Questions and Answers
What is the total length when adding 3440 cm and 160 cm?
What is the relationship between 1635 cm and 800 cm?
If you subtract 160 cm from 3440 cm, what is the result?
When comparing 3440 cm, 160 cm, and 800 cm, which statement is true?
Signup and view all the answers
If you average 3440 cm, 160 cm, and 800 cm, what is the result?
Signup and view all the answers
Which statement best describes the relationship of 3440 cm to the other two measurements?
Signup and view all the answers
Which method was used to analyze the thermal behavior of the precursor and calcined samples?
Signup and view all the answers
What was the maximum operating voltage for the mission electron microscopy used?
Signup and view all the answers
What was used as a capping agent in the experiment?
Signup and view all the answers
At what heating rate was the sample heated during the thermal analysis?
Signup and view all the answers
Which precursor was used for cobalt in the experiment?
Signup and view all the answers
What role did ammonium hydroxide solution play in the preparation process?
Signup and view all the answers
Which chemical was used as a silica precursor?
Signup and view all the answers
What was the weight range of the sample loaded in the ceramic sample holder for thermal analysis?
Signup and view all the answers
What was the primary method used to synthesize the Co/SiO2 nanocomposite powders?
Signup and view all the answers
Which phase formation was confirmed after the calcination and reduction stages?
Signup and view all the answers
The Co-gelation method was found to be the best approach for which of the following?
Signup and view all the answers
What was one of the key characteristics of the Co/SiO2 nanocomposite powders produced?
Signup and view all the answers
Which analytical techniques were used to confirm phase formation?
Signup and view all the answers
When were the Co/SiO2 nanocomposite powders received for review?
Signup and view all the answers
Where was the research conducted?
Signup and view all the answers
Which of the following best describes the received revisions for the research article?
Signup and view all the answers
What is the estimated average particle size of the cobalt oxide phase?
Signup and view all the answers
Which of the following particle sizes corresponds to the results of the pore volume measurements?
Signup and view all the answers
What shape do the cobalt particles take in the reduced sample?
Signup and view all the answers
What range of sizes do the particles in the sample fall into?
Signup and view all the answers
What method was used to obtain the particle size distribution for the cobalt oxide phase?
Signup and view all the answers
What structural formation is noted for the cobalt particles in relation to silica?
Signup and view all the answers
At what temperature was the sample calcined before reduction?
Signup and view all the answers
What is the significance of the values obtained from XRD data in this study?
Signup and view all the answers
What is the effect of adding EG as a protective agent in the formation of cobalt nanoparticles?
Signup and view all the answers
What is the maximum thermal stability achieved for cobalt nanoparticles in a silica matrix?
Signup and view all the answers
What type of nanoparticles are being discussed in the context of silica matrix?
Signup and view all the answers
What does TGA measure in the provided context?
Signup and view all the answers
What was the drying temperature for the SGP50 sample in the experiment?
Signup and view all the answers
What is indicated by the DTG curve in the experiment?
Signup and view all the answers
What is the significance of well-dispersed cobalt nanoparticles as mentioned in the content?
Signup and view all the answers
What temperature range does the TGA and DTG analysis cover?
Signup and view all the answers
Study Notes
Synthesis of Cobalt/Silica Nanocomposites
- Cobalt/silica (Co/SiO2) nanocomposite powders achieved successful synthesis through a thermal calcination-reduction process applied to gel precursors.
- The Co-gelation method effectively combines cobalt and silica sources in a single solution, optimizing the materials' preparation.
Characterization Techniques
- X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed the formation of single Co3O4 and metallic cobalt (Co) phases after calcination and reduction.
- Transmission Electron Microscopy (TEM) utilized a JEOL-1230 microscope operating at a maximum voltage of 200 kV for particle size analysis.
Materials Used
- Cobalt(II) nitrate hexahydrate (Co(NO3)2·6H2O) served as the cobalt precursor, while TEOS (Tetraethoxysilane) was used for silica.
- Ethylene glycol and dimethylformamide acted as capping and reducing agents, respectively, while ammonium hydroxide controlled the pH during synthesis.
Thermal Analysis
- Thermal behavior of the samples analyzed through Thermal Gravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) recorded data during heating up to 700°C at a rate of 10°C/min in an air stream.
- Well-dispersed cobalt nanoparticles demonstrated high thermal stability up to 400°C.
Particle Characteristics
- The cobalt oxide (Co3O4) exhibited a near-spherical shape with an average particle size of about 10 nm.
- Reduced samples displayed spherical cobalt particles within a silica matrix, forming a core/shell structure, with sizes ranging from 30-70 nm.
Pore Structure and Stability
- The addition of ethylene glycol improved pore formation during calcination and reduction, resulting in a well-dispersed arrangement within the silica matrix.
- Pore volume measurements reported values ranging from 3.10 nm to 5.73 nm across different samples.
Conclusion
- The proposed synthesis route successfully produced thermally stable Co/SiO2 nanocomposites, emphasizing the controlled synthesis and characterizations leading to favorable nanocomposite properties.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz explores the synthesis and characterization of cobalt/silica (Co/SiO2) nanocomposite powders. It covers techniques such as thermal calcination-reduction and the Co-gelation method, highlighting their effectiveness in materials preparation. Additionally, X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) are discussed for confirming material properties.