A method for rapidly preparing β-Ti without a reducing agent 3 O 5 ​

Abstract

The present invention provides a method for directly preparing β-Ti3O5 bulk and powder materials without a reducing agent under a low oxygen partial pressure environment using laser as a heat source. The main steps include irradiating and pre-treating the raw materials with laser, and carrying out vacuum melting of the pre-treated sample with laser under a low oxygen partial pressure environment, etc., to achieve the rapid preparation of high-purity β-Ti3O5 bulk and powder materials, and the preparation process is simple.

Description

Technical Field

[0001] The present invention belongs to the field of material preparation, and particularly relates to a method for rapidly preparing β-Ti 3 O 5 without a reducing agent. Background Art

[0002] Ti 3 O 5 is a kind of titanium suboxide, which has various crystal forms such as α, β, λ, γ, and δ. With the change of the external temperature, reversible phase transitions can occur between these crystal forms, bringing about changes in structure and properties, and further causing differences in physical, chemical, and optical properties. Therefore, the special properties of these crystal forms provide potential application values in gas sensors, photocatalysis, catalyst carriers, superconductivity, etc. Among them, β-Ti 3 O 5 is mainly used as an optical evaporation material in the coating field due to its stable refractive index and small oxygen release amount. At present, it has been widely used in vacuum evaporation targets of TiO 2 coatings to prepare optoelectronic devices with special functions such as antireflection and reflection. In addition, due to its low resistivity-temperature coefficient, good high-temperature stability and reproducibility, it also has potential application prospects in the field of gas sensors.

[0003] For the synthesis of Ti 3 O 5 , currently it is mainly prepared by reducing TiO 2 . Initially, metals or H 2 are used as reducing agents for preparation, such as metallic Ti and Zr. The advantage of using Ti as a reducing agent is that it does not introduce impurities, but metallic titanium is relatively expensive and the preparation time is long, usually requiring 1 - 3 h. Using Zr as a reducing agent is likely to introduce impurities and it is difficult to remove them. Reducing with H 2 is an environmentally friendly method that does not introduce impurities, but the potential risk of explosion and combustion limits its large-scale use. Carbothermal reduction is also a commonly used method. Initially, C powder is used as a reducing agent to reduce TiO 2 at high temperature in a nitrogen atmosphere to prepare Ti 3 O 5 . This method has a lower reaction temperature and the reducing agent is cheap and easily available. However, in the preparation process, it is very easy to introduce impurities due to uneven ratio and incomplete reaction. And during the reduction process, the stable interval of Ti 3 O 5 is relatively narrow, and it is easy to introduce Ti 4 O 7 or Ti 2 O 3In view of the above problems, Chinese patent CN 109704753 A proposes a method for preparing β-Ti using phenolic resin as a carbon source. 3 O 5 The preparation process requires segmented sintering, and each sintering time takes several hours (4-6h). Although the purity of the prepared product is as high as 99.99%, it takes too long and the preparation efficiency is not high. Chinese patent CN111217390 A proposes a method of preparing a gel by mixing butyl titanate or propyl titanate and ethylene glycol and drying them. λ-Ti is prepared at a lower reduction temperature. 3 O 5 However, the initial preparation process is complicated and the preparation time takes several hours (2-6 hours). In summary, all current preparation technologies require the addition of reducing agents and take several hours (at least 2 hours) to prepare. Some methods (such as the sol-gel method) have complex processes, which not only have low preparation efficiency but also introduce impurities, resulting in the Ti prepared. 3 O 5 The purity is not high.

