Perovskite oxide film proton conduction in-situ detection device and method based on resistance real-time monitoring

Abstract

The invention discloses a perovskite oxide film proton conduction in-situ detection device and method based on resistance real-time monitoring, and belongs to the technical field of functional materials and electrochemical sensing. According to the invention, a SrCoO2.5 thin film is epitaxially grown on a SrTiO3 single crystal substrate by adopting pulse laser deposition, and a Pt electrode is prepared on the surface of the thin film to form a resistance measurement structure; a sample is placed in a sealed cavity capable of independently and accurately controlling temperature, humidity and atmosphere, controllable partial pressure water vapor is introduced, a high-precision resistance meter is used for carrying out continuous, real-time and high-frequency collection on a thin-film resistor, and changes of the temperature, the humidity and the gas partial pressure along with time are synchronously recorded. The SrCoO2.5 film is subjected to hydration phase change when encountering water vapor to generate a hydrated phase SCOH, the resistivity is sharply reduced by more than four orders of magnitude, and the reciprocal 1 / R of the resistance is in a linear reduction relation along with time. The rate constant k can be directly obtained by fitting the linear section of the normalized resistor R0 / R (t).

Description

Technical Field

[0001] This invention relates to the fields of functional materials and electrochemical sensing technology, specifically to a device and method for in-situ, real-time, and quantitative detection of proton conduction dynamics in perovskite oxide thin films based on real-time resistance monitoring. Background Technology

[0002] Proton-conducting materials are core functional materials in fields such as solid oxide fuel cells, electrolyzers, gas sensors, and hydrogen storage materials. Currently, the mainstream characterization methods for proton conduction behavior include isotope tracer-secondary ion mass spectrometry (ISTS) and electrochemical impedance spectroscopy (EIS). Isotope tracer-secondary ion mass spectrometry has a complex process and long testing cycle, and can only obtain offline, static ion distribution information, making it impossible to achieve real-time dynamic monitoring. EIS can only reflect steady-state or quasi-steady-state responses and is difficult to capture rapid transient processes such as proton injection, migration, capture, and lattice chemical expansion. Existing technologies generally suffer from poor real-time performance, weak in-situ capability, insensitivity to rapid processes, and difficulty in achieving continuous monitoring under varying temperature, humidity, and atmospheric conditions, thus failing to meet the needs of studying the microscopic mechanism of proton conduction in perovskite oxides.

[0003] Therefore, developing a detection method and device that can perform in-situ, real-time, highly sensitive, and quantitative analysis of the dynamic process of proton conduction has become an urgent technical problem to be solved in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an in-situ detection device and method for proton conduction in perovskite oxide thin films based on real-time resistance monitoring. This method enables second-level dynamic tracking of the proton conduction process, in-situ testing with multi-physics coupling, and high-sensitivity quantitative analysis, solving the problems of poor real-time performance, weak in-situ capability, and inability to capture rapid dynamic processes in traditional characterization methods. Technical solution

[0005] (1) Thin film preparation: SrCoO2.5 thin film was epitaxially grown on SrTiO3(001) single crystal substrate using pulsed laser deposition technology. Deposition conditions: substrate temperature 650 ℃, oxygen partial pressure 0.1 Pa, laser wavelength 248 nm, pulse energy 300 mJ, frequency 5 Hz. The film thickness could be controlled to be 5 nm, 10 nm, 20 nm, 30 nm, and 50 nm. After deposition, the film was annealed at 500 ℃ and oxygen partial pressure 10 Pa for 30 minutes to obtain epitaxial thin film with high crystal quality and high orientation.

[0006] (2) Electrode preparation: Pt electrode with a thickness of 20 nm is deposited on the surface of SrCoO2.5 thin film by magnetron sputtering to form a two-probe or four-probe measurement structure, which ensures uniform current distribution and improves measurement accuracy and stability.

[0007] (3) Construction of in-situ testing environment: The sample is placed in a sealed temperature-controlled chamber, which can be independently and precisely controlled: temperature: 250 ℃~350 ℃; relative humidity: 10%~80%; carrier gas: N2, Ar, O2 or their mixture; total pressure: 0.1 MPa~0.5 MPa; oxygen partial pressure: 0%~5%. Water vapor is rapidly introduced through a water vapor generator at t=0 to trigger the thin film hydration reaction.

[0008] (4) Real-time resistance acquisition: A high-precision resistance meter is used to continuously acquire resistance R(t) at a frequency of 10 Hz to 100 Hz, and temperature, humidity and gas partial pressure are recorded simultaneously.

