JP3041409B2 - Manufacturing method of doped PLZT - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 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 prepared by adding L to lead zirconate titanate.
a-added ceramic, 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.

[0003] In the production of doped PLZT, conventionally, a desired amount of dopant is added onto 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 ( here a, b, c, d, and 3. showing the atomic ratio of each element), and the atomic ratio of dopant to be added when the e The atomic ratio of each element in the raw material mixture before heat sintering is a:
The method of mixing each raw material so as to obtain b: c: d: e, and then heating and sintering the raw materials has been exclusively adopted.

[0004]

By the way, the inventors of the present invention have proposed that the above-described conventional manufacturing method uses a PL
It has been found that the ZT performance is not sufficiently improved.

An object of the present invention is to provide a novel manufacturing method capable of improving the effect of adding a dopant. The present inventors have conducted intensive studies to solve the above-mentioned problems found by themselves, and as a result, have found that there is a key that can solve the problem in the mixing ratio between each material of PLZT and the dopant material at the time of mixing the materials. The present invention has been completed.

[0006]

DISCLOSURE OF THE INVENTION The doped PLZ of the present invention
The method for producing T is as follows: P in the raw material mixture before heat sintering.
b, La, Zr, Ti, and the respective materials are mixed so that the atomic ratio of each element of the dopant becomes the stoichiometric ratio in the theoretical chemical formula of the production target substance, and then the mixture is heated and sintered. Is the way.

[0007]

According to the production method of the present invention, the amount of dopant added is sufficient as compared with the conventional method, so that doped PLZT which is more excellent in the degree of improvement of the performance inherent in PLZT can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, heat sintering is performed.
Of each element of the target substance in the raw material mixture
Stoichiometry in the theoretical chemical formula of the target substance
It is important to mix each raw material so that the ratio is obtained. This
This will be described in comparison with the conventional method. Now, temporarily,
The chemical formula of PLZT to be added is Pb_aLa_bZr
_cTi_dO_Three(Where a, b, c, d, and 3 are each
Element ratio), and the dopant to be added
Let e be the atomic ratio of X. And decided by the method described below
And the dopant X contains only e in atomic ratio.
The theoretical chemical formula of the target substance_{a '}La_{b '}Zr_{c '}T
i_{d '}X_eO_ThreeThen, Pb, La, Zr, Ti, X,
Of each element in the raw material mixture
Are a ': b': c ': d': e.
You. Thus, the ratio a: b: c:
d: clearly different from e. In the present invention, the above
Each amount of a ': b': c ': d': e has some error
Is acceptable. If the error range is a ',
0.1% or less, preferably 0.05% or less
In the case of the b 'value, about 0.3% or less thereof, preferably
0.15% or less, and in the case of c ′ and d ′ values,
In each case, about 0.15% or less thereof, preferably 0.08% or less.
% Or less.

Next, a method for determining the theoretical chemical formula of the substance to be produced will be described.
A site of ZT (ie, replacement with Pb) and / or B site
Site (ie, substitution with Zr), the substitution position and substitution distribution between the A site and the B site are determined by the dopant X
Depends on the type, especially its ionic radius. Those with an ionic radius close to that of Pb mainly enter the A site, and those with an ionic radius close to that of Zr mainly
Enter the site. In addition, those having intermediate ionic radii of Pb and Zr are distributed on the A site and the B site, but the ionic radius is more likely to be closer to either Pb or Zr. Therefore, in the present invention, a theoretical chemical formula may be obtained by strictly theoretically calculating each distribution ratio of the A site and the B site. However, as a simple method, all of the ionic radii closer to Pb than Zr are used. Suppose you enter site A, but Z more than Pb
The theoretical chemical formula may be determined assuming that all substances close to r fall into the B site. When the position where the dopant enters, in other words, the doping site and the desired doping amount are determined, the theoretical formula to be obtained can be determined by the following method. That is,
When the dopant is an acceptor, oxygen is released, and when the dopant is a donor, Pb is released, so that the calculation is performed assuming that the electrical neutrality is maintained.

[0010] Of the various PLZTs to be doped, those having an atomic ratio of La 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 preferred.

As the dopant, various ones can be exemplified. As the dopant determined by the above-mentioned simple method and doped at the A site, for example, Na, K, Y, Ba, Bi
For example, Ta, W, Nb, Mg, Al, Fe, Sn, S
i. Various PLZTs to be doped
Particularly preferred dopants are Ta, W, and Nb, and also for the preferred PLZT shown in the previous section. The atomic ratio between Zr and Ti (Zr: T
Nb is particularly preferred for PLZT where i) is 50:50 to 55:45.

