Abstract: A bismuth sodium titanate (Bi0.5Na0.5TiO3) base material is modified by the partial substitution of aliovalent A-site cations such as barium (as BaO) or strontium (as SrO), as well as certain b-site donor/acceptor dopants and sintering aids to form a multi-phase system, much like known “core/shell” X7R dielectrics based solely on BaTiO3. The resulting ceramic dielectric composition is particularly suitable for producing a multilayer ceramic capacitor (10) that maintains high dielectric constant (and thus the capability of maintaining high capacitance) over a broad temperature range of from about 150° C. to about 300° C. Such capacitors (10) are appropriate for high temperature power electronics applications in fields such as down-hole oil and gas well drilling.

Abstract: A dielectric ceramic powder and multilayer ceramic capacitors made from the powders are disclosed. A dielectric start powder mixture includes at least ninety weight percent essentially pure barium titanate powder having an average particle size of from 0.2 to 1.2 microns; from 0.2 to 2.5 weight percent of barium lithium borosilicate; from 0.1 to 0.3 weight percent of MnCO3; 0.4 to 1.50 weight percent Nb205 or a niobate compound, or a molar equivalent of Ta2O5 or a tantalum compound as a grain growth inhibitor; and, 0.4 to 1.2 weight percent of gadolinium oxide (Gd2O3). The start powder mixture is calcined and then sintered in an open zirconia setter at from 950° C. to 1,025° C. to produce a dielectric ceramic body that satisfies X7R capacitor performance characteristics; that includes no hazardous heavy metal oxides; and, that may include silver-palladium electrodes having 85 weight percent or more of silver.

Abstract: The invention includes a dielectric ceramic powder mixture comprising at least ninety weight percent essentially pure barium titanate powder having an average particle size of from 0.2 to 1.2 microns; from 0.2 to 2.5 weight percent of barium lithium borosilicate flux; from 0.1 to 0.3 weight percent of MnCO3; a grain growth inhibitor such as niobium oxide or other niobate compound; and, 0.4 to 1.2 weight percent of an additive selected from the group consisting of a rare earth oxide, yttrium oxide, a combination of rare earth oxides, and a combination of yttrium oxide and rare earth oxides, such that ions of the additive(s) have an average ionic radius of about 0.97 angstroms. The dielectric ceramic powder provides a start powder for making very low firing multilayer ceramic capacitors satisfying X7R performance requirements.

Abstract: In a start powder mixture of magnesium zinc titanate and a barium lithium boro-silicate flux, it is discovered that the addition of lithium to the flux enables the manufacture of multilayer ceramic capacitors using the powder mixture, that perform to the COG standard including an accelerated life test. This addition of lithium also makes possible the sintering to maturity of COG multilayer capacitors at temperatures as low as 950° C., which in turn allows the use of silver-palladium alloy buried electrodes of high silver and low palladium content which in turn lead to higher capacitor Q and lower manufacturing costs.

Abstract: Temperature compensating capacitors and dielectric ceramic powder compositions therefor are disclosed, based upon a dual-component barium borate and zinc silicate sintering flux. The precursor dielectric ceramic powders can include (1−m) BaTiO3+(m) CaZrO3 (BTCZ composition), with m ranging from 20 mole percent to 35 mole percent, xBaO.yTiO2.zRE2O3 (rare earth composition), (RE being a rare earth metal), with x ranging from 0 m % to 30 m %, y ranging from 45 m % to 95 m %, and z ranging from 5 m % to 50 m %, or a combination of the BTCZ and rare earth composition in varying weight percents. The effective range of B2O3 in the barium borate ranges from 0.029 w % to 2.75 w % of the total dielectric composition, whereas the effective range of SiO2 in the zinc silicate ranges from 0.08 w % to 1.42 w % of the total dielectric composition.

Abstract: A ceramic powder mixture is made by combining from 96 to 98 mole percent of precursors of a stoichiometric barium zirconate titanate (BZT) wherein zirconium amounts to from 13.5 to 15.0 mole percent, and adding from 0.5 to 1.5 mole percent niobium or lanthanum, from 1.2 to 2.6 weight percent of a cadmium silicate sintering flux, essentially no lead, and from zero to 2 mole % of an alkaline earth metal to obtain in the powder mixture a ratio (A/B) of the large cations (A) to the small cations (B) in the range from 1.024 to 1.035. The mixture is calcined to obtain a powder comprised of agglomerates of essentially identical composition within the ranges given above. This powder of agglomerates may then be formed into a compact body that is sintered and fired to maturity at 1100.degree. C. to produce a mature dielectric ceramic body meeting the Y5V standard and having a dielectric constant greater than 10,000 at the Curie temperature.

Abstract: Disc and multilayer ceramic capacitors having a fine grained barium titanate body having been sintered at less than 1100.degree. C. exhibit a high dielectric constant and a smooth (X7R) temperature coefficient of capacitance. Such capacitors are made by mixing barium titanate powder of less than 0.6 micron average particle size, with around 2 weight percent of a silicate flux serving as a reactivity and sintering promoter and one weight percent Nb.sub.2 O.sub.5 serving as a reactivity and sintering inhibitor. After preparing a green body of this mixture, the body is sintered at about 1100.degree. C. In the case of making a multilayer monolithic capacitor, the buried electrodes contain no more than 30 weight percent palladium, and adjacent pairs of the buried electrodes have been spaced apart as close as 5 microns in capacitors of this fine grained high dielectric constant X7R ceramic leading to very high packing density.