JP2014189837A - Method for manufacturing high-purity neodymium, high-purity neodymium, sputtering target comprising high-purity neodymium, and rare earth magnet using high-purity neodymium as component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of providing, both efficiently and stably, a high-purity neodymium, a sputtering target comprising a high-purity neodymium, and a thin film for a rare earth magnet using a high-purity neodymium as a component.SOLUTION: In a method for manufacturing a high-purity neodymium having a gas component-excluded purity of 4N5 or higher, a neodymium batch having a purity of 4N or higher is prepared by reducing, with distilled calcium, a raw neodymium fluoride ingredient having a gas component-excluded purity of 4N or higher, and after the neodymium has been skull-melted and then cooled gradually so as to prepare a neodymium ingot, the obtained skull ingot is cut so as to remove therefrom a bottom portion in which a segregated oxide layer segment exists, and the remaining neodymium ingot is melted with electron beams so as to remove therefrom volatile substances. The method for manufacturing a high-purity neodymium stipulates a C content of 100 wt.ppm or less, an O content of 50 wt.ppm or less, Al and Fe contents of 10 wt.ppm or less each, and a Cu content of 1 wt.ppm or less.

Description

  The present invention relates to a method for producing high-purity neodymium, a high-purity neodymium, a sputtering target composed of high-purity neodymium, and a rare earth magnet containing high-purity neodymium as a component.

Neodymium (Nd) is contained in rare earth elements, but is contained in the earth's crust as a mixed complex oxide as a mineral resource. Since rare earth elements were separated from relatively rare (rare) minerals, they were named as such, but they are not rare when viewed from the entire crust.
Neodymium is a silver-white metal with an atomic number of 60 and an atomic weight of 144.2.9, and has a hexagonal close-packed structure at room temperature. The melting point is 1020 ° C., the boiling point is 3100 ° C., the density is 6.80 g / cm ³ , the surface is oxidized in air, and it is gradually dissolved in water. It is soluble in hot water and acid and has ductility and malleability. The resistivity is 64.0 × 10 ⁻⁶ Ωcm (see Riken).

In recent years, research and development of rare earth magnets using neodymium has been actively carried out (see Patent Documents 1 to 3), and since they have excellent magnetic properties, automobiles, home appliances, IT equipment, industrial equipment, medical equipment, energy equipment. Applications to a wide range of fields are expected.
By the way, miniaturization and high performance are demanded as next-generation rare earth magnets. In such a case, the influence of impurities contained in the neodymium metal on the magnetic properties is not small. In general, neodymium metal has a problem that it is easily oxidized during refining, so that it is difficult to achieve high purity, and high purity products have not existed. Further, when neodymium metal is left in the air, it is oxidized and discolored in a short time, so that there is a problem that handling is not easy.

As a method for purifying rare earth metals, a technique of reducing a rare earth metal halide with calcium or calcium hydride has been proposed about 20 years ago. Among them, there is a description of neodymium as an example of rare earth, but as a means for separating slag, it is a technique to the extent that a slag separation jig is used, and there is little disclosure about problems and purification means possessed by neodymium metal elements. (See Patent Document 4).

Thus, it can be said that neodymium metal is still in the research stage. When examining the characteristics of such neodymium metal, if the neodymium metal itself is present as a sputtering target material, a neodymium thin film can be formed on the substrate, and a rare earth magnet (Nd—Fe—B system) can be formed. It is easy to study the characteristics of a high coercivity rare earth magnet and to increase the degree of freedom as a product.

However, even if a neodymium sputtering target is produced, it is oxidized in the air in a short time (in about 10 minutes) as described above. If an oxide film is formed on the target, the magnetic characteristics may be deteriorated and a sputtering defect may be caused. Further, if left in the air for a long time, it reacts with moisture in the air and is covered with a white powder of hydroxide, and there is even a problem that normal sputtering cannot be performed.
For this reason, it is necessary to immediately vacuum-pack or prepare an anti-oxidation measure after covering the target with oil or fat, which is a very complicated operation. Due to such problems, the target material for neodymium elements has not yet been put into practical use.

