CN116216769B - Method for preparing high-purity gallium oxide by metal gallium hydrolysis method - Google Patents

Abstract

The invention relates to a method for preparing high-purity gallium oxide by a metal gallium hydrolysis method, and belongs to the technical field of metal oxide material preparation. Adding a gallium simple substance and a surfactant into electrolytic reduction water, and uniformly stirring to obtain a reaction system; at 70-100 deg.c and 4000-8000 rpm, gallium metal is dispersed into fine particles and reacted with electrolytic reduced water to produce GaOOH. GaOOH is wrapped and clamped on the floating foam generated by the surfactant and is discharged to the upper layer of the liquid, the floating foam is collected, pure water is used for cleaning, and GaOOH crystal is obtained after drying. Heating GaOOH crystal to roasting temperature at constant speed, and roasting for 2-4 h to obtain high-purity Ga ₂O₃. The invention uses metal gallium simple substance as raw material, which can avoid the problem of gallium ion failure in the traditional process. The purity of the high-purity Ga ₂O₃ prepared by the method can reach 99.99 percent; raw materials can be continuously added in proportion, so that continuous production of high-purity Ga ₂O₃ is realized, and the production efficiency is greatly improved.

Description

A method for preparing high-purity gallium oxide by hydrolysis of metallic gallium

Technical Field

The invention relates to a method for preparing high-purity gallium oxide (Ga ₂ O ₃ ) by hydrolyzing metal gallium, and belongs to the technical field of metal oxide material preparation.

Background technique

As a wide bandgap semiconductor material, Ga ₂ O ₃ has a bandgap width of up to 4.8eV to 4.9eV. In addition, Ga ₂ O ₃ has high stability in extreme environments, making it a candidate material for the fourth generation of semiconductors. In addition, Ga ₂ O ₃ can also be used to prepare power devices, ultraviolet detectors, high-energy ray detectors, etc. It can also be used as a substrate material for semiconductors such as GaN and ZnO.

At present, the methods for _{preparing Ga2O3 are} :

The gallium ammonium sulfate method first uses metal gallium and sulfuric acid to react to generate gallium sulfate, then uses gallium sulfate and ammonium sulfate to polymerize and crystallize in an aqueous solution to precipitate ammonium gallium sulfate crystals, and finally roasts them to obtain Ga ₂ O _3. The advantage of this method is that it has low requirements for the purity of raw materials, but the disadvantage is that the reaction rate of metal gallium and acid is slow, and the production efficiency is low.

The gallium alkyl alcohol method uses metal gallium to react with alkyl alcohol to generate gallium alkyl alcohol salt; the obtained gallium alkyl alcohol salt is then hydrolyzed in an aqueous solution containing alkyl alcohol to generate GaOOH, which is then calcined to obtain Ga ₂ O ₃ . The advantage of this method is that it is green and environmentally friendly, but the disadvantage is that the process is complicated.

Sol-gel method uses gallium salt (gallium halide, etc.) hydrolysis reaction to prepare GaOOH, and then roasts to obtain Ga ₂ O _3. The advantage of this method is high production efficiency, but the disadvantage is that the raw materials are difficult to store (gallium salt is easy to deliquesce and needs to be stored under vacuum), easy to fail and high cost.

The hydrothermal method uses gallium ions and alkali to prepare GaOOH under hydrothermal conditions, and then roasts it to obtain Ga ₂ O _3. The advantage of this method is that the product purity is high, but the disadvantage is that the hydrothermal method is an intermittent batch operation, which cannot achieve continuous production, has low production efficiency, and there are safety hazards in the high-pressure environment.

Summary of the invention

In view of the problems _of raw materials being easily invalid, complicated processes and low production efficiency in the prior art, the present invention proposes a method for preparing high-purity gallium oxide _Ga2O3 by hydrolysis of metal gallium, that is, using metal gallium to react with electrolytic reduced water under high-speed stirring conditions to generate GaOOH; GaOOH floats with the foam of a surfactant to separate GaOOH from the reaction system. Finally, the GaOOH is cleaned and roasted to obtain high- _{purity Ga2O3} .

The principle of preparing high- _{purity Ga2O3} by the gallium metal hydrolysis method of the present invention is:

The reaction between metal gallium and water is a redox reaction. Water oxidizes metal gallium into Ga ³⁺ . When Ga ³⁺ encounters ^OH- in electrolytically reduced water, GaOOH precipitation is immediately generated. At the same time, metal gallium reduces water into H ₂ .

