A dielectric composition is based on a BaO&mdash;MgO&mdash;Nb O system material (BMN system material) having a dielectric constant, &egr;, of about 30, a large Q-value (no-load quality coefficient) and a comparatively small absolute value of the temperature coefficient (&tgr; ) of its resonance frequency but containing no expensive Ta. The dielectric material has a composite perovskite crystal structure as the main crystal phase, wherein a predetermined amount of KNbO is added to a BMN system material. The high frequency characteristics can be further improved by partially replacing Nb with Sb and partially replacing the B site of the perovskite crystal structure with Sn.

Dielectric composition for high frequency resonators

The present invention is directed to a dielectric ceramic composition exhibiting a high unloaded quality factor and a small variation thereof. The dielectric ceramic composition of the invention containing Ba, Zn, and Ta, contains 100 parts by weight of a predominant component represented by xBaO&mdash;yZnO&mdash;(&frac12;)zTa O (x, y, and z represent compositional proportions by mol and satisfy x&plus;y&plus;z&equals;1), wherein x, y, and z fall within a quadrilateral region formed by connecting points A (x&equals;0.503, y&equals;0.152, z&equals;0.345), B (x&equals;0.497, y&equals;0.158, z&equals;0.345), C (x&equals;0.503, y&equals;0.162, z&equals;0.335), and D (x&equals;0.497, y&equals;0.168, z&equals;0.335) (sides AB, BD, DC, and CA being included) as shown in FIG. ; 0.2-1.6 parts by weight K as reduced to K O; and 0.7-8 parts by weight Ta as reduced to Ta O , wherein the ratio by weight of K to Ta falls within the range of 0.185-0.4. The dielectric resonator of the present invention is formed of the dielectric ceramic composition.

Dielectric porcelain composition and dielectric resonator using the same

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Ise, Japan

Takashi Oba