Acoustic shock wave-induced superheating-assisted dynamic recrystallization – a case study of d-tartaric acid†

Abstract

Superheating-assisted melting and crystallization are prominent subjects in condensed matter physics. However, understanding the superheating concepts under acoustic shocked conditions remains a mystery. Herein, we demonstrate superheating on the basis of dynamic recrystallization in a D-tartaric acid powder sample, which nearly attains an ideal crystal structure and morphology under the 100-shocked conditions compared to the control sample and the obtained results are evaluated by conventional diffraction, spectroscopic and microscopic techniques. From the XRD results, the intensities of the planes (100) and (110) are found to have increased under the 100-shocked conditions, whereas the intensity ratio (011)/(110) has been significantly reduced. Moreover, the intensity ratio of major internal Raman modes such as v_C–O (1694 and 1700 cm⁻¹), v_C–H (2933 and 2967 cm⁻¹) and v_O–H (3331 and 3403 cm⁻¹) has been considerably modified with respect to the number of shock pulses such that the sample produces an ideal Raman spectrum of D-tartaric acid, and thereby the intensities of the lattice Raman modes also support this claim. Most importantly, the SEM results demonstrate the formation of an ideal morphology of D-tartaric acid from the irregular morphological pattern upon exposure to 100 shocks due to the superheating and dynamic recrystallization process. The proposed technique is strongly suggested for materials processing to enhance technological significance for all classes and scales of materials.