Synthesis and Stability of Hydrogen Storage Material Aluminum Hydride

Self-reducing precursors for aluminium metal thin films: evaluation of stable aluminium hydrides for vapor phase aluminium deposition

Thin films of Al as interconnect materials and those of AlN as wide bandgap semiconductor and piezoelectric material are of great interest for microelectronic applications. For the fabrication of these thin films via chemical vapor deposition (CVD) based routes, the available precursor library is rather limited, mostly comprising aluminium alkyls, chlorides, and few small amine-stabilized aluminium hydrides. Herein, we focused on rational precursor development for Al, their characterization and comparison to existing precursors comprising stabilized aluminium hydrides. We present and compare a series of potentially new and reported aluminium hydride precursors divided into three main groups with respect to their stabilization motive, and their systematic structural variation to evaluate the physicochemical properties. All compounds were comprehensively characterized by means of nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infrared spectroscopy (FTIR), elemental analysis (EA), electron-impact ionization mass spectrometry (EI-MS) and thermogravimetric analysis (TGA). Promising representatives were further evaluated as potential single source precursors for aluminium metal formation in proof-of-concept experiments. Structure and reaction enthalpies with NH3 or H2 as co-reactants were calculated via first principles density functional theory simulations and show the great potential as atomic layer deposition (ALD) precursors for Al and AlN thin films.

Superior Dehydrogenation Performance of α-AlH3 Catalyzed by Li3 N: Realizing 8.0 wt.% Capacity at 100 °C

The high dehydrogenation temperature of aluminum hydride (AlH₃ ) has always been an obstacle to its application as a portable hydrogen source. To solve this problem, lithium nitride is introduced into the aluminum hydride system as a catalyst to optimize the dehydrogenation drastically, which reduces the initial dehydrogenation temperature from 140.0 to 66.8 °C, and provides a stable hydrogen capacity of 8.24, 6.18, and 5.75 wt.% at 100, 90, and 80 °C within 120 min by adjusting the mass fraction of lithium nitride. Approximately 8.0 wt.% hydrogen can be released within 15 min at 100 °C for the sample of 10 wt.% doping. Moderate dehydrogenation temperature slows down the inevitable self-dehydrogenation process during the ball-milling process, and the enhanced kinetics at lower temperature shows the possibility of application in the fuel cell.

Constructing α-AlH3@polymer composites with high safety and excellent stability properties via in situ polymerization

The in situ polymerization of encapsulated α-AlH3 has promising applications in aerospace and weapon fields, and the resulting α-AlH3@PVP has potential applications in solid propellant formulations.

Anodizing of Hydrogenated Titanium and Zirconium Films

Magnetron-sputtered thin films of titanium and zirconium, with a thickness of 150 nm, were hydrogenated at atmospheric pressure and a temperature of 703 K, then anodized in boric, oxalic, and tartaric acid aqueous solutions, in potentiostatic, galvanostatic, potentiodynamic, and combined modes. A study of the thickness distribution of the elements in fully anodized hydrogenated zirconium samples, using Auger electron spectroscopy, indicates the formation of zirconia. The voltage- and current-time responses of hydrogenated titanium anodizing were investigated. In this work, fundamental possibility and some process features of anodizing hydrogenated metals were demonstrated. In the case of potentiodynamic anodizing at 0.6 M tartaric acid, the increase in titanium hydrogenation time, from 30 to 90 min, leads to a decrease in the charge of the oxidizing hydrogenated metal at an anodic voltage sweep rate of 0.2 V·s^-1. An anodic voltage sweep rate in the range of 0.05-0.5 V·s^-1, with a hydrogenation time of 60 min, increases the anodizing efficiency (charge reduction for the complete oxidation of the hydrogenated metal). The detected radical differences in the time responses and decreased efficiency of the anodic process during the anodizing of the hydrogenated thin films, compared to pure metals, are explained by the presence of hydrogen in the composition of the samples and the increased contribution of side processes, due to the possible features of the formed oxide morphologies.