The configurations of TMT with respect to ideally tetrahedral T d (−43m) symmetry. (a) Cup model of TMT shown to illustrate almost spherically shaped molecules in a close-packed stacking, and (b) ball-and-stick model of TMGe manifested that one bond distance C–H, one Sn–C, one Sn–C–H/C–Sn–C angle could describe the molecular geometry.
Representative Raman spectra of TMT in the full spectral regions at ambient conditions upon compression to 49.9 GPa. The blue arrows labeled are to make the change of part Raman modes clear to observe. The value of pressure is labeled only on red spectra to exhibit clearly the possible phase transitions.
Pressure dependence of the frequencies of TMT for the observed modes in all regions at room temperature. The vertical dashed lines at near 0.9, 2.8, 10.4, 20.4, and 32.6 GPa indicate the proposed phase boundaries.
Synchrotron radiation x-ray (λ = 0.3986 Å) diffraction patterns of TMT during the pressurization from ambient conditions to 38.2 GPa.
X-ray powder diffraction patterns of liquid TMT at pressures of (a) 1.8, (b) 6.2, and (c) 12.5 GPa, respectively. The refined lattice parameters for the corresponding space groups are given, respectively. The open circles represent the measured intensities and the red lines the results of profile refinements by the best LeBail-fit with each space group. The positions of the Bragg reflections are marked by vertical lines and the difference profiles are shown at the bottoms (blue lines). The R values are R p = 0.4%, R wp = 0.7% for the fitting at 1.8 GPa, R p = 0.2%, R wp = 0.3% at 6.2 GPa, and R p = 0.3%, R wp = 0.4% at 12.5 GPa.
Electronic band structure (a) and projected density of states (b) of the P2/m TMT at 12.5 GPa. The dashed lines represent the Fermi levels.
Volume per formula unit change of TMT with pressure. The solid lines demonstrate the fitting data of phase to the Birch-Murnaghan equation of state.
Assignment of the observed Raman modes of TMT, changes of Raman modes with pressures, and the pressure coefficients of the corresponding frequencies of the Raman modes.
Calculated lattice parameters and atomic coordinates of the experimentally obtained phases with the space groups of Pmmm, P4/mmm, and P2/m at pressures of 1.8, 3.2, and 12.5 GPa, respectively.
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