JP2002069596A - Ultra-magnetostrictive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultra-magnetostrictive material having isotropic magnetostriction as well as large magnetostriction exceeding the conventional magnetostrictive effect in the temperature range from the vicinity of room temperature to 100 deg.C. SOLUTION: The ultra-magnetostrictive material has a chemical composition represented by the following general formulae: (1) La(Fed1-xAx)13-δ Dq; (2) La(Fe1-xAx-yTMy)13-δ Dq; (3) La1-zREz(Fe1-xAx)13-δDq; (4) La1-zREz(Fe1-xAx-yTMy)13-δDq; and (5) La(Fe1-a-bSiaCob)13Dq (A is at least one element among Al, Si, Ga, Ge and Sn; D is at least either of hydrogen and nitrogen; TM is at least one element among transition elements other than Fe; RE is at least one element among rare earth elements other than La; and 0.05<=x<=0.2, -1<=δ<=1, 0<q<2, 0<y<0.1, 0<Z<=0.1, 0.10<=a<=0.16 and 0<b<=0.08 are satisfied).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a giant magnetostrictive material having a large magnetostriction and suitable for a magnetostrictive element used in a magneto-mechanical displacement conversion device or the like.

[0002]

2. Description of the Related Art As an application of magnetostriction, which is distortion generated when an external magnetic field is applied to a magnetic material, a magnetostrictive filter, a magnetostrictive sensor,
There are ultrasonic delay lines, magnetostrictive vibrators, and the like. Conventional Ni-based alloys, Fe-Co alloy, ferrite, Laves-type intermetallic compound (Tb, Dy, Sm) Fe 2 or the like is used.

[0003] In recent years, with the advance of measurement engineering and the development of the field of precision machinery, the development of a displacement drive unit indispensable for micro displacement control on the order of microns has been required. As one of the driving mechanisms of the displacement driving unit, a magneto-mechanical conversion device using a magnetostrictive material is effective. However, the conventional magnetostrictive material does not have a sufficient absolute amount of displacement, and as a material for a precision displacement control drive unit on the order of microns, it cannot be satisfied not only in terms of absolute drive displacement but also in terms of precision control.

[0004] What is usually called giant magnetostrictive material is:
Among Laves-type intermetallic compounds represented by ReFe ₂ , TbFe ₂ (λs = 1753 × 10 ⁻⁶ ) and SmFe ₂
(Λs = −1560 × 10 ⁻⁶ ) [Clark (197
4): Giant magnetostrictive material, published by Nikkan Kogyo Shimbun] and has the largest saturation magnetostriction value. If only the magnitude of the magnetism is considered, a large magnetostriction (λs to ± 4000 × 10 ⁻⁶ ) is obtained in a single crystal of Dy or Tb at a low temperature of 200 K or less. Table 1 shows these examples.

[0005]

[Table 1]

[0006]

In the conventional magnetostrictive material, even if the magnetostriction is large, the temperature is lower than the temperature of liquid nitrogen, 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 view of such problems, and a super magnetostrictive material having a large magnetostriction exceeding the conventional magnetostriction effect at room temperature and having an isotropic magnetostriction has been developed. The purpose is to provide.

[0008]

SUMMARY OF THE INVENTION The present invention comprises the following items. (1) General formula: La (Fe _1-x A _x ) _13-δ D _q (where A is at least one element among Al, Si, Ga, Ge and Sn, and D is at least one of hydrogen and nitrogen One kind of element, x, δ, q, is 0.05 ≦ x ≦ 0 in atomic ratio.
2. A giant magnetostrictive material comprising a composition represented by the following formula: 2, -1≤δ≤1, 0 <q <2).

(2) General formula: La (Fe _1-x A _xy TM _y ) _13-δ D _q (where A is at least one element of Al, Si, Ga, Ge, Sn, and TM is Fe , At least one element among transition metal elements except D, hydrogen is at least one element among nitrogen, and x, y, δ, and q are 0.05 by atomic ratio.
≦ x ≦ 0.2, 0 <y <0.1, −1 ≦ δ ≦ 1, 0 <q
A giant magnetostrictive material comprising a composition represented by <2>.

