Dielectric ceramic compositions for microwave

Abstract

The present invention relates to dielectric ceramic compositions for microwave applications consisting of BaO, PbO, Nd.sub.2 O.sub.3, CeO.sub.2, La.sub.2 O.sub.3 and TiO.sub.2 or consisting of compositions including these elements and having a composition formula (I). x(Ba.sub.1-.alpha. Pb.sub..alpha.)O-y›Nd.sub.2 O.sub.3(1-.beta.-.gamma.) CeO.sub.2(.beta.) La.sub.2 O.sub.3(.gamma.) !-zTiO.sub.2 (I) wherein mol %, 6.ltoreq.x.ltoreq.20, 10.ltoreq.y.ltoreq.20, 60.ltoreq.z.ltoreq.75, x+y+z=100; and 0<.alpha..ltoreq.0.5, 0.ltoreq..beta..ltoreq.0.2, 0.ltoreq..gamma..ltoreq.0.2 and 0<1-.beta.-.gamma.<1. These dielectric ceramic compositions for microwave applications have a dielectric constant above 90 at room temperature, a temperature coefficient at the resonant frequency within +5 ppm/.degree.C. and a quality factor above 5,000 at 1 GHz, they can be used as filters, as resonator dielectrics for microwave applications, as laminated ceramic capacitors, as dielectrics for electromagnetic wave impediment filters and as dielectrics for capacitors. Further, these compositions can reduce the problems of evaporation of lead oxides and bismuth oxides, and thus can reduce the use of elements harmful to human body.

Dependencies are inferred from the claim text.