CN1061764A - The preparation of ultra-micropowder of high purity barium titanate - Google Patents

Abstract

The present invention relates to the preparation of high-purity barium titanate.At NH ₃H ₂O and H ₂O ₂Mixed solution in the Ti of mol ratio such as add ⁴⁺(or TiO ²⁺) salt and Ba ²⁺Salt, the pH of control reaction system is 8.70 ± 0.20, and the precipitation washing with reaction obtains dehydrates, and calcination promptly gets the high-purity barium titanate product under 600 ℃ of temperature, and its chemical property is good.

Description

The preparation of ultra-micropowder of high purity barium titanate

The present invention relates to the preparation of titanate, particularly the preparation of high-purity barium titanate.

Positive day of components and parts are different on the electronic industry develops towards high precision, high reliability, direction multi-functional and miniaturization.In order to satisfy the needs of making high-quality like this components and parts, at first to guarantee to prepare the ultrapure ultra-fine and homogenizing of used powder raw material.Barium titanate (BaTiO ₃) be to make a kind of main component in electrical condenser, piezoelectrics, impedance body and the semi-conductor electricity sub-element ceramic raw material.German Patent (patent No. is 2433279) and Japanese Patent (patent No. is clear 49-69399) have proposed liquid phase method respectively and have prepared titanate.Promptly in the aqueous solution of titanium ion that contains mol ratios such as having an appointment and barium ion, add excessive hydrogen peroxide (H ₂O ₂) and the aqueous solution of alkali, generate compound superoxide precipitation, will precipitate thermal degradation then and promptly obtain BaTiO ₂Product.Wherein main experimental conditions is: 1. the pH value of system should not be lower than 7; When 2. precipitating superoxide, each composition can be by order mixing arbitrarily; 3. ammoniacal liquor, KOH and NaOH all can make alkaline solution.The above condition only relates to the Ba/Ti mol ratio of preparing in the intermediate product (compound superoxide), and does not relate to purity, productive rate and each proximate analysis of products obtained therefrom.

The object of the present invention is to provide a kind of produced in high yields high-purity barium titanate (BaTiO ₂) method of super-fine powder, to satisfy the needs that the high quality components and parts are made on the electronic industry.

The present invention adopts liquid phase reaction, the pH value of strict control reaction system, and the order of addition(of ingredients) according to determining precipitates calcination at high temperature with the compound superoxide that obtains, and can make BaTiO high-purity, isometric system ₂The super-fine powder product, productive rate reaches more than 99%.

Specific embodiments of the present invention is, at NH ₃H ₂O and H ₂O ₂Mixed solution in, the Ti of mol ratios such as adding ⁴⁺(or TiO ²⁺) salt and Ba ²⁺Salt brine solution is used NH ₂H ₂The pH value of O regulator solution is in 8.70 ± 0.20 scopes, and reaction is finished and isolated compound superoxide precipitation, washes precipitation with water, and at room temperature dry with ethanol dehydration, calcination promptly gets BaTiO under 600 ℃ of temperature ₂Product.

Order of addition(of ingredients) of the present invention be make reaction system pH value by greatly to little variation, promptly to NH ₃H ₂O and H ₂O ₂Add respectively in the mixed aqueous solution or add simultaneously and contain Ti ⁴⁺And Ba ²⁺The aqueous solution of salt.The pH value of reaction system 8.70 ± 0.20 scopes that are controlled at are regulated ammonia volume and are reached.PH value as shown in table 1 is to BaTiO ₃The productive rate of product and purity have tangible influence.Table 2 has provided order of addition(of ingredients) to BaTiO ₃The influence of product.

