Preparation method of tetragonal system germanium dioxide

Abstract

The invention relates to a preparation method of tetragonal crystal system germanium dioxide, which comprises the following steps: reacting high-purity hexagonal crystal system germanium dioxide with water vapor in a closed titanium high-pressure reaction kettle, cooling to room temperature, and washing and drying the solid obtained by the reaction to obtain tetragonal crystal system germanium dioxide crystals. The tetragonal system germanium dioxide crystal obtained by the method is high in purity and free of impurity introduction, complex chemical reagents do not need to be added in the preparation process, the preparation process is greatly shortened, and a new thought is provided for preparation of a germanium dioxide crystal material with a special morphology. The method disclosed by the invention is a one-step hydrothermal reaction method, and has the advantages of simple process, convenience in operation, easiness in repetition and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing tetragonal germanium dioxide, and belongs to the technical field of mineral materials. Background Art

[0002] Germanium is a strategic key metal resource, which has extensive and important applications in high-tech fields such as semiconductors, aerospace measurement and control, nuclear physics detection, fiber optic communications, infrared optics, solar cells, chemical catalysts, and biomedicine. Germanium dioxide has a chemical formula (GeO2), and its appearance is white powder or colorless crystals. It is a tetragonal, hexagonal or amorphous body, and is the basic material for manufacturing other germanium products. Hexagonal germanium dioxide is more soluble in water, and its preparation technology is mature and the product purity is already high. Tetragonal germanium dioxide is insoluble in water. It is mainly used to manufacture optical glass with high refractive index. However, it has been reported that the preparation process of tetragonal germanium dioxide is very complicated. The intermediate process of preparation requires high temperature and high pressure (>700℃ and >2000bar) heating / melting or adding different types of alkali metal salts. The production process is long, and the equipment and facilities investment is high. The probability of secondary pollution of germanium dioxide products caused by impurities introduced during the process is high. The existing preparation method is not conducive to the large-scale preparation of tetragonal germanium dioxide, which significantly restricts its application. There is an urgent need for a preparation method that is convenient for mass production under relatively low temperature and low pressure conditions and does not require doping catalysts or process reactants into germanium dioxide, but no relevant method has been reported so far. Summary of the invention

[0003] The purpose of the present invention is to improve the deficiencies of the prior art and provide a method for preparing tetragonal germanium dioxide to solve the problem that the prior art preparation of tetragonal germanium dioxide requires relatively high temperature and high pressure conditions or introduces impurities causing secondary pollution.

[0004] To achieve the above object, the present invention adopts the following technical scheme: a method for preparing tetragonal germanium dioxide, comprising the following steps:

[0005] Step 1, high-purity hexagonal germanium dioxide is placed in an open tubular container, and the container is placed in a closed high-pressure hydrothermal autoclave, and ultrapure water is added around the tubular container in the high-pressure hydrothermal autoclave;

[0006] Step 2, after filling argon into the high-pressure hydrothermal autoclave, the high-pressure hydrothermal autoclave is closed, and then the whole is heated to 150-450° C. and kept at a constant temperature for 7 days, the tubular container containing germanium dioxide is taken out and the germanium dioxide is taken out, the germanium dioxide is washed with ultrapure water for more than 2 times, and dried to obtain tetragonal germanium dioxide.

[0007] Furthermore, the tubular container and the high-pressure hydrothermal autoclave in step 1 and step 2 are both made of titanium.

[0008] Furthermore, the ultrapure water added in step 1 is used for controlling the system pressure at 50-450 bar when heated to 150-450° C. in step 2, and the high-purity hexagonal germanium dioxide is not in direct contact with the ultrapure water in the high-pressure hydrothermal reactor.

[0009] Furthermore, an oxygen pressure controller is placed in step 1 to maintain the oxygen pressure in the high pressure hydrothermal reactor at 10 -27 ~10 -23 The oxygen pressure controller is installed in a titanium tube and isolated from the ultrapure water.

[0010] Furthermore, in step 2, argon gas is charged into the high-pressure hydrothermal autoclave for more than 3 minutes to expel all the air in the autoclave and fill it with argon gas.

[0011] Furthermore, in step 2, the product needs to be washed with ultrapure water for more than 2 times and dried in a thermostat at 80°C.

[0012] Furthermore, if the oxygen pressure in the high pressure hydrothermal reactor is not above 10 -27 ~10 -23 bar, oxygen and hydrogen are added when argon is filled in step 2 to ensure the required oxygen pressure.

[0013] The present invention utilizes water vapor to react with high-purity hexagonal germanium dioxide at high temperature, so as to promote the change of Ge-O bond structure from hexagonal structure to tetragonal structure. By adding a certain amount of water to control the pressure of water vapor in the reaction system, it is ensured that sufficient water vapor reacts with germanium dioxide to promote all hexagonal germanium dioxide to be transformed into tetragonal germanium dioxide. The addition of water vapor plays a decisive role in the phase transformation of germanium dioxide. By filling with argon gas, the reaction atmosphere is only water vapor, hydrogen and oxygen, and the oxygen pressure in the reaction process is accurately controlled. The oxygen pressure in the reaction system is accurately controlled by an oxygen pressure controller, so as to keep the valence state of germanium in germanium dioxide at +4, without +2 or other valence states of germanium generated, and the control of oxygen pressure makes the fugacity of oxygen higher than the +6 valence of Ge, and there is no +6 valence Ge.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The previous methods required high temperature and high pressure (>700°C and >2000bar) heating / melting or adding different types of alkali metal salts. The tetragonal germanium dioxide obtained by the present invention is prepared under relatively low temperature and low pressure conditions. During the preparation process, no salt substances are doped into the germanium dioxide, which provides a new idea for the preparation of special morphology and high purity germanium dioxide materials.

