Sanyo Electric Co., Ltd.

Yoko Baba

Kenichi Shibata

Hisakazu Takahashi

Kenichi Ezaki

Kazuhiko Kuroki

Yasuhiko Okamoto

Shigeyuki Yasuyama

Kenicki Ezaki

In order to obtain a microwave dielectric ceramic composition having a high dielectric constant (.epsilon.r) and a large Q value and having a temperature coefficient of resonance; frequency (.tau.f) which is close to zero, the present invention is directed to a microwave dielectric ceramic composition expressed by a composition formula of w.multidot.Li.sub.2 O-x.multidot.CaO-y.multidot.A.sub.2 O.sub.3 -z.multidot.TiO.sub.2, wherein w, x, y and z are respectively in the ranges of 0.0 mole %&lt;w.ltoreq.25.0 mole %, 0.0 mole %.ltoreq.x.ltoreq.50.0 mole %, 0.0 mole %&lt;y.ltoreq.30.0 mole %, 0.0 mole %&lt;z.ltoreq.80.0 mole % where w+x+y+z=100 mole %, and not more than 5 parts by weight of any one of ZnO, CoO, NiO and MgO is contained therein, and wherein A is selected from Sm and Nd.

Microwave dielectric ceramic composition

In order to obtain a microwave dielectric ceramic composition having a high dielectric constant (.epsilon.r) and a large Q value and having a temperature coefficient of resonance frequency (.tau.f) which is close to zero, the present invention is directed to a microwave dielectric ceramic composition expressed by a composition formula of w.Li.sub.2 O-x.CaO-y.Sm.sub.2 O.sub.3 -z.TiO.sub.2, wherein w, x, y and z are respectively in the ranges of 0.0 mole % &lt;w.ltoreq.25.0 mole %, 0.0 mole % .ltoreq.x.ltoreq.50.0 mole %, 0.0 mole % &lt;y.ltoreq.30.0 mole %, 0.0 mole % &lt;z.ltoreq.80.0 mole %, where w+x+y+z=100 mole %, and not more than 10 parts by weight of any one of MnO.sub.2, Bi.sub.2 0.sub.3, Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5 and SnO.sub.2 is contained therein.

The present invention is characterized in that in order to obtain a microwave dielectric ceramic composition having a high dielectric constant (.epsilon.) and a large Q value and having a temperature coefficient (.tau.f) which is close to zero, calcium oxide and strontium oxide, sodium oxide or lead oxide which are mixed with each other in an adjusted ratio are added to lithium oxide, samarium oxide and titanium oxide.

A microwave ceramic composition containing as main components substances expressed by a composition formula of x.BaO - y TiO.sub.2 - z.Nd.sub.2 O.sub.3 (where 0.05&lt;=x&lt;=0.25, 0.60&lt;=y&lt;=0.85, and 0.05&lt;=z&lt;=0.225) when their molar fractions are taken as x, y and z (x+y+z=1) and containing as a subcomponent one type selected from the group consisting of In.sub.2 O.sub.3, Bi.sub.2 O.sub.5, GeO.sub.2 and V.sub.2 O.sub.5.

A microwave dielectric ceramic composition which is obtained by selecting, in a composition formula of (A.sup.1+.sub.1/2 .multidot.B.sup.3+.sub.1/2) TiO.sub.3, Li.sup.1+ and Nd.sup.3+, Co.sup.3+ or Pr.sup.3+ as A.sup.1+ and B.sup.3+, respectively. The dielectric ceramic composition expressed by (A.sup.1+.sub.1/2 .multidot.B.sup.3+.sub.1/2) TiO.sub.3 has a high dielectric constant and has a temperature coefficient of resonance frequency .tau.f which is large on the minus side. MgO, CoO, ZnO, CaCO.sub.3 or SrCO.sub.3 is added to such a dielectric ceramic composition expressed by (A.sup.1+.sub.1/2 .multidot.B.sup.3+.sub.1/2 /TiO.sub.3, to improve the Q value of the dielectric ceramic composition.

A microwave dielectric ceramic composition containing as main components substances expressed by a composition formula of x.multidot.TiO.sub.2 -y.multidot.ZrO.sub.2 -z.multidot.SnO.sub.2 (where 0.30.ltoreq.x.ltoreq.0.60, 0.25.ltoreq.y.ltoreq.0.60, and 0.025.ltoreq.z.ltoreq.0.20) when their molar fractions are taken as x, y and z (x+y+z=1), and containing as additives predetermined amounts of one type selected from the group consisting of MnO, Al.sub.2 O.sub.3, CuO, Li.sub.2 O and Ga.sub.2 O.sub.3 and predetermined amounts of one type selected from the group consisting of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5.

Growing community of inventors

Osaka, Japan

Yoko Baba