JP2001274016A - Rare-earth alloy film magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare-earth alloy film magnet in which the coarsening of crystal grains is suppressed so as to prevent the disturbance of the c-axes of crystal grains which is caused by the interference between adjacent grains and results in the variation of the direction of magnetization of the magnet when the grains become coarser. SOLUTION: This rare-earth alloy film magnet has a mixed texture of an Nd2Fe14B-type crystalline phase in which the c-axes of crystals are oriented in the direction of thickness and an amorphous phase and at least one element selected from among In, Ga, Al, and, Si is added to the film of the magnet in such a way that the concentration of the element is periodically changed in the direction of thickness so that the concentration becomes higher at the portion which is in contact with a substrate. The concentration changing cycle is adjusted to 1-10 μm and the average concentration of the element is adjusted to <=5 at.%. In addition, the amorphous phase is constituted in a ferromagnetic phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth alloy film magnet for electric and electronic equipment, and more particularly to a rare earth alloy film magnet used for a small device such as a small motor, a microwave oscillator, a micromachine or a magnetic recording device.

[0002]

2. Description of the Related Art In recent years, the demand for micro magnets has been increasing with the miniaturization of devices, and in order to obtain high output, it is essential to use Nd-Fe-B based anisotropic magnets having strong magnetic force as magnets. However, in the manufacturing method by the machining of the sintered magnet, it becomes difficult to cope with the miniaturization of the magnet with each passing year, and the limit of the machining is approaching. Therefore, as a future technology, a method of forming an Nd—Fe—B-based anisotropic magnet directly on a substrate by a film forming method such as sputtering to obtain a final shape is being studied.

[0003]

SUMMARY OF THE INVENTION Nd-F by film forming method
When producing an e-B anisotropic magnet, when the film thickness is increased, there is a problem that crystal mutual interference occurs due to coarsening of crystal grains and crystal orientation is reduced. Disturbance in the orientation of the crystal axis causes variations in the magnetization direction and a decrease in the magnetic force, and causes a motor to exhibit large fluctuations in torque and a decrease in torque value.

[0004] As a solution to such a problem relating to the coarsening of crystal grains, there is, for example, one described in Japanese Patent Application Laid-Open No. 6-151226. This solution is a thin film magnet formed on the surface of the substrate 3 as shown in FIG.
The internal structure of the thin-film magnet has an R-F of less than 5 μm in the film thickness direction.
eB (R is a rare earth element containing Y) magnet layer 2 and a thickness of about 1
A metal layer 1 of 0 to 400 angstroms is alternately laminated, and an attempt is made to prevent the crystal grain from being coarsened by the metal layer 1. Furthermore, in this solution, intermittent sputtering is performed while taking a pause in film formation, thereby mitigating a rise in temperature due to plasma during film formation,
The crystal grain coarsening is prevented.

However, such a multi-layering technique in the prior art is excellent in that crystal grain coarsening can be suppressed relatively easily, but because the metal layer 1 having a heterogeneous structure is interposed therebetween. , The generation of stress, etc., has a considerable adverse effect on the magnetic properties of the Nd—Fe—B magnet layer 2. Further, in the above-described conventional intermittent sputtering method, since the substrate 3 is heated to several hundred degrees, there arises a problem of surface oxidation that occurs during the suspension of film formation.

The present invention has been made by paying attention to such problems existing in the prior art. An object of the present invention is to provide a rare earth alloy film magnet in which crystal grains are prevented from being coarsened without causing deterioration of magnetic properties.

[0007]

In order to achieve the above-mentioned object, according to the present invention, Nd in which the c-axis of the crystal is oriented in the film thickness direction is provided.
_It has a mixed structure of 2Fe ₁₄ B-type crystal phase and amorphous phase, and at least one element of In, Ga, Al, and Si is added to the film, and the element concentration is increased at a portion in contact with the substrate. And periodically changed in the film thickness direction.

[0008] Further, the changing cycle of the element concentration is 1 to 10
μm, and the average concentration is 5 atomic percent (at%)
Hereinafter, the amorphous phase is referred to as a ferromagnetic phase.

