Intelligent sensor based on high-irradiation-stability LiNbO3 piezoelectric coating and application thereof

Abstract

The invention discloses an intelligent sensor based on a high-irradiation-stability LiNbO3 piezoelectric coating and application of the intelligent sensor, and belongs to the technical field of intelligent sensors and intelligent sensing and control equipment. In the design of the intelligent sensor, target materials are fully sputtered by adjusting parameters of magnetron sputtering coating and increasing the gas content of Ar in the atmosphere, and formation of a lithium-deficient phase LiNb3O8 is weakened by reducing the content of O2. Therefore, the limitation of the purity of the target material on deposition is overcome, the preparation of the high-irradiation stable LiNbO3 piezoelectric coating can also be realized in the Li-deficient lithium niobate target material with high LiNb3O8 substance proportion, the preparation method has the advantages of wide target material application range and simple process, the production threshold of the piezoelectric coating is reduced, and more choices are provided for the production of intelligent sensors. The comprehensive performance of the running intelligent sensor is excellent, and the running intelligent sensor has good structure and function stability in a high-irradiation environment; as a sensor, the sensor has a wide prospect in the technical fields of intelligent sensing and control equipment and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent sensors and intelligent sensing and control equipment, and in particular to an intelligent sensor based on a high-irradiation-stable LiNbO3 piezoelectric coating and an application thereof. Background Art

[0002] In the fields of sensor technology, optical communication, wireless radio frequency, etc., LiNbO3 piezoelectric coating has a high piezoelectric constant and a large electromechanical coupling coefficient. It has excellent properties such as corrosion resistance and high temperature resistance (operating temperature up to 1110°C). It can simultaneously solve the high temperature environment and high-energy ultrasonic use requirements of sensors for bolts in coastal and high-temperature environments, and is therefore widely used.

[0003] At present, in the field of smart sensors, the preparation technology of LiNbO3 piezoelectric coating faces great challenges. First, in the sputtering process, the low atomic weight of the Li element brings great difficulties to the sputtering growth of LiNbO3 piezoelectric coating. Some Li atoms are easily scattered in the gas mixture and diffuse to the wall of the deposition chamber, causing Li deficiency in the deposited coating.

[0004] In order to solve this technical problem, the inventors provided a method for optimizing the acoustic wave signal of a lithium niobate sensor, a sensor and its application in the Chinese invention patent with publication number CN116855887A. By reducing the pressure in the cavity, the number of particles is reduced, the collision of various particles and the escape probability of Li particles are weakened; and the content of O particles is reduced to prevent excess oxygen from easily taking away free Li during the sputtering process. It is concluded that when the Ar / O2 flow ratio is 3 / 1, the prepared lithium niobate coating has the strongest ultrasonic performance. If the Ar / O2 flow ratio is further increased, the ultrasonic performance is weakened.

[0005] However, the inventors found in further research that the process optimized by CN116855887A is only applicable to pure LiNbO3 piezoelectric targets, and is not suitable for non-pure LiNbO3 piezoelectric targets mixed with a large amount of LiNb3O8 substances. However, in addition to the sputtering process, the preparation of LiNbO3 piezoelectric targets also has major problems. The existing commercially available targets or targets pressed and sintered with Nb2O5 powder and Li2O powder are all limited in purity. This is because the Li element is volatile during the target sintering process, and it is impossible to press out pure LiNbO3 piezoelectric targets, which are often mixed with LiNb3O8 substances, thereby further exacerbating the difficulty of depositing LiNbO3 piezoelectric coatings. The poor stability of LiNbO3 piezoelectric coatings in high-irradiation environments is caused by a variety of factors, among which the influence of target impurities on deposition is particularly serious, because high-irradiation environments can cause a large number of defects inside the material, such as vacancies and interstitial atoms. When the coating is poorly deposited, these defects will aggregate to form clusters, which will in turn cause structural changes such as dislocation loops, stacking fault tetrahedrons and voids, thereby destroying the integrity and piezoelectric properties of the coating. Therefore, the irradiation stability of the LiNbO3 piezoelectric coating made of impure LiNbO3 piezoelectric targets mixed with a large amount of LiNb3O8 substances is difficult to meet application requirements.

