A precious metal-rare earth neodymium nickelate composite film, and a preparation method and use thereof

Abstract

This invention relates to the field of composite thin film materials and hydrogen sensing technology, specifically disclosing a noble metal-rare earth neodymium nickelate composite thin film, its preparation method, and its applications. The method includes: S1, depositing noble metal stripes on the surface of neodymium nickelate as a target material; S2, transferring a strontium titanate single-crystal substrate to the high-vacuum growth chamber of a pulsed laser deposition equipment, heating the substrate, and maintaining uniform rotation of the target material and substrate; S3, ablating the target material with deposited noble metal stripes using an excimer laser, depositing the resulting feathers onto the substrate, and directly preparing a composite thin film with noble metal nanoparticles embedded in the rare earth neodymium nickelate matrix through a one-step growth process; S4, annealing the composite thin film and then cooling it to obtain a noble metal-rare earth neodymium nickelate composite thin film with good crystallinity. The noble metal-rare earth neodymium nickelate composite thin film prepared by this invention has potential applications in hydrogen sensing.

Description

Technical Field

[0001] This invention relates to the fields of composite thin film materials and hydrogen sensing technology, specifically to a noble metal-rare earth neodymium nickelate composite thin film, its preparation method, and its potential application characteristics in hydrogen sensing. Background Technology

[0002] Neodymium nickelate (NNO) is a strongly correlated electron system material with metal-insulator phase transition characteristics. Near its phase transition temperature, the crystal structure and electronic states of NNO undergo reversible transitions, accompanied by significant changes in electrical and optical properties. This characteristic makes NNO promising for applications in field-effect transistors, optical switches, and gas sensors. Hydrogenation can induce a metal-insulator phase transition in NNO, accompanied by a large change in resistivity, which provides new possibilities for the design of resistive hydrogen sensors. However, hydrogen sensors based on intrinsic NNO thin films generally suffer from problems such as demanding hydrogenation conditions, limited hydrogenation area, and insufficient hydrogen response at room temperature, making it difficult to meet the high-performance hydrogen sensing requirements for room temperature operation in practical applications. Therefore, developing a simple method for preparing NNO thin films with room temperature hydrogen response is of great significance for their practical device applications.

[0003] In recent years, the design concept of metal-oxide composite thin films has been widely applied in the field of performance regulation of functional oxide materials. Studies have shown that introducing metal nanoparticles into oxide matrices can influence the electronic structure of oxides through interfacial charge transfer and catalytic effects, thereby regulating their phase transition properties. Compared to intrinsic metal oxides, composite thin films of metal nanoparticles and metal oxide matrices have attracted widespread attention due to their interfacial effects and local field regulation capabilities. Pulsed laser deposition (PLD) technology has become a commonly used method for preparing metal oxide thin films due to its good composition retention and wide range of adjustable process parameters. However, currently, the preparation of metal-oxide composite thin films mostly employs multilayer alternating deposition or co-sputtering methods, which are complex and make it difficult to achieve uniform particle distribution in the matrix in multilayer structures. Furthermore, while spin-coating a pre-synthesized noble metal colloidal solution onto the surface of a metal oxide thin film followed by heat treatment can achieve uniform distribution of metal nanoparticles in the metal oxide thin film matrix, this method involves chemical synthesis steps, easily introduces impurities, and has poor compatibility with semiconductor processes. Furthermore, current research on metal composites mainly focuses on binary phase change metal oxide systems (such as VO2, WO3, etc.). There are currently no systematic reports on the metal composite modification of rare earth nickelate systems (such as NNO) and how to improve the room temperature hydrogen-sensitive response performance of such composite films by introducing metal nanoparticles in hydrogen sensing applications.

