A vanadate with low thermal expansion and enhanced optoelectronic and photocatalytic properties, and a sintering synthesis method and application thereof

Abstract

The present invention discloses a vanadate with low thermal expansion and enhanced optoelectronic and photocatalytic properties, as well as a sintering synthesis method and application thereof, belonging to the technical field of inorganic non-metallic materials. Using LiOH•H2O, CuO, and V2O5 as raw materials, the raw materials are weighed according to the stoichiometric molar ratio in the target product Li x Cu 2‑x V2O 7‑δ Excess V is added to compensate for its volatilization during the sintering process. The sample is fully ground and mixed evenly, and then the sample is dried to remove the excess moisture carried by the raw materials. Then the dried powder is pressed into tablets or directly placed in a muffle furnace and sintered at 600-650 °C for 5-7 h to obtain the target product. The present invention uses the hetero-valent ion Li + to partially replace Cu 2+ ions in Cu2V2O7, and uses the solid-phase method to prepare Li x Cu 2‑x V2O 7‑δ ( x = 0.01-0.09) with low thermal expansion and enhanced optoelectronic properties. The process is simple and low-cost, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the field of inorganic non-metallic materials, and particularly relates to a vanadate with low thermal expansion and enhanced optoelectronic and photocatalytic properties, and a sintering synthesis method and application thereof. Background Art

[0002] With the rapid development of electronic technology and optoelectronic technology, semiconductor devices are being widely used in fields such as communication, computing, and energy. However, with the continuous integration and miniaturization of these devices, their operating temperature and environment are gradually becoming extreme, and the requirement for the functional stability of materials is increasing. In the process of repeated heating and cooling cycles, if the heat generated by the material cannot be released, the induced thermal stress becomes a key problem in reducing functional stability, especially in high-power, high-frequency, or high-temperature environments. This thermal stress may lead to a decline in the performance of semiconductor devices, a shortening of their lifespan, or even damage.

[0003] To solve this problem, researchers have widely focused on negative thermal expansion materials (NTE). Such materials exhibit abnormal thermal contraction within a certain temperature range, that is, their volume decreases instead when the temperature rises. Negative thermal expansion materials are theoretically considered to be compatible with common semiconductor materials, thereby reducing the thermal stress generated by devices during temperature changes and improving the functional stability of the devices. However, few existing negative thermal expansion materials have optoelectronic properties. α-Cu2V2O7 is a member of the copper vanadate family and has obvious negative thermal expansion properties. At the same time, this material has also been studied more in photocatalysis, and its ferroelectric properties have been reported. However, the optoelectronic properties of α-Cu2V2O7 are weak. How to improve its optoelectronic properties and combine its negative thermal expansion to improve its optoelectronic properties has not been reported yet.

[0004] Therefore, the present application provides a method that uses the hetero-valent ion Li + to replace Cu in α-Cu2V2O7 2+ . By analogy, when a small amount of trivalent elements (such as boron, aluminum) are doped into pure silicon materials, electron-deficient positively charged holes will appear in the silicon materials. By increasing the holes, the photovoltage performance of α-Cu2V2O7 is enhanced and its expansion coefficient is regulated. This vanadate with low thermal expansion and enhanced optoelectronic properties is prepared by the solid-phase method, which is suitable for industrial production and is of great significance for solving the thermal stress problem of precision optoelectronic devices. Summary of the Invention

[0005] The purpose of the present invention is to design a vanadate with low thermal expansion and enhanced optoelectronic and photocatalytic properties, and a sintering synthesis method and application thereof.

[0006] To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0007] A sintering synthesis method of vanadate with low thermal expansion and enhanced optoelectronic and photocatalytic properties is as follows:

[0008] Using LiOH•H2O, CuO, and V2O5 as raw materials, according to the stoichiometric molar ratio in the target product Li x Cu 2-x V2O 7-δ ( x = 0.01~0.09, δ = x / 2), weigh the raw materials. Among them, the addition amount of V2O5 is excessive to compensate for its volatilization during the sintering process. After grinding and mixing the raw materials evenly, dry them and then sinter them at 600~650 °C for 5~7 h directly or after pressing to obtain the target product.

[0009] Furthermore, the molar addition amount of V2O5 is 1.01~1.1 times of the theoretical addition amount.

[0010] The vanadate Li x Cu 2-x V2O 7-δ ( x = 0.01~0.09, δ = x / 2) obtained by the above sintering synthesis method.

[0011] The application of the above vanadate Li x Cu 2-x V2O 7-δ in the photocatalytic degradation of Rhodamine B.