Table 1. pH value is to the influence of product purity, productive rate

	PH value	Purity (%)	Ba/Ti	Productive rate (%)
					3＃	8.20	91.30	0.9799	90.7
4＃	8.50	99.39	0.9929	97.8
					1＃	8.72	99.82	1.0001	99.5
2＃	8.80	99.83	1.0004	99.5
					5＃	9.00	99.41	1.0104	98.9
6＃	9.30	98.02	1.0197	93.8
					7＃	10.30	97.35	1.0471	90.7

Table 2. order of addition(of ingredients) is to the influence of product purity

The PH changing value		Product analysis
						BaO(％)	TiO 2(％)	Ba/Ti	Purity (%)
		2＃	13→8.80	65.64	34.18					1.0004	99.83
8＃	1→8.80					60.31	36.14	0.8693	91.73

Be not difficult to find out that order of addition(of ingredients) is very big to the quality influence of product.To Ti ⁴⁺And Ba ²⁺Add H in the mixed solution ₂O ₂After, add NH gradually ₂H ₂O to PH=8.80, promptly pH value, is obtained product purity and obviously descends to big variation by little, and impels a large amount of H ₂O ₂Decompose.Although increase Ba ²⁺Salt charging capacity and the continuous H that adds ₂O ₂May improve product purity, but still can not obtain high purity product, and reproducibility is bad.The present invention selects NH for use in addition ₃H ₂O regulates pH value, and can not utilize NaOH or KOH, and this is because the compound superoxide of intermediate product that generates is amorphous sediment, if in the system Na is arranged ⁺, K ⁺Plasma then is adsorbed and is difficult to washing and removes, and the existence of alkalimetal ion can reduce the chemical property of product greatly.

Creativeness of the present invention and practicality can be embodied in following embodiment.

Embodiment:

In beaker, add 30%H ₂O ₂Solution 22.0ml, 28% ammoniacal liquor 30.0ml, H ₂O150ml adds 0.2165M TiCl to this solution under constantly stirring ₄Aqueous solution 100.00ml obtains yellow transparent solution, and pH value is 8.72, adds the BaCl of 0.1909M then gradually ₂Aqueous solution 113.41ml(molar ratio Ba/Ti=1.000) obtain the milk yellow precipitation, water washing and precipitating with ethanol dehydration and at room temperature dry back calcination under 600 ℃ of temperature, gets isometric system BaTiO to there not being chlorion ₂, mean particle size is 0.015 μ, productive rate is 99.5%.The X-ray diffraction spectrogram of this product as shown in Figure 1.Table 3 is chemical constitutions of this product.

Table 3. BaTiO ₃The chemical constitution of product

	BaO	TiO 2	SrO	Na 2O	Ba/ti
						Product content of the present invention (%)	65.62	34.18	0.01	3.2×10 -4	1.0001
Japan's KYORIX company's high purity product content (%) (BT HP1)	65.63	34.19	0.01	0.01	0.9999
						Theoretical content (%)	65.75	34.25			1.0000

The BaTiO that the present invention obtains ₃Product is compared with the product of Japanese KYORIX company, has reached high-purity grade of level.And chemical property is good, after measured, and its specific inductivity mean value ε=1662, loss tangent mean value tg δ=139 * 10 ^-4, insulation strength mean value E=5.4KV/mm.

Claims (2)

1, a kind of method for preparing ultra-micropowder of high purity barium titanate is characterized in that, according to following steps:

(1) in container, adds 30%H ₂O ₂, 28% NH ₂H ₂O and an amount of water;

(2) under constantly stirring to described H ₂O ₂And NH ₂H ₂Add Ti in the aqueous solution of O ⁴⁺(or TiO ²⁺) aqueous solution of salt;

(3) use NH ₂H ₂The pH value that O regulates mixing solutions is 8.70 ± 0.20, and mixing solutions is a yellow transparent solution;

(4) in described yellow transparent solution, add Ba ²⁺Salt brine solution gets the milk yellow precipitation, and molar ratio is Ba/Ti=1.000;

(5) washing, with ethanol dehydration and at room temperature dry, calcination promptly gets the ultra-micropowder of high purity barium titanate product under 600 ℃ of temperature.

2, according to the claim 1 said method for preparing high-purity barium titanate, it is characterized in that said Ti ⁴⁺Salt brine solution is the TiCl of 0.2165M ₄The aqueous solution; Said Ba ²⁺Salt is the BaCl of 0.1909M ₂The aqueous solution.

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