[0004] In summary, existing technologies for preparing metal-oxide composite thin films have the following drawbacks: ① Existing methods for preparing metal-oxide composite thin films often employ a multi-layer alternating deposition followed by heat treatment, which is cumbersome, complex, and unsuitable for industrial production. Another method involves spin-coating a pre-synthesized noble metal colloidal solution onto the surface of a metal oxide thin film followed by heat treatment. This process involves chemical synthesis, and the noble metal nanoparticles introduced by chemical synthesis in this coating process are prone to surface contamination and poor interfacial bonding. Secondly, the introduction of metals into existing metal-oxide composite thin films often leads to excessive shifts in the metal-insulator phase transition temperature or attenuation of the phase transition amplitude, making it difficult to coordinate the control of phase transition characteristics and hydrogen response performance. Thirdly, at room temperature, intrinsic rare-earth neodymium nickelate thin films exhibit low sensitivity and slow response to hydrogen, making it difficult to meet the requirements of room-temperature hydrogen sensors. Summary of the Invention

[0005] The purpose of this invention is to provide a novel method for preparing noble metal-rare earth neodymium nickelate composite films, aiming to overcome the problems of complex preparation processes, uneven distribution of noble metal particles, and insufficient room temperature hydrogen response in existing technologies. Moreover, the method of this invention can significantly improve the crystal quality and metal-insulator phase transition performance of the prepared noble metal-rare earth neodymium nickelate composite films, achieving a synergistic improvement in phase transition characteristics and room temperature hydrogen response performance.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention provides a method for preparing a noble metal-rare earth neodymium nickelate composite film, the method comprising the following steps: S1. Using neodymium nickelate (NNO) as a target material, noble metal stripes are deposited on its surface (this step is a pretreatment process for the NNO target material). S2. Transfer the STO single crystal substrate to the high vacuum growth chamber of the pulsed laser deposition equipment, heat the substrate, and keep the target and substrate rotating at a constant speed. S3. An excimer laser is used to ablate the target material with deposited noble metal stripes, and the feather generated by the ablation is deposited onto the substrate. A composite film with noble metal nanoparticles embedded in a rare earth neodymium nickelate matrix is ​​directly prepared through a one-step growth process. S4. Anneal the composite film and then cool it to obtain a noble metal-rare earth neodymium nickelate composite film with good crystallinity.

[0007] Specifically, the method for preparing the noble metal-rare earth neodymium nickelate composite film provided by this invention is a one-step method based on target pretreatment combined with pulsed laser deposition (PLD). Leveraging the catalytic effect of noble metals in the hydrogenation process, a composite film in which noble metal nanoparticles are uniformly embedded in a rare earth neodymium nickelate (NNO) matrix is ​​successfully prepared on a strontium titanate substrate through a one-step process. Compared with intrinsic NNO films, the noble metal nanoparticle-NNO composite film prepared by this invention exhibits superior phase transition performance and significantly improved room-temperature hydrogen response performance, with the hydrogen response-related resistance modulation amplitude increased by approximately two orders of magnitude, and good cycling stability. This simple and easy-to-operate preparation method can flexibly grow different noble metal nanoparticle-NNO composite films. The method is simple to operate, and the prepared composite films have uniform crystal quality and excellent room-temperature hydrogen sensitivity.

[0008] Specifically, addressing the shortcomings of existing metal-oxide composite thin film preparation techniques as pointed out in the background art, this invention aims to provide a method for preparing noble metal-rare earth neodymium nickelate composite thin films based on the hydrogen catalysis of noble metal nanoparticles, thereby solving the following problems: ① It solves the problem of cumbersome noble metal composite preparation processes that are not conducive to industrial production; ② While maintaining the excellent metal-insulator phase transition characteristics of rare earth neodymium nickelate thin films, it achieves appropriate control of the phase transition temperature and maintains or enhances the phase transition amplitude through noble metal composites; ③ This study addresses the issue of insufficient room-temperature hydrogen response in intrinsic NNO films, improving the room-temperature hydrogen response performance of composite films and enabling them to meet the application requirements of hydrogen sensors operating at room temperature.

[0009] Furthermore, a method for preparing a noble metal-rare earth neodymium nickelate composite film: Step S1, using rare earth neodymium nickelate as a target material, covering the surface of the target material with a striped pattern mask, and then depositing noble metal by magnetron sputtering, electron beam or thermal evaporation process, and after removing the mask, forming noble metal stripes with a width of 1-2 mm and a thickness of 2-10 nm on the surface of the target material.