Among various PLZTs, a specific PLZT represented by the following equation (1), which is known to greatly exhibit the optical distortion effect:
And the theoretical formula of some doped PLZT is determined by the above-mentioned simple method, and is exemplified below. Pb _0.97 La _0.03 (Zr _0.52 Ti _0.48 ) _{1-0.03 / 4} O ₃ (1) Using Ta ⁵⁺ , W ⁶⁺ , and Nb ⁵⁺ as dopants, each atom ratio in the B site of the formula (1) The theoretical chemical formula of the one doped by 0.01 is represented by the following formula (2),
The results are 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, the one of the type (2) is manufactured.
In the case of a target product, the amount of each element in the raw material mixture
Mixing ratio, ie, Pb: La: Zr: Ti: Ta (number of atoms
Ratio) is 97.23: 3.02: 51.48: 47.5.
2: 1.00. Furthermore, as a raw material for each element,
PbO, La respectively_TwoO_Three, ZrO_Two, TiO_Two,and
Ta_TwoO_FiveIf used, the mixing ratio (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_ThreeTheoreticalization
When a chemical formula is used as a production target, it must be used as a raw material for each element.
And PbO and La respectively_TwoO_Three, ZrO_Two, Ti
O_Two, And Nb_TwoO_FiveIs used to distribute these raw materials.
The combined ratio (weight ratio) is PbO: La_TwoO_Three: ZrO_Two: T
iO_Two: Nb_TwoO_Five= 81.23: 1.85: 23.6
2: 14.14: 1.

Examples of the raw material of each element include carbonates, oxalates, hydroxides and nitrates in addition to the above-mentioned oxides. The form of the raw material is preferably in the same powder form as in the case of producing known PLZT. It is already known that the particle size also affects the characteristics, and it is preferable to select a particle size that gives the best optical distortion effect. Production of the production target substance from the raw material mixture may be conventional,
For example, after calcination, sintering is performed, and then heat treatment is performed as needed.

In the present invention, the addition amount of the dopant is not particularly limited, but it is generally preferred that the atomic ratio is 0.05 or less, and when the dopant is W, it is particularly 0.02 or less. 0.002 to 0.02, and when the dopant is Nb, 0.04 or less, particularly 0.004 or less.
When the dopant is Ta, it is particularly preferably 0.03 or less, more preferably 0.005 to 0.03.

[0016]

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

Comparative Example 1 In order to compare the conventional raw material mixing ratio shown in Section 8 with that of Example 1, 134.038 g of PbO, 3.02
6 g La ₂ O ₃ , 39.371 g ZrO ₂ , 23.
565 g of TiO ₂ and 1.368 g of Ta ₂ O ₅
A homogeneous raw material mixture consisting of In the same manner as in Example 1, this mixture was calcined at 900 ° C. in the air for 10 hours, sintered at about 1200 ° C. for 2 hours, and finally
Heat-treated in nitrogen stream for 1 hour at Ta.
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 as a conventional method was used.
Has a density higher than the theoretical density of PLZT before the dopant addition of 7.960. From this, it is considered that the substitution by the dopant does not sufficiently occur in the conventional method, and the composition becomes Pb-rich. In contrast, the material according to the method of the invention is considered to be more fully substituted. The properties as a photostrictive material include piezoelectric constant, photovoltaic current, time constant, strain, etc. It was confirmed that the material had properties.

Examples 2 to 7 Production of doped PLZT by doping 0.006 to 0.05 at an atomic ratio of W ⁶⁺ into the B site of the formula (5) to the PLZT represented by the following formula (5). went. The respective theoretical chemical formulas are the following formulas (6) to (11). PbO, La ₂ O ₃ , ZrO ₂ , TiO ₂ , and WO ₃ as raw materials are mixed at a stoichiometric ratio in accordance with the respective formulas. A raw material mixture was prepared. This mixture was calcined in the air at 900 ° C. for 10 hours in the same manner as in Example 1;
Sintered at 0 ° C for 2 hours and finally 900 ° C in nitrogen stream
After heat treatment for 6 hours, six 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)

Embodiments 8 to 13 Nb is added to PLZT represented by the formula (5).⁵⁺To B in equation (5)
Doping 0.050 to 0.05 at atomic ratio in site
Production of doped PLZT was performed. Each theory
The 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_FiveAre mixed in stoichiometric ratio according to each formula,
A compound was prepared. This mixture is the same as in Example 1.
After calcination in air at 900 ° C for 10 hours, about 1200
Sintering for 2 hours at 900 ° C, and finally for 1 hour at 900 ° C in a nitrogen stream
During the heat treatment, seven types of Nb-doped PLZT were obtained. 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)