[0004] Laser as heat source for TiO 2 Preparation of materials such as rutile TiO 2 (110) A method for preparing oxygen vacancy pair defects on the surface of TiO by irradiating a 266 nm ultraviolet laser 2 The (110) surface can allow oxygen vacancies to migrate to form oxygen vacancy pairs, and can even form a surface where oxygen vacancy pairs are dominant defects. 2 The laser preparation method uses pulsed laser to ablate P25 powder in air to prepare supported gray mesoporous TiO 2 Under laser ablation, anatase TiO 2 Towards rutile TiO 2 The transformation forms a high rutile ratio crystal phase and rich surface states (oxygen vacancies and Ti 3 + ), and at the same time, a well-contacted heterogeneous interface is formed at the interface between the anatase phase and the rutile phase, which helps to improve the carrier separation efficiency. 2 The technical idea of ​​CN115140765A is to 2 Oxygen vacancies are formed on the surface to achieve the purpose of surface modification. The crystal structure of the product is still rutile TiO 2 ; CN115744973A patent is to make anatase TiO 2 Transformed into rutile TiO with surface oxygen vacancies2 , the chemical formula of the product is still TiO 2 . Although the above patent shows that laser irradiation can achieve surface modification of TiO (formation of oxygen vacancies on the surface) and the technical effect of isomer transformation of TiO 2 ; however, there has been no report on using laser as a heat source to carry out vacuum deoxidation of TiO 2 melt and accurately prepare single-phase bulk or powder materials of titanium suboxide. 2 Summary of the Invention

[0005] To solve the above problems existing in the prior art, such as the introduction of impurities by reducing agents affecting the purity of the product, the complex preparation process with a long process and long preparation time, the present invention provides a method for rapidly preparing β-Ti 3 O 5 without a reducing agent.

[0006] The present invention directly prepares β-Ti 3 O 5 powder materials without a reducing agent under a low oxygen partial pressure environment using laser as a heat source, including the following steps:

[0007] (1) Weigh an appropriate amount of TiO 2 raw material and put it into a crucible;

[0008] (2) Set the laser parameters (power, focal length, working distance) and irradiate and pre-treat the raw material in step (1);

[0009] (3) Transfer the pre-treated sample obtained in step (2) to the reaction chamber, start the vacuum pump group of the reaction chamber, and adjust the pressure of the reaction chamber to a predetermined value;

[0010] (4) Set the laser parameters (power, focal length, working distance), carry out vacuum melting of the pre-melted sample obtained in step (3) for a certain time, and control the temperature during the process;

[0011] (5) After the melting is completed, wait for the sample to cool below 100 °C, take out the obtained bulk sample, and break it to obtain powder.

[0012] Preferably, in step (1):

[0013] The TiO 2 raw material is TiO 2 powder with a purity higher than 99.0% or formed bulk raw material.

[0014] The crucible is a high-temperature container made of a material that does not react with titanium oxide; more preferably, the crucible is a copper crucible with an internal circulating water cooling system, a pure tungsten crucible, a platinum crucible, etc.

[0015] Preferably, in step (2):

[0016] The setting of the laser parameters refers to controlling the laser focal length and working distance so that the entire sample surface can receive laser irradiation, and at the same time setting the laser output power to control the laser power density at the sample surface within the range of 1.0 - 3.0 kW / cm 2 .

[0017] The pretreatment refers to melting all the raw materials in (1) into a liquid phase by laser and obtaining a dense sample after cooling and solidification.

[0018] Preferably, in step (3):

[0019] The reaction chamber is a sealed chamber that can withstand a certain negative pressure and has a laser incident window.

[0020] The vacuum pump group refers to a device in which a fore pump such as a mechanical pump or an oil pump and a molecular pump are connected in series to extract the gas in the reaction chamber.

[0021] Adjusting the pressure of the reaction chamber to a predetermined value refers to controlling the total pressure in the chamber within the range of 10 -2 -10 -4 Pa by the vacuum pump group; or after pumping the total pressure in the chamber to 10 -2 Pa, filling with inert gases such as argon, nitrogen, helium, etc., and controlling the total pressure in the chamber to be less than 10 5 Pa, with the oxygen partial pressure range of 10 -7 -10 -16 Pa.

[0022] Preferably, in step (4):

[0023] The setting of the laser parameters refers to controlling the laser focal length and working distance so that the entire sample surface can receive laser irradiation, and at the same time setting the laser output power to control the laser power density at the sample surface within the range of 3.0 - 8.0 kW / cm 2 .

[0024] The melting for a certain time refers to the time when the sample receives laser irradiation. According to the different sample masses, the melting time is controlled within 30 s - 100 s.

[0025] The temperature control refers to dynamically adjusting the laser output power on the basis of on-line monitoring of the sample melting temperature by a non-contact optical temperature measurement device so that the sample melting temperature during the melting process is controlled within 1900 - 2500 °C.

