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This study employed the reactive force field molecular dynamics to capture atomic-level heat and mass transfer and reaction processes of an aluminum nanoparticle (ANP) oxidizing in a high temperature and pressure oxygen atmosphere, revealing detailed mechanisms for oxidation of ANPs. Temporal variations of temperature, density, mean square displacement, atom consumption rate and heat release rate of ANP have been systematically examined. In addition, the effects of environment on ANP oxidation were also evaluated. The results show that ANP undergoes four stages of preheating, melting, fast Al core and moderate shell oxidations during the whole oxidation process. The Al core starts to melt from core-shell interface with outward diffusion of core Al atoms into the shell. Intense reaction occurs between shell O and core Al atoms around interface at the end of melting, leading to fast Al core oxidation. After complete oxidation of Al core, the oxide shell continues to react with ambient O atoms. Both the initial environmental temperature and the equivalent pressure significantly influence the preheating. Oppositely, the melting stage seems almost independent any of them. While the fast Al core oxidation presents more sensitivity to the ambient equivalent pressure.

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An active oxygen species in molten carbonate is the key to elucidate the complex mechanism of the cathode reaction in MCFC. However, under acidic condition of MCFC operation (P CO 2 > 1.01 × 10 4 Pa), the exact chemical state of the active oxygen species remains unclear and is a subject of continuous debates. In this work, we present the first experimental observation of peroxocarbonate/peroxodicarbonate species in acidic molten carbonate by using in-situ Raman spectroscopic technique. The results indicate that the predominant oxygen species (O 2 2-) in basic lithium-rich melts became unstable with the increase of acidity level in the melts and reacted with CO 2 to produce peroxocarbonate or peroxodicarbonate anion. In combination with the result of theoretical calculation, it is deduced that the peroxodicarbonate mechanism is the dominant feature in the cathode reaction path in MCFC.

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Infrared thermometry and interferential microscopy for analysis of crater formation at the surface of fused silica under CO2 laser irradiation J. Appl. Phys. 111, 063106 (2012) The interaction of 193-nm excimer laser irradiation with single-crystal zinc oxide: Positive ion emission J. Appl. Phys. 111, 063101 (2012) Laser produced streams of Ge ions accelerated and optimized in the electric fields for implantation into SiO2 substrates Rev. Sci. Instrum. 83, 02B305 (2012) Formation of metallic colloids in CaF2 by intense ultraviolet light Appl. Phys. Lett. 99, 261909 (2011) Study on characteristic parameters influencing laser-induced damage threshold of KH2PO4 crystal surface machined by single point diamond turning J. Appl. Phys. 110, 113103 (2011) Additional information on J. Appl. Phys. The shock pressure generated by the glass confined regime in laser shock peening and its attenuation in the target material are investigated. First, the particle velocity of the target back free surface induced by laser generated shock pressure of this regime is measured using a photonic Doppler velocimetry system. The temporal profile of the particle velocity at the back free surface, where the elastic precursor is captured, manifests a powerful diagnostic capability of this newly developed photonic Doppler velocimetry system for tracking the velocity on short time scales in shock-wave experiments. Second, a coupling pressure analytical model, in which the material constitutive models of confined layers and target material are considered, is proposed to predict the plasma pressure profile at the surface of target. Furthermore, using the predicted shock pressure profile as the input condition, the dynamic response of the target under the shock pressure is simulated by LS-DYNA. The simulated back free surface velocity profile agrees well with that measured by the photonic Doppler velocimetry system. Finally, the attenuation behavior of stress waves and particle velocities in the depth of the target is analyzed, and it indicates an exponential decay. The corresponding empirical formulas for the attenuation behavior are given based on the numerical results.