The mixture of ferroelectric ceramic material for low-frequency capacitors

 

(57) Abstract:

Use: manufacture of ferroelectric ceramic material and the low-frequency capacitors. The inventive mixture contains MgNb2O6, PbTiO3, PbO, MnCO3and CaZrO3(or CaSnO3and BaSnO3). Effect: reduce the complexity of the manufacturing process, the firing temperature of the material and the cost of the capacitors while maintaining high values of the dielectric and electrical properties of the material and products. table 2.

The invention relates to the field of ceramic production, in particular to the composition of the charge of ferroelectric ceramic materials, and can be used in a ceramic capacitor manufacturing in the manufacture of low-frequency capacitors.

Known ferroelectric ceramic materials for capacitors based niobate magnesium, iron niobate, titanate, and additives (see application UK N 2126575).

This material has a relatively high dielectric constant ( 14000) and provides the application for internal electrodes of multilayer capacitors cheaper nl what about it is different enough high complexity of the process of obtaining, and provides no further increase the dielectric constant.

The closest in technical essence to the invention is a mixture of ferroelectric ceramic material including Pb(Mg1/3Nb2/3)O3, Pb(Fe1/2Nb1/2)O3, PbTiO3and mn containing additive MnCO3Mn(OH)2H2O (see and.with. USSR N 1364611).

Ferroelectric ceramic material on the basis of this charge is designed to produce low frequency capacitors and is characterized by a higher dielectric constant (e 16600 18000) and a wider range of operating temperatures (-60o+125oC) that provides high properties of capacitors based on it.

A significant drawback of the material on the basis of this charge is that it is characterized by a high complexity of the process to obtain it, due to the need for firing (sintering) of the workpiece material in a closed volume to prevent evaporation of lead oxide, and is characterized by a high temperature (1220 1250oC) sintering blanks from it, which limits the use as internal electrodes of the multilayer capacitor b is receiving Ag, and this, in turn, does not provide further cost reduction capacitors and higher technical result.

The proposed mixture of ferroelectric ceramic material eliminates the disadvantages of the known materials of similar purpose and achieving higher technical result, which consists in reducing the complexity of the manufacturing process, temperature firing (sintering) of the workpiece material and the cost of the capacitors while maintaining a high dielectric constant and other electrical properties of the material and capacitors from it.

The invention consists in the fact that in the inventive charge of ferroelectric ceramic material for low-frequency capacitors, including a titanate, and mn containing additive, the above technical result is ensured by the fact that the mixture additionally contains niobate magnesium, oxide of lead and powder zirconates or stannates of CaZrO3, CaSnO3and BaSnO3and as the mn containing additive contains carbon manganese in the following ratio, wt.

PbO 66 70
3, CaSnO3and BaSnO30,28 0,5

In this case, reducing the complexity of the manufacturing process, the firing temperature of the billet material and the cost of the capacitors is achieved by the fact that the introduction of the charge of powder zirconates or stannates from a number of CaZrO3and CaSnO3and BaSnO3and carbon manganese in combination with other components eliminates the need for firing blanks in a closed volume, because with regard to the introduction niobate magnesium decreases the firing temperature of the workpieces to 930 960oC and virtually eliminating the evaporation of lead oxide. In addition, the lower temperature firing (sintering) allows you to apply as internal electrodes of multilayer capacitors cheaper alloys of noble metals, such as palladium with 70-85% silver, which significantly reduces the cost of capacitors. When you type in the charge composition carbon manganese (MnCO3) improves elektroparametram (tdBand Rfrommaterial and products. The lead zirconate calcium (CaZrO3or stannat calcium (CaSnO3and stannat barium (BaSnO3) provides the ability to adjust the Curie temperature, and the oxide (PbO) and lead titanate (PbTiO

Comparative analysis of the proposed charge with the prototype shows that the material on its basis is different from the material on the basis of known charge the introduction of the magnesium niobate, lead oxide, powder zirconates or stannates from a number of CaZrO3, CaSnO3and BaSnO3and use as a mn containing additives carbon manganese. Thus, the proposed charge is new, because of its composition and ratio of the components is not known to the current level of technology.

