JPH0717447B2 - PLZT manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention has a general formula of (Pb _1-x La _x ) (Zr _1-y Ti _y ) _{1-x / 4} O ₃ (O <X 0.3 Oy 1 .0) for manufacturing PLZT.

PLZT is expected to have a wide range of applications as optoceramics such as polarizing elements, optical shutters, and image storage elements.

[Conventional technology]

Among the raw material powders of the constituents of PLZT, the zirconia raw material powder is extremely likely to aggregate. Even if a PLZT raw material powder is prepared by a dry method using such a zirconia raw material powder, the average particle size is 1
˜2 μm or more. Even if PLZT raw material powder having such a particle size is used, it is difficult to obtain PLZT having high density, high light transmittance, and optical uniformity. Further, in order to produce a high-density sintered body, a hot pressing method or a molding method such as HIP is adopted, but it is difficult to obtain a high density PLZT even if the hot pressing is applied to the raw material powder.

[Problems to be solved by the invention]

The present invention has been made to solve the above-mentioned drawbacks in the synthesis of PLZT by a dry method, and an object thereof is to prepare a modified zirconia raw material powder of a submicron class having good dispersibility, and use the powder to perform a simple dry method. The object of the present invention is to provide a method of synthesizing a PLZT powder having a high sinterability and a high bulk density, and further sintering the powder to produce a PLZT having a high density and a high light-transmitting property and being optically uniform.

[Means for solving problems]

As a result of earnest research to achieve the above object, the present inventors have found that the general formula (Pb _1-x La _x ) (Zr _1-y Ti _y ) _{1-x / 4} O ₃ (O <X 0.3, Oy 1. In the manufacturing process of PLZT by the dry method shown in (1), a solution containing an appropriate amount of at least one metal component other than zirconium and zirconium is prepared, and a hydrolysis reaction is performed to form a sol. Aggregation of Zr-containing particles is less likely to occur for uniformity, and then dried 70
It has been found that calcination at 0 to 1300 ° C can form a submicron grade powder (modified zirconia powder) with extremely few agglomerates. By using this as a raw material and mixing the compounds of the remaining constituent parts of the desired PLZT composition by a dry method, a raw material powder having excellent submicron grade powder characteristics can be easily obtained,
If this is molded and sintered, it is possible to easily obtain an optically uniform PLZT with extremely high density and high light-transmitting property even if operations such as hot pressing and HIP (hot gas pressure sintering) are omitted. Could be determined. The present invention has been completed based on this finding.

The gist of the present invention is a combination of the following three steps.

(1) A solution containing zirconium and an appropriate amount of at least one metal component other than zirconium constituting PLZT is prepared, and a hydrolysis reaction is performed to produce a sol, and the sol is dried at 700 to 1300 ° C. Calcination step: In this step, agglomeration is avoided and modified zirconia that can be used for PZT, ZT, etc. is produced.

(2) The calcined product obtained in the process of (1) and the target PL
Mix the remaining constituent compounds of the ZT composition to 500-1000
Step of calcination at ° C; In this step, the desired compound composition is obtained by adding the remaining constituents.

(3) A step of molding the obtained calcined powder and sintering at 1000 to 1300 ° C., and a method for producing PLZT.

As a compound for preparing a zirconium solution (aqueous solution or alcohol solution), zirconium oxychloride,
Examples thereof include zirconium oxynitrate, zirconium chloride, zirconium nitrate, and metallic zirconium.

As a solvent for the zirconium solution, water or alcohol that dissolves the above compound is used. All the above compounds are soluble in water, zirconium oxychloride, zirconium chloride and titanium tetrachloride are soluble in ethanol. Furthermore, in order to prepare a zirconium solution, metallic zirconium can be dissolved in aqua regia or HF and used.

As a compound for preparing a solution of at least one component other than zirconium, lead is Pb (NO ₃ ) ₂ and lanthanum is La (N
O ₃ ) ₃ , LaCl ₃ , La ₂ (SO ₄ ) ₃ and titanium include Ti (NO ₃ ) ₄ , TiCl ₄ and Ti (SO ₄ ) ₂ . Water or alcohol is used as the solvent of this solution. The zirconium solution and the solution other than zirconium may be prepared separately, or may be prepared by dissolving each compound in the same solvent. The hydrolysis reaction is performed in a heated state (around 100 ° C), and the sol is collected by filtration and washing.