[0006] In summary, under the limitations of sputtering process and target material purity, the preparation method of a new LiNbO3 piezoelectric coating is optimized and designed to improve the high irradiation stability of the LiNbO3 piezoelectric coating, which has positive significance for expanding the application of LiNbO3 piezoelectric coatings in technical fields such as smart sensors, intelligent perception and control equipment. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, in a first aspect of the present invention, a smart sensor with excellent comprehensive performance and good structural and functional stability in a high-irradiation environment is provided, wherein the piezoelectric material of the smart sensor adopts a high-irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the high-irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using magnetron sputtering coating method, prepare lithium niobate target and substrate, and adjust the target-substrate distance to the set value; (2) Adjust the temperature and vacuum degree of magnetron sputtering coating to the set values ​​to complete the preparation work; (3) Input Ar and O2, control the total flow rate to 0.9-2.3 Pa, the Ar / O2 flow ratio to 6.1 / 1-10.5 / 1, the RF power to 800-900 W, and the deposition time to 6-9 h; a highly irradiation-stable LiNbO3 piezoelectric coating is deposited.

[0008] The preparation process of the piezoelectric coating in this smart sensor has the advantage of a wide selection of lithium niobate targets, and has good applicability to pure lithium niobate targets or Li-deficient lithium niobate targets containing LiNb3O8. In particular, under the condition of using Li-deficient lithium niobate targets, a highly irradiated and stable LiNbO3 piezoelectric coating can still be prepared, which effectively expands the application of the target and provides more diverse choices for the production of smart sensors.

[0009] Preferably, in step (1), the lithium niobate target includes a pure lithium niobate target and a Li-deficient lithium niobate target containing LiNb3O8.

[0010] Based on the above sputtering conditions, the target-substrate distance is preferably controlled in the range of 3.5-6.5 cm during magnetron sputtering coating to obtain coating products with better performance. The target-substrate distance can affect the distribution of sputtered particles on the substrate surface, thereby affecting the uniformity of film thickness and deposition rate. If the target-substrate distance is too close, the coating may be bombarded by charged particles, increasing the defect density inside the coating, while if the distance is too far, the sputtering rate will be reduced, affecting the nucleation and growth of the coating.

[0011] Preferably, in step (1), the target-base distance is 3.5-6.5 cm.

[0012] The temperature range of 100-250 °C is conducive to the crystal growth and densification of the LiNbO3 coating. This temperature can promote the orderly growth of LiNbO3 crystals in the film, reduce grain boundaries and defects, and thus improve the piezoelectric coefficient and mechanical strength of the film. In addition, this temperature range also helps to control the crystallization kinetics and oriented growth of the coating, ensuring that the coating has good piezoelectric activity.

[0013] Preferably, in step (2), the temperature of the magnetron sputtering coating is 100-250 °C.

[0014] Lowering the vacuum degree before inputting Ar and O2 helps to reduce the interference of other gas molecules, allowing the subsequent sputtering process to be carried out under the target atmosphere, further improving the comprehensive performance of the prepared piezoelectric coating.

[0015] Preferably, in step (2), the vacuum degree of magnetron sputtering coating is 2-4×10 -3 Pa.

[0016] The high-irradiation-stable LiNbO3 piezoelectric coating has good applicability on the substrate. As presented in one or more embodiments of the present invention, the preparation is completed using a silicon wafer and a stainless steel substrate commonly used in the art. Under high-irradiation conditions, the LiNbO3 piezoelectric coating still maintains good functional and structural stability. Those skilled in the art can select the substrate according to actual conditions or needs.