[0010] Specifically, magnetron sputtering deposition is preferred for depositing precious metals; the width and thickness of the precious metal stripes are key parameters for controlling the final size and distribution of nanoparticles, and controllable pretreatment can be achieved through mask pattern design and evaporation time adjustment.

[0011] Specifically, in step S1 of this invention, a mask-assisted directional deposition process is adopted, using a combination design of "striped pattern mask + NNO target". Noble metal stripes are deposited on the surface of the target by magnetron sputtering, electron beam or thermal evaporation. After removing the mask, directional noble metal stripes are obtained, achieving precise "striped" patterning. Thanks to this combination design, the agglomeration problem of traditional noble metal doping can be solved. Traditional noble metal particle doping is prone to agglomeration and sedimentation problems. However, this invention uses mask-assisted deposition to achieve precise positioning of noble metal particles in the NNO matrix by "patterning first and then deposition", avoiding agglomeration and ensuring the uniformity of noble metal particle distribution.

[0012] Furthermore, a method for preparing a noble metal-rare earth neodymium nickelate composite film: the Ni:Nd element ratio in the rare earth neodymium nickelate target in step S1 is 1:(1.5~2.0).

[0013] Furthermore, a method for preparing a noble metal-rare earth neodymium nickelate composite film: the noble metal in step S1 is platinum.

[0014] Furthermore, a method for preparing a noble metal-rare earth neodymium nickelate composite thin film: Step S2, transferring a strontium titanate single crystal substrate to the high-vacuum growth chamber of a pulsed laser deposition system, with a base vacuum level lower than 2×10⁻ 5 Pa, heat the substrate to 550-680°C, and keep the target and substrate rotating at a constant speed of 2-10 rpm.

[0015] Furthermore, a method for preparing a noble metal-rare earth neodymium nickelate composite film: in step S2, the strontium titanate substrate is selected with a (001) orientation.

[0016] Specifically, in this invention, the strontium titanate substrate is preferably (001) oriented, and the substrate heating temperature is preferably 550-680°C, which can promote the surface diffusion and phase separation of noble metal atoms with the neodymium nickelate matrix, thereby achieving self-growth; the rotation speed is preferably 2-10 rpm to ensure the uniformity of film growth.

[0017] Furthermore, a method for preparing a noble metal-rare earth neodymium nickelate composite film: In step S3, an ArF excimer laser (wavelength λ = 193 nm) is used to ablate the target material with deposited noble metal stripes. The laser is in constant energy mode, and the laser energy is 80–95 mJ / cm². 2 The laser frequency is 3-5 Hz; the deposition time is 60-90 minutes; and the deposition thickness of the composite film is 50-100 nm.

[0018] Specifically, the one-step growth process in step S3 of the present invention refers to the spontaneous phase separation of noble metal atoms and rare earth neodymium nickelate matrix material on the surface of strontium titanate (STO) substrate during pulsed laser deposition (PLD) due to the difference in surface energy and the driving force of interfacial energy, forming a microstructure in which nanoparticles are uniformly embedded in the matrix.

[0019] Specifically, step S3 of this invention employs pulsed laser deposition (PLD) technology, using a pretreated NNO target (with deposited noble metal stripes) as the source, directly depositing the feathers generated by ablation onto an STO substrate, forming a composite film in which noble metal nanoparticles are embedded in the NNO matrix in one step. This process has the following technical advantages: ① Simplified process and avoidance of secondary pollution: Traditional composite film preparation usually requires "matrix deposition first + noble metal deposition", while the one-step growth process of this application reduces the sample transfer step and avoids secondary pollution (such as oxidation in the air) through "target pretreatment + in-situ deposition"; ② Guarantee of interface compatibility: The process of this application allows noble metal atoms and NNO matrix atoms to fuse in-situ during the deposition process, with no obvious gaps at the interface, which is beneficial to the synergistic effect of "hydrogen-noble metal-matrix" in the hydrogen response process; ③ It can realize "one-step embedding" of noble metal nanoparticles in the NNO matrix: Existing methods for preparing composite films using pulsed laser deposition (PLD) technology are all "multilayer alternating deposition", which cannot achieve "one-step embedding".

