We report the behaviour of carbon black (CB) nanoparticles (spherical carbon shells), subjected to external pressure, using diamond anvil cell at synchrotron facility. CB nanoparticles have been synthesized by lamp black method using olive oil as combustion precursor and ferrocene as an organometallic additive. The catalyst-assisted CB has an iron oxide (γ-Fe2O3) core and amorphous carbon shell (i.e. core–shell structure). Our present study suggests that the carbon shells are partially transparent to the applied high pressure, and result in the reduction of effective pressure that gets transferred to the iron oxide core. High-pressure Raman spectroscopy results indicate that the surrounding carbon shells get compressed with pressure and this change is reversible. However, no structural transformation was observed till the highest applied pressure (25 GPa). The Raman spectroscopy results also suggests that the carbon shells are less pressure sensitive as their pressure coefficients (dω/dP) of G-peak were calculated (3.79 cm− 1/GPa) to be less than that for other carbon allotropes.

    Abstract
    1 Introduction
    2 Experimental
    3 Results and discussion
        3.1 X-ray diffraction
        3.2 Raman spectroscopy
    4 Conclusion
    Acknowledgements 
    References

• Surakanti Srinivas Reddy(UGC-DAE Consortium for Scientific Research, Kalpakkam Node, University of Madras)
• Balmukund Shukla(Condensed Matter Physics Division, Materials Science Group)
• Soumee Chakraborty(Condensed Matter Physics Division, Materials Science Group)
• V. Srihari(High Pressure and Synchrotron Radiation Physics Division)
• G. M. Bhalerao(UGC-DAE Consortium for Scientific Research, Kalpakkam Node)
• N. V. Chandra Shekar(Condensed Matter Physics Division, Materials Science Group)