[0017] Based on the purpose of high-irradiation-stable LiNbO3 piezoelectric coating, its thickness is controlled at 12-24 μm to meet the use requirements under most conditions. Thinner high-irradiation-stable LiNbO3 piezoelectric coatings usually have faster mechanical response speeds, which is particularly important for applications that require rapid conversion of electrical energy and mechanical energy (such as smart sensors, etc.). The coating thickness can also optimize the electromechanical coupling properties of piezoelectric materials, making energy conversion more efficient. The thin-film high-irradiation-stable LiNbO3 piezoelectric coating can operate at higher frequencies, which is very beneficial for high-frequency ultrasonic equipment and sensors. And thin coatings are easier to apply to flexible substrates, increasing the shape diversity and integration of piezoelectric devices.

[0018] Preferably, the thickness of the highly radiation stable LiNbO3 piezoelectric coating is 12-24 μm.

[0019] Based on the design of the highly irradiation-stable LiNbO3 piezoelectric coating of the present invention, technicians can construct and assemble smart sensors based on the piezoelectric coating using common processes in the art according to actual conditions or needs. For example, the preparation can be simply completed by depositing a conductive metal electrode layer on the highly irradiation-stable LiNbO3 piezoelectric coating, and other process conditions can also achieve this purpose.

[0020] Preferably, the smart sensor is made by depositing a conductive metal electrode layer on a highly radiation stable LiNbO3 piezoelectric coating.

[0021] In a second aspect of the present invention, an application of the intelligent sensor according to the first aspect of the present invention is provided, specifically, an application of the intelligent sensor as a sensor in the technical field of intelligent sensing and control equipment.

[0022] Based on the above technical solution, the principle and design concept of the present invention is to adjust the parameters of magnetron sputtering coating, increase the content of Ar gas in the atmosphere to fully sputter the target material, and reduce the O2 content to weaken the formation of lithium-deficient phase LiNb3O8. In this way, the present invention overcomes the limitation of target purity on deposition, and can also realize the preparation of high-irradiation stable LiNbO3 piezoelectric coating in Li-deficient lithium niobate target with a high proportion of LiNb3O8, which reduces the production threshold of such piezoelectric coating and provides more options for the production of smart sensors.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention provides an intelligent sensor with excellent comprehensive performance and good structural and functional stability in a high-irradiation environment. In the preparation of its piezoelectric coating, the present invention overcomes the adverse effect of LiNb3O8 in the impurity target material on deposition by adjusting the magnetron sputtering coating parameters, and has the advantages of wide application of the target material and simple process.

[0024] The present invention provides an application of an intelligent sensor, which has broad prospects in the technical fields of intelligent sensing and control equipment and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The X-ray diffraction (XRD) test results of the piezoelectric coating under the conditions of Li-deficient lithium niobate target and normal lithium niobate target used in the smart sensor of the embodiment and comparative example; Figure 2 The piezoelectric and ultrasonic performance test results of the highly irradiation-stable LiNbO3 piezoelectric coating prepared in the smart sensor of Example 1; Figure 3 Test results of high-irradiation stable LiNbO3 piezoelectric coatings in smart sensors; Figure 3 (a) is the ultrasonic signal test results of Example 1-4, comparing Groups 1 and 2; Figure 3 (b) is the piezoelectric constant d of Examples 1-4 and Comparative Groups 1 and 2 33 Test results; Figure 4 The test results of the highly irradiation-stable LiNbO3 piezoelectric coating prepared in the smart sensor of Example 5; Figure 4 (a) Surface morphology of the highly irradiation-stable LiNbO3 piezoelectric coating before irradiation; Figure 4 (b) Surface morphology of the highly irradiated stable LiNbO3 piezoelectric coating after irradiation; Figure 4 (c) XRD patterns before and after irradiation; Figure 4 (d) is the piezoelectric coefficient d before and after irradiation 33 ; Figure 4 (e)-(g) are the ultrasonic signals before and after irradiation at three different measurement points; Figure 5 The morphological observation results of the highly irradiation-stable LiNbO3 piezoelectric coating prepared in the smart sensor of Example 6 before and after irradiation; Figure 5 (a) Surface morphology of highly irradiated stable LiNbO3 piezoelectric coating before irradiation; Figure 5 (b) Surface morphology after irradiation; Figure 5 (c) is the cross-sectional morphology of the highly irradiated stable LiNbO3 piezoelectric coating before irradiation; Figure 5 (d) is the cross-sectional morphology after irradiation (low magnification); Figure 5 (e) is the cross-sectional morphology after irradiation (high magnification).