[0026] In summary, from the classical thermodynamics analysis, it can be seen that vacuum has a significant promoting effect on the TiO 2 decomposition reaction, and Ti 3 O 5can stably exist within a relatively wide temperature range; meanwhile, the suboxide and O 2 generated by the decomposition of TiO 2 will react again at a lower temperature to generate TiO 2 . Therefore, to prepare Ti 2 O 3 through the decomposition reaction of TiO 5 , not only the appropriate reaction temperature needs to be controlled, but also the generated O 2 needs to be separated in time to avoid the oxidation of the product after cooling and the re-generation of TiO 2 . Therefore, Ti 2 O 3 can be prepared by vacuum melting TiO 5 for deoxidation. Further, this patent uses laser as a heat source to prepare Ti 2 O 3 by vacuum melting TiO 5 for deoxidation. The prepared Ti 3 O 5 has completely changed into another phase, and its crystal structure is also completely different from that of TiO 2 ; its essence is that TiO 2 undergoes a decomposition reaction to generate Ti 3 O 5 and O 2 . The generated O 2 is pumped out of the molten pool through vacuum or diffuses and escapes under the action of a low oxygen partial pressure concentration gradient, thereby realizing its separation from the Ti 3 O 5 melt, so that Ti 3 O 5 and O 2 will not react chemically again to re-generate TiO 2 .

[0027] The present invention uses laser as a heat source, and in a low oxygen partial pressure environment, without adding a reducing agent, β-Ti 3 O 5 can be prepared by direct deoxidation, which can effectively improve the preparation efficiency. In summary, the beneficial effects of the present invention are as follows:

[0028] 1. Preparation without a reducing agent can completely prevent the introduction of impurity elements from the source;

[0029] 2. Direct decomposition is carried out in a low oxygen partial pressure environment, and the separation of the target product and O 2 is realized, and the process is simple;

[0030] 3. Rapid preparation is carried out within dozens of seconds, greatly shortening the preparation time and improving the preparation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 For the prepared β-Ti 3 O 5 X-ray diffraction pattern of the powder

[0032] Figure 2 For the prepared β-Ti 3 O 5 Results of X-ray photoelectron spectroscopy (XPS) analysis of the powder

[0033] Figure 3 For the prepared β-Ti 3 O 5 Scanning electron microscope (SEM) image and energy dispersive spectroscopy (EDS) analysis results of the bulk Specific implementation manners

[0034] The present invention will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments are only used to illustrate the invention, but do not limit the scope of the invention in any form. In addition, it should be noted that those skilled in the art can make various modifications and improvements to the present invention. These all fall within the protection scope of the present invention.

[0035] Example 1

[0036] (1) Weigh 300 mg of TiO 2 powder raw material and put it into a copper crucible with an internal circulating water cooling system

[0037] (2) Adjust the defocus amount of the laser. Under the atmospheric environment, pre-treat the raw material in step (1) with a laser at a power density of 1.0 kW / cm 2 for 10 s to obtain a spherical sample with a diameter of about 4 mm.

[0038] (3) Place the sample obtained in step (2) in the crucible and transfer it to a vacuum chamber, and evacuate to 10 -3 Pa.

[0039] (4) After reaching the required vacuum degree, use a laser with a power density of 4.96 kW / cm 2 to act on the pre-treated sample. The melting temperature is controlled at 2000 - 2200 °C, and the action time is 60 s. Take out the prepared sample after natural cooling.

[0040] (5) Grind the obtained sample into powder and conduct XRD tests. The results are as Figure 1 shown. After comparing with the standard card, it can be seen that there are no other impurity phases in the product, which is β-Ti 3 O 5 ; Conduct XPS analysis on the obtained powder sample. The results are as Figure 2 shown. There are two valence states of Ti in the product, namely Ti 3+ and Ti4+ ; The bulk sample was analyzed by SEM-EDS, and the results are as Figure 3 shown. There are no other impurities in the product except Ti and O. Therefore, the obtained sample is a pure phase with a purity of ≥99.99%.