[0012] Advantages of the present invention:

[0013] 1. The present invention uses LiOH•H2O, CuO, and V2O5 as raw materials to prepare vanadate with low thermal expansion and enhanced optoelectronic properties. The content of Li in its target product Li x Cu 2-x V2O 7-δ is x = 0.01, 0.03, 0.05, 0.07 and 0.09.

[0014] 2. The present invention adopts the solid-phase sintering method, which has simple process and low cost, and is suitable for industrial production. Description of the drawings

[0015] Figure 1 is the X-ray diffraction (XRD) pattern of Cu2V2O7 synthesized in Example 1; [[ID=X]] [[ID=Y]]

[0016] [[ID=Z]] Figure 2 is Li 0.01 Cu1.99 V2O 7-0.005 XRD pattern of

[0017] Figure 3 Li synthesized in Example 3 0.03 Cu 1.97 V2O 7-0.015 XRD pattern of

[0018] Figure 4 Li synthesized in Example 4 0.05 Cu 1.95 V2O 7-0.025 XRD pattern of

[0019] Figure 5 Li synthesized in Example 5 0.07 Cu 1.93 V2O 7-0.035 XRD pattern of

[0020] Figure 6 Li synthesized in Example 6 0.09 Cu 1.91 V2O 7-0.045 XRD pattern of

[0021] Figure 7 Surface photovoltage spectra of samples with different doping ratios synthesized for Examples 1-6;

[0022] Figure 8 Photocatalytic performance curves of samples with different doping ratios synthesized for Examples 1-6;

[0023] Figure 9 The curves of the relative length of the synthetic samples of Examples 1-6 changing with temperature. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Example 1

[0026] The sintering synthesis method of Cu2V2O7 is as follows: CuO and V2O5 are used as raw materials. The raw materials are weighed according to the stoichiometric molar ratio of Cu:V=1:1. In order to prevent the volatilization of V during the sintering process, an excess of 5 mol% of V2O5 is added, that is, according to the molar ratio of CuO:V2O5=2:1.05. Put it in a mortar and grind it for about 2 hours, and dry it in a drying oven at 80°C for 2 hours. Use a uniaxial tablet press to press it into a cylinder with a diameter of 10 mm and a height of 5~6 mm at a pressure of 4.5 tons. Put it in a muffle furnace, heat it to 650°C at a rate of 5°C / min, sinter it for 5 hours, and naturally cool it to room temperature in the air. The XRD pattern phase analysis corresponding to the product is shown inFigure 1 , the comparison with the PDF card of standard Cu2V2O7 shows a pure phase.

[0027] Example 2

[0028] Li 0.01 Cu 1.99 V2O 7-0.005 The sintering synthesis method of, different from Example 1: Using LiOH•H2O, CuO, and V2O5 as raw materials, weighing the raw materials according to the molar ratio LiOH•H2O:CuO:V2O5 = 0.01:1.99:1.05, putting them into a muffle furnace, heating up to 640 °C at a rate of 5 °C / min and sintering for 5 h, and naturally cooling to room temperature in the air. The XRD pattern phase analysis of the product is shown in Figure 2 , the comparison with the PDF card of standard Cu2V2O7 shows a pure phase.

[0029] Example 3

[0030] Li 0.03 Cu 1.97 V2O 7-0.015 The sintering synthesis method of, different from Example 2: Weighing the raw materials according to the molar ratio LiOH•H2O:CuO:V2O5 = 0.03:1.97:1.05. The XRD pattern phase analysis of the product is shown in Figure 3 , the comparison with the PDF card of standard Cu2V2O7 shows a pure phase.

[0031] Example 4

[0032] Li 0.05 Cu 1.95 V2O 7-0.025 The sintering synthesis method of, different from Example 2: Weighing the raw materials according to the molar ratio LiOH•H2O:CuO:V2O5 = 0.05:1.95:1.05. The XRD pattern phase analysis of the product is shown in Figure 4 , the comparison with the PDF card of standard Cu2V2O7 shows a pure phase.

[0033] Example 5

[0034] Li 0.07 Cu 1.93 V2O 7-0.035 The sintering synthesis method of, different from Example 2: Weighing the raw materials according to the molar ratio LiOH•H2O:CuO:V2O5 = 0.07:1.93:1.05. The XRD pattern phase analysis of the product is shown in Figure 5 , the comparison with the PDF card of standard Cu2V2O7 shows a pure phase.