[0020] Furthermore, a method for preparing a noble metal-rare earth neodymium nickelate composite film: Step S4, the composite film is annealed in an oxygen atmosphere and then cooled to room temperature to obtain a noble metal-rare earth neodymium nickelate composite film; wherein, the oxygen pressure is 20-30 Pa, the annealing temperature is 600-720 °C, and the annealing time is 10-180 minutes.

[0021] Specifically, the annealing treatment in step S4 of the present invention is a key step to improve the crystallization quality of the composite film. The preferred annealing temperature can ensure sufficient atomic rearrangement and interface optimization. The cooling method is to cool naturally to room temperature in an oxygen atmosphere to reduce thermal stress and maintain the stability of the film structure.

[0022] The present invention also provides a noble metal-rare earth neodymium nickelate composite film, which is prepared by the above-described preparation method.

[0023] The present invention also provides an application of a noble metal-rare earth neodymium nickelate composite film, wherein the noble metal-rare earth neodymium nickelate composite film prepared by the above preparation method is used in a hydrogen sensor, that is, the noble metal-rare earth neodymium nickelate composite film prepared by the present invention has potential application characteristics in hydrogen sensing.

[0024] The beneficial effects of this invention are: To address the challenges of uniform doping and performance optimization in noble metal-rare earth neodymium nickelate composite films, this invention proposes a method for preparing such films. High-quality noble metal-rare earth neodymium nickelate composite films were prepared using strontium titanate as a substrate via a one-step growth method of target pretreatment and pulsed laser deposition. This method utilizes the surface energy difference and interfacial energy between the noble metal and the rare earth neodymium nickelate substrate to spontaneously form a composite structure in which noble metal nanoparticles are uniformly embedded in the oxide substrate during film growth. This avoids the cumbersome steps of traditional multilayer alternating deposition or chemical synthesis. This method is simple, highly controllable, and compatible with existing semiconductor processes. The resulting composite films have good crystallinity, uniform distribution of noble metal particles, excellent phase transition performance, and significant room temperature hydrogen response characteristics.

[0025] The method for preparing the noble metal-rare earth neodymium nickelate composite film provided by this invention also has the following excellent effects: ① Simple and efficient process: By using target pretreatment combined with pulsed laser deposition, the composite of noble metal nanoparticles and rare earth neodymium nickelate matrix is ​​realized in one step, avoiding cumbersome steps such as multi-layer alternating deposition and chemical synthesis, greatly simplifying the process flow and facilitating industrial production in practical applications; ② The properties of the nano-metal particles are flexible and tunable. By controlling the growth parameters, composite films with different doping concentrations can be prepared; ③ While maintaining the phase transition characteristics of rare earth neodymium nickelate metal-insulator, the composite film exhibits a resistance jump amplitude close to two orders of magnitude and stable phase transition characteristics, overcoming the problem of phase transition performance degradation caused by existing composite film preparation methods; ④ It has room temperature hydrogen-sensitive response characteristics. Utilizing the huge catalytic interface provided by the interface between the noble metal nanoparticles and the film composite, it achieves a significant response to hydrogen at room temperature, with a hydrogen response resistance modulation amplitude of more than two orders of magnitude and good cycle stability, overcoming the defect of insufficient room temperature hydrogen response of intrinsic NNO films.

