JP2929217B2 - Ferromagnetic material - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a ferromagnetic material, and more particularly to a novel intermetallic compound of a rare earth element containing Pr as an essential component and at least one transition metal of Co and Fe. A certain ferromagnetic material.

[Problems to be Solved by Conventional Techniques and Inventions] Currently, SmCo ₅ , Sm ₂ Co ₁₇ , and Nd ₂ Fe are used as rare earth ferromagnetic materials.
Sm-Co with ₁₄ B intermetallic compound and good magnetic properties
, Nd-Fe-B permanent magnet materials are applied to speakers, motors and the like. However, the use of Sm-Co based magnet materials is limited due to the high price of Sm and inferior magnet properties compared to Nd-Fe-B based magnet materials using inexpensive Nd.

In addition, Nd-Fe-B permanent magnet materials have not been used in a wide range of applications because of their inferior thermal stability and corrosion resistance of magnet properties.

Thus, the present inventors have explored the possibility of a ferromagnetic material having a crystalline magnetic anisotropy and excellent magnetic properties in a compound of a rare earth metal and a transition metal.

Furthermore, since the magnetism of the compound of a rare earth metal and a transition metal largely depends on the transition metal, a compound having a large composition ratio of the transition metal was judged to be suitable as a material having excellent magnetic properties, and the investigation was advanced.

As a compound of a rare earth metal and a transition metal, RT ₅ , R ₂ T
₁₇ are already known (KJ-Strat: IEEE Trans.Mag
n.MAG-8,511 (1972) (referred to as Reference Example 1)).

FIG. 7 is a diagram showing the saturation magnetization of RCo ₅ and R ₂ Co ₁₇ according to Reference Example 1. In this figure, Pr ₂ Co ₁₇ and Nd ₂ Co ₁₇ have high saturation magnetization characteristics.

However, Figure 8 (AERayand KJStrnat: IEEE
Trans. Magn. MAG-8,517 (1972), hereinafter referred to as Reference Example 2), both of Pr ₂ Co ₁₇ and Nd ₂ Co ₁₇ have their easy magnetization directions in the C plane of the crystal. In addition, when the magnetic field is oriented, the magnetization direction is easily rotated, and only a magnet having a weak characteristic is obtained, which is presumed to be inappropriate as a permanent magnet material.

Therefore, the technical problem of the present invention is to make the crystal c-axis direction uniaxial, which is the axis of easy magnetization, by using Pr, Co, and Fe as main elements and adding another metal element to the Pr ₂ T ₁₇ intermetallic compound. An object of the present invention is to provide a ferromagnetic material having crystal magnetic anisotropy and having excellent magnetic properties.

[Means for Solving the Problems] The present inventors have focused on Pr as a rare earth metal,
By adding Pr, Co, Fe as the main element and adding the third element M, the uniaxial magnetic anisotropy of the composition represented by the formula of R ₂ (T _{1 -y} M _y ) ₁₇ , that is, the c-axis direction The presence of a compound having an axis of easy magnetization was investigated and good results were obtained.

According to the present invention, the chemical formula: (Pr _1-x R _x ) ₂ (T _1-y M _y )
₁₇ (where R is at least one of the rare earth elements containing Y other than Pr, x is a number from 0 to 0.4, T is at least one transition metal of Co and Fe, and M is Ti, V , Cr, Mn, Zr, Nb, Mo, Hf, T
At least one of a and W, y represents a number of 0.01 to 0.2. A ferromagnetic material characterized by being an intermetallic compound represented by the formula (1) is obtained.

That is, as described above, the present invention provides a uniaxial magnetic anisotropy suitable for a permanent magnet material by adding a relatively small amount of another element M to R and T of a compound having an R ₂ T ₁₇ composition. That is,
(Pr with a rhombohedral structure having an easy axis of magnetization in the c-axis direction of the crystal
_{1-x R x) 2 (} T 1-y M y) 17 ( provided that at least one of rare earth element R, including a Y other than Pr, x is the number of 0 to 0.4)
It has been found that an intermetallic compound having a composition represented by the following formula can be obtained.

Further, the intermetallic compound of the above formula in the present invention has a unit cell larger than the above-mentioned compound having a rhombohedral structure of the R ₂ T ₁₇ composition, a c / a ratio, and has a uniaxial magnetic magnetic anisotropy. This is a ferromagnetic material having a rhombohedral structure.

In the above formula, if y is smaller than 0.01 or larger than 0.2, an intermetallic compound having desired magnetic properties cannot be obtained.

The intermetallic compound in the above formula in the present invention is a ferromagnetic material having a uniaxial anisotropy, a high saturation magnetization and a Curie temperature of 400 ° C. or more and excellent in magnetic properties.

Incidentally, it can be easily inferred that a similar metal compound can be obtained even when R is replaced with another rare earth metal containing Y other than Pr as R in the above formula. The method for producing the above compound is not limited.

Example An example of the present invention will be described with reference to the drawings.