[0035] Example 6

[0036] Li0.09 Cu 1.91 V2O 7-0.045 The sintering synthesis method of Figure 6 , compared with Example 2, is as follows: Weigh the raw materials according to the molar ratio LiOH•H2O:CuO:V2O5 = 0.09:1.91:1.05, put them into a muffle furnace, heat up to 600 °C at a rate of 5 °C / min and sinter for 7 h, and then naturally cool to room temperature in the air. The XRD pattern phase analysis of the product is shown in

[0037] Surface photovoltage test:

[0038] Figure 7 For the vanadates Li x Cu 2-x V2O 7-δ ( x = 0, 0.01, 0.03, 0.05, 0.07, 0.09) prepared in Examples 1 - 6, the surface photovoltage (SPV) test results show that with the increase of the Li + doping content, the surface photovoltage performance of the sample has a significant improvement compared with the initially undoped sample. And when the Li + doping content reaches x = 0.05, the surface photovoltage performance of the sample is the strongest (20.6 mV), and the signal intensity of its photovoltage is about 3.7 times that of the undoped Li + sample (5.6 mV).

[0039] Photocatalytic performance test:

[0040] Figure 8 For the vanadates Li x Cu 2-x V2O 7-δ ( x = 0, 0.01, 0.03, 0.05, 0.07, 0.09) prepared in Examples 1 - 6, the photocatalytic performance test results are as follows. The vanadate photocatalyst: 30 mg, and then record the change of photocatalytic degradation of 100 mL (40 mg / L) rhodamine B with time under visible light irradiation (λ > 420 nm). Through the test results, it can be found that with the increase of the Li + doping amount, the photocatalytic degradation rate under visible light irradiation increases significantly with the increase of the doping ratio ( x = 0.01 - 0.07, x = 0, the corresponding concentration C at 1 hour is 0.71 times the initial concentration C0, x=0.07 in 1 hour, the corresponding concentration C is 0.32 times the initial concentration C0, and the degradation rate increases by 2.2 times). However, further increasing the doping ratio, the photocatalytic degradation rate decreases significantly ( x =0.07~0.09).

[0041] Thermal Expansion Coefficient Test:

[0042] Figure 9 The vanadate Li prepared in Example 1-6 x Cu 2-x V2O 7-δ ( x =0, 0.01, 0.03, 0.05, 0.07, 0.09) of the relative length with temperature. + With the increase of the content, the thermal expansion changes from negative to low. After calculation, it can be seen that the expansion coefficient of Cu2V2O7 is -9.6×10 -6 ℃ -1 (Room temperature ~ 400℃); Li 0.01 Cu 1.99 V2O 7-0.005 The expansion coefficient is -8.87×10 -6 ℃ -1 (room temperature~300℃) and -2.8×10 -6o C -1 (300~400℃);Li 0.03 Cu 1.97 V2O 7-0.015 The expansion coefficient is -7.9×10 -6 ℃ -1 (room temperature~300℃) and -6×10 -6 ℃ -1 (300~400℃); Li 0.05 Cu 1.95 V2O 7-0.025 The expansion coefficient is -5.83×10 -6 ℃ -1 (room temperature~350℃) and 2×10 -6 ℃ -1 (350~400℃), Li 0.07 Cu 1.93 V2O 7-0.035 The expansion coefficient is -4.93×10 -6 ℃ -1 (room temperature~300℃) and -4×10 -6 ℃ -1 (300~400℃); Li 0.09 Cu 1.91 V2O 7-0.045The coefficient of expansion is -4.03×10 -6 °C -1 (room temperature to 330 °C) and -1×10 -6 °C -1 (330 to 400 °C).

[0043] The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and substitutions can be made, and these improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A sintering synthesis method of vanadate with low thermal expansion and enhanced optoelectronic and photocatalytic properties, characterized in that: The process is as follows: Using LiOH•H2O, CuO, and V2O5 as raw materials, according to the stoichiometric molar ratio of the target product Li x Cu 2-x V2O 7-δ , x = 0.01~0.09, δ = x / 2, weigh the raw materials, where the addition amount of V2O5 is in excess. After grinding and mixing the raw materials evenly, dry them and then sinter them at 600~650°C for 5~7 h directly or after pressing into tablets to obtain the target product. The molar addition amount of V2O5 is 1.01~1.1 times the theoretical addition amount.

2. Vanadate Li x Cu 2-x V2O 7-δ , x = 0.01~0.09, δ = x / 2.

3. Application of vanadate Li x Cu 2-x V2O 7-δ in photocatalytic degradation of Rhodamine B.

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