Acoustic shock wave-induced phase transition from an R3c-distorted rhombohedral to an R3m-rhombohedral perovskite structure: bandgap tunability and morphological evolution of porous BiFeO3 microparticles

Abstract

Bismuth ferrite (BiFeO₃) is a semiconductor with multiferroic properties, synthesized by the sol–gel method. While static high-pressure studies have advanced our understanding of the phase behavior of BiFeO₃, the effects of dynamic pressure via acoustic shock waves remain unexplored. In this study, BiFeO₃ was subjected to 100 shock pulses with 0.59 MPa pressure, 520 K temperature, and a Mach number of 1.5 to investigate its structural, optical, and morphological responses. X-Ray diffraction (XRD) analysis revealed a shock wave-induced phase transition from the rhombohedral distortive R3c phase to the rhombohedral non-distortive R3m phase. UV-Vis diffuse reflectance spectroscopy showed a significant reduction in the band gap from 2.58 eV to 2.05 eV, indicating enhanced optical absorption, which is crucial for optoelectronic applications. Scanning electron microscopy (SEM) demonstrated a morphological evolution from densely agglomerated to porous morphology due to dynamic recrystallization, which significantly enhances catalytic and sensor applications. The combination of phase transition, bandgap tunability, and morphological changes illustrates the dynamic pressure versatility response in BiFeO₃, suggesting new avenues for its use in advanced materials and devices, including energy storage, sensors, and optoelectronics.