Ngk Spark Plug Company, Limited

Nkg Spark Plug Co., Ltd.

Kazuhisa Itakura

Takashi Oba

Akifumi Tosa

Masahiko Matsumiya

Manabu Sato

Jun Otsuka

Yoshihiro Yamamoto

Katsuya Yamagiwa

Takashi Kasashima

Kazushige Obayashi

Toru Shimamori

Ken-ichi Mizuno

Toshihiro Mizui

Hisashi Koduka

Takuya Tarutani

Yuji Yasunishi

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

The present invention relates to a microwave dielectric ceramic composition exhibiting excellent dielectric characteristics, including high Qu; and to a dielectric resonator which exhibits high Qu even when of large size. The present invention provides a microwave dielectric ceramic composition containing a primary component represented by CaTiO-(1-x)REAlO[0.54&#x2266;x&#x2266;0.82] (wherein RE is composed only of an essential element La or composed of an essential element La and one or two optional elements selected from among Nd and Sm). The present invention also provides a microwave dielectric ceramic composition containing a primary component represented by the compositional formula: xCaTiO-(1-x)LnAlO[0.54&#x2266;x&#x2266;0.82] (wherein Ln is at least one species selected from among Y, La, Nd, Sm, etc.); and Na in an amount as reduced to NaO of 0.02 to 0.5 parts by mass on the basis of 100 parts by mass of the primary component. The present invention also provides a dielectric resonator produced from the aforementioned microwave dielectric ceramic composition.

Microwave dielectric porcelain composition and dielectric resonator

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

A homogeneous alumina-based sintered material having excellent grindability, low porosity and high flexural strength, and which is free of color unevenness and fluctuations in density. Predetermined amounts of Al.sub.2 O.sub.3 powder, MgO powder, CaCO.sub.3 powder and SiO.sub.2 powder are measured out, and then mixed with stirring in a ball mill. The mixture is granulated using a spray dryer, and then hydrostatically pressed to obtain a molded product having a predetermined shape. Subsequently, the molded product is stored and sintered at a temperature of 1,550.degree. C. to 1,650.degree. C., particularly 1,600.degree. C. to 1,650.degree. C. under atmospheric pressure for 2 hours. As a result, an alumina-based sintered material having a 50 percent cumulative grain size distribution in diameter of from 4 to 15 .mu.m, a 90 percent grain diameter of two to three times the 50 percent grain diameter, and a porosity of not more than 5% can be obtained. The alumina-based sintered material thus obtained exhibits a maximum load current during grinding of not more than 1.0 A/mm, particularly not more than 0.5 A/mm, and a four-point flexural strength of not less than 300 MPa, thus providing excellent grindability as well as high strength.

Alumina-based sintered material

A microwave dielectric porcelain composition having a composition represented by the formula xTiO.sub.2 -ySnO.sub.2 -zMgO, wherein x, y and z each represents an axis of mol-% in a triangular diagram, the sum of x, y and z being 100 mol-%, a pentagonal region is formed by sequentially connecting points P (x=59, y=11, z=30 ), Q (x=63, y=11, z=26), R (x=22.5, y=77.5, z=0), S (x=2, y=98, z=0), T (x=4, y=90, z=6) and P, and the formula is defined to be within the PQ, QR, ST and TP sides, but not defined by the RS side, of the pentagonal region.

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Komaki, Japan

Kazuhisa Itakura