A method for preparing λ-Ti3O5 functional materials

Abstract

This invention discloses a method for preparing λ-Ti3O5 functional materials, comprising the following steps: (1) the raw materials are TiO2 powder and oxide of metal M, and the raw materials are measured according to the molar ratio of metal element M / Ti as x:(3-x), wherein 0.09≤x≤0.40; (2) the raw materials measured in step (1) are thoroughly ground to obtain mixed powder, and the mixed powder is pressed into a mold to obtain a shaped block; (3) under an inert gas atmosphere, the shaped block obtained in step (2) is subjected to laser heating reaction with high laser power density, the laser heating reaction temperature is 1800~2300℃, to obtain sintered block A; (4) then the laser power density is slowly reduced and the laser is continuously applied to the sintered block A obtained in step (3) to obtain sintered block B; (5) after the sintered block B is naturally cooled, the λ-Ti3O5 functional material is obtained.

Description

Technical Field

[0001] This invention belongs to the field of functional materials, and in particular relates to a method for preparing λ-Ti3O5 functional materials. Technical Background

[0002] Ti3O5 is a type of titanium suboxide with various crystal forms. At room temperature, Ti3O5 exists stably as the β phase, while λ-Ti3O5 is a metastable phase at high temperatures. Due to its structural and property characteristics, λ-Ti3O5 has broad application prospects in multiple fields and is a highly promising functional material. For example, due to its broad-spectrum solar absorption and high light absorptivity, λ-Ti3O5 is considered a potential photothermal material for seawater desalination. Furthermore, the reversible phase transition between λ-Ti3O5 and β-Ti3O5 induced by external temperature and pressure, resulting in changes in the system's enthalpy, also makes it suitable as a phase change thermal storage material for waste heat recovery. However, the λ phase of Ti3O5, being a metastable phase at high temperatures, is difficult to obtain at room temperature. Currently, methods for obtaining the room-temperature stable λ phase involve preparing it as nanoparticles. For example, Chinese patent CN 104973622 B first obtains TiO2 nanoparticles through raw material pretreatment, and then obtains λ-Ti3O5 through carbon reduction. Chinese patent CN 111003727 A directly uses commercial nano-TiO2 as raw material to prepare λ-Ti3O5 through hydrogen reduction. Chinese patent CN 116375079 A proposes a method for directly preparing Ti3O5 without a reducing agent under low oxygen partial pressure using a laser as a heat source, but it can only obtain the β phase and not the λ phase. Therefore, the methods currently used all require the introduction of a reducing agent, which not only makes the preparation process complex and demanding, but also requires control of reaction temperature, time, and the amount of reducing agent, making it difficult to easily obtain λ-Ti3O5 at room temperature. Summary of the Invention

[0003] To address the aforementioned issues, this patent proposes a method that involves adding a specific metal oxide as a stabilizer and using a laser as a heat source to directly prepare λ-Ti3O5 functional materials without a reducing agent.

[0004] The technical solution adopted in this invention is as follows:

[0005] In a first aspect, the present invention provides a method for preparing λ-Ti3O5 functional materials, comprising the following steps:

[0006] (1) The raw materials are TiO2 powder and oxide of metal M. The proportion of each raw material is measured according to the molar ratio of metal element M / Ti as x:(3-x), where 0.09≤x≤0.40;

[0007] (2) Grind the measured raw materials in step (1) thoroughly to obtain a mixed powder, and press the mixed powder into a mold to obtain a shaped block;

[0008] (3) After adjusting the oxygen partial pressure in the cavity, the molded block obtained in step (2) is subjected to laser heating reaction with high laser power density. The temperature of the laser heating reaction is 1800-2300℃ to obtain sintered block A.

[0009] (4) Then slowly reduce the laser power density and keep the laser acting on the sintered block A obtained in step (3) to obtain sintered block B;

[0010] (5) The λ-Ti3O5 functional material is obtained after the sintered block B is naturally cooled.

[0011] Optionally, in step (3), the oxygen partial pressure is less than 10. -3 Pa.

[0012] Optionally, in step (3), the laser heating reaction time is 1 to 10 minutes, preferably 2 to 8 minutes;

[0013] Optionally, in step (3), the high laser power density is 1.0–10.0 kW / cm². 2 The preferred power is 3.0–8.0 kW / cm². 2 .