Therefore, the rare earth constructed as described above
In the case of similar alloy film magnets, Nd_TwoFe₁₄Between B-type crystal phases
Since there is an amorphous phase, basically Nd_TwoFe₁₄Type B
Prevents interference between crystal phases, enabling crystal growth in one direction
Thus, high crystal orientation is realized. In addition,
The added In, Ga, Al, and Si elements promote non-crystallization.
Therefore, coarsening of crystal grains is forcibly suppressed. Ma
In the unlikely event that crystal interference occurs in the early stage of the film formation process,
Would have a serious adverse effect on subsequent crystal orientation
However, in the present invention, the additive is first added at a portion in contact with the substrate.
Nd isolated and dispersed in an amorphous matrix
_TwoFe₁₄The film is formed so as to form a B-type crystal phase. So
Thereafter, the film is continuously formed with the element concentration lowered,
d_TwoFe₁₄It promotes the growth of the B-type crystal phase and occupies this crystal phase.
The moment is increasing. On the other hand, crystal grains have a growth mechanism.
It is mainly due to atomic rearrangement that occurs on the film surface.
Growth rate is the fastest. For this reason, crystal coarsening
Mutual interference initially occurs at the top of the film. This
For this reason, in the present invention, the film thickness at which crystal interference occurs is reached.
At that stage, the concentration of the element is intentionally increased,
To form Nd _TwoFe₁₄B-type crystal phase is isolated and dispersed
I'm making it. The present invention is based on repeating the above procedure.
And a very large film thickness while preventing crystal interference
It is possible to obtain a stone.

In other words, the present invention relates to In, Ga, A
Unnecessary coarsening of crystal grains is prevented by increasing the concentration of at least one element of l and Si near the substrate surface and periodically changing the concentration in the film thickness direction. By setting the period of the concentration change of the element to 1 to 10 μm and the average concentration to 5 atomic percent (at%) or less, it is possible to effectively suppress the mutual interference of crystals and realize a high crystal orientation. ing. Furthermore, a higher magnetic force is obtained by making the amorphous phase a ferromagnetic phase.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows an example of the rare earth metal film magnet according to the first embodiment. In FIG.
Reference numeral 3 denotes a substrate, 4 denotes an amorphous phase composed of a neodymium iron boron non-magnetic phase, 5 denotes an Nd ₂ Fe ₁₄ B type crystal phase, and the inside of the film magnet is Nd ₂ Fe ₁₄ B type It has a mixed structure with the crystal phase 4, and is composed of In, Ga, Al, S
Each element of i is added in the distribution of A shown in FIG.

Next, a description will be given of a sample of the first embodiment manufactured for performing a characteristic test. First, four samples were prepared for each of the elements of In, Ga, Al, and Si in the first embodiment, and all were prepared so as to have the element concentration profile of distribution A shown in FIG. Specifically, for example, when preparing a sample to which In is added,
Nd-Fe-B and Nd-F as sputtering targets
Two types of eB-In were prepared, and the distribution A of In was imparted to the inside of the film magnet by performing binary simultaneous sputtering while adjusting the input power to each target. The Ar gas pressure was 4 Pa and the substrate temperature was 560 ° C. Further, the film magnet was uniformly sputtered with a width of 1 mm and a film thickness of 100 μm on the outer surface of an iron cylindrical substrate having a diameter of 0.5 mm using a mask in combination.

Further, in order to compare the first embodiment with the conventional example, the following conventional example 1 was used as a sample of the conventional example.
And Conventional Example 2 were prepared. Conventional example 1 is Nd-Fe-
A total thickness of 10 with a Ti layer of about 100 ° interposed every 5 μm of the B layer
In the conventional example 2, Nd—Fe—B was deposited without adding any element (100 μm).
It was done.

[0014]

[Table 1]

The thus-obtained sample of the first embodiment and the sample of the conventional example were respectively magnetized in four poles, assembled into a motor as a magnet rotor, and the motor was operated to measure torque. . Table 1 shows the measurement results. The torque fluctuation rate in Table 1 means the ratio between the average value of the fluctuating torque and the fluctuation width of the fluctuating torque, although the motor torque at the time of measurement fluctuates constantly.

From the measurement results, it can be seen that the sample of Embodiment 1 to which any of the elements is added has a smaller torque fluctuation than that of Conventional Examples 1 and 2, so that the suppression of crystal grains is effectively performed. Was found to be small.
Also, the sample of Embodiment 1 to which any of the elements was added had a larger average torque value than those of Conventional Examples 1 and 2, indicating that the crystal orientation was good and the magnetic force was strong.

