JPH0930861A - Production of doped plzt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method capable of more remarkably improving performance of PLZT due to addition of a dopant in producing PLZT to which the dopant is added. SOLUTION: This producing method comprises mixing raw materials so that a ratio of number of atoms in each element of Pb, La, Zr, Ti and a dopant in raw material mixture before heating and sintering becomes a stoichiometric ratio in a theoretical chemical formula of objective doped PLZT and heating and sintering the mixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing doped PLZT which can be suitably used as a photostrictive material.

[0002]

2. Description of the Related Art PLZT is lead zirconate titanate L
Ceramics to which a is added, having the general formula: Pb _1-x L
_{a x (Zr y Ti z)} 1-x / 4 O 3 ( Note, in the formula 1-x /
4 is a substance represented by 1- (x / 4). It is well known that this substance exhibits a piezoelectric effect, an optical distortion effect, and the like. It is also known that these effects become more remarkable by adding various dopants to PLZT.

When manufacturing a doped PLZT, conventionally, a desired amount of dopant is added on a specific PLZT to which a dopant is to be added while maintaining the atomic ratio of each element in the PLZT. Had been added. That is, the chemical formula of the specific PLZT is, for example, Pb
_a La _b Zr _c Ti _d O ₃ (where a, b, c, d, and 3 represent the atomic ratio of each element), and the atomic ratio of the dopant to be added is e. The atomic ratio of each element in the raw material mixture before heating and sintering is a:
The method of mixing each raw material so as to be b: c: d: e and then heating and sintering the mixture has been exclusively used.

[0004]

SUMMARY OF THE INVENTION By the way, the inventors of the present invention have found that in the conventional manufacturing method described above, PL by a dopant is used.
I found a problem that the performance improvement of ZT was not sufficient.

An object of the present invention is to provide a new manufacturing method which can improve the effect of adding a dopant. As a result of intensive studies to solve the above problems found by the inventors, the present inventors have found that there is a key for solving the problem in the mixing ratio of each raw material of PLZT and the dopant material at the time of mixing the raw materials. The present invention has been completed.

[0006]

The doped PLZ of the present invention
The manufacturing method of T is P in the raw material mixture before heating and sintering.
It is characterized in that the respective raw materials are mixed so that the atomic ratio of each element of b, La, Zr, Ti and the dopant becomes a stoichiometric ratio in the theoretical chemical formula of the target substance to be produced, and then heat sintering is performed. Is the way.

[0007]

According to the manufacturing method of the present invention, the amount of the dopant added is sufficient as compared with the conventional method, and thus, the doped PLZT having a more excellent degree of improvement in the inherent performance of PLZT can be obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, heat sintering is performed.
The source of each element of the target substance in the raw material mixture
The number ratio is the stoichiometry in the theoretical chemical formula of the target substance.
It is important to mix the raw materials so that the ratio is achieved. This
This will be described in comparison with the conventional method. Now suppose that the dopant
The chemical formula of PLZT to be added is Pb_aLa_bZr
_cTi_dO_Three(Where a, b, c, d, and 3 are each
The atomic number ratio of elements), the dopant to be added
The atomic ratio of X is e. And decided by the method described below
And contains only e in the atomic ratio of the dopant X.
The theoretical chemical formula of the target substance_{a '}La_{b '}Zr_{c '}T
i_{d '}X_eO_ThreeThen, Pb, La, Zr, Ti, X,
The atomic ratio of these elements in the raw material mixture
To be a ': b': c ': d': e.
You. Then, the above-mentioned ratio a: b: c: in the conventional method.
d: Clearly different from e. In the present invention, the above
Each amount of a ': b': c ': d': e has a certain degree of error.
Is acceptable. The error range is a
0.1% or less, preferably 0.05% or less
In the case of b'value, it is about 0.3% or less, preferably
0.15% or less, and in the case of c'and d'values
All are about 0.15% or less, preferably 0.08
% Or less.