[0026] Figure 6 The ultrasonic signal of the highly irradiation-stable LiNbO3 piezoelectric coating and its sensor made in the smart sensor of Example 8; Figure 7This is the relationship between the acoustic time of the second longitudinal wave of the highly irradiation-stable LiNbO3 piezoelectric coating and its sensor in the smart sensor of Example 8 and the ambient temperature. DETAILED DESCRIPTION

[0027] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0028] In the following examples and comparative examples: Li-deficient lithium niobate target (impurity target with a high proportion of LiNb3O8 impurities) and normal lithium niobate target (pure target) were used (both targets were purchased from Hebei Paian Technology Co., Ltd.), and XRD was used to characterize the two targets. The results are as follows Figure 1 As shown. Figure 1 It can be seen that the peak values ​​of the normal phase LiNbO3 of the Li-deficient lithium niobate target are much lower than those of the normal lithium niobate target, while the peak values ​​of the Li-deficient phase LiNb3O8 are higher than those of the normal lithium niobate target, that is, the target materials used in the embodiments and comparative examples are mixed with a large amount of LiNb3O8 substances and lack LiNbO3 substances, and the piezoelectric coating cannot be deposited and prepared under conventional parameters (such as the test data of comparison group 1 and comparison group 2 mentioned later).

[0029] Example 1 An intelligent sensor adopts a high-irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the high-irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using the magnetron sputtering coating method, a Li-deficient lithium niobate target and a stainless steel substrate were installed in a magnetron sputtering coating machine, and the target-base distance was set to 5.3 cm; (2) Turn on the heater, mechanical pump, and molecular pump to make the temperature in the coating chamber reach 150 °C and the vacuum degree reach 2.7×10 -3 Pa, complete the preparations; (3) Ar and O2 were input, the total flow rate was controlled to be 1.5 Pa, the Ar / O2 flow ratio was 8.1 / 1, the RF power was 900 W, and the deposition time was 8 h; a 15 μm thick highly irradiated stable LiNbO3 piezoelectric coating was deposited.

[0030] To demonstrate the effect of low oxygen pressure, this embodiment also sets up comparative group 1 and comparative group 2, in which the Ar / O2 used is 3 / 1 and 6 / 1 respectively, and the other preparation parameters and steps are completely consistent with those in embodiment 1. In addition, comparative group 3 is also set up, in which the input gas is pure Ar, and the other preparation parameters and steps are completely consistent with those in embodiment 1.

[0031] In this embodiment, the piezoelectric properties and ultrasonic properties (ultrasonic performance test parameters are: emission voltage 100 V, gain 60 dB) of the high-irradiation stable LiNbO3 piezoelectric coating and the coating of the comparison group in the smart sensor are tested to study their performance in applications.

[0032] The test results of Example 1 are as follows Figure 2 The test results show that the horizontal axis represents the distance from the sputtering center, 0 cm represents the sputtering center, and it can be seen that the longitudinal wave signal at the sputtering center is 3.3 V, d 33 is 2.7 pC / N. In contrast, the piezoelectric coating prepared in comparison group 1 (Ar / O2 is 3 / 1) cannot excite an ultrasonic signal, that is, the signal is 0 V, d 33 The piezoelectric coating prepared in group 2 (Ar / O2 is 6 / 1) excites a weak ultrasonic signal, and the longitudinal wave signal at the sputtering center is 0.55V, d 33 For comparison group 3, the results show that the piezoelectric coating prepared by pure Ar cannot excite ultrasonic signals, that is, the signal is 0 V, d 33 is 0.1 pC / N.