Further, when a film is formed by sputtering using a neodymium target, generation of protrusions (nodules) on the target surface is a problem. This protrusion induces abnormal discharge, and particles are generated due to the burst of the protrusion (nodule).
The generation of particles causes the magnetic properties of the rare earth magnet to deteriorate. Since carbon (graphite) contained in neodymium is a solid matter, it is a particular problem. Since this carbon (graphite) has conductivity, it is difficult to detect and is required to be reduced.

Furthermore, neodymium is a material that is difficult to purify as described above, but in addition to the above carbon (graphite), the content of Al, Fe, and Cu is also reduced in order to strictly control the magnetic properties. Is preferred. In addition, since alkali metals and alkaline earth metals, transition metal elements, refractory metal elements, and radioactive elements may also affect magnetic properties, reduction is desired. For these reasons, the purity of neodymium is desired to be 4N5 or higher.

However, there is a problem that it is very difficult to remove rare earth elements other than neodymium contained in neodymium. In general, since rare earth elements have similar properties, some contamination is not a problem, but the present invention provides a method capable of reducing rare earth elements excluding neodymium.
Further, some mixing of gas components does not cause a big problem. In addition, since the gas component is generally difficult to remove, it is common to exclude this gas component in the purity display.

Thus, problems such as the characteristics of neodymium, the production of high-purity neodymium, the behavior of impurities in the neodymium target, and the like have not been sufficiently known. Therefore, it is desired to solve the above problems as soon as possible.

JP 2000-331810 A JP-A-6-231921 Japanese Patent Laying-Open No. 2005-50002 JP 63-11628 A

The present invention provides a manufacturing method of high-purity neodymium, high-purity neodymium, a sputtering target prepared using this high-purity neodymium, and a technique capable of stably providing a rare-earth magnet thin film formed using the sputtering target. This is the issue.

In the present invention, a raw material of neodymium fluoride having a purity excluding gas components of 4N or more is reduced with distilled calcium to produce neodymium having a purity of 4N or more, and this neodymium is induced by dissolution using a water-cooled copper crucible (skull Melting), and then gradually cooling to room temperature to agglomerate the segregated oxide that tends to occur inside the ingot at the bottom of the ingot, and put the segregated layer of oxide over the ingot from the top of the ingot. Next, the ingot obtained by dissolving the skull is cut to remove the segregation layer of oxide existing at the bottom of the ingot, and then the neodymium is dissolved by an electron beam to remove volatile substances. By removing it, a method for producing high-purity neodymium having a purity of 4N5 or higher excluding gas components is provided.

Thereby, the purity excluding gas components is 4N5 or more, aluminum (Al) and iron (Fe) in neodymium are each 10 wtppm or less, copper (Cu) is 1 wtppm or less, and rare earth elements other than neodymium High-purity neodymium having a total of 100 wtppm or less can be obtained. Furthermore, high-purity neodymium having C of 100 wtppm or less and O of 50 wtppm or less is provided.

The above high purity neodymium is a novel substance, and the present invention includes this. When used as a rare earth magnet, an Nd—Fe—B film is used. When such a film is formed, a neodymium metal with high purity is required to increase the degree of freedom in forming the film. The present invention can provide a material suitable for this.

In addition to neodymium (Nd), rare earth elements contained in neodymium include Sc, Y, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. However, due to the similar characteristics, it is difficult to separate and purify from Nd. In particular, since Pr is approximated to Nd, it is not easy to reduce Pr.
In general , a certain amount of rare earth element is allowed. However, in order to make use of the characteristics of neodymium elements, it can be said that the content of rare earth elements other than neodymium is preferably 100 wtppm or less, more preferably 10 wtppm or less. However, the main subject of the present invention is to make the purity excluding gas components 4N5 or more.

