Acoustic Shock Wave-Induced Amorphous to Crystalline Phase Transitions of Li2SO4─Raman Spectroscopic and Thermal Calorimetric Approach

In this context, we have reexamined the acoustical shock wave-induced amorphous-glassy-crystalline-amorphous phase transitions in the Li₂SO₄ sample under 0, 1, 2, and 3 shocked conditions by implementing the detailed Raman spectroscopic approach. The recorded Raman spectroscopic data clearly reveal that the transition from the amorphous-glassy-crystalline state occurs because of a significant reduction of the translational disorder of lithium cations, particularly [Li (2)] ions wherein a slight reduction of the librational disorder of SO₄ anions takes place, whereas the crystalline to amorphous transition occurs only at the third shocked condition because of the librational disorder of SO₄ anions. The double degenerate υ₂ and υ₄ Raman modes provide a clear indication of the occurrence of the librational disorder of SO₄ anions at the third shocked condition. Followed by the internal Raman modes, a detailed discussion is provided on the external Raman modes of the Li ions and SO₄ ions with respect to the observed phase transitions, wherein it is found that the regions of lattice modes are significantly altered at each and every point of phase transition. Furthermore, the thermal and magnetic measurements have been performed for the above-mentioned state of Li₂SO₄ samples, whereby the obtained results of the magnetic loops and the thermal property resemble the observed structural transitions with respect to the number of shock pulses such that the inter-relationship of the structure-electrical-magnetic-thermal properties of Li₂SO₄ could be explored.