Method for producing a capacitor dielectric with inner blocking layers

Claim 1

A method for producing a capacitor dielectric with inner blocking layers formed of polycrystalline ceramic bodies made of a material with a perovskite structure on the basis of barium titanate and containing at least two different doping substances, one of the substances causing n-type conduction inside crystallites of the crystalline bodies and the other causing p-type conduction in a titanate intermediate phase disposed between grains of the crystallites, comprising the steps of: (a) mixing starting components needed to make the bodies; (b) grinding the components and reacting said components to produce a solid reaction product at 950° C. to 1100° C.; (c) again grinding down the reaction product to a powder of desired particle size; (d) forming the bodies from the powder and an inorganic binder by pressing and then subjecting the bodies to sintering in a sintering oven at 1250° to 1450° C.; (e) promoting the influence of p-type doping substances by separting the p-type doping substances in the intermediate phase in the vicinity of the surfaces of the crystallite grains and at least partially recrystallizing by conducting said sintering of step (d) such that the bodies are first heated up to the sintering temperature at a heat-up rate of 200° K./h (°C./h) to 800° K./h at least in the temperature range from 1000° C. to the sintering temperature, maintaining the bodies at the sintering temperature for one to four hours, then slowly cooling the bodies down from the sintering temperature to at least 100° K. and some 350° K. below the sintering temperature at a rate of between 10° K./h and 100° K./h, after which remaining cooling to normal temperature is effected related to actual cooling conditions peculiar to the sintering oven being employed.

Claim 2

A method for producing a capacitor dielectric with inner blocking layers formed of polycrystalline ceramic bodies made of a material with a perovskite structure on the basis of barium titanate and containing at least two different doping substances, one of the substances causing n-type conduction inside crystallites of the crystalline bodies and the other causing p-type conduction in a titanate intermediate phase disposed between grains of the crystallites, comprising the steps of: (a) mixing starting components needed to make the bodies; (b) grinding the components and reacting said components to produce a solid reaction product at 950° C. to 1100° C.; (c) again grinding down the reaction product to a powder of desired particle size; (d) forming the bodies from the powder and an inorganic binder by pressing and then subjecting the bodies to sintering in a sintering oven at 1250° to 1450° C.; (e) promoting the influence of p-type doping substances by separting the p-type doping substances in the intermediate phase in the vicinity of the surfaces of the crystallite grains and at least partially recrystallizing by conducting said sintering of step (d) such that the bodies are first heated up to the sintering temperature at a heat-up rate of 200° K./h (°C./h) to 800° K./h at least in the temperature range from 1000° C. to the sintering temperature, maintaining the bodies at the sintering temperature for one to four hours, then slowly cooling the bodies down from the sintering temperature to at least 100° K. and some 350° K. below the sintering temperature at a rate of between 10° K./h and 100° K./h, after which remaining cooling to normal temperature is effected related to actual cooling conditions peculiar to the sintering oven being employed.