The reaction formula is

Gallium metal is oxidized to Ga ³⁺ Ga-3e ^- →Ga ³⁺

Ga ³⁺ generates GaOOH precipitation Ga ³⁺ +2OH ^- →GaOOH↓+H ⁺

Water is reduced to H ₂ 2H ₂ O+2e ^- →H ₂ ↑+2OH ^-

Overall reaction formula 2Ga+4H ₂ O→2GaOOH+3H ₂ ↑

A method for preparing high-purity gallium oxide by hydrolysis of metallic gallium, the specific steps are as follows:

(1) adding metal gallium and a surfactant into electrolytic reduction water and mixing them evenly to obtain a reaction system;

(2) The reaction system is heated to boiling to generate _H2 bubbles, and the surfactant produces foam under the _H2 bubbles;

(3) At a temperature of 70-100°C and a rotation speed of 4000-8000 rpm, the metal gallium is dispersed to form microparticles and undergoes a hydrolysis reaction with the electrolytic reduced water to generate a hydrolysis product GaOOH, which is entrained in the foam generated by the surfactant and discharged to the upper layer of the liquid;

(4) collecting the foam on the upper layer of the liquid, washing it with pure water, and drying it to obtain GaOOH crystals;

(5) The GaOOH crystal is heated to the calcination temperature at a uniform rate and then calcined for 2 to 5 hours to obtain high-purity Ga ₂ O ₃ .

The surfactant in step (1) is PVP or CTAB, and the pH value of the electrolytic reduced water is 8.5 to 11. The electrolytic reduced water is prepared by a proton exchange membrane electrolyzer. The electrolytic reduced water refers to the product obtained in the cathode tank after the ultrapure water is electrolyzed by a proton membrane electrolyzer. Since ^OH- continuously accumulates at the cathode, the pH value of the electrolytic reduced water is required to be greater than 8.5.

The electrolytic reduced water preparation mechanism is:

Under the action of the electric field, water is ionized into H ⁺ and OH ^- ; the positively charged H ⁺ moves to the cathode through the proton exchange membrane and obtains electrons to become H ₂ and is discharged. As water is continuously ionized, the H ^- in the cathode area is continuously consumed, causing OH ^- to accumulate in the cathode area, so electrolytic reduced water is obtained in the cathode area.

The above reaction formula is

Cathode: 2H ₂ O+2e ^- ＝2OH ^- +H ₂ ↑;

Anode: 2H ₂ O-4e ^- =4H ⁺ +O ₂ ↑

The prepared electrolytic reduced water contains no other cationic impurities and does not affect the final purity of the product.

The purity of the raw material metal gallium is 99.999%.

The purity of the product high-purity Ga ₂ O ₃ can reach 99.99%.

In the step (1), the solid-to-liquid ratio of the metal gallium, the surfactant and the electrolytic reduced water is g:g:mL 30-50:1:1000-2000.

The uniform heating rate of step (5) is 2-8°C/min, the calcination temperature is 300-1000°C, and the calcination time is 2-5h.

Preferably, the calcination temperature is 300-500°C, and the high-purity Ga ₂ O ₃ is α-Ga ₂ O ₃ ; the calcination temperature is 500-1000°C but does not include 500°C, and the high-purity Ga ₂ O ₃ is β-Ga ₂ O ₃ .

In the step (5), the residual active agent in the GaOOH crystal is decomposed into _CO2 gas during the roasting process and overflows, which does not affect the final purity of the product.

The beneficial effects of the present invention are:

(1) The raw material used in the present invention is metallic gallium, which is easy to store and has low cost; it can solve the problem of gallium salt being easily deliquesced and ineffective in traditional processes.

(2) The surfactant acts as a dispersant and a foaming agent in the reaction; the product GaOOH floats up with the surfactant foam, thereby separating GaOOH from the reaction system.

(3) The present invention is carried out under normal pressure and has a simple device. The raw materials can be replenished at any time during the production process to achieve efficient and continuous production of GaOOH, which is then calcined to obtain high-purity α-Ga ₂ O ₃ or β-Ga ₂ O ₃ .