[0026] The method for preparing noble metal-rare earth neodymium nickelate composite thin films provided by this invention not only offers new ideas for the preparation of other strongly correlated oxide composite thin film systems, but can also be used for the design and application of high-performance room temperature hydrogen sensors based on strongly correlated oxides. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the hydrogenation of the platinum (Pt)-neodymium nickelate (NNO) composite film prepared in Example 1; Figure 2 The SEM morphology characterization results of the platinum (Pt)-neodymium rare earth nickelate (NNO) composite film prepared in Example 1 are shown below. Figure 3 The structure characterization of the platinum (Pt)-neodymium nickelate (NNO) composite film prepared in Example 2 is shown in 3(a), where 3(a) is the XRD comparison of the intrinsic NNO film and the platinum-neodymium nickelate (Pt-NNO) composite film with different annealing times, and 3(b) is the XRD comparison of the Pt-NNO composite film before and after hydrogenation. Figure 4 The resistance-temperature test of the platinum (Pt)-neodymium nickelate (NNO) composite thin film prepared in Example 2 was compared with that of the intrinsic NNO thin film. Figure 5 The in-situ resistance-time test of the platinum (Pt)-neodymium nickelate (NNO) composite film prepared in Example 3 is shown in Figure 5(a), which is a comparison curve of the room temperature hydrogen response of the intrinsic NNO film and the Pt-NNO composite film, and Figure 5(b) is a test curve of the room temperature hydrogen response cycle stability of the Pt-NNO composite film. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example

[0030] A method for preparing a noble metal-rare earth neodymium nickelate composite film is provided, the method comprising the following specific steps: S1. Using neodymium nickelate (NNO) as a target material (the Ni:Nd element ratio in the target material is 1:2.0) and pre-treating it, that is, covering the surface of the NNO target material with a striped pattern mask, and forming metallic platinum stripes by combining the mask method with magnetron sputtering deposition, thus obtaining an NNO target material with deposited noble metal stripes. The platinum (Pt) stripe width is 1.5 mm and the thickness is 5.0 nm. S2. A 10mm × 10mm square SrTiO3 (001) oriented single crystal was selected as the substrate. It was ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water for 10 minutes each. After drying with nitrogen, it was quickly placed into the sample loading chamber of the pulsed laser deposition equipment. The SrTiO3 single crystal substrate was then transferred to the high-vacuum growth chamber of the pulsed laser deposition equipment. At this point, the background vacuum level of the growth chamber was better than (lower than) 2 × 10⁻⁻⁻⁴.5 Pa, then the STO substrate is rotated at a constant speed of 5.0 rpm, while the substrate is heated at a heating rate of 10 °C / min to 590 °C. S3. The pretreated target material (i.e., the target material with noble metal stripes) was ablated using an ArF excimer laser (wavelength λ = 193 nm). The laser energy density was 95 mJ / cm², and the laser pulse frequency was 3 Hz. The laser baffle was opened, and the feather generated by ablation was deposited onto the surface of the STO substrate. A composite film of platinum (Pt) nanoparticles embedded in a rare earth neodymium nickelate matrix was directly prepared through a one-step self-growth process. The deposition time was 60 minutes, the deposition temperature was 590℃, and the oxygen pressure during the growth process was 28.0 Pa. After the deposition process was completed, the laser baffle was closed and the laser output was stopped. S4. Continue to maintain the oxygen pressure at 28.0 Pa, anneal the obtained composite film in an oxygen atmosphere at 710 °C for 60 minutes, and then naturally cool it to room temperature in the growth chamber to obtain a platinum-rare earth neodymium nickelate composite film with good crystallinity (i.e., Pt-NNO composite film).

[0031] A schematic diagram of the hydrogenation of the platinum-rare earth neodymium nickelate composite film prepared in Example 1 above is shown below. Figure 1 As shown.

[0032] The platinum-rare earth neodymium nickelate composite film prepared in Example 1 was characterized by microscopic morphology: preliminary SEM characterization results show (e.g.) Figure 2 Pt nanoparticles are uniformly distributed on the surface of the NNO film and embedded in the NNO matrix, resulting in a dense composite film structure. Example