(3) General formula: La _1-z RE _z (Fe _1-x A _x ) _13-δ D _q (where A is at least one element of Al, Si, Ga, Ge and Sn; RE is at least one element among rare earth elements other than La, D is at least one element among hydrogen and nitrogen, and x, z, δ, and q are 0.05 ≦ by atomic ratio.
x ≦ 0.2, 0 <z ≦ 0.1, −1 ≦ δ ≦ 1, 0 <q <
A giant magnetostrictive material having a composition represented by 2).

[0011] (4) General _{formula: La 1-z RE z (} Fe 1-x A xy TM y) 13-δ D q ( although, A is Al, Si, Ga, Ge, at least one of Sn Element, TM is at least one element among transition metal elements other than Fe, RE is at least one element among rare earth elements except La, D is at least one element among hydrogen and nitrogen, x, y, and z, δ, and q are 0.05 ≦ x ≦ 0.2, 0 <y <0.1, x> y, 0 <
A giant magnetostrictive material comprising a composition represented by z ≦ 0.1, −1 ≦ δ ≦ 1, 0 <q <2).

[0012] (5) the general _{formula: La (Fe 1-ab Si} a CO b) 13 D q ( although, D is hydrogen, at least one element of nitrogen, 0.10 ≦ a ≦ 0.16,0 <B ≦ 0.08, 0 <
A giant magnetostrictive material having a composition represented by q <2).

(6) The giant magnetostrictive material according to (2) or (4), wherein TM is at least one element of Co, Ni and Cu.

(7) RE is Y, Ce, Pr, Nd, P
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
The giant magnetostrictive material according to the above (3) or (4), which is at least one element of m, Yb, and Lu.

(8) The giant magnetostrictive material according to any one of the above (1) to (7), which contains unavoidable impurities at 10 atomic% or less.

(9) 90% or more by volume of cubic N
(1) to (8), which are aZn ₁₃ type intermetallic compounds
The giant magnetostrictive material according to any one of the above.

La (Fe _1-x A _x ) which is the basis of the material of the present invention
Regarding ₁₃ , La is taken in as BCC by Fe _1-x A _x constituting the icosahedron, and when A = Si,
It is known that changing the Si amount (x) changes the magnetic transition temperature Tc (Curie temperature), _TN (Neel temperature), and magnetization Ms [K. H. J. Bushow etc.
Journal of Magnetism and
Magnetic Materials 36 (198
3) 190-296].

The present inventors have conducted detailed studies on this material, and as a result, the element of A, which is a substitution element of Fe, is changed to Si,
At least one of Al, Ga, Ge, and Zn;
It was found that by changing the amount of x, a composition having a small x and a low temperature, but at a low temperature, caused a metamagnetic transition from antiferromagnetic to ferromagnetic, and further a saturation magnetostriction (λs) of 5000 × It was found that more than 10 ^-6 could be obtained. Here, the metamagnetic transition is a phenomenon in which a magnetic field is applied to an antiferromagnetic or paramagnetic state to change into a ferromagnetic substance.

This material is anisotropic in that a conventional Laves-type magnetostrictive material such as TbFe ₂ expands and contracts in reverse (sign is opposite) when the magnitude of magnetostriction is parallel and perpendicular to the direction of the magnetic field.
La (Fe _1-x A _x ) ₁₃ extends in all directions by applying a magnetic field. In other words, applying a magnetic field increases the volume, and exhibits a magnetostrictive effect completely different from that of the conventional giant magnetostrictive material. As a result of examining the composition of this material, the amount of substitution of the element A and Co as a substitution element of Fe, and the amount of substitution of a rare earth element as a substitution element of La, a material exhibiting large magnetostriction near room temperature can be obtained. [JP 2
000-54086]. However, in order to develop magnetostriction near room temperature, the composition must be strictly controlled, and careful attention must be paid to the method of preparing and preparing the material.

The present inventors have focused on the crystal structure of the material and tried to control the structure in order to easily exhibit the giant magnetostriction effect at room temperature or higher. _{La (Fe 1-x Si x} ) Tc by applying pressure to ₁₃ is reduced. In addition, La (Fe _1-x S
magnetic transition temperature in accordance with i _x) Si amount in ₁₃ is increased to increase [JP 2000-54086.

