Method for making a BaTiO.sub.3 powder mixture the powder mixture and method for making a Y5V ceramic body therefrom

A method for making a dielectric ceramic body comprising:

• a) preparing a powder mixture having an average particle size of about 1 micron by combining:
• from 95 to 98 weight percent of precursors of a stoichiometric barium zirconate titanate (BZT) wherein zirconium amounts to from 13.5 to 15.0 mole percent of all the small cations in said BZT, and wherein up to 4 mole percent of said barium is replaced by strontium;
• from 0.5 to 1.5 mole percent of a Curie-point shifter cations,
• from a sintering flux consisting of 1.2 to 2.6 weight percent of a cadmium silicate wherein the molar ratio of CdO to SiO.sub.2 ranges from 1:1 to 3:1 inclusive,
• from zero to 0.01 mole percent of Pb,
• from zero to 2 mole percent of an alkaline earth metal selected from barium, calcium, strontium and combinations thereof to effect in said 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, wherein the alkaline-earth metals, lanthanum and cadmium are large cations;
• and titanium, zirconium, niobium and manganese are small cations;
• b) further mixing said powder mixture to form a homogenous powder mixture;
• and
• c) partially calcining said homogeneous mixture at approximately 700.degree. C. to obtain a powder comprised of agglomerates of said homogeneous powder mixture;
• d) forming a body of said calcined homogeneous mixture;
• e) applying at least two separate electrodes to said body
• f) sintering said body at about 1100.degree. C. in a closed container;
• and
• g) annealing said body at about 1050.degree. C. in an open air atmosphere to provide a mature dielectric ceramic body having a dielectric constant greater than 10,000 at the Curie temperature which lies between 0.degree.-20.degree. C.