The neodymium of the present invention contains C, N, O, S, and H as gas components. These may exist as a single element, but may exist in the form of a compound (CO, CO ₂ , SO ₂ etc.) or a compound with a constituent element. Since these gas component elements have a small atomic weight and atomic radius, even if they are present as impurities, they do not significantly affect the properties of the material unless they are contained in large amounts. Therefore, when displaying the purity, it is usual to use the purity excluding the gas component. In this sense, the purity of neodymium according to the present invention excludes gas components.
However, since the presence of a large amount of gas components is not preferable, as will be described later, the total amount of gas components such as carbon, oxygen, nitrogen, sulfur, and hydrogen is set to 500 wtppm or less as necessary.

Furthermore, high-purity neodymium in which the total amount of W, Mo, and Ta is less than 10 wtppm is provided. Since these are impurities that lower the magnetic properties, they are desirable elements to be reduced as much as possible. The premise of the present invention is to produce 4N5 or higher purity neodymium.

This invention can provide the rare earth magnet formed into a film using the sputtering target manufactured using said high purity neodymium, and this sputtering target.
When used as a rare earth magnet, Nd, Fe, and B are essential components. If necessary, rare earth elements such as Dy, Pr, Tb, Ho, and Sm, and transition metals such as Co, Cu, Cr, and Ni are used. Known elements of rare earth magnets such as elements and typical metal elements such as Al can be added. The present invention can provide a material suitable for this, and the high-purity neodymium of the present invention includes any combination with other substances during the production of the target.

The high-purity neodymium obtained as described above can greatly reduce gas components, and the total amount of gas components such as carbon, oxygen, nitrogen, sulfur, and hydrogen can be 500 wtppm or less. Furthermore, several to several tens of ppm of Ca remaining during Ca reduction can be removed by melting the ingot with an electron beam.
The ingot thus produced can be further cut into a predetermined size and made into a sputtering target through a polishing process. Thereby, the purity excluding gas components is 4N5 or more, and as residual impurities, C is 100 wtppm or less, O is 50 wtppm or less, aluminum (Al), and iron (Fe) are each 10 wtppm or less, and copper (Cu) However, it is 1 wtppm or less, and the high purity neodymium target whose total of rare earth elements other than neodymium is 100 wtppm or less can be manufactured.

Furthermore, a thin film of a rare earth magnet (Nd—Fe—B magnet) can be obtained by sputtering using the above target. These sputtering targets, rare earth magnets, and magnetic devices using these are all novel materials, and the present invention includes them.

The present invention relates to a method for producing high-purity neodymium, high-purity neodymium, a sputtering target prepared using this high-purity neodymium, a rare-earth magnet film formed using the sputtering target, and a magnetic device including the rare-earth magnet film. It has an excellent effect that it can be provided stably.

In the present invention, a neodymium fluoride raw material having a purity excluding gas components and a purity of 4N or more can be used as a high-purity neodymium raw material. These raw materials contain Na, Ca, Mg, Al, Si, Fe, Cr, Mn, La, Ce, Pr, Sm, gas components (N, O, C, H) and the like as main impurities. Yes.

Since aluminum (Al), iron (Fe), and copper (Cu) contained in neodymium are sometimes used as components of rare earth magnets, if these impurities are contained in a large amount, it may cause composition fluctuations that affect magnetic properties. In some cases, desired magnetic properties may not be obtained. In addition, iron (Fe) contained in neodymium tends to oxidize, which causes spatter failure when used as a target. Furthermore, if it is oxidized after being sputtered even if it is not oxidized in the target, the volume expands. Therefore, it may cause a deterioration of magnetic characteristics, and it is necessary to reduce this.

Moreover, calcium is reduced using neodymium fluoride as a neodymium raw material, but Fe, Al, and Cu are mixed as impurities in the calcium that is the reducing material, so that impurities from the calcium reducing material may be mixed in. There is. For this reason, it is desirable to reduce using distilled calcium whose Cu is less than 1 ppm (this amount is the usual lower limit of detection). Table 1 shows a comparison of analytical values of commercially available Ca and distilled Ca. Here, distilled Ca means a product obtained by distilling and purifying commercially available Ca at least once in a vacuum atmosphere. In the commercially available Ca in Table 1, Cu is as high as 95 wtppm, and when this commercially available Ca is used, the risk of Cu contamination increases.

