JP2021066898A - Gallium production method, sodium production method, and gallium nitride production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing gallium nitride by a Na flux method capable of cyclically reusing Na and Ga. Ga is separated and recovered from the Na—Ga alloy remaining after the growth of GaN crystals by the Na flux method is completed. Place Na-Ga alloy and HTf2N (bis (trifluoromethanesulfonyl) amide) in a container. The container is then heated to melt HTf2N. When the melt of HTf2N comes into contact with the Na-Ga alloy, the HTf2N reacts with the Na-Ga alloy to dissolve Na and partially form NaTf2N, and Ga separates as a liquid metal. Next, using low-purity Na remaining after the completion of growth of the GaN crystal by the Na flux method as an anode and an electrolytic solution, a mixture of NaTf2N recovered in the separation step of Ga and a non-metal salt of Tf2N anion prepared separately was used for electricity. Sodium is precipitated on the anode by decomposition. [Selection diagram] Fig. 1

Description

The present invention relates to a method for producing gallium, which separates gallium from an alloy of gallium and sodium. The present invention also relates to a method for producing sodium, which separates sodium from an alloy of gallium and sodium. The present invention also relates to a method for producing gallium nitride by the Na flux method.

As a method for crystal growth of GaN (gallium nitride), a Na flux method is known in which nitrogen is dissolved in a mixed melt of Na (sodium) and Ga (gallium) and GaN is epitaxially grown in a liquid phase. After growing a group III nitride semiconductor by the Na flux method, in addition to the grown GaN crystals, Na-Ga alloy, low-purity Na, etc. remain.

Patent Document 1 describes that the Na-Ga alloy remaining after GaN growth by the Na flux method is put into water or nitric acid heated to 50 to 90 ° C. to recover the separated metal Ga.

International Publication No. 2015/141604

In order to reduce the cost of the GaN growing method by the Na flux method, it is indispensable to reuse the Na-Ga alloy and low-purity Na remaining after growing.

However, both Ga and Na are base metals, and it was difficult to recover them by electrodeposition in an aqueous solution system. In the method of Patent Document 1, it is possible to separate and recover Ga from the Na—Ga alloy, but it is difficult to recover the Na component because Na is present as Na ions in the aqueous solution. , It was difficult to recycle Ga and Na cyclically and inexpensively.

Therefore, an object of the present invention is to provide a method capable of easily separating Ga from a Na—Ga alloy and easily separating Na as well.

In the first aspect of the present invention, the Na—Ga alloy is represented by the general formula H (X ¹ SO ₂ ) (X ² SO ₂ ) N, where X ¹ and X ² are fluorine or an alkyl group having 1 to 6 carbon atoms. This is a method for producing gallium, which comprises separating gallium from a Na—Ga alloy by contacting a solution containing a fluorine-containing sulfonylamide.

The fluorine-containing sulfonylamide can be _{HTf 2 N.}

The solution may be a fluorine-containing sulfonylamide aqueous solution or a fluorinated sulfonylamide melt.

As the Na—Ga alloy, an alloy that remains after the growth of gallium nitride by the Na flux method may be used.

A second aspect of the present invention is a method for producing sodium in which sodium is precipitated on the cathode by electrolysis with the anode as low-purity sodium, and the general formula H (X ¹ SO ₂ ) (X ² SO ₂ ) N is used as the electrolytic solution. , X ¹ and X ² are a mixture of a sodium salt of fluorine-containing sulfonylamide, which is an alkyl group having 1 to 6 carbon atoms, and a non-metal salt of fluorine-containing sulfonylamide, and the electrolyte solution contains fluorine. This is a method for producing sodium, which comprises recovering and using the sodium salt of fluorine-containing sulfonylamide produced in a solution by the method for producing gallium according to the first aspect of the present invention as the sodium salt of sulfonylamide.

As the low-purity sodium of the anode, those remaining after the growth of gallium nitride by the Na flux method can be used.

A third aspect of the present invention is a method for producing gallium nitride, which comprises growing gallium nitride by the Na flux method using gallium produced by the method for producing gallium according to the first aspect of the present invention.

A fourth aspect of the present invention is a method for producing gallium nitride, which comprises growing gallium nitride by the Na flux method using sodium produced by the method for producing sodium according to the second aspect of the present invention.