[0009] (5) Data Analysis Method: Using the resistance at t=0 as the reference resistance R0, the normalized resistance R0 / R(t) is calculated. The reciprocal of the resistance 1 / R decreases linearly with time, satisfying: 1 / R(t) = 1 / R0 - k·t, where k is the rate constant in s⁻¹. The proton conduction transition front velocity v satisfies: v = k·dd, where the film thickness is the thickness. By obtaining k through linear fitting, v can be calculated, thus achieving quantitative analysis of proton conduction dynamics.

[0010] An in-situ detection device and method for proton conduction in perovskite oxide thin films based on real-time resistance monitoring is disclosed, and its principle and derivation are as follows: Let the total thickness of the SrCoO2.5 film be d, the width be w, and the length be L.

[0011] When exposed to water vapor at time t = 0, a hydration reaction occurs, generating the SCOH (hydrated phase) region. This geometry is similar to that of a parallel circuit: the untransformed SCO region (resistivity ρ) SCO ) and the transformed SCOH region (resistivity ρ) SCOH They share the same electrode contacts. Their respective resistances are: Where v is the migration velocity of the SCOH / SCO phase interface (i.e., the transition front velocity), and (d - vt) and (vt) are the thicknesses of the SCO and SCOH regions at time t, respectively. The total resistance R of the thin film is given by the parallel combination of these two resistors: R SCO and R SCOH Substituting the expression into equation (1), we get: Define a geometric constant This constant is fixed for a given device. Equation (2) can be rewritten as:

[0012] Group time-related items: Known ≫ ,therefore: Applying this approximation, equation (4) simplifies to: Equation (6) predicts that during hydration, the reciprocal of the measured resistance will be... It decreases linearly with time. The slope is proportional to the transition front velocity v, and the intercept is the reciprocal of the initial resistivity before hydration begins. ,in To eliminate device-specific geometric factors, we define the normalized resistance as... , where R N R is the resistance at an arbitrarily chosen reference time (usually taken as the moment when water vapor is introduced, i.e., t=0). N = R0, according to equation (6) Note We define the experimentally measurable rate constant k as the absolute value of this slope: We define the experimentally measurable rate constant k as the magnitude of this slope: Therefore, the speed of change frontier v With film thickness d It is proportional and can be obtained by fitting the linear portion of the normalized resistance data: Rate constant k (in seconds) -1 It contains the inherent chemical kinetics information of proton conduction at a given temperature.

[0013] The present invention has the following beneficial effects: With extremely high real-time performance and a time resolution of seconds or even higher, it can continuously capture rapid transient processes such as proton injection, migration, capture, and lattice chemical expansion, breaking through the limitations of traditional methods that can only obtain steady-state / quasi-steady-state information.

[0014] In-situ multi-field coupling allows for independent and precise control of temperature, humidity, atmosphere, and water vapor partial pressure, enabling in-situ testing under thermal-humidity-chemical-electric multi-field coupling. This simulates real working environments and improves the reliability of mechanism research.

[0015] With extremely high detection sensitivity, the resistance change of SrCoO2.5 after hydration exceeds four orders of magnitude, and the electrical signal-to-noise ratio is extremely high. It can clearly and unambiguously identify the proton conduction initiation and evolution process, reducing the dependence on high-end instruments.

[0016] The kinetic parameters can be quantitatively analyzed, and the rate constant k and proton conduction front velocity v can be obtained directly through a linear model, realizing the leap from qualitative observation to quantitative analysis and providing direct data support for the conduction mechanism.

[0017] Applicable to triple conductive systems, this method can be used for triple conductor materials that simultaneously possess electron, oxygen ion, and proton conduction capabilities, and can analyze the competition and cooperation mechanisms among charge carriers.

[0018] The method is highly universal and easy to promote. Based on the general principles of resistance measurement and environmental control, it can be extended to other proton conductors that undergo significant resistance changes during hydration / dehydration, making it widely applicable.

[0019] The device is simple, low-cost, and easy to replicate. It uses mature commercial equipment, has a simple structure, and is easy to operate, making it suitable for scientific research and industrial application.

[0020] Preferably, the real-time change in resistance is used as a dynamic probe for proton conduction. The dramatic change in resistance caused by the hydration of SrCoO2.5 is directly used as a real-time, in-situ, and quantitative probe for the proton conduction process, realizing a paradigm shift from static characterization to dynamic tracking.