(Calcium reduction)
A melting crucible used for the reduction is a tantalum (Ta) crucible. In this tantalum crucible, powdered NdF ₃ and massive Ca are mixed and charged. Usually, Ca, which is a reducing material, is added in excess of about 10% from the calculated amount.
The filling in the tantalum crucible placed in the reducing device is slowly heated to 600 ° C., and during this time, the inside of the reducing device is evacuated to degas the filling. Thereafter, purified argon gas is fed in to 0.5 atm.

Further heating is performed, but the reaction starts when the packing is heated to 900 ° C. to 1100 ° C. The reaction formula is 2NdF ₃ + 3Ca → 2Nd + 3CaF ₂ . This reaction is exothermic and completes quickly. In order to improve separation of the refined metal Nd and slag containing CaF ₂ as main components, it may be maintained at a temperature about 50 ° C. higher than the melting point of Nd metal for several minutes.
The yield of metal Nd reaches about 97%. The main impurities are unreacted reducing material and slag. In addition, since Ta which is a crucible material may be mixed as an impurity, it is desirable to carry out the reduction reaction at a temperature as low as possible. In this way, metal Nd is obtained.

(Skull melting, slow cooling, machining)
By the way, the neodymium metal obtained in this way has the problem that oxygen content which is a gas component is high other than Ca which remains. Oxygen not only degrades magnetic properties when used as a rare earth magnet, but also causes spatter abnormalities such as arcing during sputtering, and as a factor impeding the formation of a uniform film, it should be reduced as much as possible. Is desirable.
In the present invention, in particular, in induction melting (skull melting) using a water-cooled copper crucible, when this is gradually cooled, most of the oxygen floating in the melt of neodymium is gradually oxidized and stays at the bottom of the furnace. Thus, it is important that the oxygen concentration inside the neodymium ingot can be significantly reduced.

Skull melting is performed under conditions in a vacuum atmosphere of 1 Pa or less by filling metal Nd as a raw material every 0.5 to 10 kg according to the size of the furnace to be used. After confirming that the raw material has melted from the viewing window attached to the furnace, hold it for a certain period of time, and then gradually reduce the output and perform slow cooling.
The slow cooling time varies depending on the capacity of the skull melting furnace, so it cannot be determined uniquely, but the correlation between the actual melting slow cooling time and the oxygen concentration of the neodymium ingot can be understood. Can be determined empirically. As described above, in the present invention, the concept that slow cooling is introduced and this leads to a decrease in oxygen concentration is particularly important. The slow cooling can be performed, for example, by a method of gradually reducing the output over 30 minutes.

And in the ingot obtained by skull dissolution, the oxygen concentration contained in an ingot can be remarkably reduced by removing the bottom portion (oxide segregation layer) of the ingot where the oxide is segregated by cutting. At this time, it is possible to remove rare earth elements other than neodymium such as Y and Sc, which are easily oxidized, and Er having a large specific gravity of oxide.
The oxide segregation layer can be easily confirmed by cutting a skull dissolution ingot and visually observing the cut surface.

(Electron beam melting)
The electron beam melting of the neodymium obtained above is carried out by irradiating the neodymium melting raw material in the furnace over a wide range. This electron beam melting can be repeated several times (2 to 4). As described above, the electron beam melting is repeatedly performed on the melting raw material over a wide range, thereby further improving the removability of high vapor pressure component elements such as Ca, Mg, Mn, and Pb.

When the output is increased, there is an effect that the residual oxygen reacts with C, and the carbon mixed in neodymium is removed as CO or CO ₂ gas. In addition, W, Mo, and Ta cause deterioration in magnetic characteristics. Therefore, when used as a magnetic device, the total amount thereof is set to less than 10 wtppm.