The type and amount of the constituent components of PLZT dissolved in the zirconium solution are preferably those that can effectively suppress the agglomeration of the zirconia powder finally obtained by adding the constituent components.

The calcination temperature is 700 to 1300 ° C. If the temperature is lower than 700 ° C, agglomeration will occur remarkably, and if it exceeds 1300 ° C, the particles tend to become coarse. A shortage of constituents other than zirconium is added to the thus obtained material and mixed. Of course, it is necessary to replenish the deficiency of the components added to zirconia. In this case, the particle size of any compound powder (mainly oxide) is submicron grade. However, even if the lead oxide powder having a coarse particle size is used, it has almost no effect on the properties of the obtained PLZT powder.

The calcination temperature of these mixtures significantly changes in the range of 500 to 1000 ° C. depending on whether Ti is contained, La is contained, or Ti and La are contained. In short, it is necessary to be above the minimum temperature at which the solid-phase reaction is almost or completely completed and within the maximum temperature range where significant particle growth does not occur.

The powder thus obtained is molded. The sintering temperature varies depending on the kind of the constituents as in the case of the calcination temperature of the mixture, but is generally in the range of 1000 to 1300 ° C. 1000 ° C
If it is lower than this, sintering will be insufficient and a high density will not be obtained, and if it exceeds 1300 ° C, the particles will become coarse or Pb will be volatilized.

Example 1 Titanium tetrachloride aqueous solution (1.250 / mol concentration) 40.0cc and zirconium oxychloride aqueous solution (1.250 / mol concentration)
(Concentration) 160.0 cc was mixed. This mixed aqueous solution is heated at 100 ° C for 10
Hydrolysis reaction is carried out by holding for 0 hours, and Ti ⁴⁺
And a sol containing Zr ⁴⁺ was obtained. After washing and drying this, 1100
It was calcined at ℃ to prepare (Zr _0.8 Ti _0.2 ) O ₂ powder.

The average particle size of this powder was 0.32 μm.

The powder 9.102gr, commercially available TiO ₂ fine powder 1.465gr, PbO powder (average particle size 15 μm) 20.311gr, and La ₂ O ₃ fine powder 1.466gr were mixed in a ball mill for one day and then calcined at 850 ° C. for 2 hours. Then, (Pb _0.91 La _0.09 ) (Zr _0.65 Ti _0.35 ) _0.978 O ₃ powder was obtained. The average particle size was 0.32 μm. 1 tor of the powder
A tablet molded in cm ² was sintered at 1200 ° C. for 10 hours in an atmosphere containing lead vapor and oxygen gas. The density of the obtained product reached 7.84, and the light transmittance was about 45% at a sample thickness of 2.5 mm using a wavelength of 600 nm.

Example 2 Titanium tetrachloride aqueous solution (1.250 / mol concentration) 40.00cc, lanthanum nitrate aqueous solution (1.250 / mol concentration) 10.0
cc and 160 cc of zirconium oxychloride aqueous solution (1.250 / mol concentration) were mixed. By holding this mixed aqueous solution at 100 ° C for 100 hours, a hydrolysis reaction occurs and La ³⁺ and Ti ⁴⁺
And a sol containing Zr ⁴⁺ was obtained. After washing and drying this, 1100
It was calcined at ℃ to prepare La _0.05 (Zr _0.8 Ti _0.2 ) O _2.075 powder.

The average particle size of this powder was 0.32 μm. 9.750 g of the powder
r Commercially available TiO ₂ fine powder 1.465gr and PbO powder (average particle size 15μ
m) 20.311 gr and 8.189 g of La ₂ O ₃ fine powder were mixed in a ball mill for one day and then calcined at 850 ° C. for 2 hours (Pb _0.91 L
a _0.09 ) (Zr _0.65 Ti _0.35 ) _0.978 O ₃ powder was obtained. The average particle size was 0.32 μm. A tablet formed by molding the powder at 1 tor / cm ² is heated to 1200 ° C in an atmosphere containing lead vapor and oxygen gas.
Sintered for 10 hours. The density of the obtained one reaches 7.81,
The light transmittance is about 2.5 mm for a sample thickness of 2.5 mm using a wavelength of 600 nm.
It was 40%.

