1 / 13

Recent Magnetic Results on Rhombohedral C 60

Recent Magnetic Results on Rhombohedral C 60. S.Buga, M. Belli, M.Mazzani, D.Pontiroli, A.Goffredi, M.Riccò. FerroCarbon Final Meeting Crete, September 2008. Outline. Introduction Magnetic Measurements Room Temperature Ferromagnetism Polymer Sructure and Ferromagnetism

ulla
Télécharger la présentation

Recent Magnetic Results on Rhombohedral C 60

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Recent Magnetic Resultson Rhombohedral C60 S.Buga, M. Belli, M.Mazzani,D.Pontiroli, A.Goffredi, M.Riccò FerroCarbon Final Meeting Crete, September 2008

  2. Outline • Introduction • Magnetic Measurements • Room Temperature Ferromagnetism • Polymer Sructure and Ferromagnetism • Discussion and conclusions

  3. Depolymerizes at 430 – 450 K Rhombohedral C60

  4. Synthesis Parameters • Samples of Pressure-induced Rh C60 polymer were obtained by high-pressure high-temperature treatment of pristine C60 : • Duration 30’ • Pressure 5.5 GPa • Temperature different for each samplerange from 775° to 900°C

  5. Magnetic Measurements • The samples were handled in air • The pellets were broken in an agate mortar to obtain small fragments • Magnetic Characterization included • A magnetization curve M(H) at 300 K, recorded varying the field from +5 T to -5 T • Magnetization as a function of temperature(Field Cooling and Zero Field Cooling)and Low temperature M(H) (for some samples only) • All the measurements were performed with automatic background subtraction.

  6. Untreated sample

  7. Diamagnetic &Ferromagnetic Contributions • In each sample there’s a weak Ferromagnetic contribution(few hundreds µemu/g)

  8. Diamagnetic &Ferromagnetic Contributions • Samples synthesized at 800°C reproducibly show a much stronger Ferromagnetic contribution(few memu/g)

  9. Room-Temper. Ferromagnetism Significantly strong ferromagnetic contribution is observed only in samples synthesized at 800°C 800° C 825° C 850 °C 900° C

  10. Room-Temperature Ferromagnetism Ferromagnetism is obtained only in case of very SPECIFIC CONDITIONS OF SYNTHESIS

  11. Ball-Milled Sample One of the magnetic samples (synthesized at 800°C) underwent ball-milling in condition similar to ball-milling of graphite and… …the polymer lattice was completely destroyed

  12. …the ferromagnetic contribution increased or, considering inhomogenities of these samples,did not change Conclusion:Ferromagnetism does not dependon polymer structure

  13. Conclusions • Relatively strong room-temperature ferromagnetism was confirmed in Rh-C60 synthesized in very specific conditions • We can exclude it come from impurities as other sample does not show such an high magnetic signal • Ferromagnetism seems not to depend on rhombohedral polymer structure

More Related