Next, a method for determining the theoretical chemical formula of the target substance to be produced will be described. Generally, the dopant is PL
A site of ZT (ie substitution with Pb) and / or B
The site (that is, the substitution with Zr) is doped, and the substitution position and the substitution allocation to the A site and the B site are determined by the dopant X.
, And in particular it depends on its ionic radius. Those whose ionic radius is close to that of Pb mainly enter the A site, and those whose ionic radius is close to that of Zr are mainly B
Enter the site. Further, the intermediate ones of the ionic radii of Pb and Zr are distributed and enter the A site and the B site, but the ionic radii are mostly in the closer one of Pb and Zr. Therefore, in the present invention, the theoretical chemical formula may be obtained by rigorously theoretically calculating the respective distribution ratios to the A site and the B site, but as a simple method, all those that are closer to Pb than Zr in terms of ionic radius are If you enter site A, on the other hand, Z rather than Pb
The theoretical chemical formula may be determined by assuming that all those close to r enter the B site. When the position where the dopant enters, in other words, the dope site and the desired doping amount are determined, the theoretical chemical formula to be obtained can be determined by the following method. That is,
When the dopant is an acceptor, oxygen is eliminated, while when the dopant is a donor, Pb is eliminated, so that electrical neutrality is maintained.

Among various PLZTs to be doped, one having an La atomic ratio of 0.02 to 0.04 or an atomic ratio between Zr and Ti (Zr: T).
Those in which i) is 50:50 to 55:45 are particularly preferable.

As the dopant, various kinds can be exemplified, but as the dopant which is determined by the above-mentioned simple method and is doped into the A site, for example, Na, K, Y, Ba and Bi are used.
And the B site is doped with, for example, Ta, W, Nb, Mg, Al, Fe, Sn, S
i, etc. Various types of PLZT to be doped
, And also for the preferred PLZTs listed in the previous section, particularly preferred dopants are Ta, W, and Nb. Atomic ratio between Zr and Ti (Zr: T
Nb is particularly preferable for PLZT in which i) is 50:50 to 55:45.

Among various PLZTs, a specific PLZT represented by the following equation (1), which is known to greatly show the optical distortion effect, is shown.
As an example, the theoretical chemical formula of some doped PLZT is determined by the above-mentioned simple method and illustrated below. Pb _0.97 La _0.03 (Zr _0.52 Ti _0.48 ) _{1-0.03 / 4} O ₃ (1) Ta ⁵⁺ , W ⁶⁺ , and Nb ⁵⁺ are used as dopants, and the atomic ratio of each is within the B site of the formula (1). The theoretical chemical formulas of 0.01 doped with
Shown in (3) and (4). Pb _0.965 La _0.03 (Zr _0.5148 Ti _0.4752 Ta _0.01 ) _{1-0.03 / 4} O ₃ (2) Pb _0.960 La _0.03 (Zr _0.5148 Ti _0.4752 W _0.01 ) _{1-0.03 / 4} O ₃ (3) Pb _0.965 La _0.03 (Zr _0.5148 Ti _0.4752 Nb _0.01 ) _{1-0.03 / 4} O ₃ (4)

Therefore, for example, a product of the formula (2) is manufactured.
When it is used as a target product, the amount of each element in the raw material mixture
Mixing ratio, that is, Pb: La: Zr: Ti: Ta (number of atoms
Ratio) is 97.23: 3.02: 51.48: 47.5.
It becomes 2: 1.00. Furthermore, as a raw material for each element,
PbO and La respectively_TwoO_Three, ZrO_Two, TiO_Two,and
Ta_TwoO_FiveIs used, the mixing ratio of these raw materials (weight
Ratio) is PbO: La_TwoO _Three: ZrO_Two: TiO_Two: T
a_TwoO_Five= 98.23: 2.23: 28.71: 17.
18: 1. Also, Pb_0.960La_0.03(Zr
_0.5096Ti_0.4704Nb_0.02)_{1-0.03 / 4}O_ThreeBecomes theoretical
When the scientific formula is used as the production target,
PbO and La respectively_TwoO_Three, ZrO_Two, Ti
O_Two, And Nb_TwoO_FiveIs used to distribute these ingredients.
The total ratio (weight ratio) is PbO: La._TwoO_Three: ZrO_Two: T
iO_Two: Nb_TwoO_Five= 81.23: 1.85: 23.6
It becomes 2: 14.14: 1.

In addition to the above oxides, carbonates, oxalates, hydroxides, nitrates and the like are also exemplified as the raw materials for each element. The form of the raw material is preferably the same powder form as in the case of known production of PLZT. Further, it is already known that the particle size also affects the characteristics, and it is preferable to select the particle size that gives the best optical distortion effect. The production of the production target substance from the raw material mixture may be conventional,
For example, calcination is followed by sintering, and then heat treatment is performed if necessary.

