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Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
Superparamagnetism of Cu2Se nanoparticles.
Soo-Whan Kim1, Kyu Joon Lee, Myung-Hwa Jung
1Department of Physics, Sogang University, Seoul 121-742, South Korea.
Journal of Nanoscience and Nanotechnology
|September 13, 2012
Summary
Copper selenide (Cu2Se) nanoparticles synthesized via hot-injection transform from diamagnetic to paramagnetic upon air exposure due to surface oxidation. This change is linked to the formation of copper vacancies and oxidation of copper ions.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Chemistry
Background:
- Copper selenide (Cu2Se) is a promising material with applications in thermoelectric and optoelectronic devices.
- Understanding the phase stability and magnetic properties of Cu2Se nanoparticles is crucial for their technological implementation.
- Nanoparticle synthesis methods influence their structural and magnetic characteristics.
Purpose of the Study:
- To synthesize Cu2Se nanoparticles using the hot-injection method.
- To investigate the structural and phase evolution of Cu2Se nanoparticles upon air exposure.
- To characterize the magnetic properties of pristine and air-exposed Cu2Se nanoparticles.
Main Methods:
- Hot-injection synthesis of Cu2Se nanoparticles.
- X-ray diffraction (XRD) for structural and phase analysis.
- Magnetic property measurements (SQUID magnetometry).
Main Results:
- Synthesized ~7 nm stoichiometric cubic Cu2Se nanoparticles.
- Observed a shift in XRD peaks upon air exposure, indicating a transition to nonstoichiometric Cu2-deltaSe with copper vacancies.
- Pristine nanoparticles were diamagnetic, while air-exposed nanoparticles became paramagnetic with superparamagnetic behavior (blocking temperature of 150 K).
Conclusions:
- Air exposure induces significant structural and magnetic changes in Cu2Se nanoparticles.
- The observed paramagnetic behavior is attributed to the oxidation of Cu+ to Cu2+ and the formation of copper vacancies.
- These findings highlight the sensitivity of Cu2Se nanoparticle properties to environmental conditions.
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