A fifth aspect of the present invention is gallium nitride produced by the Na flux method using gallium produced by the method for producing gallium according to the first aspect of the present invention and sodium produced by the method for producing sodium according to the second aspect of the present invention. It is a method for producing gallium nitride, which is characterized by growing gallium nitride.

According to the present invention, Ga can be easily separated from the Na—Ga alloy, and Na can also be easily separated. Further, according to the present invention, Ga and Na can be recycled and inexpensively reused in the Na flux method, and the cost can be significantly reduced.

The figure which schematically showed the reuse of Ga and Na in 1st Embodiment. The figure which showed the flowchart of 1st Embodiment. The figure which showed the structure of the crystal growth apparatus. A photograph of Ga separated and recovered from the Na-Ga alloy.

(First Embodiment)
The first embodiment is a method for producing GaN in which GaN is grown by the Na flux method. Ga and Na are separated from low-purity Na or Na—Ga alloy remaining after the growth and reused cyclically in the Na flux method. This is a method for manufacturing GaN. FIG. 1 is a diagram schematically showing a flow of reuse of Ga and Na. Further, FIG. 2 is a diagram showing the process of the first embodiment by a flowchart. As shown in FIG. 1, the first embodiment includes a Na flux method step S1, a Ga separation step S2, and a Na electrorefining step S3.

(Outline of Na flux method)
First, the outline of the Na flux method will be described. The Na flux method is a method in which a gas containing nitrogen is supplied and dissolved in a mixed melt containing Na as a flux and Ga as a raw material, and GaN is epitaxially grown in a liquid phase. As Ga, those separated in the Ga separation step of the first embodiment can be used. Further, as Na, those separated in the electrolytic refining step of Na of the first embodiment can be used.

C (carbon) may be added to the mixed melt. By adding C, the crystal growth rate can be increased. In addition, the mixed melt contains materials other than C for the purpose of controlling physical properties such as the conduction type and magnetism of group III nitride semiconductors for crystal growth, promoting crystal growth, suppressing miscellaneous crystals, and controlling the growth direction. Dopants may be added. For example, Ge (germanium) or the like can be used as the n-type dopant, and Mg (magnesium), Zn (zinc), Ca (calcium) or the like can be used as the p-type dopant.

The gas containing nitrogen is a gas of a nitrogen molecule or a compound containing nitrogen such as ammonia as a constituent element, and may be a mixed gas thereof, and further, a gas containing nitrogen is mixed with an inert gas such as a rare gas. May be.

In the Na flux method, GaN is grown on the seed substrate using a seed substrate (seed crystal). The seed substrate may be placed in the mixed melt before being heated or pressurized, or may be placed in the mixed melt after reaching the growth temperature and the growth pressure by heating and pressurizing. As the seed substrate, a self-standing substrate made of GaN or a template substrate can be used.

The template substrate has a configuration in which a GaN layer having a c-plane as a main surface is formed via a buffer layer on a base substrate as a base. The base substrate is sapphire, ZnO, spinel, or the like. The GaN layer may be grown by any method such as the MOCVD method, the HVPE method, and the MBE method, but the MOCVD method and the HVPE method are preferable in terms of crystallinity and growth time.

(Structure of crystal growth device)
Next, as the configuration of the crystal growth apparatus used in the Na flux method, for example, the crystal growth apparatus 1000 having the following configuration is used.

FIG. 3 is a diagram showing the configuration of the crystal growth apparatus 1000. As shown in FIG. 3, the crystal growth apparatus 1000 includes a pressure vessel 1100, a pressure vessel lid 1110, an intermediate chamber 1200, a reaction chamber 1300, a reaction chamber lid 1310, a rotary shaft 1320, a turntable 1330, and the like. It has a side heater 1410, a lower heater 1420, a gas supply port 1510, a gas exhaust port 1520, and a vacuum drawing exhaust port 1530.

The pressure vessel 1100 is a housing of the crystal growth apparatus 1000. The pressure vessel lid 1110 is arranged at a position vertically below the pressure vessel 1100. The intermediate chamber 1200 is a chamber inside the pressure vessel 1100. The reaction chamber 1300 is a chamber for accommodating the crucible CB1 and growing a GaN crystal inside the crucible CB1. The reaction chamber lid 1310 is a lid of the reaction chamber 1300.

