Phase transition pathway by a co-operative pseudo-Jahn teller effect under microwave radiation

We will present unstable material phase retention under microwave radiation experimentally and theoretically discuss the underlying physics of the process. The intrinsic dielectric loss in a material can be explained by lifetime broadened two-phonon difference processes. At temperatures near the phase transition, this absorption can lead to disruption of long-range order between different localized Jahn teller active sites leading to order-disordered phases and phase retention in the crystal structure. In this work, we investigate the effect of microwave radiation on structural phase transitions and present the results for the case of bismuth oxide. There have been five polymorphs of Bi₂O₃ reported, including α, β, δ, γ, and ε, with α-Bi₂O₃ being the stable phase at room temperature. However, under microwave radiation, we can synthesize the metastable β phases at room temperature. The sample is characterized using X-ray diffraction, Raman spectroscopy, DSC, and UV-Vis spectroscopy to evaluate the structure and different phases in the sample. These metastable states are structurally related, and different phases can emerge depending on the temperature and intensity at which the sample is irradiated with the microwave.