As described above, rare earth elements are generally excluded from the purity of high-purity neodymium, that is, high-purity neodymium is allowed to contain rare earth elements. It is technically difficult to remove due to the similar characteristics, and due to the closeness of this characteristic, even if it is mixed as an impurity, the fact that a large variation in characteristic has not been confirmed. Is based.
Under such circumstances, the contamination of other rare earths is tolerated to some extent, but it is needless to say that it is desirable to reduce the amount when neodymium itself is to improve its characteristics. In the present invention, the total of rare earth elements other than neodymium can be 100 wtppm or less. This is one of the remarkable features of the present invention.
Further, the reason why the purity excluding the gas component is 4N5 or more is that it is difficult to remove the gas component, and counting this does not serve as a measure for improving the purity. In general, the presence of some amount is harmless compared to other impurity elements.

When forming a thin film of a rare earth magnet, the sputtering method is an excellent method for forming a thin film. Therefore, it is effective to produce a high purity neodymium sputtering target using the above neodymium ingot.
The target can be manufactured by normal processing such as forging, rolling, cutting, and finishing (polishing). In particular, the manufacturing process is not limited and can be arbitrarily selected.

From the above, the purity excluding gas components is 4N5 or more, C is 100 wtppm or less, O is 50 wtppm or less, aluminum (Al) and iron (Fe) are each 10 wtppm or less, and copper (Cu) is 1 wtppm or less. In addition, a high-purity neodymium having a total content of rare earth elements other than neodymium of 100 wtppm or less and a total content of W, Mo, Ta (crucible) of less than 10 wtppm can be obtained.
When manufacturing the target, the high-purity neodymium ingot is cut into a predetermined size, and this is cut and polished.

Further, high-purity neodymium can be deposited on the substrate by sputtering using this high-purity target. Thus, the purity excluding gas components is 4N5 or more, C is 100 wtppm or less, O is 50 wtppm or less, aluminum (Al) and iron (Fe) are each 10 wtppm or less, and copper (Cu) is 1 wtppm or less. In addition, a neodymium thin film containing high-purity neodymium as a component in which the total of rare earth elements other than neodymium is 100 wtppm or less can be formed on the substrate. The film on the substrate reflects the composition of the target, and a high-purity neodymium film can be formed.

The rare earth magnet can be used as the high-purity neodymium itself, but can also be formed as a mixture, alloy or compound with other magnet materials.
In this case, it can be achieved by simultaneous sputtering of the neodymium target material manufactured according to the present invention and another magnetic material target, or by sputtering using a mosaic target made of the neodymium and other magnetic material of the present invention. . The present invention includes these. The content of impurities varies depending on the amount of impurities contained in the raw material, but by adopting the above method, each impurity can be adjusted within the above numerical range.
This invention provides the technique which can provide the high purity neodymium obtained by the above, the sputtering target which consists of high purity neodymium, and the thin film for rare earth magnets which has high purity neodymium as a main component efficiently and stably.

  Next, examples will be described. In addition, this Example is for understanding easily and does not restrict | limit this invention. That is, other embodiments and modifications within the scope of the technical idea of the present invention are included in the present invention.

Example 1
As a raw material of neodymium to be processed, a raw material of neodymium fluoride having a purity of 4N was used. Metal neodymium is a material that has recently been attracting attention, but commercially available metal neodymium has a problem that its purity is low and its quality is not constant.
On the other hand, for neodymium fluoride, it is possible to obtain a high-purity material even with a commercial product. However, since this neodymium fluoride cannot be used as it is, it is necessary and important to use this neodymium fluoride raw material having a purity of 4N to produce high-purity metal neodymium efficiently and stably.

Table 2 shows analytical values of the neodymium fluoride raw material. Among these, the following elements can be mentioned as impurities contained abundantly. Na: 2.2 wtppm, Al: 2.5 wtppm, Si: 7.5 wtppm, Cl: 100 wtppm, Cu: <1 wtppm, Zn: <0.5 wtppm, C: 160 wtppm, N: 440 wtppm, O: 9.1 wt%, H : 1.1 wt%, containing many gas components.
On the other hand, about rare earth elements, they are Ce: 8.6 wtppm, Pr: 40 wtppm, Sm: 5.5 wtppm, etc., and these impurities are also comparatively few. The use of a raw material having a relatively low rare earth element in this way is effective for a purity of 4N5 including rare earths (excluding neodymium).

