JP3466481B2 - Giant magnetostrictive material - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a giant magnetostrictive material which has a large magnetostriction and is suitable for a magnetostrictive element used in a magnetic-mechanical displacement conversion device or the like.

[0002]

2. Description of the Related Art Magnetostrictive filters, magnetostrictive sensors,
There are ultrasonic delay lines, magnetostrictive oscillators, etc. Conventional Ni-based alloys, Fe-Co alloy, ferrite, Laves-type intermetallic compound (Tb, Dy, Sm) Fe 2 or the like is used.

In recent years, along with the progress of measurement engineering and the development of precision machinery field, it is necessary to develop a displacement driving unit which is indispensable for micro displacement control on a micron order. A magnetic-mechanical conversion device using a magnetostrictive substance is effective as one of the driving mechanisms of the displacement driving unit. However, the conventional magnetostrictive material does not have a sufficient absolute amount of displacement, and as a micron-order precision displacement control drive material, it is not satisfactory not only in terms of absolute drive displacement but also in precision control.

What is usually called a giant magnetostrictive material is
Among the Laves type intermetallic compounds represented by ReFe ₂ , TbFe ₂ (λs = 1753 × 10 ⁻⁶ ) and SmF
e ₂ (λs = −1560 × 10 ⁻⁶ ) [Clark (1
974): Giant magnetostrictive material, published by Nikkan Kogyo Shimbun], and has the largest saturation magnetostriction value. In addition, if only the magnitude of magnetostriction is observed, Dy and Tb at low temperatures of 200 K or less
Magnetostriction (λs ~ ± 4000 × 10 ^-6 )
Has been obtained.

[0005]

In the conventional magnetostrictive material, an applied magnetic field is applied because the temperature is below the liquid nitrogen temperature even if the magnetostriction is large, the actual magnetostriction is small, and the magnetostriction is anisotropic. There is a problem that the direction is limited and the structure of the device is restricted, and a high-performance magnetostrictive material that solves these problems is expected.

The present invention has been made in consideration of these problems, and provides a giant magnetostrictive material having a large magnetostriction that exceeds the conventional magnetostriction effect at room temperature and has isotropic magnetostriction. The purpose is to provide.

[0007]

The present invention comprises the following items. ( 1 ) General formula La _1-Z RE _Z (Fe _{1-X AX} ) ₁₃ (where A is at least one element of Al, Si, Ga, Ge and Sn, and RE is a rare earth element other than La). Of these, at least one element, x and z are in atomic ratio of 0.05 ≦.
A giant magnetostrictive material having a composition represented by x ≦ 0.2, 0 <z ≦ 0.1).

( 2 ) La _1-Z RE _Z (Fe _1-X A
_X-Y TM _{Y) 13} (however, A is Al, Si, Ga, Ge, at least one element of Sn, TM is at least one element of transition metal elements, RE is a rare earth element other than La At least one of these elements, x, y, and z, is in atomic ratio of 0.05 ≦.
A giant magnetostrictive material having a composition represented by x ≦ 0.2, 0 <y <0.1, 0 <z ≦ 0.1).

( 3 ) RE is Y, Ce, Pr, Nd, P
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
The giant magnetostrictive material according to ( 1 ) or ( 2 ) above, which is at least one element selected from m, Yb, and Lu.

First, regarding La (Fe _1-X A _X ) ₁₃ , La is B ₁ by Fe _1-X A _X constituting an icosahedron.
It is taken in as CC, and if A = Si, then Si
It is known that the magnetic transition temperatures Tc, TN and the magnetization Ms are changed by changing the amount (x). [K. H. J.
Buschow et al., Journal of Magne
tism and Magnetic Material
ls 36 (1983) 190-296] As a result of detailed investigations on this material, the present inventors have determined that the element A, which is a substituting element for Fe, is at least one of Si, Al, Ga, Ge, and Zn. Change the amount of x (0.05 ≦ x
≦ 0.2), it was found that a composition with small x causes a metamagnetic transition from antiferromagnetism to ferromagnetism at a low temperature. FIG. 1 shows an example of La (Fe0.
88Si0.12) 13 test data is shown. That is, according to FIG. 1, the metamagnetic transition is 210 K,
It occurs at 2T or more.