[0014] Optionally, in step (4), the rate at which the laser power density is slowly reduced is 0.1–2 kW / cm². 2 The preferred value is 0.5–1.2 kW / cm². 2 .

[0015] Optionally, the specific steps for adjusting the oxygen partial pressure described above are as follows: after extracting the gas from the reaction chamber used to contain the molded block, control the total pressure of the chamber at 10. -2 ~10 -4 Pa adjusts the oxygen partial pressure in the chamber or extracts the gas and then fills it with inert gas to adjust the oxygen partial pressure in the chamber. Specifically, the shaped block obtained in step (2) is placed in a crucible and then transferred to the reaction chamber. Specifically, the inert gas includes inert gases such as nitrogen, argon, and helium.

[0016] The process includes the following steps:

[0017] Preferably, in step (1):

[0018] The TiO2 and metal M oxides are powders with a purity higher than 99.9%.

[0019] The oxide of the metal M can be at least one of MgO, Al2O3, Sc2O3, V2O3, Cr2O3, MnO, and FeO.

[0020] Preferably, in step (2):

[0021] The pressing pressure is 5-20 MPa, preferably 8-15 MPa, and the holding time is 5-10 min.

[0022] In a second aspect, the present invention provides a λ-Ti3O5 functional material prepared by the preparation method described in the first aspect of the present invention.

[0023] The beneficial effects of this invention are:

[0024] This invention utilizes a strategy of adding metal oxides and employs laser as a heat source to directly prepare λ-Ti3O5 functional materials without a reducing agent, achieving a stable λ-Ti3O5 phase at room temperature. The method can directly use ordinary TiO2 powder as raw material, eliminating the need to prepare TiO2 powder into nanoparticles. Furthermore, the method eliminates the need to prepare λ-Ti3O5 into nanoparticles, allowing for direct λ-Ti3O5 preparation at room temperature. By using laser as a heat source for direct reduction under low oxygen partial pressure, the process is simple and significantly improves preparation efficiency. Attached Figure Description

[0025] Figure 1 This is the X-ray diffraction pattern of the sample prepared in Example 1.

[0026] Figure 2 This is the X-ray diffraction pattern of the sample prepared in Example 2.

[0027] Figure 3 This is the X-ray diffraction pattern of the sample prepared in Example 3.

[0028] Figure 4 This is the X-ray diffraction pattern of the sample prepared in Example 4.

[0029] Figure 5 This is the X-ray diffraction pattern of the sample prepared in Example 5.

[0030] Figure 6 This is the X-ray diffraction pattern of the sample prepared in Example 6.

[0031] Figure 7 This is the X-ray diffraction pattern of the sample prepared in Example 7.

[0032] Figure 8 X-ray diffraction pattern of the sample prepared in Comparative Example 1 Detailed Implementation

[0033] The present invention will be further described below with reference to embodiments. It should be understood that the embodiments are only used to further illustrate and explain the invention, and are not intended to limit the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Unless otherwise specified, percentages in this manual refer to percentages by mass.

[0035] Example 1

[0036] (1) Weigh a certain proportion of TiO2 and MgO powder, and the molar ratio of metal element atoms (Mg / Ti) is x:(3-x).

[0037] (2) Grind the raw materials measured in step (1) thoroughly, and press them into shape in a mold at 8 MPa for 5 minutes to obtain block raw materials.

[0038] (3) Place the sample obtained in step (2) in the crucible and transfer it to the reaction chamber, adjusting the oxygen partial pressure to 10. -8 Pa.

[0039] (4) After reaching the required oxygen partial pressure, at 6.0 kW / cm 2 The laser power density was applied to the sample for 1 minute, and the temperature was controlled at 2200℃.

[0040] (5) 0.2kW / cm² after high laser power density treatment 2 The power density decreases slowly and continues to act on the sample.

[0041] (6) Take out the prepared sample after it has cooled naturally.

[0042] When x = 0.1, the λ phase accounts for 96.59%; when x = 0.09, the λ phase accounts for 95.53%.

[0043] Example 2

[0044] (1) Weigh a certain proportion of TiO2 and Al2O3 powders, and the molar ratio of metal element atoms (Al / Ti) is x:(3-x).

[0045] (2) Grind the raw materials measured in step (1) thoroughly, and press them into shape in a mold at 10 MPa for 5 minutes to obtain block raw materials.

[0046] (3) Place the sample obtained in step (2) in the crucible and transfer it to the reaction chamber, adjusting the oxygen partial pressure to 10. -7 Pa.