(3) The gallium metal hydrolysis process of the present invention uses electrolytically reduced water, without the introduction of other impurities such as cations, and omitting the purification process; and the electrolytically reduced water can self-degrade and does not produce harmful substances.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an XRD diagram of the product GaOOH in Examples 1 to 3;

FIG2 is a SEM image of the GaOOH product in Examples 1 to 3;

FIG3 is an XRD diagram of the product α-Ga ₂ O ₃ in Examples 1 to 3;

FIG4 is a SEM image of the product α-Ga ₂ O ₃ in Examples 1 to 3;

FIG5 is an XRD diagram of the product β-Ga ₂ O ₃ in Examples 4 to 6;

FIG. 6 is a SEM image of the β-Ga ₂ O ₃ product in Examples 4 to 6.

Detailed ways

The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

Example 1: A method for preparing high-purity gallium oxide by hydrolysis of metallic gallium, the specific steps are as follows:

(1) adding metal gallium and surfactant (PVP) to electrolytic reduced water and mixing them uniformly to obtain a reaction system; wherein the electrolytic reduced water is prepared by a proton exchange membrane electrolyzer, the pH value of the electrolytic reduced water is 8.5, and the solid-liquid ratio of metal gallium, surfactant (PVP) and electrolytic reduced water is 30:1:1000 g:g:mL;

(2) The reaction system is heated to boiling to generate H ₂ bubbles, and the surfactant (PVP) generates foam under the H ₂ bubbles;

(3) At a temperature of 70°C and a rotation speed of 4000 rpm, metal gallium is dispersed to form particles with a diameter of less than 10 μm and undergoes a hydrolysis reaction with electrolytic reduced water to generate a hydrolysis product GaOOH, which is entrained in the foam generated by the surfactant (PVP) and discharged to the upper layer of the liquid;

(4) collecting the foam on the upper layer of the liquid, washing it with pure water, and drying it to obtain GaOOH crystals;

The XRD pattern of the product GaOOH in this embodiment is shown in FIG1 , and the SEM pattern of the product GaOOH is shown in FIG2 ; it can be seen from FIG1 and FIG2 that the product GaOOH is successfully prepared, and GaOOH is a monoclinic crystal cluster. By calculation, the yield of the product GaOOH is about 86.2%;

(5) The GaOOH crystal is heated uniformly at a heating rate of 8°C/min to a calcination temperature of 320°C, and then calcined at a constant temperature for 2h to obtain high-purity Ga ₂ O ₃ ;

The high-purity Ga ₂ O ₃ product of this embodiment is detected by XRD, and the high-purity Ga ₂ O ₃ is α-Ga ₂ O ₃ , and α-Ga ₂ O _{3 is a monoclinic crystal; the XRD diagram of the product α-Ga 2 O 3 in this} embodiment is shown in FIG3, and the SEM diagram of the product α-Ga ₂ O ₃ is shown in FIG4.

The purity of the high-purity α-Ga ₂ O ₃ in this embodiment is 99.991%.

Example 2: A method for preparing high-purity gallium oxide by hydrolysis of metallic gallium, the specific steps are as follows:

(1) adding metal gallium and a surfactant (CTAB) to electrolytically reduced water and mixing them uniformly to obtain a reaction system; wherein the electrolytically reduced water is prepared by a proton exchange membrane electrolyzer, the pH value of the electrolytically reduced water is 9, and the solid-liquid ratio of the metal gallium, the surfactant (CTAB) and the electrolytically reduced water is 40:1:1500 g:g:mL;

(2) The reaction system is heated to boiling to generate H ₂ bubbles, and the surfactant (CTAB) produces foam under the H ₂ bubbles;

(3) At a temperature of 85°C and a rotation speed of 6000 rpm, the metal gallium is dispersed into particles with a diameter of less than 5 μm and undergoes a hydrolysis reaction with electrolytic reduced water to generate a hydrolysis product GaOOH, which is entrained in the foam generated by the surfactant (CTAB) and discharged to the upper layer of the liquid;

(4) collecting the foam on the upper layer of the liquid, washing it with pure water, and drying it to obtain GaOOH crystals;

The XRD pattern of the product GaOOH in this embodiment is shown in FIG1 , and the SEM pattern of the product GaOOH is shown in FIG2 ; it can be seen from FIG1 and FIG2 that the product GaOOH is successfully prepared, and GaOOH is a monoclinic crystal cluster. By calculation, the yield of the product GaOOH is about 88.7%;

(5) The GaOOH crystal was heated at a rate of 6°C/min to a calcination temperature of 400°C, and then calcined at a constant temperature for 4 hours to obtain high-purity Ga ₂ O ₃ ;

The high-purity Ga ₂ O ₃ product of this embodiment is detected by XRD, and the high-purity Ga ₂ O ₃ is α-Ga ₂ O ₃ , and α-Ga ₂ O _{3 is a monoclinic crystal; the XRD diagram of the product α-Ga 2 O 3 in this} embodiment is shown in FIG3, and the SEM diagram of the product α-Ga ₂ O ₃ is shown in FIG4.

