研究目的
To investigate how the grain size and temperature influence the electrical properties of SnO2 nanopowder synthesized by gel combustion method.
研究成果
SnO2 nanoparticles with varying grain sizes were successfully synthesized using gel combustion method. The DC electrical conductivity increases with temperature, showing semiconducting behavior, and decreases with decreasing grain size due to increased surface-to-volume ratio. Activation energy increases with smaller grain sizes. The method allows control over electrical properties by adjusting the fuel-to-oxidizer ratio.
研究不足
The study is limited to SnO2 nanoparticles synthesized by gel combustion method; other synthesis methods may yield different results. The electrical measurements are on thick films, which might not fully represent bulk or thin film properties. The range of grain sizes and temperatures studied may not cover all possible variations.
1：Experimental Design and Method Selection:
The study uses gel combustion method to synthesize SnO2 nanoparticles by varying the fuel (citric acid) to oxidizer (nitric acid) molar ratio. The prepared samples are characterized using XRD, SEM, and EDAX to analyze structure, morphology, and composition. DC electrical conductivity is measured as a function of temperature.
2：Sample Selection and Data Sources:
Samples are prepared with different molar ratios of HNO3 (0, 2, 4, 6.2, 8, 10 moles) to vary grain size. Data is collected from synthesized powders and thick films on silicon glass substrates.
3：2, 8, 10 moles) to vary grain size. Data is collected from synthesized powders and thick films on silicon glass substrates.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Raw materials include tin(II) chloride dihydrate (SnCl2.2H2O, 99.99%, Merck), nitric acid (HNO3, 70%, Merck), citric acid (C6H8O7, 99.5%, Merck), distilled water. Equipment includes Pyrex vessel for heating, XRD with Cu-Kα radiation (λ=1.5418 ?), SEM (Hitachi Model S-3200N), EDAX, Keithley source meter (Model-2000) for resistance measurement.
4：2H2O, 99%, Merck), nitric acid (HNO3, 70%, Merck), citric acid (C6H8O7, 5%, Merck), distilled water. Equipment includes Pyrex vessel for heating, XRD with Cu-Kα radiation (λ=5418 ?), SEM (Hitachi Model S-3200N), EDAX, Keithley source meter (Model-2000) for resistance measurement.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Dissolve raw materials in distilled water, heat at 90°C with stirring to form polymeric precursor, raise temperature to 300°C for combustion, calcinate ashes at 800°C for 1 hour. Coat thick films on substrates using doctor blade method. Characterize with XRD, SEM, EDAX. Measure DC conductivity from 308K to 670K using source meter.
5：Data Analysis Methods:
Grain size calculated using Scherrer relation from XRD data. Electrical conductivity calculated using σ = t/(R*A), activation energy from Arrhenius plot (lnσ vs. 1000/T).
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