[0033] A method for preparing a noble metal-rare earth neodymium nickelate composite film is provided, the method comprising the following specific steps: S1. Using neodymium nickelate (NNO) as a target material (the Ni:Nd element ratio in the target material is 1:1.5) and pre-treating it, that is, covering the surface of the NNO target material with a striped pattern mask, and forming metallic platinum stripes by combining the mask method with magnetron sputtering deposition, thus obtaining an NNO target material with deposited noble metal stripes. The platinum (Pt) stripe width is 1.0 mm and the thickness is 10.0 nm. S2. A 10mm × 10mm square SrTiO3 (001) oriented single crystal was selected as the substrate. It was ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water for 10 minutes each. After drying with nitrogen, it was quickly placed into the sample loading chamber of the pulsed laser deposition equipment. The SrTiO3 single crystal substrate was then transferred to the high-vacuum growth chamber of the pulsed laser deposition equipment. At this point, the background vacuum level of the growth chamber was better than (lower than) 2 × 10⁻⁻⁻⁴. 5Pa, then the STO substrate is rotated at a constant speed of 2.0 rpm, while the substrate is heated at a heating rate of 10 °C / min to 650 °C. S3. The pretreated target material (i.e., the target material with deposited noble metal stripes) was ablated using an ArF excimer laser (wavelength λ = 193 nm). The laser energy density was 90 mJ / cm², and the laser pulse frequency was 3 Hz. The laser baffle was opened, and the feather generated by ablation was deposited onto the surface of the STO substrate. A composite film of platinum (Pt) nanoparticles embedded in a rare earth neodymium nickelate matrix was directly prepared through a one-step self-growth process. The deposition time was 90 minutes, the deposition temperature was 650℃, and the oxygen pressure during the growth process was 30.0 Pa. After the deposition process was completed, the laser baffle was closed and the laser output was stopped. S4. Continue to maintain the oxygen pressure at 30.0 Pa, and anneal the obtained composite film in an oxygen atmosphere at 650 °C for 0 minutes, 10 minutes and 60 minutes respectively. Then, allow it to cool naturally to room temperature in the growth chamber to obtain a series of platinum-rare earth neodymium nickelate composite films (Pt-NNO composite films) with different annealing times.

[0034] Crystal structure characterization was performed on a series of platinum-neodymium rare earth nickelate composite films with different annealing times prepared in Example 2 above: XRD test results show (e.g.) Figure 3 a) Obvious platinum (Pt) (111) diffraction peaks were observed in both platinum-rare earth neodymium nickelate composite films, indicating that Pt nanoparticles exhibit out-of-plane preferred growth, which is due to the lowest surface energy of the Pt (111) plane among all major crystal planes; at the same time, comparing the composite films before and after annealing, the NNO (001) diffraction peaks were clearly visible in the annealed composite film, indicating that annealing can significantly improve the crystallinity of the NNO matrix in the composite film. XRD tests before and after hydrogenation showed (e.g. Figure 3 (b) After hydrogen gas was introduced, the NNO (001) diffraction peak of the composite film shifted slightly to a lower angle, indicating that hydrogenation caused NNO lattice expansion, which is consistent with the hydrogenation results of intrinsic NNO films reported in the literature.

[0035] Electrical performance tests were conducted on the temperature-dependent resistance of a series of platinum-neodymium rare-earth nickelate composite films prepared in Example 2 above with different annealing times: resistance-temperature curves are shown (e.g.) Figure 4 The resistance change of the resulting composite film during the metal-insulator phase transition is close to that of the intrinsic NNO film, and the resistance modulation amplitude of the composite film increases with the extension of annealing time. This is attributed to the annealing treatment improving the crystal quality of NNO. Example