The purity of the high-purity α-Ga ₂ O ₃ in this embodiment is 99.992%.

Example 3: A method for preparing high-purity gallium oxide by hydrolysis of metallic gallium, the specific steps are as follows:

(1) adding metal gallium and surfactant (PVP) to electrolytic reduced water and mixing them uniformly to obtain a reaction system; wherein the electrolytic reduced water is prepared by a proton exchange membrane electrolyzer, the pH value of the electrolytic reduced water is 10, and the solid-liquid ratio of metal gallium, surfactant (PVP) and electrolytic reduced water is 50:1:2000 g:g:mL;

(2) The reaction system is heated to boiling to generate H ₂ bubbles, and the surfactant (PVP) generates foam under the H ₂ bubbles;

(3) At a temperature of 98°C and a rotation speed of 8000 rpm, the metal gallium is dispersed to form particles with a diameter of less than 1 μm and undergoes a hydrolysis reaction with the electrolytic reduced water to generate a hydrolysis product GaOOH, which is entrained in the foam generated by the surfactant (PVP) and discharged to the upper layer of the liquid;

(4) collecting the foam on the upper layer of the liquid, washing it with pure water, and drying it to obtain GaOOH crystals;

The XRD pattern of the product GaOOH in this embodiment is shown in FIG1 , and the SEM pattern of the product GaOOH is shown in FIG2 ; from FIG1 and FIG2 , it can be seen that the product GaOOH is successfully prepared, and GaOOH is a monoclinic crystal cluster. By calculation, the yield of the product GaOOH is about 92.5%;

(5) The GaOOH crystal was heated uniformly at a heating rate of 2°C/min to a calcination temperature of 500°C, and then calcined at a constant temperature for 6 hours to obtain high-purity Ga ₂ O ₃ ;

The high-purity Ga ₂ O ₃ product of this embodiment is detected by XRD, and the high-purity Ga ₂ O ₃ is α-Ga ₂ O ₃ , and α-Ga ₂ O _{3 is a monoclinic crystal; the XRD diagram of the product α-Ga 2 O 3 in this} embodiment is shown in FIG3, and the SEM diagram of the product α-Ga ₂ O ₃ is shown in FIG4.

The purity of the high-purity α-Ga ₂ O ₃ in this embodiment is 99.995%.

Example 4: A method for preparing high-purity gallium oxide by hydrolysis of metallic gallium, the specific steps are as follows:

(1) Preparation of GaOOH crystals: The preparation method of GaOOH crystals in this embodiment is the same as that in Example 1;

(2) The GaOOH crystal was heated at a rate of 8°C/min to a calcination temperature of 600°C, and then calcined at a constant temperature for 2h to obtain high-purity Ga ₂ O ₃ ;

The XRD pattern of the product β-Ga ₂ O ₃ in this example is shown in FIG5 , and the SEM pattern of the product β-Ga ₂ O ₃ is shown in FIG6 . As can be seen from FIG5 and FIG6 , the high-purity Ga ₂ O ₃ is β-Ga ₂ O ₃ , and β-Ga ₂ O ₃ is a monoclinic crystal. A large number of holes appear on the surface of the β-Ga ₂ O ₃ crystal. The holes are analyzed to be water vapor channels generated by the decomposition of GaOOH during the calcination process, and the reaction formula is: 2GaOOH→H ₂ O↑+Ga ₂ O ₃ .

The purity of the high-purity β-Ga ₂ O ₃ in this embodiment is 99.992%.

