The crystal structure of Bi2Te3 with space group R-3 m.
The Hall coefficients as function of pressure at 30 K up to 6.8 GPa. The carrier type of p-type Bi2Te3 does not change until 6.8 GPa.
The resistance of Bi2Te3 single crystal as function of temperature at various pressures showing superconductivity at phase I (a); HP I (II) (b); HPIII (c).
The superconducting transition of Bi2Te3 with applied magnetic field H perpendicular to the ab-plane of single crystal at 9 GPa (a) and 30 GPa (b). Insets show the change of Tc with H, the upper critical fields Hc2(0) are extrapolated to be 4.2 T and 2.1 T, respectively, using the Werthdamer-Helfand-Hohenberg formula.
(a) The evolution of x-ray diffraction reflections with pressure at phase I. No new reflection emerges lower than 8 GPa; (b) The red (8.6 GPa), green (14.3 GPa), and blue (14.3 GPa) arrows indicate new reflections of HP I, HP II, and HP III, respectively, induced by pressure; (c) The evolution of x-ray diffraction reflections with pressure at HP III, which has BCC structure with Im-3 m space group. A charge transfer from Bi to Te leads to the random distribution of Bi and Te atoms on the BCC sites.
The crystal structure phase diagram of Bi2Te3: the phase I from 0 to 8 GPa has a rhombohedral R-3 m structure; the HP I (8∼16 GPa), HP II (13∼16 GPa), and HP III (>16 GPa) have monoclinic sevenfold C2/m structure, eightfold C2/c structure, and BCC Im-3 m structure, respectively.
(a) The resistance of Bi as function of temperature at various pressures showing superconductivity above 3.5 GPa; (b) the resistance of Te as function of temperature at various pressures showing superconductivity above 26 GPa; (c) the comparison of superconductivity of Bi2Te3, Bi, and Te with the error bars marked.
The superconducting phase diagram of Bi2Te3 single crystal as function of pressure. The symbols represent experimental data; the color area belongs to the range of superconducting phases. The blue part (3-8 GPa) is related to the TSC range with phase I structure.
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