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Updated: Jan 19, 2026

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production
Published on: December 6, 2021
Structure and Magnetism of Co2Ge Nanoparticles
Onur Tosun1, Frank M Abel2, Balamurugan Balasubramanian3,4
1Department of Physics and Astronomy, University of Delaware, Newark, DE 19711, USA. onurt@udel.edu.
Cobalt-germanium nanoparticles exhibit structural changes upon annealing, transforming from superparamagnetic to ferromagnetic with a significantly higher Curie temperature. This shift is attributed to the formation of a new cobalt-rich orthorhombic phase.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Cobalt-germanium (Co2Ge) nanoparticles are of interest for their magnetic properties.
- Understanding the structure-property relationship in nanoparticles is crucial for material design.
Purpose of the Study:
- To investigate the structural and magnetic properties of Co2Ge nanoparticles.
- To explore the effects of annealing on these properties.
Main Methods:
- Cluster-beam deposition (CBD) for nanoparticle synthesis.
- X-ray diffraction (XRD) for structural analysis.
- Thermomagnetic measurements for magnetic property evaluation.
Main Results:
- As-made 5.5 nm Co2Ge nanoparticles showed a mix of hexagonal and orthorhombic structures, exhibiting superparamagnetism with a blocking temperature of 20 K.
- Annealed (823 K, 12 h) nanoparticles grew to 13 nm and developed a new orthorhombic phase.
- Annealed nanoparticles displayed ferromagnetic behavior with a high Curie temperature of 815 K.
Conclusions:
- Annealing induces significant structural and magnetic property changes in Co2Ge nanoparticles.
- The formation of a new Co-rich orthorhombic phase is responsible for the enhanced ferromagnetic properties at higher temperatures.
- These findings highlight the potential for tuning magnetic properties of Co2Ge nanoparticles through controlled annealing.
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