This tendency indicates that A is another element, Al,
It was almost the same in the case of Ga, Ge and Zn. Further detailed study of the composition revealed that, as shown in FIG. 2, the one having a saturation magnetostriction (λs) of more than 5000 × 10 ⁻⁶ can be obtained by the metamagnetic transition. Here, the metamagnetic transition is a phenomenon in which a ferromagnetic substance is changed by applying a magnetic field to the antiferromagnetic or paramagnetic state. As shown in FIG. 2, La (Fe _0.88 Si _0.12 ) ₁₃ is 205
Λs of up to 5000 × 10 ⁻⁶ has been obtained in K,
Also, La (Fe _0.86 Si _0.14 ) ₁₃ has 220
A λs of more than 3000 × 10 ⁻⁶ is obtained for K.
For comparison, TbFe ₂ , Fe _1.005 (Rh _0.85
Pd _0.15 ) _0.995 is 2500 × 10 ⁻⁶ at room temperature.
It is about λs.

Moreover, while the conventional magnetostrictive material is anisotropic in that the expansion and contraction are opposite (signs are opposite to each other) when the magnitude of the magnetostriction is parallel to and perpendicular to the magnetic field direction, the material of the present invention applies a magnetic field. By doing so, it extends in all directions, in other words, by applying a magnetic field, the volume increases, and there is a magnetostriction effect that is completely different from conventional materials. However, Fe
However, a large magnetostriction cannot be obtained at room temperature (RT) by replacing Si with. Therefore, in order to bring the metamagnetic transition temperature Tc to near room temperature, substitution with an additional element was examined.

With respect to the ratio of Fe to A in the above material , the magnetic transition temperature rises as A increases, and becomes close to room temperature. At the same time, the saturation magnetization becomes smaller. La in FIG.
The test results for (Fe _1-X Si _X ) ₁₃ are shown.
Similar results were obtained for the other A elements. In general, when x is less than 0.05, the NaZn ₁₃ type crystal structure cannot be maintained, and the metamagnetic transition that exhibits magnetostriction disappears. On the other hand, when x exceeds 0.3, the ferromagnetic state becomes stable, and the metamagnetic transition that similarly exhibits magnetostriction is not observed.

Further, a part of A is TM (Co, Ni, C
When it is replaced with u) , the number of 3d electrons of Fe, which is responsible for magnetism, is changed by changing the amount of TM , and it has an effect of changing the magnetic transition temperature Tc and the strength of the magnetization (Ms). T at this time
It is preferable to change the composition (y) of M within the range of 0 ≦ y <0.1. When y is 0.1 or more, the magnetic property of Fe is affected, so that a metamagnetic transition that exhibits magnetostriction occurs. It is not suitable because it disappears. In particular, when TM is Co, the number of 3d electrons of Fe, which is responsible for magnetism, is changed by changing the composition of the substitutional element Co, which has the effect of changing the magnetic transition temperatures Tc, TN and the strength of magnetization. At this time, the composition (y) of Co is 0 <y
It is preferable to change within the range of ≦ 0.08, and y is 0.08
If it exceeds, the magnetism of Fe itself is affected, so that the metamagnetic transition expressing magnetostriction does not occur, which is not suitable. Preferably, the composition of Co is 0.04 ≦ y ≦ 0.06.
Is effective in increasing the magnetic transition temperature Tc and obtaining the magnetostriction effect near room temperature.

Then, in claims 1 and 2 of the present invention ,
By substituting a part of La with another rare earth element RE (Nd, Gd, etc.), the effect of reducing the saturation magnetic field was found.
It was The upper limit of the substitution amount (z) is 0.1. When z exceeds 0.1, R rather than NaZn ₁₃ type compound structure is formed.
E ₂ Fe ₁₇ becomes stable, metamagnetic transition due to the NaZn ₁₃ structure does not occur, and as a result, giant magnetostriction cannot be obtained. In the present invention, inclusion of inevitable impurities of 10 atomic% or less is acceptable.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. After the materials having the compositions shown in Table 1 were prepared by arc melting, a sample heat-treated at 1050 ° C. for 168 hours in vacuum was cut out with a diamond cutter. SQUID (manufactured by Quantum Design Co., Ltd.) was used for magnetization characteristics and thermomagnetic characteristics, and magnetostriction was measured in a superconducting magnet from 4.2 K to room temperature using a capacitance method. Samples for magnetization, thermomagnetism measurement, and magnetostriction measurement were cut out into 2 mm × 2 mm × 2 mm and used.

As a result, the composition shown in Table 1 has a metamagnetic transition temperature at room temperature (250-350 K), that is, a very large magnetostriction characteristic in the vicinity of room temperature. In addition, the embodiment has the effect of reducing the saturation magnetic field.