[0036] A method for preparing a noble metal-rare earth neodymium nickelate composite film is provided, the method comprising the following specific steps: S1. Using neodymium nickelate (NNO) as a target material (the Ni:Nd element ratio in the target material is 1:1.5) and pre-treating it, that is, covering the surface of the NNO target material with a striped pattern mask, and forming metallic platinum stripes by combining the mask method with magnetron sputtering deposition, thus obtaining an NNO target material with deposited noble metal stripes. The platinum (Pt) stripe width is 1.0 mm and the thickness is 10.0 nm. S2. A 10mm × 10mm square SrTiO3 (001) oriented single crystal was selected as the substrate. It was ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water for 10 minutes each. After drying with nitrogen, it was quickly placed into the sample loading chamber of the pulsed laser deposition equipment. The SrTiO3 single crystal substrate was then transferred to the high-vacuum growth chamber of the pulsed laser deposition equipment. At this point, the background vacuum level of the growth chamber was better than (lower than) 2 × 10⁻⁻⁻⁴. 5 Pa, then the STO substrate is rotated at a constant speed of 2.0 rpm, while the substrate is heated at a heating rate of 10 °C / min to 650 °C. S3. The pretreated target material (i.e., the target material with deposited noble metal stripes) was ablated using an ArF excimer laser (wavelength λ = 193 nm). The laser energy density was 90 mJ / cm², and the laser pulse frequency was 3 Hz. The laser baffle was opened, and the feather generated by ablation was deposited onto the surface of the STO substrate. A composite film of platinum (Pt) nanoparticles embedded in a rare earth neodymium nickelate matrix was directly prepared through a one-step self-growth process. The deposition time was 90 minutes, the deposition temperature was 650℃, and the oxygen pressure during the growth process was 30.0 Pa. After the deposition process was completed, the laser baffle was closed and the laser output was stopped. S4. Continue to maintain the oxygen pressure at 30.0 Pa, anneal the obtained composite film in an oxygen atmosphere at 650 °C for 60 minutes, and then naturally cool it to room temperature in the growth chamber to obtain a platinum-rare earth neodymium nickelate composite film with good crystallinity (i.e., Pt-NNO composite film).

[0037] The room temperature hydrogen response performance of the platinum-neodymium rare earth nickelate composite film prepared in Example 3 was tested: the prepared composite film was placed in a closed cavity, and a mixed gas with a volume fraction of 5% hydrogen / 95% argon was introduced into the cavity at a flow rate of 10-100 sccm. Electrical tests were performed to preliminarily characterize its hydrogen response effect at room temperature (the electrical tests used a four-probe test method to measure resistance, and the resistance change of the composite film was monitored in real time. In DC voltage mode, the bias voltage range was 0.5-10V, the data acquisition interval was 1-10s, the temperature test range of the variable temperature resistance was 10-300K, and the test temperature for the change of composite film resistance over time during hydrogenation was room temperature). The in-situ resistance-time curve measured at room temperature during the hydrogenation process of 1 hour with H2 / Ar mixed gas was plotted. Figure 5 The results showed a significant change in the resistance of the Pt-NNO composite film, and compared with the intrinsic NNO film, the protonation response of the Pt-NNO composite film was improved by about two orders of magnitude. This is mainly attributed to the larger hydrogen catalytic interface area provided by the nano-interface between the Pt nanoparticles and the NNO matrix. The in-situ electrical cycling test measured at room temperature initially showed that the composite film has stable response performance to hydrogen and can be applied to the field of hydrogen sensors.

[0038] A noble metal-rare earth neodymium nickelate composite film can be prepared using the above-described preparation method. The noble metal-rare earth neodymium nickelate composite film prepared by this invention has the following technical effects: ① SEM characterization results show (see...) Figure 2 Platinum (Pt) nanoparticles are uniformly distributed on the surface of the NNO film and embedded in the NNO matrix, resulting in a dense composite film structure without significant agglomeration; ② XRD characterization shows (see...) Figure 3 a) Platinum (Pt) nanoparticles in the composite film exhibit out-of-plane preferential growth at (111) plane. Simultaneously, the NNO (001) diffraction peak of the Pt-NNO composite film can be observed. Compared to the unannealed composite film, the annealed NNO (001) diffraction peak is sharper and has a narrower full width at half maximum (FWHM), indicating that annealing can maintain good crystallinity of the NNO matrix in the composite film; ③ XRD characterization of the composite film before and after hydrogenation shows (see...) Figure 3 b) The (001) diffraction peak of the hydrogenated Pt-NNO composite film shifts slightly to a lower angle, indicating that hydrogenation causes NNO lattice expansion. This is consistent with the hydrogenation results of intrinsic NNO films reported in existing research literature, indicating that the composite film of this invention achieves room temperature hydrogenation; ④ The temperature-dependent resistance RT electrical test shows (see...) Figure 4 The metal-insulator phase transition temperature of the Pt-NNO composite film of this invention is around 120K, and the resistance change before and after the phase transition is close to two orders of magnitude. Compared with the unannealed composite film, the resistance modulation amplitude of the annealed composite film is greater. This result is consistent with the XRD data. Further surface annealing treatment significantly improves the crystallinity of the composite film; ⑤ Resistance-time (R-Time) electrical tests show (see...) Figure 5 ), Figure 5 Compared to intrinsic NNO films, Pt-NNO composite films exhibit a significant resistive response during room-temperature hydrogenation; furthermore, Figure 5 The electrical cycling test results in b show that the composite film of this application has stable room temperature hydrogen response performance, and the response amplitude does not decrease significantly after multiple cycles, demonstrating good stability and repeatability.

