| abstract |
Prodn. of capacitors of barrier layer ceramic based on substd. and/or doped Sr titanate involves forming the grain boundary layers in a two-stage process comprising: (i) a first stage in which one or more barrier layer-forming cpds., selected from silicates, titanates, manganates, aluminates or niobates of Ba, Sr, Ca, La, Y, Fe, Ni, Co, Mn, Cu and/or Si and/or two or more oxides of these metals, are added to the unsintered ceramic material such that, during the special sintering process, the cpds. are enriched in the grain boundary regions to produce insulating barrier layers; and (ii) further increase in breakdown resistance by diffusion of Bi, B and/or Pb oxides into the material in a second heat treatment process. USE/ADVANTAGE - Uniformly good barrier layer formation is achieved so that the finished capacitors are highly insulating and highly voltage resistant. Electrical breakdown does not occur even at field strengths of about 3 kV/mm. Claimed uses of the ceramic are for dielectric plate capacitors, tube capacitors and multilayer capacitors. |