In the present invention, the amount of the dopant added is not particularly limited, but generally, the atomic ratio is preferably 0.05 or less, and when the dopant is W, it is especially 0.02 or less, 0.002 to 0.02, especially 0.04 or less when the dopant is Nb, and further 0.00
2 to 0.04, and when the dopant is Ta, it is preferably 0.03 or less, and more preferably 0.005 to 0.03.

[0016]

EXAMPLES The present invention will be described in more detail with reference to examples. Example 1 In order to produce Ta-doped PLZT having a theoretical chemical formula represented by the above formula (1), 133.324 g of Pb was added.
O, 3.025 g La ₂ O ₃ , 38.969 g Zr
O ₂ , 23.325 g TiO ₂ , and 1.357 g
A uniform raw material mixture consisting of Ta ₂ O ₅ was prepared.
This mixture was calcined at 900 ° C. in the air for 10 hours, then sintered at about 1200 ° C. for 2 hours, and finally heat-treated at 900 ° C. for 1 hour in a nitrogen stream to obtain Ta-doped PLZT.

Comparative Example 1 In order to compare the case of the conventional raw material mixing ratio shown in the above section 8 with Example 1, 134.038 g of PbO, 3.02
6 g La ₂ O ₃ , 39.371 g ZrO ₂ , 23.
565 g TiO ₂ and 1.368 g Ta ₂ O ₅
A uniform raw material mixture consisting of and was prepared. In the same manner as in Example 1, this mixture was calcined at 900 ° C. in the atmosphere for 10 hours, then sintered at about 1200 ° C. for 2 hours, and finally 900
Heat-treated in nitrogen stream at ℃ for 1 hour, Ta-doped PLZ
T was obtained. Table 1 shows the characteristics of each Ta-doped PLZT obtained from Example 1 and Comparative Example 1.

[0018]

[Table 1]

As shown in Table 1, Comparative Example 1 which is a conventional method
The substance has a density higher than the theoretical density 7.960 of PLZT before the addition of the dopant. From this, it is considered that the conventional method does not sufficiently perform the substitution with the dopant and has a Pb-rich composition. In contrast, the material according to the method of the present invention is considered to be more fully substituted. The characteristics of the photostrictive material are that the substance obtained by the production method of the present invention is superior to conventional substances in terms of energy conversion efficiency and response speed such as piezoelectric constant, photocurrent, time constant, and strain. It was confirmed that it has properties.

Examples 2 to 7 A PLZT represented by the following formula (5) was doped with W ⁶⁺ in the B site of the formula (5) in an atomic ratio of 0.005 to 0.05 to produce a doped PLZT. went. The respective theoretical chemical formulas are represented by the following formulas (6) to (11), respectively, and the raw materials PbO, La ₂ O ₃ , ZrO ₂ , TiO ₂ , and WO ₃ are mixed in a stoichiometric ratio according to the respective formulas to obtain a uniform mixture. Various raw material mixtures were prepared. This mixture was calcined in the atmosphere at 900 ° C. for 10 hours as in Example 1, and then about 120
Sinter at 0 ° C for 2 hours and finally at 900 ° C in a nitrogen stream for 1 hour.
After heat treatment for 6 hours, 6 types of W-doped PLZT were obtained. Pb _0.97 La _0.03 (Zr _0.52 Ti _0.48 ) _{1-0.03 / 4} O ₃ (5) Pb _0.965 La _0.03 (Zr _0.5174 Ti _0.4776 W _0.005 ) _{1-0.03 / 4} O ₃ (6) Pb _0.960 La _0.03 (Zr _0.5148 Ti _0.4752 W _0.010 ) _{1-0.03 / 4} O ₃ (7) Pb _0.955 La _0.03 (Zr _0.5122 Ti _0.4728 W _0.015 ) _{1-0.03 / 4} O ₃ (8) Pb _0.950 La _0.03 (Zr _0.5096 Ti _0.4704 W _0.020 ) _{1- 0.03 / 4} O ₃ (9) Pb _0.940 La _0.03 (Zr _0.5044 Ti _0.4656 W _0.030 ) _{1-0.03 / 4} O ₃ (10) Pb _0.920 La _0.03 (Zr _0.4940 Ti _0.4560 W _0.050 ) _{1-0.03 / 4} O ₃ ( 11)