Example 5: A method for preparing high-purity gallium oxide by hydrolysis of metallic gallium, the specific steps are as follows:

(1) Preparation of GaOOH crystals: The preparation method of GaOOH crystals in this embodiment is the same as that in Example 2;

(2) The GaOOH crystal was heated at a rate of 6°C/min to a calcination temperature of 800°C, and then calcined at a constant temperature for 4 hours to obtain high-purity Ga ₂ O ₃ ;

The XRD pattern of the product β-Ga ₂ O ₃ in this example is shown in FIG5 , and the SEM pattern of the product β-Ga ₂ O ₃ is shown in FIG6 . As can be seen from FIG5 and FIG6 , the high-purity Ga ₂ O ₃ is β-Ga ₂ O ₃ , and β-Ga ₂ O ₃ is a monoclinic crystal. A large number of holes appear on the surface of the β-Ga ₂ O ₃ crystal. The holes are analyzed to be water vapor channels generated by the decomposition of GaOOH during the calcination process, and the reaction formula is: 2GaOOH→H ₂ O↑+Ga ₂ O ₃ .

The purity of the high-purity β-Ga ₂ O ₃ in this embodiment is 99.993%.

Example 6: A method for preparing high-purity gallium oxide by hydrolysis of metallic gallium, the specific steps are as follows:

(1) Preparation of GaOOH crystals: The preparation method of GaOOH crystals in this embodiment is the same as that in Example 2;

(2) The GaOOH crystal was heated uniformly at a heating rate of 2°C/min to a calcination temperature of 1000°C, and then calcined at a constant temperature for 6 hours to obtain high-purity Ga ₂ O ₃ ;

The XRD pattern of the product β-Ga ₂ O ₃ in this example is shown in Figure 5, and the SEM pattern of the product β-Ga ₂ O ₃ is shown in Figure 6. As can be seen from Figures 5 and 6, the high-purity Ga ₂ O ₃ is β-Ga ₂ O ₃ , and β-Ga ₂ O ₃ is a monoclinic crystal; a large number of holes appear on the surface of the β-Ga ₂ O ₃ crystal, and the holes are analyzed to be water vapor channels generated by the decomposition of GaOOH during the calcination process, and the reaction formula is: 2GaOOH→H ₂ O↑+Ga ₂ O ₃ .

The purity of the high-purity β-Ga ₂ O ₃ in this embodiment is 99.996%.

The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims (4)

1. A method for preparing high-purity gallium oxide by a metal gallium hydrolysis method is characterized in that a metal gallium simple substance and electrolytic reduction water are subjected to hydrolysis reaction under high-speed stirring to prepare GaOOH, and then roasting treatment is carried out to obtain high-purity Ga ₂O₃; the method comprises the following specific steps:

(1) Adding gallium metal and a surfactant into electrolytic reduction water, and uniformly stirring to obtain a reaction system; the pH value of the electrolytic reduction water is 8.5-11;

(2) The reaction system is heated to boiling and generates H ₂ bubbles, and the surfactant generates froth under the H ₂ bubbles;

(3) Dispersing gallium metal into particles at 70-100 ℃ and 4000-8000 rpm, and carrying out hydrolysis reaction with electrolytic reduction water to generate a hydrolysis product GaOOH, wherein the GaOOH is wrapped in the froth and discharged to the upper layer of the liquid;

(4) Collecting floating foam on the upper layer of the liquid, cleaning with pure water, and drying to obtain GaOOH crystals;

(5) Heating GaOOH to a roasting temperature at a constant speed, and roasting for 2-4 hours to obtain high-purity Ga ₂O₃; the roasting temperature is 300-1000 ℃ and the roasting time is 2-6 h; the roasting temperature is 300-500 ℃, and the high-purity Ga ₂O₃ is alpha-Ga ₂O₃; roasting at 500-1000 ℃ and not including 500 ℃, and the high-purity Ga ₂O₃ is beta-Ga ₂O₃.

2. The method for preparing high-purity gallium oxide by using a gallium metal hydrolysis method according to claim 1, wherein: the surfactant in the step (1) is PVP or CTAB.

3. The method for preparing high-purity gallium oxide by using a gallium metal hydrolysis method according to claim 1, wherein: the solid-liquid ratio g of the metal gallium simple substance, the surfactant and the electrolytic reduction water in the step (1) is 30-50:1:1000-2000.

4. The method for preparing high-purity gallium oxide by using a gallium metal hydrolysis method according to claim 1, wherein: the uniform temperature rising rate in the step (5) is 2-8 ℃/min.