[0033] Example 2 An intelligent sensor adopts a high-irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the high-irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using the magnetron sputtering coating method, a Li-deficient lithium niobate target and a stainless steel substrate were installed in a magnetron sputtering coating machine, and the target-base distance was set to 5.3 cm; (2) Turn on the heater, mechanical pump, and molecular pump to make the temperature in the coating chamber reach 150 °C and the vacuum degree reach 2.7×10 -3 Pa, complete the preparations; (3) Ar and O2 were input, the total flow rate was controlled to be 1.5 Pa, the Ar / O2 flow ratio was 7 / 1, the RF power was 900 W, and the deposition time was 8 h; a 14 μm thick highly irradiated stable LiNbO3 piezoelectric coating was deposited.

[0034] Example 3 An intelligent sensor adopts a high-irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the high-irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using the magnetron sputtering coating method, a Li-deficient lithium niobate target and a stainless steel substrate were installed in a magnetron sputtering coating machine, and the target-base distance was set to 5.3 cm; (2) Turn on the heater, mechanical pump, and molecular pump to make the temperature in the coating chamber reach 150 °C and the vacuum degree reach 2.7×10 -3Pa, complete the preparations; (3) Ar and O2 were input, the total flow rate was controlled to be 1.5 Pa, the Ar / O2 flow ratio was 9.2 / 1, the RF power was 900 W, and the deposition time was 8 h; a 15 μm thick highly irradiated stable LiNbO3 piezoelectric coating was deposited.

[0035] Example 4 An intelligent sensor adopts a high-irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the high-irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using the magnetron sputtering coating method, a Li-deficient lithium niobate target and a stainless steel substrate were installed in a magnetron sputtering coating machine, and the target-base distance was set to 5.3 cm; (2) Turn on the heater, mechanical pump, and molecular pump to make the temperature in the coating chamber reach 150 °C and the vacuum degree reach 2.7×10 -3 Pa, complete the preparations; (3) Ar and O2 were input, the total flow rate was controlled to be 1.5 Pa, the Ar / O2 flow ratio was 10.5 / 1, the RF power was 900 W, and the deposition time was 8 h; a 15 μm thick highly irradiated stable LiNbO3 piezoelectric coating was deposited.

[0036] The test method of Example 1 was used to compare the ultrasonic signals and piezoelectric constants d excited by the piezoelectric coatings prepared at the sputtering center of Groups 1 and 2. 33 Tested, the results are as follows Figure 3 As shown. Figure 3 It can be seen that the ultrasonic signals and piezoelectric constants of the piezoelectric coatings prepared with Ar / O2 of 7 / 1, 8.1 / 1, 9.2 / 1, and 10.5 / 1 are all higher than those of the group with Ar / O2 of 6 / 1. That is, the present invention successfully achieves the preparation of highly irradiation-stable LiNbO3 piezoelectric coatings under the condition of using lithium niobate targets with a high proportion of LiNb3O8 by reducing the oxygen partial pressure.

[0037] Example 5 An intelligent sensor adopts a high-irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the high-irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using the magnetron sputtering coating method, a Li-deficient lithium niobate target and a stainless steel substrate were installed in a magnetron sputtering coating machine, and the target-base distance was set to 4.7 cm; (2) Turn on the heater, mechanical pump, and molecular pump to make the temperature in the coating chamber reach 150 °C and the vacuum degree reach 2.7×10 -3 Pa, complete the preparations; (3) Ar and O2 were input, the total flow rate was controlled to be 1.0 Pa, the Ar / O2 flow ratio was 8.3 / 1, the RF power was 900 W, and the deposition time was 8 h; an 18 μm thick highly irradiated stable LiNbO3 piezoelectric coating was deposited.

[0038] The surface morphology of the highly irradiation-stable LiNbO3 piezoelectric coating of the smart sensor of this embodiment before irradiation was observed by SEM; silver paste was applied and the piezoelectric coefficient d of the highly irradiation-stable LiNbO3 piezoelectric coating before irradiation was measured. 33 , ultrasonic signal (ultrasonic performance test parameters: emission voltage 100 V, gain 50 dB). Then, 800 keV, Ar ion irradiation experiment was carried out with a dose of 4×10 16 ions / cm 2 Observe the surface morphology and crystal structure after irradiation; apply silver paste and measure the piezoelectric coefficient d after irradiation 33 , ultrasonic signal (ultrasonic performance test parameters are: emission voltage 100 V, gain 50 dB). And combined with XRD to characterize the crystal structure of the coating before and after irradiation.