[0047] (4) After reaching the required oxygen partial pressure, use 8.0 kW / cm 2 The laser power density was applied to the sample for 3 minutes, and the temperature was controlled at 2100℃.

[0048] (5) 0.5kW / cm² after high laser power density treatment 2 The power density decreases slowly and continues to act on the sample.

[0049] (6) Take out the prepared sample after it has cooled naturally.

[0050] When x = 0.12, the λ phase accounts for 92.14%; when x = 0.11, the λ phase accounts for 90.37%; and when x = 0.1, the λ phase accounts for 87.43%.

[0051] Example 3

[0052] (1) Weigh a certain proportion of TiO2 and Sc2O3 powders, and the molar ratio of metal element atoms (Sc / Ti) is x:(3-x).

[0053] (2) Grind the raw materials measured in step (1) thoroughly, and press them into shape in a mold at 8 MPa for 5 minutes to obtain block raw materials.

[0054] (3) Place the sample obtained in step (2) in the crucible and transfer it to the reaction chamber, adjusting the oxygen partial pressure to 10. -7 Pa.

[0055] (4) After reaching the required oxygen partial pressure, at 10.0 kW / cm 2 The laser power density was applied to the sample for 5 minutes, and the temperature was controlled at 2200℃.

[0056] (5) 0.2kW / cm² after high laser power density treatment 2 The power density decreases slowly and continues to act on the sample.

[0057] (6) Take out the prepared sample after it has cooled naturally.

[0058] When x = 0.1, the λ phase accounts for 96.79%; when x = 0.09, the λ phase accounts for 92.30%.

[0059] Example 4

[0060] (1) Weigh a certain proportion of TiO2 and V2O3 powders, and the molar ratio of metal element atoms (V / Ti) is x:(3-x).

[0061] (2) Grind the raw materials measured in step (1) thoroughly, press them in a mold at 10 MPa, and hold the pressure for 10 minutes to obtain block raw materials.

[0062] (3) Place the sample obtained in step (2) in the crucible and transfer it to the reaction chamber, adjusting the oxygen partial pressure to 10. -7 Pa.

[0063] (4) After reaching the required oxygen partial pressure, at 6.0 kW / cm 2 The laser power density was applied to the sample for 2 minutes, and the temperature was controlled at 1800℃.

[0064] (5) 0.6kW / cm² after high laser power density treatment 2 The power density decreases slowly and continues to act on the sample.

[0065] (6) Take out the prepared sample after it has cooled naturally.

[0066] When x = 0.3, the λ phase accounts for 96.06%; when x = 0.25, the λ phase accounts for 94.45%.

[0067] Example 5

[0068] (1) Weigh a certain proportion of TiO2 and Cr2O3 powders, and the molar ratio of metal element atoms (Cr / Ti) is x:(3-x).

[0069] (2) Grind the raw materials measured in step (1) thoroughly, and press them into shape in a mold at 15 MPa for 5 minutes to obtain block raw materials.

[0070] (3) Place the sample obtained in step (2) in the crucible and transfer it to the reaction chamber, adjusting the oxygen partial pressure to 10. -8 Pa.

[0071] (4) After reaching the required oxygen partial pressure, at 3.0 kW / cm 2 The laser power density was applied to the sample for 8 minutes, and the temperature was controlled at 1800℃.

[0072] (5) 0.9 kW / cm² after high laser power density treatment 2 The power density decreases slowly and continues to act on the sample.

[0073] (6) Take out the prepared sample after it has cooled naturally.

[0074] When x = 0.4, the λ phase accounts for 93.58%; when x = 0.35, the λ phase accounts for 91.52%.

[0075] Example 6

[0076] (1) Weigh a certain proportion of TiO2 and MnO powder, and the molar ratio of metal element atoms (Mn / Ti) is x:(3-x).

[0077] (2) Grind the raw materials measured in step (1) thoroughly, and press them into shape in a mold at 10 MPa for 5 minutes to obtain block raw materials.

[0078] (3) Place the sample obtained in step (2) in the crucible and transfer it to the reaction chamber, adjusting the oxygen partial pressure to 10. -9 Pa.

[0079] (4) After reaching the required oxygen partial pressure, use 9.0 kW / cm 2 The laser power density was applied to the sample for 5 minutes, and the temperature was controlled at 2200℃.

[0080] (5) 0.6kW / cm² after high laser power density treatment 2 The power density decreases slowly and continues to act on the sample.