This is because the average Fe-Fe distance is increased and the Tc is increased by replacing Fe in Fe _1-x A _x constituting the icosahedron as shown in FIG. 1 with Si. Conversely, Tc by applying pressure to the _{La (Fe 1-x Si x} ) 13
Is also known to decrease.

[0022] Against this background, the present inventors have added interstitial elements to the materials, La without changing the crystalline structure _{(Fe 1-x Si x)} 13 Fe-Fe interactions of Control, in other words, control of the magnetic transition temperature.

FIG. 2 is a diagram showing the temperature dependence and the magnetic field dependence of the magnetization M and strain ΔL / L of La (Fe _0.88 Si _0.12 ) ₁₃ . As the temperature increases, the magnetization of La (Fe _0.88 Si _0.12 ) ₁₃ decreases at Tc = 195K, changes from a ferromagnetic material to a paramagnetic material, and at the same time, the strain ΔL / L also becomes Tc.
= 195K. In addition, 2 near Tc = 195K
The magnetization at 00K is a paramagnetic material, but shows a metamagnetic transition that changes to a ferromagnetic material when a magnetic field is applied, and the strain ΔL / L increases accordingly. Thus, La (Fe _0.88
The strain ΔL / L of Si _0.12 ) ₁₃ shows a good correlation with the magnetization M. Applying a magnetic field to paramagnetic La (Fe _0.88 Si _0.12 ) ₁₃ just below Tc causes a phase change from a paramagnetic material to a ferromagnetic material (metamagnetic transition), which increases the lattice constant and volume. This is the magnetostrictive effect of the material. As described above, the present material is characterized in that not only a large volume change is caused by applying a magnetic field but also a large volume change is caused by a temperature change near Tc.

La (Fe_0.88Si_0.12)₁₃Occludes hydrogen
FIG. 3 shows an X-ray diffraction diagram in the case of the above. Shown at the bottom
Is NaZn₁₃Type X-ray diffraction line, La (Fe
_0.88Si_0.12)₁₃And La (Fe_0.88Si_0.12)₁₃H
_1.6Are all NaZn₁₃Indicating the mold and storing hydrogen
And each diffraction line is shifted to the low angle side, and the overall lattice constant
It can be seen that is larger. Thermal expansion measurement of this material
FIG. 4 shows the results of the measurement. Thermal expansion △ L / L is temperature
When increased, Tc shows a large decrease, and La (Fe_0.88
Si_0.12)₁₃Has a Tc of 190K, whereas La
(Fe_0.88Si_0.12)₁₃H_1.6Is Tc = 333K and room temperature
(300K). Therefore, as shown in FIG.
The large magnetostriction effect near Tc is caused by La (Fe_0.88S
i_0.12)₁₃H _1.6In case of 50 ℃ (333K)
It can be said that the magnetostrictive effect is exhibited. Further, as shown in FIG.
Tc can be reduced by reducing the amount of hydrogen storage.
Large magnetostriction effect at any temperature below Tc
be able to. At this time, the hydrogen is NaZn in FIG.₁₃Unit cell
Fe inside^I-Fe^IIs coordinated in the middle.

FIG. 6 shows the magnetic transition temperature (Curie temperature) and the lattice constant at room temperature when the hydrogen storage amount of La (Fe _0.88 Si _0.12 ) ₁₃ H _q is changed. By changing the amount of hydrogen, Tc changes from 190K (-83 ° C) to 340K (67 ° C).
° C). At this time, the lattice constant at room temperature increases due to the increase in the hydrogen storage amount,
Accordingly, the Curie temperature Tc increases. When Tc exceeds room temperature, La (Fe _0.88 Si _0.12 ) ₁₃ H _q changes from a ferromagnetic material to a paramagnetic material at room temperature, so that the lattice constant increases discontinuously.

FIG. 7 shows La (Fe _0.88 Si _0.12 ) ₁₃ H
Each temperature of _1.6 (Tc = 333K) (330, 336,
338, 342K), it is paramagnetic and has no magnetization immediately above Tc, but when a magnetic field is applied, the magnetization appears and large magnetostriction occurs. As the temperature increases from Tc, a high magnetic field is required to generate the magnetostrictive effect.
It is desirable to use in the range of c-5) K to (Tc + 10) K. Preferably, it is used at Tc ± 5K.