[0021] Preferably, the high-sensitivity mechanism based on the SrCoO2.5 hydration phase transition utilizes the unique effect of SrCoO2.5 undergoing a structural phase transition in water vapor, accompanied by a resistivity decrease of more than four orders of magnitude, to form a high signal-to-noise ratio and high-reliability detection basis.

[0022] Preferably, the multi-field controllable in-situ testing system constructs a sealed cavity that can independently and precisely control temperature, humidity, and atmosphere, achieving highly stable and adjustable environmental parameters and providing a guarantee for dynamic detection.

[0023] Preferably, the resistance-time linear dynamics model establishes a linear relationship between 1 / R(t) and time, enabling the direct extraction of the rate constant k and the transition front velocity v, thus forming a complete quantitative analytical method. Attached Figure Description

[0024] Figure 1. Schematic diagram of the in-situ proton conduction detection device. Figure 2. Conductivity-time variation curves of SrCoO2.5 thin films with different thicknesses. Figure 3. Proton conduction velocity-time curves for films of different thicknesses. Detailed Implementation Substrate treatment: SrTiO3 (001) single crystal substrate was used. It was ultrasonically cleaned with acetone, ethanol and deionized water for 10 minutes each, and then dried with nitrogen before being placed in the deposition chamber.

[0025] Thin film deposition: Pulsed laser deposition was performed using a KrF laser with a wavelength of 248 nm, a single pulse energy of 300 mJ, a repetition rate of 5 Hz, a substrate temperature of 650 ℃, a cavity oxygen partial pressure of 0.1 Pa, and a deposition thickness of 5 nm.

[0026] Annealing treatment: After deposition, maintain oxygen partial pressure of 10 Pa, heat to 500 ℃, hold for 30 minutes, and then cool to room temperature with the furnace.

[0027] Electrode fabrication: Pt electrodes were deposited on the thin film surface by magnetron sputtering with a sputtering power of 30 W, an argon flow rate of 30 sccm, a deposition thickness of 20 nm, a four-probe structure, and an electrode spacing of 200 μm.

[0028] Test environment setup: The sample was placed in a sealed temperature-controlled chamber, and the temperature was set to 290 ℃, relative humidity to 40%, water vapor partial pressure to 0.3 kPa, carrier gas to be high-purity argon, oxygen partial pressure to 0%, and total chamber pressure to 0.1 MPa.

[0029] Data acquisition: A high-precision resistance meter was used with a sampling frequency of 20 Hz. The sampling was continuously collected for 800 seconds, with the moment when water vapor was introduced being t=0.

[0030] Data processing: Taking the resistance at t=0 as R0, calculate R0 / R(t), fit the linear segment, R²=0.992, and obtain k=0.025 s-1.

[0031] Results: v = k·d = 0.025 × 5 = 0.125 nm / s, the proton conduction process is clearly measurable. Substrate, deposition, annealing, and electrode processes: Same as in Example 1, except that the film thickness was adjusted to 30 nm.

[0032] Test conditions: temperature 290 ℃, humidity 40%, argon atmosphere, oxygen partial pressure 0%.

[0033] Data acquisition parameters: sampling frequency 20 Hz, test time 800 seconds.

[0034] Fitting results: k = 0.008 s⁻¹, R² = 0.995.

[0035] The calculation result is: v = 0.008 × 30 = 0.24 nm / s, which conforms to the linear relationship of v = k·d. Sample: 30 nm SrCoO2.5 thin film, process as in Example 2.

[0036] Test conditions: temperature 330 ℃, relative humidity 70%, water vapor partial pressure 0.6 kPa, argon atmosphere, oxygen partial pressure 0%.

[0037] Data acquisition and fitting: Sampling frequency 20 Hz, linear fitting R² = 0.994, k = 0.032 s⁻¹.

[0038] Results: v = 0.032 × 30 = 0.96 nm / s, temperature and humidity significantly increased the proton conduction rate. Sample: 50 nm SrCoO2.5 thin film, deposition, annealing, and electrode processes were the same as in Example 1.

[0039] Test conditions: temperature 290 ℃, humidity 40%, argon atmosphere.

[0040] Fitting results: k = 0.0048 s⁻¹, R² = 0.991.

[0041] Calculation results: v = 0.0048 × 50 = 0.24 nm / s. The velocity is stable under thick film, and the model is reliable. Sample: 30 nm SrCoO2.5 thin film, process as in Example 2.