(Calcium reduction of raw material)
The melting crucible used for the reduction was a tantalum (Ta) crucible. In this tantalum crucible, powdered NdF ₃ : 14.0 kg and massive Ca: 4.6 kg were mixed and charged. Ca which is a reducing material was distilled Ca having an analytical value shown in Table 1 and was added in excess of about 10% from the calculated amount.
The filler in the tantalum crucible placed in the reducing apparatus was slowly heated to 600 ° C. During this time, the filling was degassed while evacuating the reducing apparatus. Thereafter, purified argon gas was introduced to a pressure of 0.5 atm.

The heating temperature was further increased. When the charge was heated to 900-1100 ° C., the reaction started. The reaction formula is 2NdF ₃ + 3Ca → 2Nd + 3CaF ₂ . This reaction was exothermic and completed quickly. In order to improve separation of the refined metal and the slag, the temperature was maintained at a temperature about 50 ° C. higher than the melting point of the Nd metal. Since the melting point of Nd is 1020 ° C., the heating temperature was adjusted to + 50 ° C., ie 1070 ° C. In this way, metal Nd is obtained.

Table 3 shows analytical values of metal Nd. As shown in Table 3, Al: 2.7 wtppm, Si: 8.1 wtppm, Ca: 0.8 wtppm, Fe: 5.3 wtppm, Cu: <0.05 wtppm, Mo: <0.05 wtppm, Ta: <5 wtppm , W: <0.1 wtppm, C: 110 wtppm, N: 100 wtppm, O: 440 wtppm, S: <10 wtppm, H: 10 wtppm.
Although it was a result by Ca reduction, there was much Ca and oxygen (O) content was also high.

(Skull melting, slow cooling, machining)
For skull dissolution, a φ80 mm water-cooled copper crucible was used. Then, the above-mentioned calcium-reduced neodymium metal was dissolved at an output of 50 kW. Next, it was confirmed that the entire amount of neodymium was dissolved from the viewing window, and was held for 30 minutes after dissolution, and then the output was reduced stepwise and finally the output was turned off. The slow cooling can be finely adjusted depending on the scale of the apparatus used. Thereby, an oxide can be segregated at the bottom of the ingot, and the oxygen concentration in the ingot can be reduced by removing the oxide segregation layer by machining (cutting).

(Electron beam melting)
Next, the neodymium obtained by cutting and removing the oxide segregation layer at the bottom of the ingot after the skull dissolution was subjected to electron beam melting. Electron beam (EB) melting is performed by irradiating the neodymium raw material in the furnace over a wide range with a low-power electron beam. The EB dissolution time is 30 minutes. This produced an EB melted ingot. At the time of EB dissolution, highly volatile component elements were volatilized and removed.

By the above, high purity neodymium was able to be manufactured. Table 4 shows analytical values of the high purity neodymium after the electron beam melting. As shown in Table 4, Al: 2.2 wtppm, Si: 6.5 wtppm, Ca: <0.01 wtppm, Fe: 4.5 wtppm, Cu <0.05 wtppm, Zn <0.05 wtppm, Mo <0.05 wtppm Ta <5 wtppm, W: <0.1 wtppm, C: 80 wtppm, N: 100 wtppm, O: 40 wtppm, S <10 wtppm, H: <10 wtppm. All were satisfied and the conditions of the present invention were satisfied.

In addition, residual Ca that could not be reduced when calcium was reduced could be greatly reduced. In the present example, since high-purity neodymium fluoride having a rare earth element other than neodymium of 100 wtppm or less was used in the selection of raw materials, neodymium after electron beam melting could be similarly set to 100 wtppm or less. .

The neodymium ingot thus obtained was hot-pressed as necessary, further machined (forged, rolled, cut) and polished to obtain a disk-shaped target of φ140 mm × 6 mmt. The weight of this target was 330 g. This is further bonded to a backing plate to obtain a sputtering target. As a result, a high-purity neodymium sputtering target having the above component composition could be obtained. In addition, since this target has high oxidizability, it can be said that it is preferable to store or transport it by vacuum packing.