[0041] Example 2

[0042] (1) Weigh 400 mg of TiO 2 powder raw material and put it into a pure tungsten crucible

[0043] (2) Adjust the defocus amount of the laser. Under the atmospheric environment, use a laser with a power density of 2.0 kW / cm 2 to pre-treat the raw material in step (1) for 10 s to obtain a spherical sample with a diameter of about 5 mm.

[0044] (3) Place the sample obtained in step (2) in the crucible and transfer it to a vacuum chamber. Evacuate to 10 -2 Pa, fill it with helium gas, and control the total pressure in the chamber to be lower than 10 5 Pa, and the oxygen partial pressure is 10 -7 Pa.

[0045] (4) After reaching the required vacuum degree, use a laser with a power density of 4.5 kW / cm 2 to act on the pre-treated sample. Control the melting temperature at 2100 - 2300 °C and the action time at 65 s. Take out the prepared sample after natural cooling.

[0046] (5) The obtained sample is a pure phase with a purity of ≥99.99%.

[0047] Example 3

[0048] (1) Weigh 500 mg of TiO 2 powder raw material and put it into a platinum crucible with a circulating water cooling system at the bottom

[0049] (2) Adjust the defocus amount of the laser. Under the atmospheric environment, use a laser with a power density of 2.5 kW / cm 2 to pre-treat the raw material in step (1) for 10 s to obtain a spherical sample with a diameter of about 6 mm.

[0050] (3) Place the sample obtained in step (2) in the crucible and transfer it to a vacuum chamber. Evacuate to 10 -4 Pa.

[0051] (4) After reaching the required vacuum degree, use a laser with a power density of 5.5 kW / cm 2 to act on the pre-treated sample. Control the melting temperature at 2200 - 2400 °C and the action time at 70 s. Take out the prepared sample after natural cooling.

[0052] (5) The obtained sample is a pure phase with a purity of ≥ 99.99%.

[0053] Example 4

[0054] (1) Weigh 600 mg of TiO 2 powder raw material and put it into a pure tungsten crucible

[0055] (2) Adjust the defocus amount of the laser. Under atmospheric environment, use a laser with a power density of 3.0 kW / cm 2 to pre-treat the raw material in step (1) for 10 s to obtain a spherical sample with a diameter of about 7 mm.

[0056] (3) Place the sample obtained in step (2) in the crucible and transfer it to a vacuum chamber. Evacuate to 10 -3 Pa, fill with nitrogen, and control the total pressure in the chamber to be lower than 10 5 Pa, and the oxygen partial pressure is 10 -12 Pa.

[0057] (4) After reaching the required vacuum degree, use a laser with a power density of 7.5 kW / cm 2 to act on the pre-treated sample. Control the melting temperature at 2300 - 2500 °C and the action time for 100 s. Take out the prepared sample after natural cooling.

[0058] (5) The obtained sample is a pure phase with a purity of ≥ 99.99%.

[0059] Example 5

[0060] (1) Weigh 200 mg of TiO 2 powder raw material and put it into a copper crucible with an internal circulating water cooling system

[0061] (2) Adjust the defocus amount of the laser. Under atmospheric environment, use a laser with a power density of 1.0 kW / cm 2 to pre-treat the raw material in step (1) for 10 s to obtain a spherical sample with a diameter of about 3 mm.

[0062] (3) Place the sample obtained in step (2) in the crucible and transfer it to a vacuum chamber. Evacuate to 10 -3 Pa, fill with argon, and control the total pressure in the chamber to be lower than 10 5 Pa, and the oxygen partial pressure is 10 -16 Pa.

[0063] (4) After reaching the required vacuum degree, use a laser with a power density of 3.0 kW / cm 2 to act on the pre-treated sample. Control the melting temperature at 1900 - 2100 °C and the action time for 60 s. Take out the prepared sample after natural cooling.

[0064] (5) The obtained sample is a pure phase with a purity of ≥99.99%.

[0065] Example 6

[0066] (1) Weigh 500 mg of TiO 2 powder raw material and put it into a platinum crucible with a circulating water cooling system at the bottom.

[0067] (2) Adjust the defocus amount of the laser. Under the atmospheric environment, use a laser with a power density of 3.0 kW / cm 2 to pre-treat the raw material in step (1) for 10 s to obtain a spherical sample with a diameter of about 6 mm.