In the present invention, the element A, which is a substitution element for Fe, is at least one of Si, Al, Ga, Ge, and Zn, and the ratio of Fe to A increases as the ratio of A increases. The temperature rises and the saturation magnetization decreases. La (Fe
_1-x A _x ) ₁₃ , if x is less than 0.05 as a whole,
The crystal structure of Zn ₁₃ type cannot be maintained, and the metamagnetic transition that develops magnetostriction disappears. On the other hand, when x exceeds 0.3, the ferromagnetic state becomes stable, and no metamagnetic transition that similarly expresses magnetostriction is observed. Therefore, in the present invention, a preferable range is 0.05 ≦ x ≦ 0.2. By changing the amount of TM (Co, Ni, Cu) in claim 2 or the like, the number of 3d electrons of Fe that changes the magnetic property changes, and has an effect of changing the magnetic transition temperature Tc and the strength of the magnetization (Ms). At this time, the composition of y is preferably changed within the range of 0 ≦ y <0.1. When y is 0.1 or more, the magnetic property of Fe itself is affected, so that a metamagnetic transition that develops magnetostriction occurs. It is unsuitable. Especially when TM is Co,
3 of Fe that plays a role in magnetism by changing the composition of the substitution element Co
The number of d-electrons changes, 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 preferably changed within a range of 0 <y ≦ 0.08. If y exceeds 0.08, the metamagnetism that develops magnetostriction to affect the magnetism of Fe itself is obtained. Magnetic transition does not occur and is not suitable. Preferably, the composition of Co is 0.04 ≦
It is effective that y ≦ 0.06 increases the magnetic transition temperature Tc and obtains a magnetostrictive effect near room temperature.

In the third and fourth aspects, replacing a part of La with another rare earth element (Nd, Gd, etc.) has an effect of reducing the saturation magnetic field. The upper limit of the substitution amount (z) is 0.1. When z exceeds 0.1, RE ₂ Fe ₁₇ becomes more stable than having a NaZn ₁₃ type compound structure, and Na
Metamagnetic transition due to the Zn ₁₃ structure does not occur, and as a result, giant magnetostriction cannot be obtained.

In the first, second, third, fourth and fifth aspects,
By causing (H, N) to penetrate into the NaZn ₁₃ type compound structure, there is an effect that the interaction of the Fe—Fe alloy is changed and the magnetic transition temperature is raised. At this time, the amount of hydrogen is q ≧ 2.
In this case, the crystal structure of the NaZn ₁₃ type cannot be maintained, and the metamagnetic transition that develops magnetostriction disappears. On the other hand, when the amount of nitrogen is q> 1.6 or more, the NaZn ₁₃ type crystal structure cannot be maintained, and the metamagnetic transition that develops magnetostriction disappears. As a result, giant magnetostriction cannot be obtained. Further, in the present invention, unavoidable impurities of 10 atomic% may be included.

[0030]

Embodiments of the present invention will be described below. After a material having the composition shown in Table 2 was produced by arc melting, a sample heat-treated at 1050 ° C. in vacuum for 168 hours was cut out with a diamond cutter. Magnetization characteristics and thermomagnetic characteristics were measured using SQUID (manufactured by Quantum Design), and magnetostriction was measured in a superconducting magnet from 4.2K to 373K using a capacitance method. The shape of the sample for measuring magnetization and thermomagnetism and the sample for measuring magnetostriction were cut out to 2 mm × 2 mm × 2 mm for use.

As a result, in the composition shown in Table 2, in the temperature range from around room temperature to 100 ° C., in this case (250
K-400K), and has a metamagnetic transition temperature, in other words, exhibits a very large magnetostriction characteristic.

[0032]

[Table 2]

[0033]

As described above, the giant magnetostrictive material of the present invention has an isotropic and extremely large magnetostrictive characteristic at room temperature or higher as compared with the characteristics of the conventional magnetostrictive material. Thereby, it has extremely excellent characteristics as a constituent material of a micro-displacement control drive unit on the order of μm, a vibrator for generating a strong sound wave, a sensor, and the like.

[Brief description of the drawings]

FIG. 1 shows a NaZn ₁₃ type crystal structure La (FeAl, Si)
₁₃ is shown.

FIG. 2 is a graph showing temperature dependence and magnetic field dependence of magnetization M and strain ΔL / L of La (Fe _0.88 Si _0.12 ) ₁₃ .

