Stabilization of 9/10-Fold Structure in Bismuth Selenide at High Pressures

Abstract

We report joint theoretical and experimental research on the high-pressure structures of bismuth selenide (Bi2Se3) up to 50 GPa. Our first-principles structure prediction via calypso methodology meets our high-pressure X-ray diffraction experiments performed in diamond anvil cell. We established that the ambient-pressure rhombohedral phase transforms to a monoclinic C2/m structure at 9.8 GPa, and then to a monoclinic C2/c structure at 12.4 GPa. Above 22.1 GPa, we were able to identify that Bi2Se3 develops into a novel 9/10-fold structure, which was not taken by its other family members Bi2Te3 and Sb2Te3. The large differences in atomic core and electronegativity of Bi and Se are suggested to be the physical origin of the stabilization of this 9/10-fold structure. Our research work allows us to reveal a rich chemistry of Bi in the formation of 6, 7, 8, and 9/10-fold covalent bond with Se at elevated pressures.

Structural phase transitions in Bi2Se3 under high pressure

“…The high-pressure phase of Bi 2 Se 3 transformed from the C 2/ m phase has three debating candidates, which are Im -3 m 14, C 2/ m (CN = 9/10)15 and I 4/ mmm 16. To clarify the polymorphism in Bi 2 Se 3 , we further enumerate the experimental XRD data around 30 GPa from this work and calculated XRD results with the three candidate space groups reported in the literatures (Fig.…”

“…The unit cell volume for R -3 m phase obtained from this work matches the literature results in refs 14 and 16 well, but exhibits smaller volume than that in ref. 15 at the same pressure. This contradiction may be due to the different preparation techniques used to synthesize the samples.…”

“…The Raman modes of Bi 2 Se 3 were inactive over 27.8 GPa suggesting that Bi 2 Se 3 crystallized into a disordered body-centered cubic (BCC) ( Im -3 m ) structure above that pressure. Concurrently, high pressure XRD studies on Bi 2 Se 3 have also been performed by other research groups15−17. However, the assignments of the high-pressure phase for Bi 2 Se 3 are controversial from different literatures as shown in Fig.…”

High-Pressure Studies of Bi2S3

“…5,12,44 In particular, the heaviest member of this series, i.e., Bi 2 Te 3 undergoes three structural transitions up to 52 GPa. 5,10,11 In particular, the starting R3̅ m phase transforms into a monoclinic structure (C2/m, Z = 4) with 7-fold cationic coordination above 8 GPa.…”

Pressure-Stabilized Tin Selenide Phase with an Unexpected Stoichiometry and a Predicted Superconducting State at Low Temperatures

“…On the other hand, due to the increasing Se atomic percentage, the number of electrons which each Se atom accepts decreases. The electron transfers given by Bader charge analysis are significantly smaller than the standard oxidation numbers, which may be related to the mixed ionic and covalent bond characters as discussed in SnSe [47], Pb 1−x Sn x Se [48] and the V-VI compounds [49].…”