(Example 1) The composition of Pr ₂ (Co _0.93 Ti _0.07 ) ₁₇ was changed to a relative amount Pr: 23.0 wt.
%, Co: 72.5 wt%, and Ti: 4.5 wt%. At the start of melting, a slight excess of Pr was present to compensate for evaporation loss during melting.

The obtained Pr ₂ (Co _0.97 Ti _0.07 ) ₁₇ alloy was pulverized, and the powder was formed in a magnetic field. Vibrating sample magnetometer (VS
Magnetization change at room temperature when an external magnetic field is gradually applied to the obtained molded body in a direction parallel to the applied magnetic field (M) and a direction perpendicular to the applied magnetic field (（) and perpendicular to the applied magnetic field (⊥). Was measured.

 The result is shown in FIG.

At room temperature, Pr ₂ (Co _0.93 Ti _0.07 ) ₁₇ intermetallic compound has an anisotropic magnetic field of about 20 KOe and a saturation magnetization of about 11.5 KG, and has excellent magnetic properties.

Furthermore, to determine the crystal structure and easy magnetization direction of Pr ₂ (Co _0.93 Ti _0.07 ) ₁₇ , X-ray diffraction was performed on the compact formed in a magnetic field. FIG. 2 is a diffraction pattern obtained by performing X-ray diffraction on two surfaces perpendicular to the direction of the applied magnetic field during molding.

The Pr ₂ (Co _0.93 Ti _0.07 ) ₁₇ intermetallic compound has a rhombohedral crystal structure of Th ₂ Zn ₁₇ type, and its lattice constant, c / a ratio, and unit cell volume are a = 8.476Å and c = 12.170Å, c / a = 1.4
53, V = 766.5Å is ^3, Pr ₂ Co ₇ intermetallic compound without the addition of Ti (a = 8.415Å, c = 12.170Å, c / a = 1.446Å, V = 746.
3Å ³ ) It has a larger c / a ratio and unit cell. Comparing the diffraction patterns for each plane, the relative intensity of the diffraction peak from the (006) plane increases in the diffraction pattern for the vertical plane.
Conversely, in the diffraction pattern for the parallel plane, the relative intensity tails of the diffraction peaks from both the (300) and (220) surfaces increase. From these facts, the Pr ₂ (Co _0.93 Ti _0.07 ) ₁₇ intermetallic compound has a rhombohedral structure and an easy magnetization direction in the c-axis direction.

Thus, by substituting a part of Co of Pr ₂ Co ₁₇ with Ti, it is possible to change the easy magnetization direction from within the crystal C plane to the c-axis direction. Therefore, Pr ₂ (Co _0.93 T
Since _i0.07 ) ₁₇ has an easy magnetization direction in the crystal c-axis direction, this material is extremely useful for application to permanent magnets.

The Curie temperature was determined by measuring the temperature change of the saturation magnetization of the Pr ₂ (Co _0.93 Ti _0.07 ) ₁₇ alloy. Since the Curie of this material is as high as about 800 ° C, it is possible to use it for a wide range of applications because there is little restriction on the operating temperature when considering practical use.

Example 2 Ferromagnetic materials having various compositions represented by Pr ₂ (Co _1-y Ti _y ) ₁₇ (where y is 0.01 to 0.20) were produced in the same manner as in Example 1.

The saturation magnetization of the obtained material of each composition was measured using a VSM at room temperature. FIG. 3 shows a change in saturation magnetization with respect to the composition of Pr ₂ (Co _{1 -y} Ti _y ) ₁₇ . This material has good magnetic properties while allowing a wide solid solution range for Ti.

Also, the direction of easy magnetization of this material is in the above composition range (y: 0.
01 to 0.20) in the crystal c-axis direction.

That is, it can be said that this material is not only useful for application to permanent magnets, but also advantageous in production such as yield.

In addition, this material, when the solid solution amount y of Ti is less than 0.01,
It has an easy magnetization direction in the crystal C plane, and if it is larger than 0.20, it cannot be obtained stably.

(Example 3) Pr ₂ (Co _1-xy Fe _x Ti _y ) was obtained in the same manner as in Examples 1 and _2.
Ferromagnetic materials having various compositions represented by ₁₇ (x is 0 to 1.0, y is 0.01 to 0.20) were produced.

The saturation magnetization of the obtained material of each composition was measured at room temperature using a VSM.

FIG. 4 shows the change in saturation magnetization with respect to the composition of Pr ₂ (Co _1-xy F _x Ti _y ) ₁₇ . In this material, Co can be replaced by Fe, and F
As the content of e increases, the saturation magnetization increases, showing the highest saturation magnetization at about x = 0.7.

It also shows good magnetic properties for the composition of Ti. Since this material has a wide solid solution range not only for Ti but also for Fe and has good magnetic properties, it can be said that it is more advantageous in manufacturing.