[0042] Test conditions: temperature 290 ℃, humidity 40%, oxygen partial pressure set to 0%, 2%, and 5% respectively.

[0043] Test results: 0% O2: k = 0.008 s⁻¹; 2% O2: k = 0.0072 s⁻¹; 5% O2: k = 0.0065 s⁻¹.

[0044] Conclusion: Increased oxygen partial pressure slightly inhibits proton conduction.

[0045] This invention utilizes mature commercial equipment such as pulsed laser deposition, magnetron sputtering, sealed temperature-controlled chambers, and high-precision resistance meters. The preparation and testing process is stable, repeatable, and scalable. It can be widely applied in fields such as the research and development of perovskite proton conductor materials, the screening of key materials for solid oxide fuel cells, the development of high-sensitivity humidity / gas sensors, and the study of proton conduction mechanisms, and has significant industrial applicability.

Claims

1. A method for in-situ detection of proton conduction in perovskite oxide thin films based on real-time resistance monitoring, characterized in that, Includes the following steps: (1) Using pulsed laser deposition technology, SrCoO2.5 thin films are epitaxially grown on SrTiO3 single crystal substrates to form uniform epitaxial films with a thickness of d; (2) Pt electrodes are prepared on the surface of the SrCoO2.5 thin film by magnetron sputtering to form a resistance measurement electrode pair; (3) The prepared sample is placed in a sealed temperature-controlled cavity, and the internal temperature, relative humidity and partial pressure of the gas atmosphere are independently and precisely controlled; (4) The carrier gas flow rate is controlled by a mass flow meter, and water vapor with a preset partial pressure is introduced into the cavity by a water vapor generator, so that the sample is exposed to the water vapor environment at t=0; (5) Under the set temperature, humidity and atmosphere conditions, the resistance of the thin film is continuously and in real time collected by a high-precision resistance meter; (6) The curves of resistance, temperature, relative humidity and water vapor partial pressure change with time are recorded synchronously; (7) The normalized resistance R0 / R is calculated with the resistance at t=0 as the reference resistance R0. (t), fit the linear segment of the reciprocal of the resistance changing with time to obtain the rate constant k; (8) calculate the proton conduction transition front velocity v according to the relationship v=k・d to realize the quantitative acquisition of proton conduction dynamic parameters.

2. The method according to claim 1, characterized in that, The thickness d of the SrCoO2.5 film is 5 nm, 10 nm, 20 nm, 30 nm or 50 nm.

3. The method according to claim 1, characterized in that, The sampling frequency for resistance acquisition is 10 Hz to 100 Hz, and the sampling time interval is no more than 1 second.

4. The method according to claim 1, characterized in that, The test temperature was 250 ℃~350 ℃, the relative humidity was 10%~80%, the total pressure of the chamber was 0.1 MPa~0.5 MPa, and the oxygen partial pressure was 0%~5%.

5. The method according to claim 1, characterized in that, The preparation conditions for the SrCoO2.5 thin film were as follows: substrate temperature 650 ℃, oxygen partial pressure 0.1 Pa, and annealing at 500 ℃ and oxygen partial pressure 10 Pa for 30 minutes after deposition.

6. The method according to claim 1, characterized in that, The criterion for judging linear fit is a coefficient of determination R² ≥ 0.

98.

7. A proton conduction in-situ detection device for implementing the method of claim 1, characterized in that, include: The substrate holder is used to fix the test sample with SrCoO2.5 thin film and Pt electrode; the sealed temperature control chamber is equipped with a heating module, a humidity control module, a gas inlet, a gas outlet and a mass flow meter; the high-precision resistance measurement module is connected to the Pt electrode on the sample to collect the thin film resistance in real time; the data synchronous acquisition and processing module synchronously records the resistance, temperature, humidity and gas partial pressure data, and performs linear fitting on the resistance-time curve, outputting the rate constant k and the proton conduction front velocity v.

8. The apparatus according to claim 7, characterized in that, The sealed temperature-controlled cavity is equipped with an optical window, which allows for simultaneous in-situ characterization using Raman spectroscopy, infrared spectroscopy, or X-ray diffraction.

9. The apparatus according to claim 7, characterized in that, The device is equipped with temperature and humidity sensors, which can provide real-time feedback on the environmental parameters inside the cavity.

10. The application of the method according to claim 1, characterized in that, In-situ, real-time, and quantitative characterization of quantum conduction kinetics of SrCoO2.5 and its derivative perovskite oxides.

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