(Comparative Example 1)
As a raw material for neodymium, a commercial product having a purity of 2N5 to 3N shown in Table 5 was used. The commercially available neodymium used in Comparative Example 1 is a 50 mm square × 30 mmt plate. The weight of one sheet was 500 to 600 g, and three sheets of this material, 1.7 kg in total, were used.

  The main impurities shown in Table 5 are Li: 51 wtppm, Na: 1.5 wtppm, Mg: 5.9 wtppm, Al: 63 wtppm, Si: 92 wtppm, Ti: 29 wtppm, Cr: 32 wtppm, Mn: 11 wtppm, Fe: It was 0.25 wt%, Cu: 11 wtppm, Zn: 0.65 wtppm, C: 390 wtppm, N: <10 wtppm, O: 74 wtppm, S: 24 wtppm, H: <10 wtppm.

Next, EB dissolution was performed under the same conditions as in the example. At the time of EB dissolution, highly volatile component elements were volatilized and removed.
As a result, 1.7 kg of high-purity neodymium ingot could be produced. Table 6 shows analytical values of the high-purity neodymium thus obtained.

As shown in Table 6, the main impurity elements in neodymium after electron beam melting are as follows. Li: <0.005 wtppm, Na: <0.05 wtppm, Mg: <0.05 wtppm, Al: 82 wtppm, Si: 77 wtppm, Ti: 33 wtppm, Cr: 25 wtppm, Mn: 0.45 wtppm, Fe: 0.28 wt%, Cu: 31 wtppm, Zn: <0.05 wtppm, C: 440 wtppm, N: 120 wtppm, O: 130 wtppm, S: 33 wtppm, H: 20 wtppm.
As is clear from the above, Al and Fe could not be reduced, and the gas components were not sufficiently reduced. Overall, the amount of impurities was larger than in the above-described example, and the object of the present invention could not be achieved.

High-purity neodymium obtained by the present invention, sputtering target prepared from high-purity neodymium, and thin film for rare-earth magnets comprising high-purity neodymium as a component exhibit particularly good magnetic properties as a magnetic device, such as thin-film for rare-earth magnets Useful as.

Claims (12)

A raw material of neodymium fluoride having a purity excluding gas components of 4N or more is reduced with distilled calcium to produce neodymium having a purity of 4N or more, and after this reduced neodymium is skull-dissolved, it is gradually cooled to produce an ingot. Next, the obtained skull ingot is cut to remove the segregation layer of oxide existing at the bottom of the ingot, and this is then dissolved by an electron beam to remove volatile substances. A method for producing high-purity neodymium having a purity of 4N5 or higher. The method for producing high-purity neodymium according to claim 1, wherein C is 200 wtppm or less, O is 50 wtppm or less, Al and Fe are each 10 wtppm or less, and Cu is 1 wtppm or less. . The method for producing high-purity neodymium, wherein the total amount of W, Mo, and Ta is less than 10 wtppm.   The method for producing high-purity neodymium according to any one of claims 1 to 3, wherein the rare-earth elements other than neodymium are 100 wtppm or less in total.   It is a manufacturing method of high purity neodymium, Comprising: A gas component shall be 500 wtppm or less in total amount, The manufacturing method of high purity neodymium as described in any one of Claims 1-4 characterized by the above-mentioned. A high-purity neodymium having a purity of 4N5 or higher excluding gas components, C of 100 wtppm or less, O of 50 wtppm or less, and Al, Fe, and Cu each of 10 wtppm or less. The high-purity neodymium according to claim 6, wherein the total amount of W, Mo, and Ta is less than 10 wtppm.   The high purity neodymium according to claim 6 or 7, wherein the high purity neodymium is a total amount of rare earth elements other than neodymium being 100 wtppm or less.   It is high purity neodymium, Comprising: A gas component is 500 wtppm or less in total amount, The high purity neodymium as described in any one of Claims 6-8 characterized by the above-mentioned. The sputtering target produced using the high purity neodymium as described in any one of Claims 6-9. A rare-earth magnet thin film formed using the sputtering target according to claim 10.   A magnetic device comprising the rare earth magnet thin film according to claim 11.