(Example 4) the following _{equation, Pr 2 (Co 1-xy} Fe x M y) 17, (M is, V, Cr, Mn, Zr , Nb,
Ferromagnetic materials having various compositions represented by (Mo, Hf, Ta, W) were prepared. Table 1 shows the range of x and y in which the composition compound represented by the above formula is stably present with respect to M.

In addition, this material shows good magnetic properties for the compositions of M, x, and y shown in Table 1.

(Example 5) (Pr _1-x Rx) ₂ (Co _0.93 Ti _0.07 ) ₁₇ (where R is La, Ce, N
d, x were ferromagnetic materials having various compositions represented by 0 to 0.4).

Even when Pr is substituted by R, the composition compound represented by the above formula exists stably and has an easy axis of crystal c-axis.

FIG. 5 shows (Pr _1-x Rx) ₂ (Co _0.93 T
i _0.07) is a diagram showing the saturation magnetization of the composition the compound of _17.

In FIG. 5, good magnetic characteristics are exhibited for any substitution of R. Therefore, it can be said that the present material can be produced without using a highly pure Pr as a raw material without significantly deteriorating the magnetic properties, is advantageous in production, and is superior in cost performance. Further, it can be easily inferred that the present material can be obtained even when two or more kinds of R are substituted.

(Example 6) (Pr _1-x Rx) ₂ (Co _0.93 Ti _0.07 ) ₁₇ (where R is Sm, Gd, T
b, x were ferromagnetic materials having various compositions represented by 0 to 0.3).

Even when Pr is substituted by R, the composition compound represented by the above formula is stably present and has an easy axis of magnetization in the crystal c-axis direction.
FIG. 6 shows that (Pr _1-x Rx) ₂ (Co _0.93 Ti
_0.07 ) It is a figure which shows the saturation magnetization of the composition compound of ₁₇ .

In FIG. 6, the saturation magnetization is reduced for any substitution of R, but the magnetic properties are good enough to be used as a ferromagnetic material. Further, it is presumed that the present material can be obtained even for the substitution of heavy rare earth elements other than R. Further, from Example 5 and the present example, it can be easily inferred that even if a part of Pr is replaced with another rare earth element containing Y, it is possible to obtain the present material having good magnetic properties.

[Effects of the Invention] As described above, according to the present invention, (Pr _1-x R _x ) ₂ T ₁₇ exists in a binary system of a rare earth metal and a transition metal mainly containing Pr.
By adding another element M to a compound (where R is a rare earth element other than Pr containing Y and x is a number from 0 to 0.4),
It has an easy axis of magnetization in the crystal c-axis direction (Pr _1-x −R _x ) ₂ (T
_1-y M _y ) ₁₇ (where T is at least one transition metal of Co and Fe, and M is Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta, W At least one kind, y represents a number of 0.01 to 0.2.) A ferromagnetic material can be obtained, and magnetic properties and cost performance are excellent (Pr _1−x −R _x ) ₂ (T _1−y M _y ) ₁₇ ferromagnetic materials can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an initial magnetization curve of Pr ₂ (Co _0.93 Ti _0.07 ) ₁₇ , and FIGS. 2 (1) and (2) are diagrams showing Pr ₂ − (Co _0.93 Ti _0.07 ) ₁₇
(1) shows a plane perpendicular to the direction of the applied magnetic field, and (2) shows a plane parallel to the direction of the applied magnetic field. FIG. 3 is a diagram showing the saturation magnetization of Pr ₂ (Co _{1 -y} Ti _x ) ₁₇ , FIG. 4 is a diagram showing the saturation magnetization of Pr ₂ (Co _{1 -xy} F _x Ti _y ) ₁₇ , and FIG. FIG. 6 shows the saturation magnetization of (Pr _1-x Rx) ₂ − (Co _0.93 Ti _0.07 ) _17. FIG. 6 shows another example of the saturation magnetization of (Pr _{1 -x} Rx) ₂ (Co _0.93 Ti _0.07 ) _17. Figure 7 shows the conventional RCo ₅ , R ₂ Co ₁₇
FIG. 8 shows an example of the saturation magnetization of a conventional R ₂ (Co _1-x F
It is a diagram showing a magnetization easy axis of the e _{x) 17.}

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Claims (2)

(57) [Claims] 1. The chemical formula: (Pr _1-x R _x ) ₂ (T _{1- y My} ) ₁₇ (where R is at least one kind of rare earth element containing Y other than Pr, and x is 0 to 0.4) T is at least one transition metal of Co and Fe, M is at least one of Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta and W, and y is 0.01 The ferromagnetic material is an intermetallic compound represented by the following formula: 2. The chemical formula, (Pr _1-x R _x ) ₂ (T _{1- y My} ) ₁₇ (where R is at least one of rare earth elements including Y other than Pr, and x is 0 to 0.4) T is at least one transition metal of Co and Fe, M is at least one of Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta and W, and y is 0.01 to 0.2. Which is a rhombohedral intermetallic compound.