[0039] Test results such as Figure 4 As shown. Among them, Figure 4 (a) Surface morphology of the highly irradiation-stable LiNbO3 piezoelectric coating before irradiation. Figure 4 (b) is the surface morphology of the highly irradiated stable LiNbO3 piezoelectric coating after irradiation. Figure 4 (c) is the XRD spectrum before and after irradiation. Figure 4 (d) is the piezoelectric coefficient d before and after irradiation 33 , Figure 4 (e)-(g) are the ultrasonic signals before and after irradiation at three different measurement points. It can be seen that the surface morphology of the piezoelectric coating is only changed to a limited extent under high irradiation environment, and its crystal structure and piezoelectric coefficient d 33 , the ultrasonic signal remains unchanged compared with the value before irradiation, and has good structural and functional stability.

[0040] Example 6 An intelligent sensor adopts a high-irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the high-irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using the magnetron sputtering coating method, a Li-deficient lithium niobate target and a silicon wafer substrate were installed in a magnetron sputtering coating machine, and the target-base distance was set to 4.7 cm; (2) Turn on the heater, mechanical pump, and molecular pump to make the temperature in the coating chamber reach 150 °C and the vacuum degree reach 2.7×10 -3 Pa, complete the preparations; (3) Ar and O2 were input, the total flow rate was controlled to be 1.0 Pa, the Ar / O2 flow ratio was 8.3 / 1, the RF power was 900 W, and the deposition time was 8 h; an 18 μm thick highly irradiated stable LiNbO3 piezoelectric coating was deposited.

[0041] The surface and cross-sectional morphology of the highly irradiated stable LiNbO3 piezoelectric coating of the smart sensor of this embodiment before irradiation were observed by SEM. Then, 800keV and Ar ion irradiation experiments were carried out with a dose of 4×10 16 ions / cm 2 , and observe the surface and cross-sectional morphology after irradiation again.

[0042] Test results such as Figure 5 As shown. Among them, Figure 5 (a) Surface morphology of the highly irradiated stable LiNbO3 piezoelectric coating before irradiation. Figure 5 (b) is the surface morphology after irradiation. Figure 5 (c) is the cross-sectional morphology of the highly irradiated stable LiNbO3 piezoelectric coating before irradiation. Figure 5 (d) is the cross-sectional morphology after irradiation (low magnification). Figure 5 (e) is the cross-sectional morphology of the highly irradiated stable LiNbO3 piezoelectric coating after irradiation (high magnification). 16 ions / cm 2 The ion irradiation only changed the morphology of the coating surface layer of 1.5 μm, and the coating still had excellent columnar crystal morphology.

[0043] Example 7 In the smart sensor of this embodiment, the high radiation stable LiNbO3 piezoelectric coating is used as follows Figure 1 The normal lithium niobate target (pure target) shown in the figure, and the remaining preparation parameters and steps are completely consistent with those in Example 1, and a highly irradiation-stable LiNbO3 piezoelectric coating with excellent ultrasonic performance is also prepared.

[0044] Example 8 An intelligent sensor adopts a high-irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the high-irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using the magnetron sputtering coating method, a Li-deficient lithium niobate target and a Ti10Al4V bolt (M14×55) were installed in the magnetron sputtering coating machine, and the target-base distance was set to 4.9 cm; (2) Turn on the heater, mechanical pump, and molecular pump to make the temperature in the coating chamber reach 150 °C and the vacuum degree reach 2.7×10 -3 Pa, complete the preparations; (3) Ar and O2 were input, the total flow rate was controlled to be 1.1 Pa, the Ar / O2 flow ratio was 8.1 / 1, the RF power was 900 W, and the deposition time was 8 h; a 19 μm thick highly irradiated stable LiNbO3 piezoelectric coating was deposited.