Embodiments 14 to 19 Ta5 ⁺ is added to PLZT represented by the formula (5) by using B of the formula (5).
Manufacture of doped PLZT in which 0.01 to 0.05 doping was performed at an atomic ratio in the site. The respective theoretical chemical formulas are the following formulas (18) to (23), and the raw material Pb
O, La ₂ O ₃ , ZrO ₂ , TiO ₂ , and Ta ₂ O
₅ was mixed in stoichiometric ratio according to each formula to prepare a homogeneous raw material mixture. This mixture was prepared in the same manner as in Example 1,
After calcining in the air at 900 ° C. 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 six kinds 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
The photovoltaic power and photovoltaic current of the doped PLZT obtained from each of Examples 4 to 19 were measured. FIGS. 1, 3, and 5 show Examples 2 to 7, Examples 8 to 13, and Example 14 respectively.
19 to 19 show changes in photovoltaic power with respect to the dopant amount. On the other hand, FIG. 2, FIG. 4, FIG.
The change of the photovoltaic current with respect to the dopant amount of Examples 8 to 13 and Examples 14 to 19 is shown.

[0024]

As described above, in the production of PLZT to which a dopant is added by the production method of the present invention,
The dopant to be added can be sufficiently substituted at an intended ratio, whereby the effect of the addition of the dopant to improve the characteristics is more remarkably exhibited.

[Brief description of the drawings]

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

FIG. 2 shows each W-doped PLZT obtained in Examples 2 to 7
3 is a graph showing the photovoltaic current with respect to the amount of W doping for each of FIGS.

FIG. 3 shows each Nb-doped PL obtained in Examples 8 to 13.
5 is a graph showing the photovoltaic power versus the Nb doping amount for ZT.

FIG. 4 shows each Nb-doped PL obtained in Examples 8 to 13.
9 is a graph showing the photovoltaic current with respect to the Nb doping amount for ZT.

FIG. 5 shows each Ta-doped P obtained in Examples 14 to 19.
4 is a graph showing the photovoltaic power versus the amount of Ta doping for LZT.

FIG. 6 shows each Ta-doped P obtained in Examples 14 to 19.
4 is a graph showing a photovoltaic current with respect to a Ta doping amount for LZT.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Takase 807-1, Nonoshita, Jukucho, Tosu-shi, Saga Prefecture Inside the Kyushu Institute of Industrial Technology (72) Inventor Toshiyuki Baba 8-Nishinomachi, Higashi-Mukojima, Amagasaki City, Hyogo Prefecture Inside Mitsubishi Cable Industry Co., Ltd. (72) Keisuke Yamamoto, Inventor Keisuke Yamamoto 8 Higashi-Mukojima Nishinocho, Hyogo Prefecture Inside Mitsubishi Cable Industry Co., Ltd. (72) Inventor Makoto Hiraoka 8, Higashi-Mukojima Nishinocho, Hyogo Prefecture Mitsubishi Electric Cable Industry Co., Ltd. In-house examiner Yuichi Fukakusa (56) References JP-A-51-1511 (JP, A) JP-A-48-55883 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/49

Claims (10)

(57) [Claims] 1. P in a raw material mixture before heat sintering
b, La, Zr, Ti, and the respective materials are mixed so that the atomic ratio of each element of the dopant becomes the stoichiometric ratio in the theoretical chemical formula of the production target substance, and then the mixture is heated and sintered. A method for producing 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.
The method for producing doped PLZT according to claim 1 or 2, wherein i) is from 50:50 to 55:45. 4. The dopant according to claim 1, wherein the dopant is one or more selected from the group consisting of Ta, W and Nb.
The method for producing doped PLZT according to any one of the above. 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 is 0.02 or less.
Manufacturing method of ZT. 7. The doped P according to claim 5, wherein the dopant is Nb and the atomic ratio 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 is 0.03 or less.
Manufacturing method of LZT. 9. The production target substance is a Ta-doped substance having a theoretical chemical formula represented by the following formula (A), and the raw materials and their mixing weight ratios are represented by the following formula (B). 2. The method for producing 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 production target substance is an Nb-doped material having a theoretical chemical formula represented by the following formula (C), and raw materials and their mixing weight ratio are represented by the following formula (D). 2. The method for producing 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)