[Example 3] Lanthanum nitrate aqueous solution (1.250 / mol concentration) 22.652cc and zirconium oxychloride aqueous solution (1.250 / mol concentration) 160cc
Were mixed. By holding this mixed aqueous solution at 100 ° C. for 100 hours, a hydrolysis reaction was performed to obtain a sol containing La ³⁺ and Zr ⁴⁺ . This is washed and dried, then calcined at 1100 ° C and La
_0.09 Zr _0.6357 O _1.406 powder was obtained.

The average particle size of this powder was 0.32 μm.

The powder (18.723 gr), commercially available TiO ₂ fine powder (5.507 gr) and PbO powder (average particle size 15 μm) (40.895 gr) were mixed with a ball mill all day and night, and then calcined at 850 ° C. for 2 hours (Pb _0.91 La _0.09 ) (Zr
₀₂₆₅ Ti _0.35 ) _0.978 O ₃ powder was obtained. The average particle size is 0.41μ
It was m. A tablet obtained by molding the powder at 1 tor / cm ² was sintered at 1200 ° C. for 10 hours in an atmosphere containing lead vapor and oxygen gas. The density of the obtained product reached 7.80, and the light transmittance was about 36% when the wavelength was 600 nm and the sample thickness was 2.5 mm.

[Comparative example]

Commercially available PbO, TiO ₂ , ZrO ₂ , and La ₂ O ₃ powders were _added (Pb _0.91 La _0.09 ) (Zr
_0.65 Ti _0.35 ) _0.978 O ₃ was added and mixed in a ball mill for one day and then calcined at 900 ° C. for 2 hours. This powder was molded at 1 t / cm ² and sintered under the same conditions as in Examples 1, 2 and 3.

The density of the obtained PLZT was about 7.6, but it did not become a transparent sintered body. The average particle size of the powder during calcination is 2.8.
was μm.

〔The invention's effect〕

According to the method of the present invention, the zirconia powder (modified zirconia powder) containing at least one of the constituents of PLZT in the first step can be made into submicron particles having extremely few secondary particles. It is possible to obtain an excellent effect that a submicron-class PLZT raw material powder can be easily obtained by a simple dry method, and PLZT having good translucency and high density can be obtained from the raw material powder. In addition, the following effects can be obtained.

1) Since the modified zirconia powder obtained by calcination is sufficiently dispersed, the calcinated product can be supplied as a raw material powder without requiring a crushing step.

2) PL obtained from the calcined modified zirconia powder by a dry method
The ZT powder is also obtained in a monodisperse state, and therefore has a property of being easily sinterable and having a high density even if the crushing step is omitted.

3) PLZT for optoelectronics, which requires extremely high density and high optical homogeneity, can be made to have theoretical density extremely high by omitting operations such as hot pressing and HIP (hot gas pressure sintering). It can be obtained with high density.

4) By mass-producing the modified zirconia powder having excellent powder characteristics, PLZT having an arbitrary composition can be supplied at extremely low cost.

Claims (3)

[Claims] 1. A PLZT represented by the general formula (Pb _1-x La _x ) (Zr _1-y Ti _y ) _{1-x / 4} O ₃ (O <X0.3 Oy1.0) is constituted. An appropriate amount of at least one metal component other than zirconium, and a solution containing zirconium is prepared, a hydrolysis reaction is carried out to produce a sol, and the sol is dried and calcined at 700 to 1300 ° C., 2. The calcined product obtained in the step (1) and the compound of the remaining constituents of the intended PLZT composition are mixed to obtain 500.
Calcination process at ~ 1000 ° C, 3. The obtained calcined powder is molded to 1000 to 1300 ° C.
A method of manufacturing PLZT, which comprises a step of sintering at.