FIG. 3 La (Fe _0.88 Si _0.12 ) ₁₃ H _q (q = 0.
0, 1.6).

FIG. 4: La (Fe _0.88 Si _0.12 ) ₁₃ H _q (q = 0.
6 is a graph showing the temperature dependence of strain ΔL / L of (0, 1.6).

FIG. 5 is a graph showing a change in Tc when hydrogen of La (Fe _0.88 Si _0.12 ) ₁₃ H _1.6 is released.

FIG. 6 shows the Curie temperature (Tc) of La (Fe _0.88 Si _0.12 ) ₁₃ H _q and the lattice constant at room temperature.

FIG. 7: La (Fe _0.88 Si _0.12 ) ₁₃ H _1.6 (Tc = 3
33K) (330, 336, 338, 342)
17 shows a magnetization curve in K).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shun Fujieda 2-4-2, Aoyama, Taishiro-ku, Sendai, Miyagi Prefecture (72) Inventor Yoshiaki Iijima 1-37-2, Kamo, Izumi-ku, Sendai City, Miyagi Prefecture (72) Inventor Jinjo Yamazaki 1-5-15 Yagiyamahonmachi, Taihaku-ku, Sendai City, Miyagi Prefecture (72) Inventor Hideki Takeda 3-38-5 Izumichuo, Izumi-ku, Sendai City, Miyagi Prefecture

Claims (9)

[Claims] 1. General formula: La (Fe _1-x A _x ) _13-δ D
_q (where A is at least one element of Al, Si, Ga, Ge and Sn, D is hydrogen and at least one element of nitrogen, and x, δ, and q are atomic ratios of 0.05 ≦ x ≤
0.2, −1 ≦ δ ≦ 1, 0 <q <2) A giant magnetostrictive material comprising a composition represented by the following formula: 2. General formula: La (Fe _1-x A _xy TM _y )
_13-δ D _q (where A is Al, Si, Ga, Ge, Sn
, TM is at least one element of transition metal elements other than Fe, D is hydrogen and at least one element of nitrogen, and x, y, δ, and q are atomic ratios of 0.1. 05 ≦ x ≦ 0.2, 0 <y <0.1, −1 ≦ δ ≦
1. A giant magnetostrictive material having a composition represented by the following formula: 1, 0 <q <2). 3. General formula: La _1-z RE _z (Fe _1-x A _x )
_13-δ D _q (where A is Al, Si, Ga, Ge, Sn
, RE is at least one element among rare earth elements other than La, D is at least one element among hydrogen and nitrogen, and x, z, δ, and q are 0.05 by atomic ratio. ≦ x ≦ 0.2, 0 <z ≦ 0.1, −1 ≦ δ ≦
1. A giant magnetostrictive material having a composition represented by the following formula: 1, 0 <q <2). 4. A general formula: La _1-z RE _z (Fe _{1-x Axy} T
_{M y) 13-δ D q} ( although, A is Al, Si, Ga, G
e, at least one element of Sn, TM is at least one element of transition metal elements other than Fe, and RE is L
a is at least one element among rare earth elements except a, D is at least one element among hydrogen and nitrogen, x, y, z,
δ and q are 0.05 ≦ x ≦ 0.2 and 0 <y <0.
1, x> y, 0 <z ≦ 0.1, −1 ≦ δ ≦ 1, 0 <q <
A giant magnetostrictive material having a composition represented by 2). 5. The general _{formula: La (Fe 1-ab Si} a CO b)
₁₃ D _q (where D is at least one element of hydrogen and nitrogen, 0.10 ≦ a ≦ 0.16, 0 <b ≦ 0.08,
A giant magnetostrictive material having a composition represented by 0 <q <2). 6. The giant magnetostrictive material according to claim 2, wherein TM is at least one element of Co, Ni, and Cu. 7. RE is Y, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
4. An element which is at least one element of b and Lu.
Or the giant magnetostrictive material according to claim 4. 8. The giant magnetostrictive material according to claim 1, which contains unavoidable impurities at 10 atomic% or less. 9. A cubic NaZ having a volume ratio of 90% or more.
giant magnetostrictive material according to any one of claims 1 to 8 is n ₁₃ type intermetallic compound.