摘要:

This paper reviews the existing literature relating to the nature of surface conduction on solid dielectrics. Literature on the variations in conductance caused by changes in the ambient humidity, temperature and pressure; different dielectric materials and surfaces; surface contamination and the nature and magnitude of an applied voltage gradient, are also reviewed. The scope of the paper is limited to a consideration of conduction through films adsorbed on solid dielectrics in the form of plates or cylinders.

DOI:10.1049/piee.1965.0235

出版商:IEE    

年代:1965

数据来源: IET

摘要:

A capacitance/volume ratio of 3 μF/cm3has been achieved in an encapsulated ceramic capacitor without the use of precious metal for the electrodes. A modified form of barium titanate which can be sintered in a reducing atmosphere to yield a high-resistivity dielectric has been developed as the dielectric. Capacitors are made by assembling plastic-bound layers of barium titanate, with layers of powdered nickel deposited between them, and firing to burn out the organic matter and to sinter the nickel electrodes and the dielectric material.The substitution of carefully selected low-permittivity material for the barium titanate leads to units in the 100–10000pF range with losses less than 0.001 and very low temperature coefficients.

DOI:10.1049/piee.1965.0237

出版商:IEE    

年代:1965

数据来源: IET

摘要:

Electrical properties of a number of ceramics containing calcium titanate with additions of 2Bi2O35TiO2and others consisting essentially of Bi2O32TiO2have been measured, and a composition CaTiO3, 0.08(2Bi2O3, 5TiO2has been prepared with a permittivity of 187, low loss (tan δ<0.002 at 1 Mc/s) and a temperature coefficient of −970 parts in 106degC.The electrical properties of ceramics consisting of calcium titanate and calcium titanosilicate have also been studied and found to include a zero-temperature-coefficient composition with a permittivity of more than 80 and low loss (tan δ<0.0005 at 1 Mc/s).Xray data for these ceramics are given, and the occurrence in them of a cubic pyrochlore-type phase of bismuth titanate is reported. This pyrochlore type of bismuth titanate may be produced with a zero temperature coefficient of permittivity.The possible use of some of these ceramics as capacitor dielectrics with controlled temperature coefficients is indicated.

DOI:10.1049/piee.1965.0238

出版商:IEE    

年代:1965

数据来源: IET