[0045] (4) Depositing a Ag electrode layer on the surface of the LiNbO3 piezoelectric coating to form an intelligent sensor: using pure Ag target material, inputting Ar gas, the total flow rate is 1.2 Pa, the RF power is 700 W, the target-base distance is 7.5 cm, and the coating time is 20 min.

[0046] (5) The prepared intelligent sensor was used to carry out online temperature monitoring tests in a muffle furnace: the ambient temperatures were set to 34°C, 200°C, 400°C, 600°C, and 800°C, and the ultrasonic signal was measured in real time (the ultrasonic performance test parameters were: emission voltage of 200 V and gain of 60 dB).

[0047] Under different ambient temperature conditions, the ultrasonic signal and the acoustic time of the second longitudinal wave are obtained. Figure 6 , 7 The acoustic time of the second longitudinal wave is linearly related to the loaded temperature, which shows that the highly irradiated stable LiNbO3 piezoelectric coating and its sensor prepared by this patent can be used for online temperature detection. In addition, it can be seen that at an ambient temperature of 800°C, the LiNbO3 piezoelectric coating and its sensor can still excite acoustic wave signals, which means that the highly irradiated stable LiNbO3 piezoelectric coating prepared by this technology also has high temperature resistance.

[0048] In summary, the present invention adjusts the parameters of magnetron sputtering coating, increases the Ar gas content in the atmosphere, so as to fully sputter the target material, and reduces the O2 content to weaken the formation of the lithium-deficient phase LiNb3O8. This overcomes the limitation of the target purity on deposition, and can also achieve the preparation of high-irradiation stable LiNbO3 piezoelectric coating in Li-deficient lithium niobate targets with a high proportion of LiNb3O8. It has the advantages of wide application of target materials and simple process, reduces the production threshold of such piezoelectric coatings, and provides more options for the production of smart sensors. The prepared smart sensor has excellent comprehensive performance and good structural and functional stability under high irradiation environment. It has broad prospects in technical fields such as intelligent sensing and control equipment.

[0049] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. An intelligent sensor, characterized in that: The piezoelectric material of the intelligent sensor adopts a highly irradiation-stable LiNbO3 piezoelectric coating; wherein the preparation method of the highly irradiation-stable LiNbO3 piezoelectric coating comprises the following steps: (1) Using magnetron sputtering coating method, prepare lithium niobate target and substrate, and adjust the target-substrate distance to the set value; (2) Adjust the temperature and vacuum degree of magnetron sputtering coating to the set values ​​to complete the preparation work; (3) Input Ar and O2, control the total flow rate to 0.9-2.3 Pa, the Ar / O2 flow ratio to 6.1 / 1-10.5 / 1, the RF power to 800-900 W, and the deposition time to 6-9 h; a highly irradiation-stable LiNbO3 piezoelectric coating is deposited.

2. The smart sensor according to claim 1, characterized in that: In the step (1), the lithium niobate target includes a pure lithium niobate target and a Li-deficient lithium niobate target containing LiNb3O8.

3. The smart sensor according to claim 1, characterized in that: In the step (1), the target-base distance is 3.5-6.5 cm.

4. The smart sensor according to claim 1, characterized in that: In the step (2), the temperature of the magnetron sputtering coating is 100-250°C.

5. The smart sensor according to claim 1, characterized in that: In the step (2), the vacuum degree of the magnetron sputtering coating is 2-4×10 -3 Pa.

6. The smart sensor according to claim 1, characterized in that: The smart sensor is made by depositing a conductive metal electrode layer on a highly radiation-stable LiNbO3 piezoelectric coating.

7. The highly radiation stable LiNbO3 piezoelectric coating according to claim 1, characterized in that: The thickness of the highly radiation-stable LiNbO3 piezoelectric coating is 12-24 μm.

8. An application of the smart sensor according to any one of claims 1 to 7, characterized in that: As a sensor in the field of intelligent perception and control equipment technology.

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