Structure and adsorption abilities of nanoporous Ti,V-(N, He) coatings.

Alexsey Guglya 1Aleksander Goncharov 1Victor Kolobrodov 1Ruslan Vasilenko 1Yuriy Nikitenko 2

1. Kharkov Institute of Physics and Technology (KIPT), Akademiskaja 1, Kharkov 61108, Ukraine
2. Joint Institute of Nuclear Research, Dubna, Russian Federation

Abstract

The basic idea of this work is to create nanocrystalline composite materials with high level of porosity and good adsorption properties. It was investigated structure and adsorption characteristics Ti,V-(N, He) coatings  deposited onto Ti substrate using the ion-beam assisted deposition technology. The results of the research show that the ion beam assisted deposition can be used to obtain nanoporous structures. It was shown that Ti and V deposition during high energy N2 and He ions bombardment leads to nanocrystalline fcc structures formation with equiaxed and fine-dispersed pores. The average size of grains in V-(N2, He) and Ti-(N2, He) coatings is equal 20 nm, porous – 15 nm. Beside equiaxed pores there are many long, presumably gas-vacancy, 100-200 nm length formations. These formations create the system of inner cannels in coatings. The average size of grains in Ti,V-(N2, He) coatings is equal
60 nm. Only equiaxed pores are present. The electric resistance of such materials exceeds that of powder vanadium nitrides by factor of 10. A sign of the temperature coefficient of resistance changes from a negative to the positive one in the temperature range of 250 to 350°C.

The results of adsorption studies showed that the obtained structures have a rather developed inner specific surface: Ti-(N2, He) – 20.3 m2/g, V-(N2, He) – 38.3 m2/g,  Ti,V-(N2, He) - 69 m2/g. From studying of isotherm of adsorption it has been established that the main contribution to the process of hydrogen storage at low temperatures is made by the created porous structure. For all coatings took place the increasing of hydrogen adsorption from the pressure ~ 0.15 MPa.  The largest specific quantity hydrogen was adsorbed by Ti,V – (N2, He) structure - ~ 350 cm2/g. At elevated temperatures the absorption capacity of the intermetallide and nitride phases may increase.

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Presentation: Invited oral at E-MRS Fall Meeting 2009, Symposium I, by Alexsey Guglya
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-08 09:32
Revised:   2009-06-07 00:48
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