Nanostructured hydrides

In mechanochemical activation it would be the action of several of the aforementioned parameters, and their relative importance is often difficult to separate. There may be also other phenomena and synergetic effects too, which have not been elucidated yet. Whatever are the mechanisms, mechanochemical activation works amazingly well, and presents an attractive alternative to thermal activation. It also provides easy, top-bottom method for manufacturing nanostructured hydrides and nanocarbons. 

A primary method of mechanochemical synthesis of nanostructured hydrides (nanohydrides) is processing by mechanical (ball) milling. Processes of manufacturing of nanocrystalline/nanostructured hydrides by ball milling are shown in Fig. 1.21. 

Inclusion of the surface energy terms gives a new van t Hoff relation (3,4), showing that size reduction lowers the enthalpy of hydride formation (A// ) for the nanostructured hydride as long as is positive. As seen in Eq. (2),... 

R. Varin, Songlin Li, T. Czujko, Z. Wronski, An Overview of the Controlled Mechano-Chemical Synthesis of Nanostructured Complex Hydride Mg2FeH6,13 th International Conference on Processing and Fabrication of Advanced Materials-PFAM XIII, Singapore, December 6-8,2004. 

Fig. 1.1 A novel vision of refueling/retail station for fuel ceU-powered vehicles based on the concept of the off-board recharging of spent hydride fuel and the mechanochemical synthesis of nanostructured hydrogen storage materials in baU-miU plants. Such is not the currently accepted vision of hydrogen economy but one which may turn out to be viable alternative to onboard...

R.A. Varin, S. Li, Z. Wronski, O. Morozova, T. Khomenko, The effect and sequential and continuous high energy impact mode on the mechano-chemical synthesis of nanostructured complex hydride Mg FeH, J. Alloys Compd. 390 (2005) 282-296. 

V. Berube, G. Radtke, M. Dresselhaus, G. Chen, Size effects on the hydrogen storage properties of nanostructured metal hydrides a review, Int. J. Energy Res. 31(6-7) (2007) 637-663. 

Z.S. Wronski, Electrochemical storage of hydrogen in nanostructured solid-state hydrides and nanocarbons, International Conference on Processing and Fabrication of Advanced Materials- PFAM XII, Singapore (2004). Stallion Press, Singapore-London, pp. 275-287. 

R.A. Vatin, Ch. Chiu, T. Czujko, Z. Wronski, Feasibilty study of the direct mechano-chemical synthesis of nanostructured magnesium tetrahydroaluminate (alanate) [Mg(AIH )J complex hydride, Nanotechnology 16 (2005) 2261-2274. 

As discussed in Sect. 1.3, the major objective of mechanical (ball) milling is to obtain a substantial nanostructuring of hydrides (nanohydrides), which in effect can... 

In essence, metal/intermetallic hydrides of AB, AB (Laves phases), AB, and A B have not been improved to any remarkable extent since the end of the 1990s. Nevertheless, there have been some efforts directed to either improvement of synthesis or properties of metal/intermetallic hydrides particularly by application of ball milling associated with nanostructuring. Some of these more recent efforts will be briefly discussed in the following sections. 

H. Fujii, S. Orimo, K. Ikeda, Cooperative hydriding properties in a nanostructured Mg Ni-H... 

S. Orimo, H. Fujii, K. Ikeda, Notable hydriding properties of a nanostructured composite material of the Mg Ni-H system synthesized by reactive mechanical grinding, Acta mater. 45 (1997) 331-341. 

X. Liu, Y. Zhu, L. Li, Hydriding and dehydriding properties of nanostructured Mg Ni aUoy prepared by the process of hydriding combustion synthesis and subsequent mechanical grinding , /. Alloys Compd 425 (2006) 235-238. 

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