Complex hydrides composition

The progress of hydrogen storage and its container materials were reviewed. AB2 nanocrystalline alloy, Ti-NaAlH4 complex hydride and Mg/MWNTs composite are promising hydrogen storage materials. 

The Li-Mg-B-N-H structure possesses storage capacity of more than 10 wt.% at around 150-200 "C. However, the reversibility of the hydrogen sorption characteristics was determined using pressure-composition isotherms as shown in Figure 6. From this study, we found reversible hydrogen absorption-desorption behavior (-3-4 wt.%) of the new complex hydride Li-Mg-B-N-H. The improvement in temperature and reversible hydrogen storage capacity were unaffected even after ten... 

We haved attempted carrying out similar coupling reactions using other olefine complexes. Reduction of MC14 (PMe3)3(M=Mo,W) with Na-Hg, under propylene, give yellow complexes of composition M(C3 H6) (PMe3)4. The appearance of an IR ab sorry---r "-------g—A" "" 1700 cm 1 and of a hydride... 

In the steroid field, a comparison of product ratios with those resulting from reductions with alkali metals reveals both similarities and differences, which led Dauben and co-workers [i] to postulate in 1956 that the observed stereochemical composition of products is a consequence of the interplay of two opposed factors. So successful was Dauben s treatment that it provided a virtually complete qualitative explanation of the relative proportions of axial and equatorial alcohols from reduction of each of the common steroid ketones. Dau-ben s approach developed from Barton s recognition in 1953 [46] that sterically unhindered ketones are reduced by complex hydrides as well as by metal/alcohol systems to give... 

Gold(III) also forms complex hydrides with LiAlH and LiBH, stable only at low T. Analyses of the precipitated solids lead to such compositions as Al Au Hj, of unknown structure. ... 

Various high conductivity materials have been alloyed with metal hydrides to form enhanced heat transport composite materials. Eaton et al. [31] experimented with various alloyed metal additives including copper, aluminum, lead, and lead-tin. The samples were alloyed at elevated temperature (200-600 °C) and cycled. In many samples, cycling resulted in the separation and fracture of the alloy and thus a reduction in composite thermal conductivity. Sintered aluminum structures of 20% solid fraction have been integrated with LaNis hydride materials with success, resulting in effective thermal conductivities of 10-33 W/mK [32-34]. Temperatures required for this process and added mass and volume may exclude application to some complex hydrides. 

Barkhordarian, G., Klassen, T., Domheim, M. and Bormann, R. (2007) Unexpected kinetic effect of MgB2 in reactive hydride composites containing complex borohydrides. Journal of Alloys and Compounds, 440, L18-L21. 

The complex hydrides composed of iVT+ and (BH4) are "Borohydride." The borohydrides are quite attractive for hydrogen storage materials because of their extremely high hydrogen capacities due to high hydrogen composition in the anion as shown in Table 5.6,... 

There are few systematic guidelines which can be used to predict the properties of AB2 metal hydride electrodes. Alloy formulation is primarily an empirical process where the composition is designed to provide a bulk hydride-forming phase (or phases) which form, in situ, a corrosion— resistance surface of semipassivating oxide (hydroxide) layers. Lattice expansion is usually reduced relative to the ABS hydrides because of a lower VH. Pressure-composition isotherms of complex AB2 electrode materials indicate nonideal behaviour. 

---