Analysis of the Stabilizing Interactions and Thermodynamic Studies in Aluminum-Transition Metal Alloys (Ti, Sc, Mn, Fe) Using Solid-State Electron Density
James Tembei Titah,
Coulibaly Wacothon Karime,
Josh McLoud
Issue:
Volume 9, Issue 1, June 2021
Pages:
1-6
Received:
9 February 2021
Accepted:
23 February 2021
Published:
3 March 2021
Abstract: The solid-state structures of Aluminum-Transition Metal (Al3TM) Alloys (TM = Ti, Sc, Mn, Fe), have been explored in detail using computational electron density methods. Topological analysis of the electron density in Al3Ti alloys revealed two interesting types of interactions between the atoms in the layered Al3Ti alloy structure lattice; viz. Al-Al and Al-Ti interactions. Two types of both Al-Al interactions and Al-Ti interactions were observed between the atoms in the same plane (2.725 Å apart), and those on adjacent planes or layers (2.884 Å apart). All interactions in the same plane of the Al3Ti alloy are stronger than those on adjacent planes, owing to the high values of the electron density and the bond distances between the interacting atoms (Table 1). The Laplacian of the electron density in a plane of the alloy indicates that Ti atoms are polarized towards the Al-atoms thereby transferring most of their valence electron density to Al (Figure 2b). Similar interactions were observed in Al3Sc alloy but these interactions were weaker than those in Al3Ti alloy. This signifies that Ti and Al atoms in the alloy are interchangeable or completely miscible, and indicates an increased stability of the alloy compared to Al3Sc alloy. In addition, analysis of Al3Mn and Al3Fe alloys indicate that these alloys were more stable compared to Al3Ti and Al3Sc alloys. Furthermore, the thermodynamic studies of Al3TM alloys (TM = Ti, Sc, Mn, Fe) were investigated. The results confirm the conclusion that Al3Ti and other Al-based transition metal alloys play little or no active role in the reversible re/dehydrogenation of Ti-doped NaAlH4. These alloys are thermodynamically stable.
Abstract: The solid-state structures of Aluminum-Transition Metal (Al3TM) Alloys (TM = Ti, Sc, Mn, Fe), have been explored in detail using computational electron density methods. Topological analysis of the electron density in Al3Ti alloys revealed two interesting types of interactions between the atoms in the layered Al3Ti alloy structure lattice; viz. Al-A...
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The Motion of Ions Confined in a Molecular Channel
David Antony Morton-Blake
Issue:
Volume 9, Issue 1, June 2021
Pages:
7-18
Received:
10 December 2020
Accepted:
18 December 2020
Published:
14 May 2021
Abstract: In order to understand the features governing the motion of ions in a molecular environment the migrational features of Na+ and Cl− ions in a molecular channel composed of stacked crown ether 6-CE-18 rings is followed using molecular dynamics, which shows that Na+ is subject to a much greater dynamic hindrance than the Cl− ion. The effects of the fluctuating electric fields of the atomic constituents in the channel on the motion of the migrants are investigated by clamping them so as to remove the fluctuations. The dynamic system is simulated both in vacuo and in water. For both it is found that the fluctuating electric fields of the channel and water atoms play a significantly greater role in the ion motions than do fluctuations in the ‘non-bonded’ interactions. The effect of temperature on the dynamics is investigated. Oscillatory trajectories are followed via the force and the potential energy profiles of the system over the timestep range of the molecular dynamics.
Abstract: In order to understand the features governing the motion of ions in a molecular environment the migrational features of Na+ and Cl− ions in a molecular channel composed of stacked crown ether 6-CE-18 rings is followed using molecular dynamics, which shows that Na+ is subject to a much greater dynamic hindrance than the Cl− ion. The effects of the f...
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