The rotation shaft 1320 can rotate forward and negatively. The rotary shaft 1320 can be rotationally driven by a motor (not shown). The turntable 1330 can rotate around the rotation shaft 1320. The side heater 1410 and the lower heater 1420 are for heating the reaction chamber 1300.

The gas supply port 1510 is a supply port for supplying a gas containing nitrogen gas to the inside of the pressure vessel 1100. The gas exhaust port 1520 is for exhausting gas from the inside of the pressure vessel 1100. The evacuated exhaust port 1530 is for evacuating the pressure vessel 1100.

The crystal growth apparatus 1000 can adjust the temperature and pressure inside the crucible CB1 and rotate the crucible CB1. Therefore, inside the crucible CB1, a semiconductor single crystal can be grown from a seed crystal under desired conditions.

(About Na flux method step S1)
Next, a method for producing GaN by the Na flux method using the crystal growth apparatus 1000 (Na flux method step S1) will be described.

First, the atmosphere inside the furnace is replaced with an inert gas, the inside of the furnace is heated, and then the inside of the furnace is evacuated to sufficiently reduce the outgas components such as oxygen in the furnace.

Next, predetermined amounts of Na and Ga are measured in a glove box in which the atmosphere such as oxygen and dew point is controlled. After that, the seed substrate and the weighed predetermined amounts of Na and Ga are charged into the crucible CB1. If necessary, an additive element such as carbon may be added.

Next, the crucible CB1 on which the raw materials are arranged is placed on the turntable 1330 in the reaction chamber 1300, the reaction chamber 1300 is sealed, and the reaction chamber 1300 is further sealed in the pressure vessel 1100. Then, after evacuating the inside of the reaction chamber 1300 and the inside of the pressure vessel 1100, a gas containing nitrogen is supplied to the inside of the reaction chamber 1300 and the inside of the pressure vessel 1100. When the pressure reaches the crystal growth pressure, the temperature inside the furnace is raised to the crystal growth temperature. The crystal growth temperature is, for example, 700 ° C. or higher and 1000 ° C. or lower, and the crystal growth pressure is, for example, 2 MPa or higher and 10 MPa or lower. In the process of raising the temperature, the solid Na and the solid Ga in the crucible CB1 are melted into a liquid to form a mixed melt.

Next, when the temperature in the reaction chamber 1300 reaches the crystal growth temperature, the mixed melt is agitated by rotating the crucible CB1 so that the concentration distribution of Na and Ga in the mixed melt becomes uniform. When nitrogen dissolves in the mixed melt and becomes supersaturated, GaN crystal growth starts from the upper surface of the seed substrate. The stirring may be started before the temperature in the reaction chamber 1300 reaches the crystal growth temperature.

After sufficiently growing GaN crystals on the upper surface of the seed substrate while maintaining the crystal growth temperature and crystal growth pressure, the rotation of the 坩 堝 CB1 is stopped, the GaN crystals are pulled up from the 坩 堝 CB1, and then the heating of the reaction chamber 1300 is stopped. Then, the temperature is lowered to room temperature, the pressure is also lowered to normal pressure, and the growth of the GaN crystal is completed. Then, the crucible CB1 and the grown GaN crystal are taken out from the crystal growth apparatus 1000. Na—Ga alloy and Na remain in the crucible CB1. This residual Na contains some Ga and other impurities and is of low purity. Further, the Na-Ga alloy is _{considered to be Ga 8} Na ₅ or Ga ₄ Na, or a mixture thereof. The GaN crystal may be cooled as it is without being pulled up from the crucible CB1 and taken out together with the Na—Ga alloy in the next step.

Next, in an inert gas atmosphere such as argon, the crucible CB1 is heated to a temperature equal to or higher than the melting point of Na (for example, 100 ° C. or higher) to melt Na, and the melted Na is discharged from the crucible CB1 and recovered. This Na is used in the electrolytic refining step of Na described later. The crucible CB1 may be heated to 900 ° C. or higher to evaporate Na and recover. Then, the Na-Ga alloy remaining in the crucible CB1 is recovered. Na that could not be washed away and Na adhering to the Na—Ga alloy may be removed by treating with water or ethanol.

