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AssigneesNippon Soken, Inc., Denso Corporation
InventorsAtsuhiro Sumiya, Hitoshi Shindo, Eturo Yasuda, Takumi Kataoka, Toshiatsu Nagaya, Akira Fujii, Takashi Yamamoto
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An object of the present invention is to make it possible to sinter a PZT dielectric ceramic material at a desired low temperature and to prevent deterioration of the performance of the base material. According to the present invention, an auxiliary oxide is used that is made by adding the oxide of at least one of tungsten and molybdenum to lead oxide in the following proportions. PbOx+(WO3y+MoO3z) where x+y+z=1, 0.005<y+z<0.4 and y, z≧0. 0.5 mol % to 20 mol % of this auxiliary oxide is added to a mixture of a stock material of dielectric ceramic material or calcination thereof that has a composition of ABO3 type dielectric ceramic material where 0.9 molar ratio or more lead is included in site A assuming the proportion of site B is 1, and the material is mixed, formed and sintered. The content of tungsten and molybdenum combined is less than 0.098 mole in proportion to 1 mole of lead and the density of the dielectric ceramic material after sintering is 7.5 g/cm3 or larger. The auxiliary oxide is dispersed in the calcined powder to form a liquid phase at a desired temperature, thereby to accelerate the sintering, thus making it possible to sinter at a lower temperature.
A low-temperature sintered dielectric ceramic material having a composition of ABO3 type dielectric ceramic material where a 0.9 molar ratio or more lead is included in site A assuming the proportion of site B is 1, and at least one of tungsten and molybdenum is included, while density of the dielectric ceramic material, after sintering, is 7.5 g/cm3 or larger, and the content of tungsten and molybdenum combined is less than 0.098 mole to 1 mole of lead.
An auxiliary oxide to be used as an additive when sintering a ceramic material, and is made by adding the oxide of at least one of tungsten and molybdenum to lead oxide, while the content of tungsten and molybdenum combined is set in a range from 0.5 mol % to 40 mol %.
An auxiliary oxide to be used as an additive when sintering a ceramic material, and is made by calcination of an mixture of lead oxide and oxide of at least one of tungsten and molybdenum added to lead oxide, while the content of tungsten and molybdenum combined is set in a range from 0.5 mol % to 40 mol %.
Dependencies are inferred from the claim text.