Table 1 Sample composition Tc, (K) Saturation magnetic field (T) Magnetostrictive property (× 10 ⁻⁶ ) La _0.9 Nd _0.1 (Fe _0.88 Si _0.12 )
₁₃ 195 7 5000 (Implementation
Example) La _0.9 Gd _0.1 (Fe _0.88 Si _0.12 )
₁₃ 195 8 5000 (Implementation
Example) La (Fe _0.88 Si _0.12 ) ₁₃ 195 1
0 5000 La (Fe _0.86 Co _0.02 Si _0.12 ) ₁₃ 2
30 10 5000 La (Fe _0.84 Co _0.04 Si _0.12 ) ₁₃ 2
70 10 4500 La (Fe _0.82 Co _0.06 Si _0.12 ) ₁₃ 3
10 10 4500 La (Fe _0.80 Co _0.08 Si _0.12 ) ₁₃ 3
40 10 4000 La (Fe _0.88 Co _0.03 Si _0.09 ) ₁₃ 2
40 10 5000 La (Fe _0.88 Co _0.05 Si _0.07 ) ₁₃ 2
70 10 3500 La (Fe _0.88 Co _0.04 Si _0.08 ) ₁₃ 2
40 10 4500 La (Fe _0.875 Co _0.04 Si _0.085 )
₁₃ 245 10 4300 La (Fe _0.87 Co _0.04 Si _0.09 ) ₁₃ 2
50 10 4200 La (Fe _0.875 Al _0.125 ) _{13 2001}
0 2500 La (Fe _0.86 Ni _0.02 Si _0.12 ) ₁₃ 2
10 10 2000 La (Fe _0.84 Ni _0.06 Si _0.12 ) ₁₃ 2
30 10 2000 Comparative Example [Giant Magnetostrictive Material: A, E Clark, Hiroshi Eda (published by Nikkan Kogyo Shimbun)] Composition Temperature (K) Magnetostrictive Property (× 1
0 ^-6) TbFe ₂ (crystal) RT 1753 TbFe _{2 (amorphous) RT 308 SmFe 2 RT -1560 Tb} 2 Fe 2 ( casting) RT 13
1 Tb ₂ Fe ₁₇ RT -14 Tb (single crystal) 220 about 2000 Dy (single crystal) 100 about 3500 Ni RT-33 Co RT -52 Fe RT -9 60% Co-40% Fe RT 68 CoFe ₂ O ₄ RT -110

[0019]

As described above, the giant magnetostrictive material of the present invention has an isotropic and extremely large magnetostrictive characteristic near room temperature as compared with the characteristic of the conventional magnetostrictive material. As a result, it has extremely excellent characteristics as a constituent material of a micro displacement control drive unit, a strong sound wave generating oscillator, a sensor, and the like.

[Brief description of drawings]

FIG. 1 shows magnetization curves of La (Fe _0.88 Si _0.12 ) ₁₃ at various temperatures.

FIG. 2 shows the magnetic field dependence of magnetostriction of various magnetostrictive materials.

FIG. 3 is a graph showing the relationship between Tc and Ms with respect to the amount of Si in La (Fe _1-X Si _X ) ₁₃ .

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-145761 (JP, A) JP-A-53-64798 (JP, A) JP-A-58-3294 (JP, A) JP-A-7- 118786 (JP, A) JP 8-293634 (JP, A) JP 5-148594 (JP, A) JP 1-236665 (JP, A) JP 3-183738 (JP, A) JP-A-6-145838 (JP, A) JP-A-2002-69596 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 38/00 303 H01L 41/20

Claims (3)

(57) [Claims] 1. A general formula La _1-Z RE _Z (Fe _1-X A
_X ) ₁₃ (where A is at least one element of Al, Si, Ga, Ge, and Sn, RE is at least one element of rare earth elements other than La, and x and z are 0.05 in atomic ratio). ≤
A giant magnetostrictive material having a composition represented by x ≦ 0.2, 0 <z ≦ 0.1). 2. La _1-Z RE _Z (Fe _1-X A _XY)
TM _Y ) ₁₃ (where A is at least one element of Al, Si, Ga, Ge, and Sn, TM is at least one element of transition metal elements, and RE is at least one of rare earth elements other than La). The atomic elements of the seed elements, x, y, and z are 0.05 ≦
A giant magnetostrictive material having a composition represented by x ≦ 0.2, 0 <y <0.1, 0 <z ≦ 0.1). 3. RE is Y, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
2. At least one element selected from b and Lu.
Alternatively, the giant magnetostrictive material according to item 2.