Examples 8 to 13 PLZT represented by the formula (5) was added with Nb⁵⁺In equation (5) B
Doping with 0.050-0.05 in atomic ratio in the site
A doped PLZT was manufactured. Each theorization of each
The scientific formula is the following formulas (12) to (17), and the raw material P
bO, La_TwoO _Three, ZrO_Two, TiO_Two, And Nb_Two
O_FiveAccording to each formula in a stoichiometric ratio to obtain a uniform raw material mixture.
A compound was prepared. This mixture is the same as in Example 1.
Approximately 1200 after calcination at 900 ° C in air for 10 hours
Sintered at ℃ for 2 hours, finally 900 ℃, at 1:00 in nitrogen stream
Heat treatment was performed for 7 hours to obtain 7 types of Nb-doped PLZT. Pb_0.968La_0.03(Zr_0.5174Ti_0.4776Nb_0.005)_{1-0.03 / 4}O_Three(12) Pb_0.965La_0.03(Zr_0.5148Ti_0.4752Nb_0.010)_{1-0.03 / 4}O_Three(13) Pb_0.963La_0.03(Zr_0.5122Ti_0.4728Nb_0.015)_{1-0.03 / 4}O_Three(14) Pb_0.960La_0.03(Zr_0.5096Ti_0.4704Nb_0.020)_{1-0.03 / 4}O_Three(15) Pb_0.955La_0.03(Zr_0.5044Ti_0.4656Nb_0.030)_{1-0.03 / 4}O_Three(16) Pb_0.945La_0.03(Zr_0.4940Ti_0.4560Nb_0.050)_{1-0.03 / 4}O_Three(17)

Examples 14 to 19 Ta ⁵⁺ is added to PLZT represented by the formula (5) as B in the formula (5).
A doped PLZT in which 0.01 to 0.05 of atomic ratio was doped in the site was manufactured. The respective theoretical chemical formulas are represented by the following formulas (18) to (23), and the raw material Pb is
O, La ₂ O ₃ , ZrO ₂ , TiO ₂ , and Ta ₂ O
₅ was mixed in a stoichiometric ratio according to each formula to prepare a uniform raw material mixture. This mixture was added as in Example 1,
After calcination at 900 ° C. in the air for 10 hours, sintering was performed at about 1200 ° C. for 2 hours, and finally, heat treatment was performed at 900 ° C. in a nitrogen stream for 1 hour to obtain 6 types of Ta-doped PLZT. Pb _0.968 La _0.03 (Zr _0.5174 Ti _0.4776 Ta _0.005 ) _{1-0.03 / 4} O ₃ (18) Pb _0.965 La _0.03 (Zr _0.5148 Ti _0.4752 Ta _0.010 ) _{1-0.03 / 4} O ₃ (19) Pb _0.963 La _0.03 (Zr _0.5122 Ti _0.4728 Ta _0.015 ) _{1-0.03 / 4} O ₃ (20) Pb _0.960 La _0.03 (Zr _0.5096 Ti _0.4704 Ta _0.020 ) _{1-0.03 / 4} O ₃ (21) Pb _0.955 La _0.03 (Zr _0.5044 Ti _0.4656 Ta _0.030 ). _{1-0.03 / 4} O ₃ (22) Pb _0.945 La _0.03 (Zr _0.4940 Ti _0.4560 Ta _0.050 ) _{1-0.03 / 4} O ₃ (23)

Examples 2 to 7, Examples 8 to 13, and Example 1
Photovoltaic power and photovoltaic current were measured for the doped PLZT obtained from each of Examples 4 to 19. FIGS. 1, 3, and 5 show Examples 2 to 7, Examples 8 to 13, and Example 14 respectively.
19 shows the change in photovoltaic power with respect to the amount of dopant of -19. On the other hand, Examples 2 to 7 are shown in FIGS.
The change of the photovoltaic current with respect to the amount of dopants of Examples 8 to 13 and Examples 14 to 19 is shown.

[0024]

As described above, according to the manufacturing method of the present invention, in manufacturing PLZT doped with a dopant,
It was possible to sufficiently substitute the dopant to be added in an intended ratio, whereby the effect of improving the characteristics by the addition of the dopant became more remarkable.

