JPS6287460A - Manufacture of plzt light transparent ceramics - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Field of Industrial Application) The present invention relates to a method for manufacturing P L Z T translucent ceramics.

PLZT translucent ceramics are used in optoelectronics such as optical shutters, optical (Schiff 9 image storage devices, goggles, transparent sounding bodies 1 display devices).

It is expected to be used as a light modulation device.

P I, Z T and d in the present invention, a general formula having a perovskite structure, (Pbl=1La)c) [(Z
ry-Ti 1-y) t-10 King] 03. Mo[-kuke (Pbl-2rl 2 Lax >< Zry 11T
il=y)Os (where x=0.01~0.3
．． y=0.05-0.95. The term refers to ceramics represented by cationic pores) and intermediate compositions between the two.

(Prior art) PLZT translucent ceramics is produced by making raw powder, molding, and then hot pressing in air or oxygen atmosphere.
It is manufactured by adding excess clams and sintering them in a liquid phase in an atmosphere of oxygen and lead. In this case, it is extremely important that the raw material powder be uniform, low cost, and easily sinterable.

Conventional methods for producing raw material powder for P LZ T translucent ceramics and No. 17 include dry method and alkoxide method.

The oxalate method is known.

The dry method is a method in which the constituent compounds are mixed and calcined, but it is difficult to achieve a uniform composition with this method, and the calcining temperature must be adjusted to complete the solid phase reaction of PLZT. Since it is necessary to increase the particle size, this has the disadvantage that the particles become coarse and easily sinterable.

The alkoxide method involves blending lead oxide powder, zirconium alkoxide solution, titanium alkoxide solution, and lanthanum acetate solution, followed by drying and pulverizing.

This method requires expensive alkoxides, acetates, etc., which not only results in high costs (99,9
% or higher purity reagents, and alkoxides,
There are drawbacks such as the complicated manufacturing process of acetate and poor workability.

In the oxalate method, a titanium oxynitrate solution is made from titanium alkoxide and nitric acid, and this is mixed with a zirconia nitrate solution and ammonium oxalate powder to form a mixed solution of titanyl ammonium oxalate and zirconium ammonium oxalate, and then 61!1 m of lead is added to this. The method involves mixing N solution and lanthanum nitrate solution to produce a composite oxalate coprecipitate, followed by evaporation to dryness, thermal decomposition, pulverization, and calcining. This method requires a large number of expensive chemicals and a reagent with high purity of -H of 99.9% or more, which not only results in high costs, but also
The disadvantage is that the process is complicated and workability is poor.

The reason behind the idea of such a wet method using expensive alkoxides and titanium oxynitrate is that when cheap titanium tetrachloride is used as a titanium raw material, when titanium tetrachloride is used in the precipitation method, titanium tetrachloride The chlorine reacts with lead to form a white precipitate, making wet coprecipitation impossible.

(Problems to be Solved) As a method to solve these drawbacks of the conventional method, the present inventors invented a so-called multi-stage wet method in which double precipitation is formed without co-precipitating all of the constituent components at the same time. and filed a special fraud application. (Special M Showa 59-22 Wpla) Due to the twist,
It has become possible to synthesize an inexpensive and easily sinterable powder, but when this method is adopted, lead or titanium forms a precipitate alone in the precipitate formation process, so the general formula ABO3 (
However, A of the perovskite compound represented by A represents a 12-coordinated metal element of oxygen, and a 6-coordinated metal element of oxygen of Company B.
Some variation in composition is observed at the site or B site.

The present invention is to provide a method for manufacturing PLZT translucent ceramics that solves this problem without losing the characteristics of the multi-stage wet method. A multi-stage wet method of lanthanum as an aqueous solution.

Precipitation was carried out using a combination of a mixed aqueous solution of lanthanum, zirconium, and titanium as the Mizusawa solution, and a combination of a lead aqueous solution as the aqueous solution, VC, titanium or lead V↑, and a single element.

For this reason, control of the powder properties of these elements has been a primary concern. It was also said that 8+Tako's method causes compositional fluctuations.

The present invention is a solution to the problems of To1+ et al. through intensive research.

That is, by forming part of the zirconium aqueous solution as a mixed aqueous solution with a titanium aqueous solution or a lead aqueous solution,
It was also possible to control the powder properties of the titanium or lead elements, thereby eliminating compositional variations.

According to the present invention, the calcination temperature is lower than that of the conventional method, and therefore it is possible to obtain a fine powder of 0.15 μm at tX (
It was also possible to completely eliminate compositional fluctuations of 0 to 1, which are the most common.

