| 摘要 |
A robust alkaline earth metal titanate ceramic dielectric structure is formed by firing together a layer of resistivity less than 1000 ohm-cm. at 25 DEG C., rendered semi-conducting by incorporation of 0.1-0.5% of an additive, e.g. a compound or mixture of compounds containing ions of V, Nb, La or other rare earth metals, U, W, Th, Bi, Sb or F, particularly Nb2O5, and an applied thin layer which is a dielectric due to the absence of additive. Barium titanate may be ball-milled with distilled water, allowed to settle, the supernatant water removed, 5% methyl cellulose in water added to the slurry as binding agent, the mixture dried at 100 DEG C. for 3-4 hours. and the dried product broken up and sieved to 300-100 mesh. The powder plus additive is compacted at 100 p.s.i. to form a disc, rod or tube. The dielectric layer, 0.1-20 mil. thick, of barium titanate as prepared above, or of a mixture of alkaline earth metal titanates, with or without the addition of a zirconate or stannate, is applied to the intermediate body as a powder, slurry or slip, and the coated body is compressed under 10,000 p.s.i. and fired in air at 1218-1500 DEG C. for 1/2 -2 hrs. to form a single integrated unit. In one modification, two dielectric layers are applied to opposite surfaces of the intermediate body, or the dielectric layer may be sandwiched between semiconducting layers. Capacitors are formed by applying suitable electrodes to the appropriate surfaces of the dielectric structures and stacks of capacitors may be made up. |