(About Ga separation step S2)
Next, Ga is separated and recovered from the Na—Ga alloy. The step (Ga separation step S2) will be described. First, the container Na-Ga alloy and hTF ₂ N; add (bis (trifluoromethanesulfonyl) amide 1,1,1-Trifluoro-N [(trifluoromethyl ) sulfonyl] methanesulfonamide). In addition, an inert gas such as argon is supplied into the container and discharged. Then the vessel was heated to melt the hTF ₂ N. Thus, contacting the melt solution and Na-Ga alloy hTF ₂ N. Of course, HTf ₂ N may be melted first, and a Na—Ga alloy may be added to the melt.

The heating temperature is _{arbitrary as long as it is at least the temperature at which HTf 2} N melts, and is, for example, 60 ° C. or higher. However, in order to suppress evaporation of hTF ₂ N, preferably 100 ° C. or less, more preferably 80 ° C. or less.

In _{addition to HTf 2} N, a fluorine-containing sulfonyl amide represented by the following general formula such as _{Hf 2 N (bis (fluoromethanesulfonyl) amide) can be used.} The fluorine-containing sulfonylamide is represented by the general formula H (X ¹ SO ₂ ) (X ² SO ₂ ) N, and X ¹ and X ² are fluorine or an alkyl group having 1 to 6 carbon atoms. It is preferably HTf ₂ N, Hf ₂ N, and more preferably HTf ₂ N.

When the hTF ₂ N thawing liquid and Na-Ga alloy contacts, partially dissolved Na reacts and the hTF ₂ N and Na-Ga alloy NaTf ₂ N (sodium bis (trifluoromethanesulfonyl) amide) Is formed and Ga is isolated as a liquid metal. Moreover, hydrogen is generated by the reaction of hTF ₂ N and Na-Ga alloy. Hydrogen is discharged out of the container together with argon.

When hTF ₂ reaction of N and Na-Ga alloy is completed, cool the hTF ₂ N containers to collect the residue in the vessel. Then, Ga is separated from the residue. The separation of Ga from the residue is carried out, for example, as follows. First, the residue is added to water _{to dissolve unreacted HTf 2} N and then filtered. Next, dried filtrate, filtrate was dissolved NaTf ₂ N was charged such as acetone and filtered. Then, Ga can be separated and recovered by recovering the filter having a metallic luster. Besides, it may be recovered Ga by a method such as flush out hTF ₂ N by heating. _{In addition, NaTf 2} N is recovered by evaporating acetone from the filtrate after Ga separation. The recovered NaTf ₂ N is used in the electrolytic refining step of Na in the next step.

As described above, Ga separated from the Na—Ga alloy has extremely high purity and can be reused as a raw material for the Na flux method.

HTF ₂ N mechanisms of the reaction due to contact between the melt solution and Na-Ga alloy is unknown, it is presumed as follows. In hTF ₂ N melt liquid of a result of the potential difference between the Na and Ga progresses oxidation reaction of Na proceeds and dissolution reaction of Na becomes the driving force, leaves the Na-Ga alloy as Na ^+, Ga peripheral It is probable that the Na component of the substance disappeared and the Ga was separated as a simple substance. Further, it is considered that H ⁺ _{from HTf 2} N was reduced and hydrogen was generated in the vicinity of the Na-Ga alloy. Furthermore, Na ⁺ is HTf ₂ Tf ₂ N from N ^- ionic bonds to NaTf ₂ N is generated, but, Ga reacts with hTF ₂ N and since they are not Ga ions not dissolve in melted liquid of hTF ₂ N It is probable that it was not.

(About the electrolytic refining step S3 of Na)
Next, Na is electrolytically purified using the low-purity Na recovered after the completion of growth of the GaN crystal by the Na flux method and NaTf ₂ N recovered in the Ga separation step, and Na is separated and recovered. The step (Na electrolytic refining step S3) will be described.

In electrolytic refining, low-purity Na recovered after completion of growth of GaN crystals by the Na flux method is used as an anode. Further, as the electrolytic solution, a mixture of NaTf ₂ N recovered in the Ga separation step and a separately prepared non-metal salt of _{Tf 2 N anion is used.} A conductive member or purified sodium is used as the cathode. Then, a DC voltage is applied between the anode and the cathode to deposit sodium on the cathode. The _{reason for using a non-metal salt of Tf 2} N anion is to prevent a decrease in the purity of Na to be purified. When sufficient sodium is deposited on the cathode, the sodium is recovered.