[0016] 2. The method for preparing tetragonal germanium dioxide of the present invention is a one-step hydrothermal reaction method, which has the advantages of simple process, convenient operation, easy repetition, and convenient industrial promotion.

[0017] 3. The tetragonal germanium dioxide provided by the present invention has high purity and can be widely used as a raw material for the manufacture of high-refractive-index optical glass and the study of the physical and chemical properties of germanium. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The XRD spectrum of tetragonal germanium dioxide prepared in Example 1;

[0019] Figure 2 This is the Raman spectrum of the tetragonal germanium dioxide prepared in Example 1. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described in detail below through embodiments, which are intended to explain the present invention rather than to limit it.

[0021] Example 1

[0022] Step 1, high-purity hexagonal germanium dioxide (>99.99%) is placed in an open titanium small tube container, and then placed in a closed titanium high-pressure hydrothermal autoclave, and a certain amount of ultrapure water is added to the high-pressure hydrothermal autoclave, and an oxygen pressure controller is placed; Step 2, in step 1, after the various reagents are added, argon is filled into the titanium autoclave, and then the titanium autoclave is sealed, and then the whole is heated to 450° C. and kept at a constant temperature for 7 days, and the system pressure in the control system is 150 bar, and the reactant high-purity hexagonal germanium dioxide reacts in the water vapor phase of 150 bar, and the oxygen pressure is 10 -24 bar. After quenching and cooling after 7 days of heating, take out the small titanium container containing germanium dioxide and then take out the germanium dioxide, wash it with ultrapure water for more than 2 times, and then dry it to obtain high-purity tetragonal germanium dioxide. XRD analysis is performed on it, and the results are shown in Figure 1 ; Raman spectroscopy analysis was performed on it, and the results are shown in Figure 2 .

[0023] Figure 1 The XRD diffraction patterns and Figure 2 The Raman spectra given show that the spectra of the obtained samples are completely consistent with the standard tetragonal germanium dioxide spectra, indicating that the prepared samples are tetragonal germanium dioxide. It can be seen from the figure that tetragonal germanium dioxide has no impurity peaks and the purity of tetragonal germanium dioxide is >99.9%.

[0024] Example 2

[0025] Step 1, high-purity hexagonal germanium dioxide (>99.99%) is placed in an open titanium tube container, and then placed in a closed titanium high-pressure hydrothermal autoclave, and a certain amount of ultrapure water is added to the high-pressure hydrothermal autoclave, and an oxygen pressure controller is placed; Step 2, in step 1, after the various reagents are added, argon is filled into the titanium autoclave, and then the titanium autoclave is closed, and then the whole is heated to 300° C. and kept at a constant temperature for 7 days, and the system pressure in the control system is 100 bar and the oxygen pressure is 10 -25 bar. After quenching and cooling after 7 days of heating, take out the small titanium container containing germanium dioxide and then take out the germanium dioxide, wash it with ultrapure water for more than 2 times, and then dry it to obtain high-purity tetragonal germanium dioxide with a purity of >99.9%.

[0026] Example 3

[0027] Step 1, high-purity hexagonal germanium dioxide (>99.99%) is placed in an open titanium small tube container, and then placed in a closed titanium high-pressure hydrothermal autoclave, and a certain amount of ultrapure water is added to the high-pressure hydrothermal autoclave, and an oxygen pressure controller is placed; Step 2, in step 1, after the various reagents are added, argon is filled into the titanium autoclave, and then the titanium autoclave is closed, and then the whole is heated to 150° C. and kept at a constant temperature for 7 days, and the system pressure in the control system is 50 bar and the oxygen pressure is 10 -26 bar. After quenching and cooling after 7 days of heating, take out the small titanium container containing germanium dioxide and then take out the germanium dioxide, wash it with ultrapure water for more than 2 times, and then dry it to obtain high-purity tetragonal germanium dioxide with a purity of >99.9%.

[0028] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for preparing tetragonal germanium dioxide, It is characterized in that The steps include: Step 1, high-purity hexagonal germanium dioxide is placed in an open tubular container, and the container is placed in a closed high-pressure hydrothermal autoclave, and ultrapure water is added around the tubular container in the high-pressure hydrothermal autoclave; Step 2, after filling argon into the high-pressure hydrothermal autoclave, the high-pressure hydrothermal autoclave is closed, and then the whole is heated to 150-450° C. and kept at a constant temperature for 7 days, the tubular container containing germanium dioxide is taken out and the germanium dioxide is taken out, the germanium dioxide is washed with ultrapure water, and dried to obtain tetragonal germanium dioxide.

2. The method for preparing tetragonal germanium dioxide according to claim 1, It is characterized in that The tubular container and the high-pressure hydrothermal autoclave in step 1 and step 2 are both made of titanium.

3. The method for preparing tetragonal germanium dioxide according to claim 1, It is characterized in that The ultrapure water added in step 1 is used for controlling the system pressure at 50-450 bar when heated to 150-450° C. in step 2, and the high-purity hexagonal germanium dioxide is not in direct contact with the ultrapure water in the high-pressure hydrothermal reactor.

4. The method for preparing tetragonal germanium dioxide according to claim 1, It is characterized in that Place the oxygen pressure controller as described in step 1 to keep the oxygen pressure in the high pressure hydrothermal reactor at 10 -27 ~10 -23 bar range.

5. The method for preparing tetragonal germanium dioxide according to claim 1, It is characterized in that In the step 2, argon gas is filled into the high pressure hydrothermal autoclave for more than 3 minutes.

6. The method for preparing tetragonal germanium dioxide according to claim 1, It is characterized in that In step 2, the product needs to be washed with ultrapure water for more than 2 times and dried in a thermostat at 80°C.

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