[Brief description of drawings]

FIG. 1 is each W-doped PLZT obtained in Examples 2 to 7.
Is a graph showing photovoltaic power with respect to W doping amount.

2 is each W-doped PLZT obtained in Examples 2 to 7. FIG.
Is a graph showing the photocurrent with respect to the W doping amount.

FIG. 3 is each Nb-doped PL obtained in Examples 8 to 13
It is a graph which shows the photovoltaic power with respect to Nb doping amount about ZT.

FIG. 4 is an Nb-doped PL obtained in each of Examples 8 to 13.
It is a graph which shows the photovoltaic current with respect to Nb doping amount about ZT.

FIG. 5: Each Ta-doped P obtained in Examples 14 to 19
It is a graph which shows the photovoltaic power with respect to Ta doping amount about LZT.

6 is each Ta-doped P obtained in Examples 14 to 19 FIG.
It is a graph which shows the photocurrent with respect to Ta doping amount about LZT.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Morito Akiyama 807 Nonoshita, Yadomachi, Tosu City, Saga Prefecture 1 Kyushu Institute of Industrial Technology, Institute of Industrial Technology (72) Akira Takase Innocho, Yadomachi, Tosu City, Saga Prefecture Address 807 1 Kyushu Institute of Industrial Science and Technology (72) Inventor Toshiyuki Baba 8 Nishinomachi, Higashimukaijima, Amagasaki City, Hyogo Prefecture Mitsubishi Densen Kogyo Co., Ltd. (72) Keisuke Yamamoto Nishinoyuki Higashimushima, Amagasaki City, Hyogo Prefecture 8th Town Mitsubishi Electric Wire & Cable Co., Ltd. (72) Inventor Makoto Hiraoka 8th Nishinomachi, Higashimukaijima, Amagasaki City, Hyogo Prefecture Mitsubishi Electric Wire & Wire Co., Ltd.

Claims (10)

[Claims] 1. P in a raw material mixture before heating and sintering
It is characterized in that the respective raw materials are mixed so that the atomic ratio of each element of b, La, Zr, Ti and the dopant becomes a stoichiometric ratio in the theoretical chemical formula of the target substance to be produced, and then heat sintering is performed. Manufacturing method of doped PLZT. 2. The atomic ratio of La is 0.02 to 0.04.
The method for producing doped PLZT according to claim 1, wherein 3. The atomic ratio (Zr: T) between Zr and Ti.
i) is 50: 50-55: 45, The manufacturing method of the doped PLZT of Claim 1 or 2. 4. The dopant is one or more selected from the group consisting of Ta, W and Nb.
5. The method for manufacturing the doped PLZT according to any one of 1. 5. The method for producing doped PLZT according to claim 4, wherein the atomic ratio of the dopant is 0.05 or less. 6. The doped PL according to claim 5, wherein the dopant is W and the atomic ratio thereof is 0.02 or less.
ZT manufacturing method. 7. The doped P according to claim 5, wherein the dopant is Nb and the atomic ratio thereof is 0.04 or less.
Manufacturing method of LZT. 8. The doped P according to claim 5, wherein the dopant is Ta and the atomic ratio thereof is 0.03 or less.
Manufacturing method of LZT. 9. A Ta-doped material having a theoretical chemical formula represented by the following formula (A), wherein the raw material and a mixing weight ratio thereof are represented by the following formula (B). 1. The method for manufacturing the doped PLZT according to 1. Pb _0.965 La _0.03 (Zr _0.5148 Ti _0.4752 Ta _0.01 ) _{1-0.03 / 4} O ₃ (A) PbO: La ₂ O ₃ : ZrO ₂ : TiO ₂ : Ta ₂ O ₅ = 98.23: 2.2 3:28 .71: 17.18: 1 (B) 10. The Nb-doped material having a theoretical chemical formula represented by the following formula (C) as a substance to be produced, wherein the raw materials and their mixing weight ratio are represented by the following formula (D). 1. The method for manufacturing the doped PLZT according to 1. Pb _0.960 La _0.03 (Zr _0.5096 Ti _0.4704 Nb _0.02 ) _{1-0.03 / 4} O ₃ (C) PbO: La ₂ O ₃ : ZrO ₂ : TiO ₂ : Nb ₂ O ₅ = 81.23: 1.8 5:23 .62: 14.14: 1 (D)