Chemistry of inorganic compounds – Oxygen or compound thereof – Metal containing
Patent
1985-02-05
1989-12-26
Doll, John
Chemistry of inorganic compounds
Oxygen or compound thereof
Metal containing
C01G 1900, C01G 2100
Patent
active
048897060
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method of manufacturing fine powder of lead stannate, PbSnO.sub.3, which is one of dielectrics.
2. Background Art
Recently, a manufacturing method for making dielectrics of fine powder has been studied from various aspects and as an example of the use of such finely-powdered dielectrics, there is known that such dielectrics are applied to make a ceramic capacitor. As an electronic product is required to be made small in size and high in mounting density, a capacitor is required to be made small in size, light in weight, large in capacity and high in mounting density similarly to other electronic parts. For this reason, in the ceramic capacitor, the dielectrics must be formed into fine powder in order to make the ceramic layer thin and uniform in thickness. In the prior art, for the purpose of improving sintering property, temperature characteristic and the like, upon heat treatment, lead oxide PbO, for example, is added thereto. However, upon the heat treatment, there occurs a problem that since a part of lead oxide is evaporated, it becomes impossible to produce a ceramic capacitor having a uniform characteristic. Accordingly, in order to lower the sintering temperature to prevent the lead oxide from being evaporated and to obtain the ceramic capacitor having the uniform characteristic, it is desired that the dielectrics are made of fine powder.
Alternatively, as a raw material for an electrostriction material, a piezo-electric material, a transparent ceramic material and the like, in view of improving the sintering property and the temperature characteristic thereof, such a material is appreciated that it is small in diameter of its fine powder and the particle size thereof is uniform.
As one of such dielectrics, there is known lead stannate PbSnO.sub.3. While such a method was tried to react lead oxide PbO with tin dioxide SnO.sub.2 in solid-phase under normal pressure and at high temperature so as to obtain PbSnO.sub.3, PbSnO.sub.3 thus made is thermally decomposed into Pb.sub.2 SnO.sub.4 and SnO.sub.2 under normal pressure and at high temperature so that this manufacturing method is inappropriate. On the other hand, it is discovered that PbSnO.sub.3 made by the high pressure synthesizing experiment is transferred from pyrochroi phase to perovskite phase and it is surmised that under normal temperature and normal pressure, the pyrochroi phase would be a stable phase. In the prior art manufacturing method of forming PbSnO.sub.3 which is obtained in the solid-phase reaction into fine powder, such substance is ground by using a ball mill and so on and then sieved. However, disadvantages of this prior art method are such ones that a long duration of time is required for finely grinding the substance in the ball mill, an impurity such as metal oxide and so on is mixed therewith, the particle size distribution is poor and also the existence of powder having large size cannot be avoided. Accordingly, until the present, fine powder of lead stannate of excellent quality is not yet obtained as a host or an additive to the materials for electronic parts.
In view of the above aspect, the present invention is to provide a method of manufacturing fine powder of lead stannate which is high in purity and uniform in particle size.
DISCLOSURE OF INVENTION
In a method of manufacturing fine powder of lead stannate according to this invention, hydrolyzed product of tin compound or soluble stannate is reacted with lead salt in aqueous solution which has neutral property or alkaline property to thereby produce fine powder of lead stannate. According to this manufacturing method, it is possible to manufacture fine powder of lead stannate which is high in purity and uniform in particle size.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram showing an X-ray diffraction pattern of fine powder of PbSnO.sub.3 which is made by the present invention;
FIG. 2 is a photograph of the fine powder of PbSnO.sub.3 shot by a scanning electron microscope;
FIG. 3 is a ch
REFERENCES:
patent: 3141902 (1964-07-01), Huntley et al.
Sienko et al., Chemistry, Second Edition (1961), McGraw-Hill Book Company, pp. 485, 486.
Suzuki Masayuki
Tamura Hidemasa
Uedaira Satoru
Yamanoi Hiroshi
Doll John
Lange Wayne A.
Sony Corporation
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