In electrolysis in which the anode is low-purity Na and the electrolyte is _{a non-metal salt of NaTf 2} N and Tf ₂ N anions, sodium has a high ionization tendency, so only sodium elutes from the anode into the electrolyte and other impurities. Does not elute. On the other hand, only sodium ions in the electrolytic solution are precipitated on the cathode. Therefore, high-purity Na can be purified, and the purity can be higher than that of general industrial Na.

The non-metal salts of Tf ₂ N anions, tetraalkylammonium salts of Tf ₂ N anions are preferred. It does not react with sodium, and is to be uniformly mixed with NaTf ₂ N. In particular, _{a tetraethylammonium salt of Tf 2} N anion (tetraethylammonium Tf ₂ N), a _{tetrabutylammonium salt of Tf 2} N anion (tetrabutylammonium Tf ₂ N), or a mixture thereof is preferable. This is because the melting point of the electrolytic solution can be lowered without lowering the durability and safety of the electrolytic solution, and Na can be purified more easily. For example, the melting point of the electrolytic solution can be 70 to 150 ° C.

The above is the _{case where HTf 2} N is used in the separation step S2 of Ga, but more generally, when the fluorine-containing sulfonylamide is used in the separation step S2 of Ga, the fluorine-containing sulfonylamide is used in the electrolytic purification step S3 of Na. And the non-metal salt of the fluorine-containing sulfonylamide thereof may be used as the electrolytic solution.

The molar ratio of the non-metal salt of NaTf ₂ N to Tf ₂ N anion is such that the melting point of the electrolytic solution can be sufficiently lowered and the non-metal salt of _{NaTf 2} N and Tf _{2 N anion are not separated.} If there is, it is optional. For example, when the electrolytic solution is NaTf ₂ N and tetraethylammonium Tf ₂ N, the molar ratio can be 1: 4 to 1: 9, and when the electrolytic solution is NaTf ₂ N and tetrabutylammonium Tf ₂ N. The molar ratio can be in the range of 2: 3 to 1: 9.

The temperature of the electrolytic solution may be any temperature as long as it is equal to or higher than the melting point, but 120 to 170 ° C. is preferable from the viewpoint of easy current flow and prevention of the reaction between the purified sodium and the electrolytic solution.

In the Na electrolytic refining step S3, low-purity Na recovered after the completion of growing GaN crystals by the Na flux method is used as the anode, but all or part of the anode may be prepared separately as low-purity Na. Good. For example, industrial Na or the anode of a NaS battery can be used. Here, low-purity Na means that the purity is lower than that of purified Na. Further, in the electrolytic refining step S3 of Na, NaTf ₂ N recovered in the separation step of Ga is used as a part of the electrolytic solution, but a separately prepared one may be used.

(About reuse of Ga and Na)
Since Na is not consumed in the Na flux method, most of the Na used in the Na flux method can be recovered by the electrolytic refining step S3 of Na. Then, the Na purified and recovered in the electric field purification step S3 of Na can be reused in the Na flux method. Further, Ga separated from the Na—Ga alloy in the Ga separation step S2 can be purified and reused in the Na flux method.

(Summary)
As described above, in the first embodiment, Na and Ga can be separated from the low-purity Na and Na—Ga alloy remaining after the growth of the GaN crystal by the Na flux method and reused cyclically. Therefore, the raw material cost of the Na flux method can be reduced, and the production cost of the GaN crystal can be significantly reduced.

(Second Embodiment)
In the second embodiment, instead of melting liquid of hTF ₂ N which has been used in the Ga separation step S2 of the first embodiment, a hTF ₂ N aqueous solution. In this case as well, HTf ₂ N reacts with the Na-Ga alloy as in the first embodiment, Na is dissolved from the Na-Ga alloy to _{form a part of NaTf 2} N, and Ga is isolated as a liquid metal. , Hydrogen is generated. With hTF ₂ N aqueous solution, it is possible to further improve the purity of Ga.

Temperature of hTF ₂ N aqueous solution is arbitrary as long as the range of the liquid state, the reaction with higher temperatures Na-Ga alloy progresses rapidly, preferably to 30 ° C. or higher, 40 ° C. or higher Is more preferable. However, if the temperature is too high, evaporation becomes intense, so 70 ° C. or lower is preferable.