The analysis of other technical solutions in the art, such as and. C. the USSR N 1551696 and U.S. patent N 4287075, allows us to conclude that the proposed charge involves an inventive step, because the peculiarities of its structure and its significant differences explicitly does not follow from the prior art. In addition, the mixture is industrially applicable, which follows from the results of experimental verification of the achieved technical result and practical problems in the field of ceramic capacitor production takes place.

The possibility of carrying out the invention is confirmed by the following information pertaining to the optimum composition of the mixture, examples of the component and Tehnologichesky ceramic material for low-frequency capacitors based on the proposed mixture was prepared as follows.

Pre-prepared sintered magnesium niobate (MgNb2O6by synthesis of oxides of magnesium and niobium at 1150oC with subsequent grinding. Then cooked spec, combined in a desired ratio, is mixed with a given quantity of the other components of PbO, PbTiO3, powder of lead zirconate or stannate from a number of CaZrO3, CaSnO3and BaSnO3and MnCO3and get a mixture of ferroelectric ceramic material. The resulting mixture is synthesized at 750 800oC and ground to a specific surface area of not less than 5000 cm2/g, and thus, the ferroelectric ceramic material. In the process of synthesis mixture MgNb2O6connected with PbO and forms a ternary oxide Pb(Mg1/3Nb2/3)O3that is the basis of ferroelectric material, modified spicami PbTiO3, CaZrO3(or CaSnO3and BaSnO3and the addition of MnCO3. From the obtained after synthesis of the charge material in a known manner, for example by film technology, get a ceramic film, and then the workpiece multilayer monolithic capacitors, which is sintered with a simultaneous burn-in of internal electrodes at 930 980oC then it is hty, illustrating the invention are the following optimal compositions in wt. are given in table.1.

Properties of ferroelectric ceramic material on the basis of the proposed charge and low-frequency capacitors from it are confirmed by the test results, the details of which are given in table.2.

As follows from the table.2, the ferroelectric ceramic material on the basis of the proposed charge at substantially the same level dielectric and electrical parameters in comparison with a prototype.with. USSR N 1364611 has a temperature sintering (firing) 270 300oC below that allows you to apply for internal electrodes of cheaper precious metals, such as alloy Ag-Pb in the ratio of 85:15% and significantly reduce the cost of products. In addition, the material in comparison with the prototype does not require prevent evaporation of lead oxide, more simple in composition, characterized by a smaller number of heat treatments, indicating a less time consuming process of obtaining it.

The optimal composition and the possibility of reproduction of the proposed charge is confirmed by the fact that with the introduction of the mixture of PbO, MnCO3, CaZrO3(or CaSnO3and BaSnO3) less mperature sintering blanks of material above the optimum, the need arises to prevent evaporation of lead oxide. With the introduction of these components in quantities beyond part 3, a significant reduction of the sintering temperature of the material is not achieved, because the reduced content of the main component and reduces the value of the dielectric constant below the permissible limit.

It was established experimentally that the greatest technical result is achieved at the stated ratio of the components of the mixture.

The practical application of the mixture for the manufacture of low-frequency capacitors reduces the complexity of obtaining material, reducing the temperature of sintering and cost of capacitors based on it.

Currently, the formula has been developed and the process of obtaining material on the basis of the proposed charge, and made an experimental batch of material and products were tested, the results of which confirmed the technical result.

The mixture of ferroelectric ceramic material for low-frequency capacitors, comprising titanate, niobate magnesium and carbon manganese, characterized in that it further contains an oxide of lead and lead zirconate or stannat from the series: CaZrO3, CaSnO3
MnCo30,01 0,05

PbO 66 70

The lead zirconate or stannat from a number of CaZrO3, CaSnO3, BaSnO3- 0,28 0,5 V

 

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