In the magnet of the first embodiment, Nd
_TwoFe₁₄The B-type crystal phase 5 contains Nd_TwoFe ₁₄In addition to B, N
One kind of rare earth elements other than d and transition metal elements other than Fe
The above may be included. For example, (Nd, Tb)
_Two(Fe, Co)₁₄Phase B, (Nd, Tb)_Two(Fe, N
i)₁₄Phase B, (Nd, Tb)_Two(Fe, Co, Ni)₁₄
Phase B, (Nd, Tb, Ho)_Two(Fe, Co, Ni)₁₄
The phase B may be used. Also, the amorphous phase 4 is neodymium.
Phase, neodymium oxide phase, neodymium
It may be an iron phase, a neodymium boron phase, or the like. Also,
The substrate 3 is made of iron, cobalt, nickel, titanium, etc.
Pure metals and alloys such as iron cobalt and iron nickel, quartz gas
Oxides such as glass and alumina, nitrides such as titanium nitride
Can be widely used.

Embodiment 2 FIG. FIG. 2 shows an example of the rare earth metal film magnet according to the second embodiment. As shown in FIG. 3, this structure has a substrate 3, an amorphous phase 4 composed of a neodymium iron boron non-magnetic phase, and a Nd ₂ Fe ₁₄ B type crystal phase 5, and the inside of the film magnet is Nd ₂ Fe ₁₄ Embodiment 2 is similar to Embodiment 1 in that it has a mixed structure of B-type crystal phase 5 and amorphous phase 4, but the distribution of at least one element of In, Ga, Al, and Si is shown in FIG. Embodiment 2 is different from Embodiment 1 in that it is added in the distribution of B shown in FIG.

Next, a description will be given of a sample according to the second embodiment prepared for performing a characteristic test. Four samples of Embodiment 2 were prepared for each of the added elements of In, Ga, Al, and Si, and all were prepared so as to have the element concentration profile of distribution B shown in FIG. This manufacturing method is the same as that of the first embodiment except for the element concentration profile. The samples obtained in this manner in the second embodiment and the same ones as in the conventional examples 1 and 2 described in the description of the first embodiment are similar to those in the first embodiment. The magnet rotor was pole-magnetized, and this was assembled into a motor and operated to measure torque.

[0020]

[Table 2]

Table 2 shows the measurement results. Each sample of Embodiment 2 to which any of the elements was added was the same as that of Conventional Examples 1 and 2.
Since the torque fluctuation becomes smaller, it was found that crystal grains were effectively suppressed and the variation in magnetization was small. In addition, each sample of Embodiment 2 to which any of the elements was added had a larger average torque value than those of Conventional Examples 1 and 2, indicating that the crystal orientation was good and the magnetic force was strong.

Embodiment 3 FIG. In the third embodiment, the substrate is T
It is an i-plate, and the concentration distribution of each additive element of In, Ga, Al, and Si is a Gaussian distribution having a half-value width of 0.15 μm and a peak concentration of 5 at%. The thickness was 100 μm. The third embodiment is the same as the first embodiment except for the above points.

Next, a sample manufactured for measuring the coercive force according to the third embodiment will be described. Samples according to the third embodiment include In, Ga, A
Eight types with different concentration cycles were prepared by multi-source simultaneous sputtering for each of the elements to which l and Si were added. This manufacturing method is the same as that in Embodiment 1 except for the substrate material and the concentration profile of the element to be added.

FIG. 3 shows the results of measuring the coercive force of each of these samples. From FIG. 3, each sample of the third embodiment has a concentration distribution cycle of 1 μm for the added element.
It was found that a large coercive force of 400 KA / m or more was obtained at m or more. Next, FIG. 4 shows the results of evaluating the crystal orientation of each sample. FIG. 4 shows that the scan axis of the X-ray diffractometer was set to θ / 2θ, and the X-ray diffraction pattern was measured while changing the offset angle の of the sample setting. From the dependence of the integral intensity I, I (ψ) / I (0) =
0.5 and consisting [psi value (= ψ ₅₀₎ a result of obtaining, [psi
_The smaller the value of _50, the higher the crystal orientation.
From this Figure 4, none of the samples according to the third embodiment, the period has a relatively low value [psi ₅₀ in the range of 1 to 10 [mu] m, thereby it was found that crystal orientation is good.

Embodiment 4 In the fourth embodiment, the substrate is T
It is an i-plate, and the concentration distribution of each of the additional elements of In, Ga, Al, and Si is a Gaussian distribution having a half-peak width of 1.5 μm and a constant peak concentration. , And a total thickness of 100 μm. Except for these points, the structure is the same as that of the first embodiment.

