研究目的
To improve the electrochemical properties of LaFeO3-δ perovskite as cathode by strontium and cobalt doping in lanthanum and iron sites.
研究成果
Porous and crack-free La1-xSrxCo0.2Fe0.8O3-δ thin films with nanometric grain size were successfully synthesized using ultrasonic spray pyrolysis. All films exhibited a single orthorhombic perovskite phase. Increasing strontium content from 0 to 0.4 enhanced conductivity (from 4.2 to 67.1 S/m at 250°C) and reduced activation energy (from 0.41 to 0.24 eV), indicating improved electrochemical performance. The film with x=0.4 shows potential as a cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). Future work could explore higher doping levels and different synthesis parameters to optimize performance further.
研究不足
The study is limited to strontium doping levels up to x=0.4; higher doping may lead to phase changes not observed here. Measurements were conducted in air and at specific temperature ranges (e.g., 150-500°C for some samples), which may not cover all operational conditions. The ultrasonic spray pyrolysis method may have constraints in film uniformity and scalability.
1：Experimental Design and Method Selection:
Ultrasonic spray pyrolysis (USP) was used to synthesize nanostructured La1-xSrxCo0.2Fe0.8O3-δ thin films with 0 ≤ x ≤ 0.4, followed by sintering in air. The method was chosen for its simplicity, low cost, and ability to produce porous, nanostructured films with good stoichiometric control.
2：2Fe8O3-δ thin films with 0 ≤ x ≤ 4, followed by sintering in air. The method was chosen for its simplicity, low cost, and ability to produce porous, nanostructured films with good stoichiometric control.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: Films were prepared with varying strontium content (x from 0 to 0.4) using precursor solutions of metal nitrates (La(NO3)3·6H2O, Sr(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O) dissolved in 75% deionized water and 25% ethanol, with a total metal ion concentration of 0.04 M.
3：4) using precursor solutions of metal nitrates (La(NO3)3·6H2O, Sr(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O) dissolved in 75% deionized water and 25% ethanol, with a total metal ion concentration of 04 M.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment includes an ultrasonic nebulizer (atomizer), substrate heater, temperature controller, Rigaku Ultima IV diffractometer (XRD), Jeol JSM 7600F Field Emission SEM with EDS OXFORD INCAx-act analyzer, Jeol JSPM-420 Scanning Probe Microscope (AFM), and Solartron 1260 AC impedance analyzer. Materials include metal nitrates (Fluka, Sigma-Aldrich, Alfa Aesar), deionized water, ethanol, and Pyrex glass substrates.
4：Experimental Procedures and Operational Workflow:
Precursor solution was nebulized using ultrasonic nebulizer, aerosol transported by air carrier gas (120 mL/min flow rate) to substrate heated at 450°C, with nozzle-to-substrate distance of ~2.5 cm and deposition time of 20 min. Films were annealed at 500°C for 2 h. Structural analysis by XRD (20-70° 2θ range), morphological analysis by SEM and AFM, and transport properties by impedance spectroscopy (0.1 Hz–3.2 MHz frequency range) were performed.
5：5 cm and deposition time of 20 min. Films were annealed at 500°C for 2 h. Structural analysis by XRD (20-70° 2θ range), morphological analysis by SEM and AFM, and transport properties by impedance spectroscopy (1 Hz–2 MHz frequency range) were performed.
Data Analysis Methods:
5. Data Analysis Methods: XRD data analyzed using OriginLab software for FWHM and crystallite size via Scherrer equation. Impedance data fitted to equivalent circuit model using Zview software. Conductivity and activation energy calculated from Arrhenius equation.
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