Concentration of hTF ₂ N aqueous solution is arbitrary as long as it reacts with the Na-Ga alloy can be, for example, 0.1 to 10 mol / L.

Hereinafter, specific examples of the present invention will be described with reference to the drawings, but the present invention is not limited to the examples.

A GaN crystal was grown on the seed substrate by the Na flux method using the crystal growth apparatus 1000. Specifically, it is as follows. First, the atmosphere inside the furnace (inside the reaction chamber 1300 and the pressure vessel 1100) was replaced with nitrogen gas, the inside of the furnace was heated, and vacuuming was performed to reduce oxygen and water content in the furnace.

Next, the seed substrate, solid Ga, and solid Na were placed in the crucible CB1 made of alumina in the glove box. In addition, graphite powder was also put into the crucible CB1 for the purpose of improving the growth rate. As the seed substrate, a sapphire substrate having a uniformly flat GaN layer formed by the MOCVD method was used.

Next, the crucible CB1 was carried into the furnace, the furnace was sealed, nitrogen was supplied into the furnace, and the pressure inside the furnace was pressurized to 3 MPa. The crucible CB1 was put into a transport container and carried into the furnace so that Na in the crucible CB1 would not be oxidized in the glove box and in the carry-in route. Next, the furnace was heated to a growth temperature (860 ° C.), and the growth of GaN crystals on the seed substrate was started.

After 60 hours had passed from the start of growing the GaN crystal, the temperature and pressure were returned to normal temperature and pressure while holding the grown GaN crystal in the mixed melt, and the growth of the GaN crystal was completed. Then, the crucible CB1 was taken out from the furnace.

Next, the crucible CB1 was heated to 150 ° C. by a hot plate to melt Na, and Na was poured out from the crucible CB1 to recover low-purity Na. Next, the Na-Ga alloy remaining in the crucible CB1 was taken out and recovered. When the Na-Ga alloy was dissolved in aqua regia and analyzed by an ICP-AES apparatus, the Ga ratio of the Na-Ga alloy was 37 at%.

Then, a sealed put hTF ₂ N 50 g, the Na-Ga alloy 10.7 g, a screw cap bottle. A screw cap bottle capable of supplying and discharging gas was used, and Ar was supplied and discharged, and Ar gas was flowed into the container. Then, the screw cap bottle was heated to 90 ° C. and held for 210 minutes. HTF ₂ N in the course of temperature increase becomes liquid melted and a state in which there are Na-Ga alloy in its liquid. The hydrogen gas from the surface of the Na-Ga alloy in contact with hTF ₂ N of the liquid was confirmed to have occurred. Further, it was confirmed that the mass of liquid metal is generated melt solution of hTF ₂ N.

Then, the screw cap bottle was cooled to room temperature. Then, a secondary distilled water was placed in a screw cap bottle, the hTF ₂ N unreacted dissolved in water and filtered. Next, the filter was dried, put into acetone, NaTf ₂ N was dissolved in acetone, and the mixture was filtered. Among the filters, those having a metallic luster were separated and recovered.

When a metallic luster was dissolved in aqua regia and analyzed by an ICP-AES apparatus, it was found to have a purity of 97.6% Ga. Further, when acetone was evaporated from the filtrate and the recovered powder was analyzed by FT-IR, it was found that it contained _{NaTf 2 N.} FIG. 4 is a photograph of Ga separated and recovered from the Na—Ga alloy.

Further, when the heating temperature of the screw cap bottle was changed from 90 ° C. to 60 ° C. and the holding time was changed from 210 minutes to 1640 minutes, Ga could be similarly separated and recovered from the Na-Ga alloy. The purity of Ga at this time was 99.9% or more.

From the results of Example 1, separating the Ga from Na-Ga alloy with hTF ₂ N, can be recovered was confirmed. It was also confirmed that _{NaTf 2 N was formed.}

Electrolysis was carried out using the low-purity Na recovered after growing the GaN crystal of Example 1 as an anode and the electrolytic solution as a mixture of NaTf ₂ N and tetraethylammonium Tf ₂ N. As NaTf ₂ N, the one separated and recovered from _{the HTf 2} N melt after Ga separation from the Na-Ga alloy of Example 1 was used. The molar ratio of NaTf ₂ N to tetraethylammonium Tf ₂ N was 1: 4. The temperature of the electrolytic solution was 120 ° C.

