Preparation of diamond nanocrystals from catalysed carbon black in a high magnetic field

Abstract

Under a static high magnetic field of 10 T, diamond-like carbon (DLC) nanocrystals and graphite-coated n-diamond nanoparticles have been synthesized after a pyrogenation of carbon black and a nanometre-sized iron catalyst at atmospheric pressure and a temperature of 1100 °C. The product is analysed by x-ray diffraction, Raman spectroscopy, transmission electron microscopy and electron-probe microanalysis. The average size of the DLC nanopowders is about 20 nm, and that of the graphite-coated n-diamond particles is about 100 nm. The yield of diamond is as high as 30%.

Influence of periodic magnetic field on the growth of CVD diamond films at lower temperature

“…At the same time, it is improved that the static magnetic field will cause the non-uniform deposition on the substrates [8]. Meanwhile, the declining of the surface free energy of diamond films also plays an important role in depositing process [9,17], and the increase in the growth rate of diamond films may attribute mainly to the combined affection of the magnetic field and thermal pyrolysis. …”

“…It is reported by Wen et al [9] and Little et al [10] recently that diamond film can be deposited under static magnetic field (MF) with an intensity of 10-20 T. Both of them reported that diamond nanoparticles can be synthesized from carbon black under a static high magnetic field, and the yield of diamond increased by 30% with the presentation of magnetic field. According to their analysis, the magnetic field can reduce the surface energy of diamond, and promote the growth rate of diamond film.…”

Synthesis and crystal structure of n-diamond

“…The observed d spacings (Table 11) showed a good match with those for n-diamond. Table 11 Comparison of d spacing for n-diamond produced by CVD in high magnetic field 32 with standard data and previous CVD study, 29 …”

“…[29][30][31] It is noteworthy that the lattice constant of the high temperature c-Fe allotrope (,0 . 365 nm) 80 is close to those of diamond and n-diamond.…”

Ab initio prediction of superdense tetragonal and monoclinic polymorphs of carbon

“…It is worth noting that a new allotrope of carbon, socalled n-diamond [32][33][34][35][36][37] , exhibits a distinct diffraction peak around 50.8 o that very closed to the main peak of these new carbon polymorphs. For comparison, a typical experimental XRD spectra found in Fe-catalyzed carbon black heat treatment at 1400…”