New Method Of Ultrahard Material Synthesis - 1048 Words

New Method in Ultrahard Material Synthesis: CS2 Catalyzed Ultrahard Fullerite Ultrahard materials is a broad category define by materials that are harder than diamond. Diamond, thought to be the hardest material for centuries hasn’t been the hardest material seen by scientists in a long time. Many materials have been developed or discovered recently that surpass the 150 GPa hardness of diamond by as much as 100%. There are many ways to measure the hardness of a material, from the classic scratch test to more complicated bulk modulus calculations. Other tests of hardness include indentation and rebound tests, or measurements of the elastic and shear modulus. Ultrahard fullerite is one such material that has surpassed diamond with values†¦show more content†¦Structural studies of fullerite are hampered by its lack of a 4 or 6 fold axis, so long-term periodicity in fullerite’s crystal lattice isn’t possible for covalently-bonded fullerene molecules in three dimensions. TEM studies have shown a sequence of FCC phases that have been ex plained by bonded fullerene chains formation. Because of this difficulty, researchers have turned to Raman spectroscopy to study the polymerization, which has features explained by the C60 phonon spectra perturbations by intermolecular covalent bonding. The 3D polymerized phases produced in ultrahard fullerite synthesis are phase IV and V, where phase V is the desired ultrahard fullerite. Phase V is translucent in the near IR or visible range having a Raman spectrum containing two broad peaks around 1550 cm-1 and around 500 cm-1. Prior to research by Popov et al., the synthesis conditions of ultrahard fullerite depended on a degree of plastic deformation and stress tensor variation of a sample under compression. The minimum required pressure for synthesis was 13 GPa at 1100 K, or 18 GPa at room temperature, both of which aren’t suitable for industrial production without a catalyst. The polymerization of fullerene molecules starts under sunlight irradiation at ambient temperatures to create dimers. These simple conditions for these intermolecular bonds to form led researchers to hypothesize