[0081] (6) Take out the prepared sample after it has cooled naturally.

[0082] When x = 0.2, the λ phase accounts for 94.63%; when x = 0.15, the λ phase accounts for 90.27%; and when x = 0.1, the λ phase accounts for 80.64%.

[0083] Example 7

[0084] (1) Weigh a certain proportion of TiO2 and FeO powder, and the molar ratio of metal element atoms (Fe / Ti) is x:(3-x).

[0085] (2) Grind the raw materials measured in step (1) thoroughly, and press them into shape in a mold at 15 MPa for 10 minutes to obtain block raw materials.

[0086] (3) Place the sample obtained in step (2) in the crucible and transfer it to the reaction chamber, adjusting the oxygen partial pressure to 10. -7 Pa.

[0087] (4) After reaching the required oxygen partial pressure, at 7.0 kW / cm 2 The laser power density was applied to the sample for 6 minutes, and the temperature was controlled at 1900℃.

[0088] (5) 0.2kW / cm² after high laser power density treatment 2 The power density decreases slowly and continues to act on the sample.

[0089] (6) Take out the prepared sample after it has cooled naturally.

[0090] When x = 0.225, the λ phase accounts for 97.16%; when x = 0.2, the λ phase accounts for 96.81%.

[0091] Comparative Example 1

[0092] (1) Weigh a certain proportion of TiO2 and Al2O3 powders, and the molar ratio of metal element atoms (Al / Ti) is x:(3-x).

[0093] (2) Grind the raw materials measured in step (1) thoroughly, and press them into shape in a mold at 10 MPa for 5 minutes to obtain block raw materials.

[0094] (3) Place the sample obtained in step (2) in the crucible and transfer it to the reaction chamber, adjusting the oxygen partial pressure to 10. -7 Pa.

[0095] (4) After reaching the required oxygen partial pressure, use 8.0 kW / cm 2 The laser power density was applied to the sample for 3 minutes, and the temperature was controlled at 2100℃.

[0096] (5) The sample was taken out after being subjected to high laser power density and then allowed to cool naturally. Since no power reduction step was performed, Ti2O3 impurity phase appeared in the product.

Claims

1. A method for preparing λ-Ti3O5 functional materials, comprising the following steps: (1) The raw materials are TiO2 powder and oxide of metal M. The proportion of each raw material is measured according to the molar ratio of metal element M / Ti as x:(3-x), where 0.09≤x≤0.40; (2) Grind the measured raw materials in step (1) thoroughly to obtain a mixed powder, and press the mixed powder into a mold to obtain a shaped block; (3) After adjusting the oxygen partial pressure in the cavity, the molded block obtained in step (2) is subjected to laser heating reaction with high laser power density. The temperature of the laser heating reaction is 1800-2300℃ to obtain sintered block A. (4) Then slowly reduce the laser power density and keep the laser acting on the sintered block A obtained in step (3) to obtain sintered block B; (5) The λ-Ti3O5 functional material is obtained after the sintered block B is naturally cooled. The oxide of the metal M is at least one of MgO, Al2O3, Sc2O3, V2O3, Cr2O3, MnO, and FeO. In step (3), the oxygen partial pressure is below 10. -3 Pa; In step (4), the rate at which the laser power density is slowly reduced is .

2. The method as described in claim 1, characterized in that, In step (3), the laser heating reaction takes 1 to 10 minutes.

3. The method as described in claim 1, characterized in that, In step (3), the high laser power density is 1.0–10.0 kW / cm². 2 .

4. The method as described in claim 1, characterized in that, In step (4), the rate at which the laser power density is slowly reduced is .

5. The method as described in claim 1, characterized in that, The specific steps for adjusting the oxygen partial pressure are as follows: After extracting the gas from the reaction chamber used to contain the molded block, control the total pressure of the chamber at [value missing]. Pa adjusts the oxygen partial pressure in the chamber or extracts the gas and then fills it with inert gas to adjust the oxygen partial pressure in the chamber.

6. The method as described in claim 1, characterized in that, In step (1), the TiO2 and the oxide of metal M are powders with a purity higher than 99.9%.

7. The method as described in claim 1, characterized in that, In step (2), the pressing pressure is 5-20 MPa and the holding time is 5-10 min.

8. A λ-Ti3O5 functional material, prepared by the method described in any one of claims 1 to 7.

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