As a result of electrolysis, Na was precipitated on the cathode. When this Na was recovered and elementally analyzed, it was found to have a higher purity than general industrial Na.

From the results of Example 2, it was found that Na can be purified to high purity from low-purity Na or Na-Ga alloy after GaN growth.

Using Ga separated and recovered from the Na—Ga alloy according to Example 1 and Na purified according to Example 2, GaN crystals were grown by the Na flux method in the same manner as in Example 1. However, for Ga, the shortfall was supplemented with Ga prepared separately. The grown GaN crystal had the same quality as the GaN crystal grown according to Example 1.

From the results of Example 3, it was found that it is possible to grow GaN crystals by the Na flux method, which can recycle Na and Ga cyclically.

In Ga separation and recovery from Na-Ga alloy in Example 1, it was used hTF ₂ N aqueous solution instead of melting liquid of hTF ₂ N. Concentration of hTF ₂ N is a 1.5 mol / L, temperature was 40 ° C.. Other than that, the conditions were the same as in Example 1. As a result, the same reaction as in Example 1 occurred. That is, Na in the Na-Ga alloy _{was dissolved in the HTf 2} N aqueous solution, Ga was separated from the Na-Ga alloy, hydrogen gas was generated, and NaTf ₂ N was formed in the aqueous solution. Moreover, when Ga separated from the Na-Ga alloy was recovered and the purity was measured, it was found to be 99.99%.

Results of Example 4, by using the hTF ₂ N aqueous solution, separated from the Na-Ga alloy, improvement of purity Ga recovering it has been found that improved.

The present invention can be applied to the reuse of the residue after growing a group III nitride semiconductor by the Na flux method.

1000: Crystal growth device 1100: Pressure vessel 1200: Intermediate chamber 1300: Reaction chamber 1410: Side heater 1420: Lower heater 1510: Gas supply port 1520: Gas exhaust port

Claims (10)

The Na-Ga alloy is represented by the general formula H (X ¹ SO ₂ ) (X ² SO ₂ ) N, and X ¹ and X ² contain fluorine or a fluorine-containing sulfonylamide which is an alkyl group having 1 to 6 carbon atoms. The gallium is separated from the Na-Ga alloy by contacting the solutions.
A method for producing gallium, which is characterized by the fact that. The fluorinated sulfonyl amides are hTF ₂ N, a manufacturing method of a gallium according to claim 1, characterized in that. The method for producing gallium according to claim 1 or 2, wherein the solution is a fluorine-containing sulfonylamide aqueous solution. The method for producing gallium according to claim 1 or 2, wherein the solution is a melt of a fluorine-containing sulfonylamide. The method for producing gallium according to any one of claims 1 to 4, wherein the Na-Ga alloy that remains after the growth of gallium nitride by the Na flux method is used. In the method for producing sodium in which sodium is precipitated on the cathode by electrolysis with the anode as low-purity sodium.
The electrolytic solution is represented by the general formula H (X ¹ SO ₂ ) (X ² SO ₂ ) N, and X ¹ and X ² are fluorine or a sodium salt of a fluorine-containing sulfonylamide which is an alkyl group having 1 to 6 carbon atoms. , A mixture of the above-mentioned fluorine-containing sulfonylamide with a non-metal salt,
As the sodium salt of the fluorine-containing sulfonylamide in the electrolytic solution, the sodium salt of the fluorine-containing sulfonylamide produced in the solution by the method for producing gallium according to any one of claims 1 to 5 is recovered. To use
A method for producing sodium, which is characterized by the fact that. The method for producing sodium according to claim 6, wherein the low-purity sodium that remains after the growth of gallium nitride by the Na flux method is used. A method for producing gallium nitride, which comprises growing gallium nitride by the Na flux method using gallium produced by the method for producing gallium according to any one of claims 1 to 5. A method for producing gallium nitride, which comprises growing gallium nitride by the Na flux method using sodium produced by the method for producing sodium according to claim 6 or 7. A Na flux method using gallium produced by the method for producing gallium according to any one of claims 1 to 5 and sodium produced by the method for producing sodium according to claim 6 or 7. A method for producing gallium nitride, which comprises growing gallium nitride by.

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