Next, according to the fourth embodiment, In, G
For the sample to which each element of a, Al and Si was added,
Six kinds of samples having different peak concentrations were produced by the multiple simultaneous sputtering method. Note that the manufacturing method of Embodiment 4 is the same as that of Embodiment 1 except for the substrate and the element concentration profile.

FIG. 5 shows the results of measuring the coercive force of each of these samples. In the figure, the element concentration indicates the average concentration in the film. From this figure, it can be seen that all samples according to the fourth embodiment have a coercive force of 40
It was found that good characteristics of 0 KA / m or more could be obtained.

Embodiment 5 In the internal configuration of the film magnet according to the first embodiment, the amorphous phase 4 is changed to a neodymium iron boron ferromagnetic phase by adjusting the composition of the Nd—Fe—B target. Next, the fifth embodiment
A sample according to the fifth embodiment manufactured to measure the torque of the motor using the rotor manufactured by the method will be described. The manufactured sample according to the fifth embodiment uses Si as an additive element, and the Si concentration distribution is represented by the distribution curve of A shown in FIG. The method of manufacturing this sample is the same as that of the first embodiment except that the element concentration profile and the amorphous phase 4 are a neodymium iron boron ferromagnetic phase.

[0029]

[Table 3]

Each of the samples of the fifth embodiment thus obtained was magnetized in four poles, incorporated into a motor as a magnet rotor, and the motor was operated to measure the torque. Table 3
Shows this result. For comparison, the same table also shows the results for the additive element Si in the first embodiment. From Table 3, this Embodiment 5 is
Since the amorphous phase 4 is a ferromagnetic phase, it has been found that a larger average torque can be obtained than in the first embodiment.

[0031]

Since the present invention is configured as described above, it has the following effects. According to the first to fourth aspects of the present invention, Nd ₂ F in which the c-axis of the crystal is oriented in the film thickness direction.
It has a mixed structure of e ₁₄ B-type crystal phase and amorphous phase, and at least one element of In, Ga, Al, and Si is added to the film, and the concentration of this element is increased in a portion in contact with the substrate. In addition, since the thickness is periodically changed in the film thickness direction, coarsening of crystal grains is prevented, and characteristics with high crystal orientation and small variations in magnetization can be realized. Therefore, when the rare earth alloy film magnet of the present invention is used for a motor, torque fluctuation of the motor can be reduced.

According to the second aspect of the present invention, since the change period of the element concentration is 1 to 10 μm, in addition to the above-mentioned effects, the mutual interference of crystals is effectively suppressed, and high crystal orientation is obtained. Can be realized.

According to the third aspect of the present invention, since the average concentration of the element is 5 at% or less, in addition to the above-mentioned effects, the mutual interference of crystals is effectively suppressed to realize high crystal orientation. can do.

According to the fourth aspect of the present invention, since the amorphous phase is ferromagnetic, a higher magnetic force can be obtained in addition to the above-mentioned effects.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a membrane magnet according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining a film magnet according to a second embodiment of the present invention.

FIG. 3 is a characteristic diagram of coercive force of a film magnet according to Embodiment 3 of the present invention.

FIG. 4 is a characteristic diagram of crystal orientation of a film magnet according to Embodiment 3 of the present invention.

FIG. 5 is a characteristic diagram of a coercive force of a film magnet according to Embodiment 4 of the present invention.

FIG. 6 is a cross-sectional view for explaining a conventional membrane magnet.

[Explanation of symbols]

Reference Signs List 1 metal layer, 2 R-Fe-B magnet layer, 3 substrate, 4
Non-crystalline phase, 5 Nd-Fe-B type crystalline phase.

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Toshio Umemura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Mitsubishi Electric Corporation 5E049 AA01 AA09 AC01 BA01 BA29 DB02 GC01

Claims (4)

[Claims] 1. Nd ₂ having a crystal c-axis oriented in a film thickness direction.
It has a mixed structure of an Fe ₁₄ B-type crystal phase and an amorphous phase, and at least one element of In, Ga, Al, and Si is added to the film, and the concentration of this element is increased in a portion in contact with the substrate. And a periodic change in the film thickness direction. 2. The change period of the element concentration is 1 to 10 μm.
The rare earth alloy film magnet according to claim 1, wherein 3. The rare earth alloy film magnet according to claim 1, wherein the average concentration of the element is 5 at% or less. 4. The rare earth alloy film magnet according to claim 1, wherein the amorphous phase is ferromagnetic.