Switchable Phase Transformation (Orthorhombic–Hexagonal) of Potassium Sulfate Single Crystal at Ambient Temperature by Shock Waves
A. Sivakumar, S. Reena Devi, S. Sahaya Jude Dhas, S. Sahaya Jude Dhas, R. Mohan Kumar, K. Kamala Bharathi, S. A. Martin Britto Dhas, S. A. Martin Britto Dhas
Abstract
In this research article, the shock wave induced switchable phase transition (β to α and α to β) of potassium sulfate (K2SO4) crystal is demonstrated. The test crystals are subjected to shock waves of one pulse and two pulses, respectively, and their crystallographic properties are compared with the control test sample. Fourier transform Raman spectroscopy (FT-Raman), ultraviolet–visible spectroscopy (UV–vis), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and dielectric studies are performed to understand the reversible phase transformation of potassium sulfate crystal enabled by the impact of shock waves. The bulk grain resistance (Rg) and capacitance Cg values of control K2SO4 crystal, post first shock, and second shock at room temperature are observed to be 88 MΩ, 92 MΩ, and 88 MΩ and 84 pF, 23 pF, and 84 pF, respectively. The dielectric relaxation time (τg) reveals the fact that the phase reversal occurs after the second shock. The values of τg for control K2SO4 crystal, post first shock, and second shock are calculated to be 7.39, 2.10, and 7.39 ms, respectively. The crystallographic and analytical studies reveal that the sample β-K2SO4 is transformed to α-K2SO4 during the first shock pulse loaded condition, and it comes back to the phase of β-K2SO4 as and when loaded with the second shock pulse.