[0039] The above-described preferred embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the invention. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a noble metal-rare earth neodymium nickelate composite thin film, characterized in that, The method includes the following steps: S1. Using neodymium nickelate rare earth as a target material, noble metal stripes are deposited on its surface; S2. Transfer the strontium titanate single crystal substrate to the high vacuum growth chamber of the pulsed laser deposition equipment, heat the substrate, and keep the target and substrate rotating at a constant speed. S3. An excimer laser is used to ablate the target material with deposited noble metal stripes, and the feather generated by the ablation is deposited onto the substrate. A composite film with noble metal nanoparticles embedded in a rare earth neodymium nickelate matrix is ​​directly prepared through a one-step growth process. S4. Anneal the composite film and then cool it to obtain a noble metal-rare earth neodymium nickelate composite film with good crystallinity.

2. The method for preparing a noble metal-rare earth neodymium nickelate composite thin film according to claim 1, characterized in that, Step S1: Using neodymium nickelate as the target material, a striped pattern mask is covered on the surface of the target material. Then, noble metal is deposited by magnetron sputtering, electron beam or thermal evaporation process. After removing the mask, noble metal stripes with a width of 1-2 mm and a thickness of 2-10 nm are formed on the surface of the target material.

3. The method for preparing a noble metal-rare earth neodymium nickelate composite thin film according to claim 1 or 2, characterized in that, In step S1, the Ni:Nd element ratio in the rare earth neodymium nickelate target is 1:(1.5~2.0).

4. The method for preparing a noble metal-rare earth neodymium nickelate composite thin film according to claim 1 or 2, characterized in that, The precious metal used in step S1 is platinum.

5. The method for preparing a noble metal-rare earth neodymium nickelate composite thin film according to claim 1, characterized in that, Step S2: Transfer the strontium titanate single crystal substrate to the high-vacuum growth chamber of the pulsed laser deposition system, with a base vacuum level below 2×10⁻⁻⁻⁴. 5 Pa, heat the substrate to 550-680°C, and keep the target and substrate rotating at a constant speed of 2-10 rpm.

6. A method for preparing a noble metal-rare earth neodymium nickelate composite thin film according to claim 1 or 5, characterized in that, In step S2, the strontium titanate substrate is selected with a (001) orientation.

7. The method for preparing a noble metal-rare earth neodymium nickelate composite thin film according to claim 1, characterized in that, In step S3, an ArF excimer laser is used to ablate the target material with deposited noble metal stripes. The laser is in constant energy mode, and the laser energy is 80–95 mJ / cm². 2 The laser frequency is 3-5 Hz; the deposition time is 60-90 minutes; and the deposition thickness of the composite film is 50-100 nm.

8. The method for preparing a noble metal-rare earth neodymium nickelate composite thin film according to claim 1, characterized in that, Step S4: Anneal the composite film in an oxygen atmosphere and then cool it to room temperature to obtain a noble metal-rare earth neodymium nickelate composite film. The oxygen pressure is 20–30 Pa, the annealing temperature is 600–720 °C, and the annealing time is 10–180 minutes.

9. A noble metal-rare earth neodymium nickelate composite film, characterized in that, The composite film was prepared by the preparation method described in any one of claims 1 to 8.

10. The use of a noble metal-rare earth neodymium nickelate composite film, characterized in that, The noble metal-rare earth neodymium nickelate composite film prepared by the preparation method according to any one of claims 1 to 8 is used in a hydrogen sensor.

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