[0068] (3) Place the sample obtained in step (2) in the crucible and transfer it to a vacuum chamber, and evacuate it to 10 -2 Pa.

[0069] (4) After reaching the required vacuum degree, use a laser with a power density of 8.0 kW / cm 2 to act on the pre-treated sample. The melting temperature is controlled at 2150 - 2350 °C, and the action time is 80 s. Take out the prepared sample after natural cooling.

[0070] (5) The obtained sample is a pure phase with a purity of ≥99.99%.

[0071] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit it; although the present patent has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included within the protection scope of the present invention.

Claims

1. A method for rapidly preparing β-Ti 3 O 5 without a reducing agent It is characterized in that It includes the following steps: (1) Weigh an appropriate amount of TiO 2 raw materials and put them into a crucible; (2) Set the laser focal length and working distance so that the entire sample surface can receive laser irradiation. At the same time, set the laser output power to control the laser power density at the sample surface to be in the range of 1.0 - 3.0 kW / cm 2 , and perform irradiation pretreatment on the raw materials in step (1); (3) Transfer the pretreated sample obtained in step (2) to the reaction chamber, start the vacuum pump group of the reaction chamber, and adjust the pressure in the reaction chamber to a predetermined value; wherein, adjusting the pressure in the reaction chamber to a predetermined value means controlling the total pressure in the chamber within the range of 10 -2 to 10 -4 Pa by the vacuum pump group; or evacuating the total pressure in the chamber to 10 -2 Pa by the vacuum pump group and then filling with argon, nitrogen, or helium, and controlling the total pressure in the chamber to be less than 10 5 Pa, with the oxygen partial pressure range being 10 -7 to 10 -16 Pa; (4) Set the laser focal length and working distance so that the entire sample surface can receive laser irradiation. At the same time, set the laser output power to control the laser power density at the sample surface to be in the range of 3.0 - 8.0 kW / cm 2 , and perform vacuum melting on the pre-melted sample obtained in step (3), and conduct temperature control during the process; (5) After the melting is completed, wait for the sample to cool below 100 °C, take out the obtained bulk sample, and obtain powder after crushing.

2. The method for rapidly preparing β-Ti without a reducing agent according to claim 1 3 O 5 and It is characterized in that In step (1), the TiO 2 raw material is TiO 2 powder with a purity higher than 99.0% or formed bulk raw material.

3. The method for rapidly preparing β-Ti without a reducing agent according to claim 1 3 O 5 and It is characterized in that In step (1), the crucible is a high-temperature container made of a material that does not react with titanium oxide through processing.

4. Method for rapidly preparing β-Ti without a reducing agent according to claim 3 3 O 5 ​ It is characterized in that In step (1), the crucible is a copper crucible with an internal circulating water cooling system, a pure tungsten crucible or a platinum crucible.

5. A method for rapidly preparing β-Ti without a reducing agent according to claim 1 3 O 5 thereof It is characterized in that In step (2), the pretreatment refers to melting all the raw materials in (1) into a liquid phase by laser and obtaining a dense sample after cooling and solidification.

6. The method for rapidly preparing β-Ti without a reducing agent according to claim 1 3 O 5 and It is characterized in that In step (3), the reaction chamber is a sealed chamber that can withstand a certain negative pressure and has a laser incident window.

7. A method for rapidly preparing β-Ti without a reducing agent according to claim 1 3 O 5 method It is characterized in that In step (3), the vacuum pump group refers to a device that consists of a mechanical pump or an oil pump and a molecular pump in series to pump out the gas in the reaction chamber.

8. The method for rapidly preparing β-Ti without a reducing agent according to claim 1 3 O 5 and It is characterized in that In step (4), the melting for a certain time refers to the time when the sample receives laser irradiation. According to the different masses of the samples, the melting time is controlled within 30 s to 100 s.

9. The method for rapidly preparing β-Ti without a reducing agent according to claim 1 3 O 5 and It is characterized in that In step (4), the temperature control refers to dynamically adjusting the laser output power on the basis of on-line monitoring of the sample melting temperature by a non-contact optical temperature measurement device, so that the sample melting temperature during the melting process is controlled within 1900 - 2500 °C.

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