The phase transition of Co3O4 into CoO is demonstrated by the impact of shock waves and the mechanism is studied and reported. The required quantity of Co3O4 nanoparticle (NPs) is synthesized by co...

Shock Wave Driven Solid State Phase Transformation of Co3O4 to CoO Nanoparticles

The present work is designed to investigate the impact of shock waves on Zinc Ferrite nanoparticles (ZnFe2O4) NPs. The test material was prepared by precipitation method and shock wave recovery experiment is done by tabletop pressure driven shock tube. The shock wave induced changes in structural, morphological and magnetic properties are noticed by various analytical techniques such as powder X-ray Diffractometer (PXRD), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) and the obtained PXRD results shows no significant structural changes. Switchable paramagnetic to superparamagnetic behaviour is observed during the shock wave loaded conditions. The mechanism of shock wave induced magnetic phase transition is discussed.

Shock wave-induced switchable magnetic phase transition behaviour of ZnFe2O4 ferrite nanoparticles

Silver oxide nanoparticles (AgO NPs) were synthesized by implementing chemical reduction process and two different samples of AgO NPs were loaded with 100 as well as 200 pulses of successive shock waves of Mach number 2.2 so as to investigate the aftermath effect. Various characteristic analytical techniques were carried out for the samples utilizing Powder X-ray diffractometer (PXRD), Ultra-Violet diffuse reflectance spectroscope (UV-DRS), Field emission scanning electron microscope (FE-SEM) and Vibrating sample magnetometer (VSM) to find stabilities of crystallographic, spectroscopic, morphological and magnetic behaviors and also to analyze the changes occurring on the properties of the test material due to the impulsion of shock waves. From the obtained XRD patterns, the mean value of grain sizes of unshocked, 100 and 200 shocked AgO NPs is found to be 20, 20.6 and 26 nm, respectively. FE-SEM images reveal that the mean values of particle sizes increase as the counting of shock pulses are increased. The particles sizes are computed to be 72 nm, 112 nm, and 162 nm for the unshocked, 100 and 200 shocked AgO NPs, respectively. Whereas, the values of magnetization of AgO NPs have reduced with regard to the number of shock waves in such a way that the value of 2.183 emu/g for the unshocked AgO NPs is found to have reduced to 1.801 and 1.416 emu/g for 100 and 200 shocks, receptively. The band gap energy of the unshocked and shocked AgO NPs is observed to have the same value of 2.1 eV. From the experiential results, it is very well established that the title material’s properties such as crystalline and molecular structure, band gap energy are stable; whereas, the magnetic properties and surface morphology undergo subtle changes at shocked conditions.

Structural, optical and magnetic properties of silver oxide (AgO) nanoparticles at shocked conditions

Fe2O3 nanoparticles were synthesised by sol-gelmethod and loadedwith shock pulses of 50, 100 and 150 havingMach number 2.2. To explore the effect of shockwaves on hematite-α—Fe2O3 nanoparticles, the treated and untreated nano particles were analyzed by studying various properties such as structural,molecular,morphological andmagnetic behaviourwhichwere observed through the analytical techniques such as powder XRD, FTIR, SEMandVSM, respectively. The observed results obviously demonstrate that the synthesisedα—Fe2O3 nanoparticles portray their degree of crystalline nature and structure related properties which are strongly altered by the impact of shock waves.

Shock wave recovery studies on structural and magnetic properties of α—Fe2O3 NPs

The physical properties of potassium dihydrogen phosphate powder samples have been investigated before and after shock loading. The optical transmittance and bandgap energy were derived by ultraviolet (UV) diffuse reflectance spectroscopy (DRS). The molecular and structural stability of the test crystal after shock loading were confirmed. Test crystals were exposed to 50 and 100 controlled shock pulses with corresponding Mach number of 2.2 then probed by Fourier-transform infrared (FTIR) spectroscopy and powder x-ray diffraction analysis. FTIR spectra showed no considerable changes in the molecular bands of the crystal after shock loading. XRD analysis illustrated the appearance of a few secondary peaks after 50 and 100 shock pulses but retaining the original crystal phase, which may be due to orientation defects and microdistortions of the crystal caused by the impact of shock waves.

Impact of Shock Waves on Molecular and Structural Response of Potassium Dihydrogen Phosphate Crystal

Shock wave recovery experiment on crystalline materials is a hot research topic for aerospace applications. In this research article, authors present and demonstrate the stability of physical properties of ZnO nano rods (ZnO NRs) under shock wave loaded conditions. The test sample is synthesized by hydrothermal method and the shock waves were generated using a table top semi automatic pressure driven shock tube. A shock wave of 2.2 Mach number which has a transient pressure of 2.0 MPa and temperature 864 K was made to strike four test samples for the counts of 50,100,150 and 200, respectively. The shock loaded samples were subjected to XRD and optical analysis so as to understand the influence of shock waves in the structural and optical properties. The results show that ZnO NRs have magnificent molecular, optical, structural and morphological stability for 50,100 and 150 shocks. Though, when the number of shock pulses was increased to 200 and a blue shift was observed in UV-vis spectrum, no changes in structural properties took place which was evidenced from XRD. From this shock wave recovery experiment, it is clear that ZnO NRs are highly stable against shock waves and hence this material is suggested for the aerospace and military applications.

https://iopscience.iop.org/article/10.1088/2053-1591/aafae6/pdf

M Muralidhr Nayak

Papers

Structural, optical, and morphological stability of ZnO nano rods under shock wave loading conditions