The gist of the present invention is the general formula (
Pbl)(La)0 ((Zr)*Ti1zν)l−÷
Sundried] 03° (Pb1-T lower 4, ax) (Zry-T
it=y)03 (However, X=0.01 to 0.3.
y = o, os ~ 0.95, the opening represents a cation vacancy) Transparent material formed by sintering an intermediate composition between the two, or a powder compact in which an excess of lead of 10 wtcX or less is added to these compositions. In the production of photosensitive PLZT ceramics, an aqueous solution of lead, lanthanum, zirconium, and titanium components is prepared, and a part of the zirconium aqueous solution and the lanthanum aqueous solution are mixed with either the lead aqueous solution or the titanium aqueous solution to form an aqueous solution Afi#. Separately, the remaining amount of the zirconium aqueous solution was mixed with the remaining one of the lead aqueous solution and the titanium aqueous solution, and the aqueous solution was FA-conditioned. A homogeneous precipitate of all components is made by uniformly mixing the precipitate formed with the other aqueous solution remaining in the aqueous solution in which this precipitate is dispersed.
Temporarily at ℃! 1000 to 12
A method for producing translucent ceramics characterized by hot pressing at 80° C. in air or an atmosphere without oxygen, or sintering at normal pressure in an atmosphere containing a mixture of oxygen and lead vapor.

Component compounds for preparing an aqueous solution of PI, Z T-based components in 11, and 17, oxynitrates and sulfur salts.

nitrates, acetates, formates, oxalates, oxychlorides,
There are chlorides, dark substances, and gold leaves. If these are not soluble in water, add mineral acids etc. 1. It can be made soluble.

Examples of the precipitate forming liquid include ammonia, ammonium carbonate, caustic alkali, soda carbonate, oxalic acid, ammonium oxalate, and organic reagents such as oxine and amino acid. All you have to do is choose the appropriate one from these.

Preferably, the 11% solution is stirred to form a precipitate of the constituent components.

Furthermore, after the formation of a certain precipitate, the filtrate may be removed, and the type or concentration of the precipitate-forming liquid may be changed to one suitable for the remaining components, and the precipitate may be precipitated.

When an alcohol such as ethanol is used in addition to cleaning the precipitate, good results can be obtained by suppressing the coagulation of the precipitate in the subsequent drying and calcination steps.

The obtained precipitate is dried and calcined at 500 to 1100°C. If the calcination temperature is less than 500°C, the PLZT production reaction and degassing will not be completed, and if it exceeds 500°C, P I, Z
The solid phase reaction of T is completed, and the bulk density of the resulting PLZT powder becomes low. From an X-ray perspective, PLZT $-phase f
When the temperature is increased to 1100°C, the PLZT powder particle force #11 increases and the sinterability deteriorates.

Therefore, it is appropriate that the calcination temperature is 500 to 1100°C. As a result, a uniform P I, Z T powder having a high bulk density and easy sinterability can be obtained.

Next, it is shaped and sintered. For sintering, performing hot pressing in air is inexpensive and advantageous, but performing this in an oxygen atmosphere can increase sinterability. In addition, by performing pressureless sintering with a lead-containing compound such as perovskite compound coexisting in a closed room that allows oxygen and air to pass through, the atmosphere contains lead vapor. It is possible to suppress the scattering of

lρ00 If the sintering crystal value is lower than i'C, sintering is insufficient,
If the temperature exceeds 1280°C, lead scattering becomes noticeable, and it is necessary to remove the lead.

Example 1 300 cc tl of an aqueous solution containing lead nitrate 30.140F, lanthanum nitrate 2.925F, and zirconium oxynitrate 7.347F was prepared and stirred to produce 4N
It was dropped into aqueous ammonia 1i to form a coprecipitate of hydroxide. While stirring the hydroxide solution in which this coprecipitate was suspended, 200 cc of an aqueous solution in which zirconium oxynitrate '1.34' IP and titanium tetrachloride 6.490F were dissolved was added dropwise, and lead, titanium, zirconium, Dense precipitate of lanthanum hydroxide? :4#ta. After washing with water, it was calcined at 600℃ for 1 hour to obtain Pbo, st Lao, os (Zro, as a
PI, ZT raw material powder having a composition of 0477503 (Tio3s) was obtained. When the powder was observed using an electron microscope, it was found to consist of uniform particles with an average particle size of about 0.1 μm.

Also, according to X-ray diffraction, it was completely phosphorus-phase. No variation in trench composition was observed. The powder, which does not contain excessive lead, was molded under a pressure of 1.5 tons to a diameter of 12 mm and a thickness of 2 m, and then molded under a mixed atmosphere of oxygen gas and lead vapor at normal pressure of 120 m.
Sintering was performed at 0°C for 24 hours. The obtained sintered body has a transmittance of 72
The demand is approximately equal to the theoretical transmittance tl, and the second-order electro-optic coefficient is
It was a PLZT ceramic exhibiting 9.2 x 10"-16 m'/V".

Comparative example Contains lead nitrate 30.140F, lanthanum nitrate 2.925F, zirconium oxynitrate 14.694jll
300 cclli of an aqueous solution was prepared, and this was dropped into 1 l of stirred 4N ammonia water to form a coprecipitate of hydroxide.

While stirring the aqueous solution in which this coprecipitate was suspended, 100% of an aqueous solution containing 6,490 F of titanium tetrachloride was dissolved.
cc was added dropwise to obtain a homogeneous precipitate of hydroxides of lead, titanium, zirconium, and lanthanum.After washing with 0 water, it was calcined at 600°C for 1 hour to obtain PbO, 91tao, oe (Zro, a
s・Tio3s) 0.977503 f) AI
A synthetic OP[, ZTi material powder was obtained.

