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

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. [ABSTRACT FROM AUTHOR]