Tetragonal polymerized phase ofC60

Abstract

Experimental evidence of the existence of the polymerized tetragonal ͑T͒ phase of C 60 as a stable highpressure one is presented. Using different p,T paths of high-pressure-high-temperature treatment, phase T was obtained as a product of phase conversions of a monomeric fcc and two polymerized phases of C 60 ͑including a rhombohedral one͒ at 2.2 GPa and 873 K. The dramatic differences in the rates of phase-T formation from monomeric and polymerized states of the system testified to the difference in the mechanisms of phase-T formation. The x-ray-diffraction pattern, IR, and Raman spectra of the almost pure phase T are presented.

Far-infrared vibrational properties of high-pressure high-temperatureC60polymers and theC60Long1, Musfeldt2, Kamarás3 et al. 2000Phys. Rev. B292330View full textAdd to dashboardCite

“…26,28,[30][31][32] Such treatments usually have focused on the Raman spectra, for which calculated mode strengths are more reliable, 28,33 and which exhibit lowfrequency features characteristic of intermolecular vibrations. 3,14,15,34,35 In this paper, we report far-infrared ͑FIR͒ vibrational properties of the 2ϩ2 cycloaddition dimer, and the 1D orthorhombic and 2D rhombohedral HPHT C 60 polymers whose structures are shown in Fig. 1.…”

“…18 In the linked fullerene structures, symmetry reduction of the ball yields spectra of increasing complexity, partly manifest in splitting of modes derived from the degenerate T 1u and H g vibrations of I h C 60 . 3,4,14,16,[22][23][24][25][26] Mode splittings of the rhombohedral HPHT polymer and linear chain RbC 60 were initially treated by group theory analysis, based on a weak perturbation assumption. 24 Later work found, however, that the weak perturbation picture is inadequate to explain certain widely split or shifted modes in the HPHT polymers and dimer.…”

Low Band Gap and Ionic Bonding with Charge Transfer Threshold in the Polymeric Lithium Fulleride Li4C60

“…Undoped C 60 polymerizes either into a rhombohedral phase, characterized by hexagonal networks of molecules linked via [2 + 2]cycloaddition bonds which are coplanar with the hexagonal planes, or into a tetragonal phase, in which half the [2 + 2]cycloaddition bonds are coplanar with the networks while the others are orthogonal to them. 9,15 In Mg fullerides, the formation of a rhombohedral phase is reported, 16 while the 2D polymer phase of Na 4 C 60 consists of planar rectangular networks where each molecule forms four single bonds within the plane. 10 The rectangular polymer networks in Li-doped C 60 were initially thought to consist of [2 + 2]-cycloaddition bonds.…”

Far-infrared vibrational properties of tetragonalC60polymer

“…Recently, the R polymer was reported to display ferromagnetism at 300 K. 12 Among the O, T, and R polymers, the T polymer is the most difficult to prepare and isolate. 8,9 Therefore, the material is relatively unexplored experimentally, and infrared ͑IR͒ studies on the pure T-polymer phase are rare. 10 The vibrational spectrum of isolated C 60 shows four sharp IR peaks of T 1u origin, as expected for a cage with icosahedral symmetry.…”