Acoustic shock wave-induced reversible phase transition (rhombohedral to hexagonal) of bismuth telluride

Bismuth telluride (Bi₂Te₃), due to its thermoelectric properties, is an interesting semiconducting material for optoelectronics and energy conversion devices; still, it has limited stability and durability. Under high pressure, we can fine-tune its performance, potentially enhancing its capabilities. The presented work uses the semi-automatic Reddy tube to explore the behavior of bismuth telluride under dynamic pressure. Commercially available bismuth telluride was purchased and subjected to different numbers of shock pulses of 100, 200, 300, and 400 with 2 MPa transient pressure and 864 K transient temperature. XRD, Raman, UV-DRS, PL, and SEM were used to characterize Bi₂Te₃ and shock-loaded Bi₂Te₃. The XRD and Raman study confirms that the Bi₂Te₃ underwent phase transition from Bi₂Te₃ to Bi₄Te₅ (rhombohedral to hexagonal) at 300 shock pulses. The optical property of Bi₂Te₃ was determined using UV-DRS and PL; the bandgap and PL intensity changed with respect to the number of shock pulses. A scanning electron microscope was used to analyze sample morphology. Our findings reveal the reversible phase transition of bismuth telluride from Bi₂Te₃ to Bi₄Te₅ under dynamic shock waves, something that has not been reported earlier. Using traditional synthesis methods, Bi₄Te₅ consume a lot of time, leading to impurities and problems of sample quality. Our results reveal that a rapid and reversible phase transition and unique response to dynamic shock waves will allow excellent technological applications without requiring lengthy and complex synthesis methods, offering enhanced stability and potential advancements in energy conversion devices. The process detailing how shock waves initiate the phase transition is explained.