A new phase transition in the T-P diagram of C₆₀fullerite

Abstract

The earlier high-pressure stndy of Cw concenmted on the orientational transition and mom-temperature transformations observed in diamond anvils. This work presents a parl of the T-P phase diagram for solid Cw at pressures up to 20 kbar in the temperahlre range extended to 700 K. A new phase region is outlined herein. The new phase is retained to ambient conditions and preliminarily characterized. The new phase is more dense than the initial Cm by al least 8.5% and less compressible by -1.5 times. Its crystal svucmre is very different from the well known face-centred cubic and simple cubic phases, and its recovely to a cubic phase is associated with an endothermal heat effect of -23 I g-', The nature and the lhemcdynamic stability of the new phase are discussed in connection with polymerization of & molecules, which seem likely.

Uniformly dimerized C60 film prepared by deposition under in situ photoirradiation

“…The fcc structure contracted by 3.7% and its recovery after annealing at 543 K has been reported for an HPHT-treated C60 material ͑5 GPa at 573 K͒, 4 and similar lattice changes have been reported for an HPHT-treated C60 crystal ͑2 GPa at 700 K͒. 24 The small peak shifts from the perfect fcc position by dimerization are attributed to the distorted fcc structure observed for C60 subjected to HPHT treatment at 1.5 GPa and 423 K. 25 Figures 3͑a͒-3͑c͒ show the Raman spectra obtained for a 480-nm-thick in situ irrad. C60 film, the same film after annealing at 523 K for 48 h, and a pristine C60 film, respectively.…”

Crystalline structure and properties of diamond-like materials

“…• C, some atoms of fullerite initially consisting only of tri-coordinated carbon atoms begin transforming to the tetra-coordinated state [10]. This gives rise to inter-fullerene covalent bonds and initiates formation of a hybrid structure consisting of tri-and tetracoordinated atoms.…”

Structure and Electronic Properties of the Hybrid Carbon Phase Formed by Polymerization of Bundles of Nanotubes (6,0)

“…Возможно существование четырех структурных классов гибридных углеродных фаз - углеродных материалов синтезирован экспериментально воздействием на фуллереновые конденсаты высокими давлениями [5][6][7][8]. Теоретически предсказана возможность существования еще большего разнообразия графитоалмазных гибридных фаз и наноструктур [9][10][11][12][13][14][15].…”