As a result of powder X-ray diffraction, a different phase with a perovskite structure was observed, and it was not a single phase of PI, ZT. Therefore, it is thought that there is some compositional variation even during firing at high temperatures.

The powder was powdered under a pressure of 1.5t/QI/I to a diameter of 12
Fight.

Molded to a thickness of 2cm and placed at 1200°C in an oxygen gas atmosphere.

Sintered at 300 Krtld. 2 of the obtained sintered body
The order electro-optic coefficient was 8.5×10”−”η■8.

Example 2 Lanthanum nitrate 2.925f, zirconium oxynitrate 7
．． 200 cc of aqueous solution #4 containing 347F and 6.490ji of titanium tetrachloride was prepared, and this was dropped into stirred 4N ammonia water IIL to form a coprecipitate of hydroxide. While stirring the cloudy aqueous solution of this coprecipitate, 30.1405' of lead nitrate and 7.3' of zirconium oxynitrate were added.
Dropped into 200 cc of an aqueous solution containing 47F,
A homogeneous precipitate of lead, titanium, zirconium, and lanthanum hydroxides was obtained. After washing with water, calcining at 600℃ for 1 hour to produce Pb
o, olLao, oo (Zro, as・Tio, 3s
) 0.9775 (Pi, ZT raw material powder with composition 13 was obtained. The powder was molded into a shape with a diameter of 12 and a thickness of 2 under a pressure of tst%-, and heated at 1200°C under an oxygen gas atmosphere at 30°C.
The obtained P was hot pressed at 0 kg/l and sintered for 5 hours. 1. The tensile strength of the ZT sintered body was 72, and the secondary electro-optic coefficient was 9.2 It had all the advantages of the law and was able to improve upon its disadvantages as well.

(1) Among the raw material components of P L Z T, lead and titanium are not co-precipitated, so cheap titanium tetrachloride can be used as a titanium raw material.

(2) P1. In order to generate a double precipitate without coprecipitating all of the constituent components of Z
i is in a mutually dispersed state, and there is little formation of secondary particles during drying and calcining as in conventional co-precipitation of all components.

Therefore, a material with high bulk density and easy sinterability can be obtained.

P1. ZT can be easily obtained.

(4) High-density P without the non-uniform composition of conventional dry methods 1. Z'r translucent ceramics can be easily obtained.

(5) Reasons such as the process is simple, the chemicals used are inexpensive, there is no need to use high-purity chemicals, and even a simple solid phase pressureless sintering method can achieve translucency and color. As a result, high-performance translucent PI, ZT ceramics can be produced at extremely low cost.

Furthermore, P1. A phosphor phase of ZT was obtained, and it became possible to synthesize a fine powder with better reactivity.

In addition, compositional fluctuations are sufficiently eliminated, and by sintering the powder in a mixed atmosphere of oxygen gas and lead vapor at normal pressure or by hot pressing in an oxygen atmosphere, good permeability and secondary 'A ceramics exhibiting the optical effect can now be obtained.

Applicant: Director, Institute of Inorganic Materials, Science and Technology Agency Yu Goto

Claims (6)

[Claims] (1) General formula (Pb_1_-_xLa_x) [(Zr_y・Ti_1
____y)_1-(x/4)□(x/4)]O_3, (
Pb_1_-_xLa_x)(Zr_y・Ti_1_-
_y) O_3 (x=0.01~0.3, y=0
．． 05 to 0.95, □ represents a cation vacancy) or an intermediate composition of both, or 10 wt% to these compositions.
In the production of translucent PLZT ceramics by sintering the following powders with excessive lead added, a four-component aqueous solution is made from water-soluble lead, lanthanum, zirconium, and titanium compounds, and a portion of the zirconium aqueous solution is Prepare an aqueous solution by mixing lanthanum and lanthanum aqueous solution with either lead aqueous solution or titanium aqueous solution, and separately mix the remaining amount of zirconium aqueous solution with the remaining lead aqueous solution or titanium aqueous solution to prepare an aqueous solution. After forming a precipitate by mixing an excess amount of the precipitate-forming liquid with one kind, the remaining aqueous solution is uniformly mixed with the aqueous solution in which this precipitate has been dispersed to form a homogeneous precipitate of all components, and this is A method for producing translucent ceramics, which comprises calcining at a temperature of 1000 to 1280C, followed by molding the calcined product and sintering at a temperature of 1000 to 1280C. (2) The method according to claim (1), wherein the mixed aqueous solution is a combination of a part of the zirconium aqueous solution, a lanthanum aqueous solution, and a lead aqueous solution. (3) The method according to claim (1), wherein one of the mixed aqueous solutions is a combination of a part of a zirconium aqueous solution, a lanthanum aqueous solution, and a titanium aqueous solution. (4) The method according to claim (1), which comprises hot pressing in air after forming the calcined product. (5) The method according to claim (1), wherein after forming the calcined product, hot pressing is performed in an oxygen atmosphere. (6) The method according to claim 4(1), wherein after the calcined product is formed, it is sintered under normal pressure in a mixed atmosphere of oxygen and lead vapor.