Discovery of eight-coordinated layered phase of SbBr3 under high pressure

Abstract

Layered trihalides have attracted significant interest due to their potential applications in optical and spintronic devices. Herein, we report a combined experimental and theoretical investigation of antimony tribromide (SbBr3) under high pressure (up to 30 GPa) using synchrotron x-ray diffraction, Raman spectroscopy, alternating current (AC) impedance measurements, and first-principles calculations. The results indicate that SbBr3 transforms from a molecular phase (space group Pbnm) to an eight-coordinated layered phase (space group P21/a) at 7.6 GPa. A partial density of states analysis reveals that the eight-coordinated layered geometry of SbBr3 is rooted in the electron transfer from the Sb p orbital to the Br p orbital. Furthermore, based on AC impedance measurements, the resistance decreases with increasing pressure due to the gradual narrowing of the bandgap of SbBr3 in the Pbnm phase. The positive resistance–pressure relationship in the P21/a phase is attributed to the low carrier mobility caused by lattice distortion. Our current findings not only provide information on the phase diagram and electronic transport of SbBr3 but also expand the realm of layered functional materials in molecular trihalides.