JPS6366008B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a composition for producing a high dielectric constant porcelain material. In particular, the present invention relates to a composition for producing a small, large-capacity, high-standard ceramic capacitor material that has a high dielectric constant, a significantly small temperature change rate of the dielectric constant, and a good loss angle at high frequencies. Structure of conventional example and its problems BaTiO ₃ ceramic material is a well-known high dielectric constant ceramic material. Such porcelain materials are made of BaTiO ₃ with another titanate compound (e.g.
SrTiO ₃ , MgTiO ₃ , PbTiO ₃ and/or
_However , when the dielectric constant of such conventional porcelain materials is as high as 3000 or 4000, the rate of change in dielectric constant with respect to temperature changes is 50%.
% or more, and the sintering temperature at the time of production is as high as 1360-1380°C. Furthermore, when the rate of change in dielectric constant with respect to temperature change is set to 10% or 20%, the dielectric constant is as low as 1000 or 2000, and it also has many drawbacks such as poor loss angle at high frequencies. Purpose of the Invention The present invention aims to improve the drawbacks of BaTiO ₃ ceramic materials as described above, namely, to have a high dielectric constant, a small rate of change in dielectric constant with respect to temperature changes, and a good loss angle at high frequencies. It is an object of the present invention to provide a composition for producing a porcelain material which can be sintered at a relatively low temperature and is suitable for mass production. Structure of the Invention The present invention provides solid solution particles with a diameter of 0.2 μm or more.
0.7μm _BaTiO3 powder 94-99.5wt% and NiO powder
0.05-0.7 wt%, _{Nb2O5 powder} 0.2-1.5 wt%,
The composition consists of 0.02-0.3% by weight of _CeO2 powder, 0.02-0.3% by weight of _SiO2 powder and _{0.05-1.5 %} by weight of _{Pb2Bi2Ti4O13 powder} for making a high dielectric constant porcelain material. The particle size of the BaTiO ₃ powder used in the composition of the present invention is preferably 0.2 μm to 0.7 μm; if it deviates from this range, the rate of change in dielectric constant with respect to temperature changes will increase, and the sintering temperature will increase. Undesirable. Furthermore, when the proportion of BaTiO ₃ powder used in the composition of the present invention exceeds 99.5% by weight, the loss angle of the sintered porcelain material at high frequencies becomes poor and the rate of change in dielectric constant becomes large. Further, if it is less than 94% by weight, the sinterability of the composition becomes unstable, which is not preferable. If the proportion of NiO powder used in the present invention exceeds 0.7% by weight, the rate of change in dielectric constant of the sintered porcelain material with respect to temperature changes will increase, and if it is less than 0.05% by weight, the dielectric constant of the sintered porcelain material will decrease, and The rate of change in dielectric constant also becomes large, which is not preferable. Also, the proportion of Nb ₂ O ₅ powder is 1.5
If it exceeds 0.2% by weight, the loss angle becomes worse.
Below this, the rate of change in dielectric constant becomes large. Moreover, if the proportion of CeO ₂ powder exceeds 0.3% by weight, the loss angle becomes poor, and if it is less than 0.02% by weight, the rate of change in dielectric constant increases, which is not preferable. If the proportion of SiO ₂ powder exceeds 0.3% by weight, the rate of change in dielectric constant becomes large, and if the proportion of SiO 2 powder exceeds 0.02% by weight, the dielectric constant decreases and the rate of change in dielectric constant becomes large, which is not preferable. Finally, when the proportion of Pb ₂ Bi ₂ Ti ₄ O ₁₃ powder exceeds 1.5% by weight, the dielectric constant decreases,
If it is less than 0.05% by weight, the rate of change in dielectric constant becomes large, which is not preferable. In making the composition of the present invention, BaCO ₃ and TiO ₂ are first mixed in equimolar ratios, and then the mixture is
The mixture is held at 1050°C to 1200°C for about 2 hours and then sintered and ground to produce BaTiO ₃ powder with a particle size of 0.2μm to 0.7μm. Next, NiO, Nb ₂ O ₅ , CeO ₂ , SiO ₂ , Pb ₂ Bi ₂ Ti ₄ O ₁₃ powders are prepared and weighed so that the above composition ratio is achieved. These powders are mixed in a wet manner using a urethane resin-lined hot mill and a urethane-lined ball to prevent impurities from being mixed. When producing a porcelain material using the composition according to the present invention, a binder such as polyvinyl alcohol is added to the mixture prepared as described above, and the mixture is compressed into a desired shape under an appropriate pressure, usually 1000 kg/cm ² . Shape. The molded body is then sintered, and when the composition of the present invention is used, the temperature is generally 1220°C to 1250°C.
C. for several hours, preferably 2 hours. Note that when preparing solid solutions of BaTiO ₃ and Pb ₂ Bi ₂ Ti ₄ O ₁₃ in advance, the raw material compounds are not necessarily equimolar;
It may be increased or decreased up to 0.5 mole. Description of Examples The present invention will be described below with reference to Examples. Examples BaTiO ₃ , NiO, Nb ₂ O ₅ , with a particle size of 0.2 μm to 0.7 μm,
Each powder of CeO ₂ , SiO ₂ and Pb ₂ Bi ₂ Ti ₄ O ₁₃ was
Samples 1 to 15 were prepared by mixing them in the proportions shown in the table. Add appropriate polyvinyl alcohol binder to each sample and apply a pressure of 1000Kg/cm ² to a diameter of 12mm and a thickness of 0.4mm.
It was compression molded into a disk. Then each disc was heated to 1220℃~
It was baked at 1250°C for 2 hours. Silver electrodes were applied to the sintered disks thus obtained and baked at 750 to 800°C, and the electrical properties of each sintered disk were measured. The results are shown in Table 2.

【table】

【table】

【table】

[Table] Reference examples BaTiO ₃ based porcelain materials that are well known in the past, namely MgTiO ₃ , SrTiO ₃ , PbTiO ₃ or
A ceramic material using CaTiO ₃ was created by the method shown in the example, and its electrical properties were measured. The components of each porcelain material are shown in Table 3, and the measurement results are shown in Table 4.
Shown in the table.

【table】

【table】

[Table] Effect of the invention In Tables 1 and 2, sample numbers 3 to 10
are samples within the scope of the present invention, and the others are comparative samples. As is clear from the data in Table 2, all of the sintered porcelain materials made from the composition of the present invention are dense porcelains, and their electrical properties also have higher dielectric constants than conventional materials and comparative examples. , the high frequency loss angle is good, and the temperature change rate is also small and stable. Further, the composition of the present invention can be sintered at a relatively low sintering temperature of 1220 to 1250°C, and has great industrial value. Furthermore, as is clear from the data in Table 4 of Reference Examples, the rate of temperature change in conventional porcelain materials was large.
In contrast, the porcelain material according to the present invention has a small temperature change rate and is stable, and is clearly superior.

Claims (1)

[Claims] 1 Particles with a diameter of 0.2 μm to 0.7 μm that have become a solid solution
_BaTiO3 powder 94~99.5% by weight and NiO powder 0.05~
0.7% by weight, _Nb2O5 powder _0.2-1.5 % by _weight , _CeO2 powder 0.02-0.3% _by weight, _SiO2 powder _{0.02-0.3% by weight and Pb2Bi2Ti4O13 powder} 0.05-1.5% by weight. Composition for dielectric constant porcelain materials.