Abstract: A deactivating element for a magnetic surveillance marker has the form of a wire with substantially-circular cross-section in which alternating body segments are of a magnetizable material having a magnetic remanence of at least 0.2 Tesla and a non-magnetizable material respectively; the non-magnetizable material has a magnetic saturation of not more than 0.05 Tesla.

Abstract: A power of an alloy of Ni and Mg, La, Be or Li, consisting of crystallites having a grain size lower than 100 nm and a crystalline structure allowing hydrogen absorption. This powder which is preferably obtained by mechanical grinding, may consist of cristallites of Mg2Ni, LaNi5 or of Ni-based alloys of Be or Li having a grain size lower than 100 nm. The powder may also consist of cristallites of formula Mg2−xNi1+x, x ranging from −0.3 to +0.3, which have a grain size lower than 100 nm, and preferably lower than 30 nm. This crystalline powder is particularly useful for storing and transporting hydrogen. Indeed, it has been discovered that such Ni-based nanocrystalline powder requires no or only one single activation treatment at low temperature to absorb hydrogen. It has also been discovered that the kinetic of absorption and diffusion of hydrogen within the powder is much faster. This can be explained by the presence of a large number of grain boundaries.

Abstract: Disclosed is a method for inducing desorption of hydrogen for a metal hydride by applying thereto sufficient energy to induce hydrogen desorption by endothermic reaction. The energy that is so-applied is non-thermal and selected from the group consisting of mechanical energy, ultrasonic energy, microwave energy, electric energy, chemical energy and radiation energy.

Abstract: A powder of an alloy of Ni and Mg, La, Be or Li, consisting of crystallites having a grain size lower than 100 nm and a crystalline structure allowing hydrogen absorption. This powder which is preferably obtained by mechanical grinding, may consist of cristallites of Mg.sub.2 Ni, LaNi.sub.5 or of Ni-based alloys of Be or Li having a grain size lower than 100 nm. The powder may also consist of cristallites of formula Mg.sub.2-x Ni.sub.1+x, x ranging from -0.3 to +0.3, which have a grain size lower than 100 nm, and preferably lower than 30 nm. This crystalline powder is particularly useful for storing and transporting hydrogen. Indeed, it has been discovered that such Ni-based nanocrystalline powder requires no or only one single activation treatment at low temperature to absorb hydrogen. It has also been discovered that the kinetic of absorption and diffusion of hydrogen within the powder is much faster. This can be explained by the presence of a large number of grain boundaries.

Abstract: Disclosed is a very light-weight, Mg and Be-based material which has the ability to reversibly store hydrogen with very good kinetics. This material is of the formula (M.sub.1-x A.sub.x) D.sub.y wherein M is Mg, Be or a combination of them; A is an element selected from the group consisting of Li, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Nb, Mo, In, Sn, O, Si, B, C and F; D is a metal selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Ir and Pt (preferably Pd); x is a number ranging from 0 to 0.3; and y is a number ranging from 0 to 0.15. This material is in the form of a powder of particles of the formula M.sub.1-x A.sub.x as defined hereinabove, having an average size ranging from 0.1 to 100 .mu.m, each particle consisting of nanocrystalline grains having an average size of 3 to 100 nm or having a nano-layered structure with a layer spacing of 3 to 100 nm. Some of these particles have clusters of metal D attached thereto, with an average size ranging from 2 to 200 nm.

Abstract: Disclosed is a nanocrystalline composite useful for hydrogen storage, which provides optimum hydrogenation conditions along with high hydrogen storage capacity. This composite is the combination of at least one high temperature metal hydride such as Mg or Mg.sub.2 Ni, which has a high hydrogen storage capacity by weight but requires high temperatures for hydrogen absorption and desorption, with at least one low temperature metal hydride such as FeTi, LaNi.sub.5, Nb, Mn or Pd, which has a low hydrogen storage capacity by weight but does not require high temperatures for hydrogen absorption and desorption. The high and low temperature metal hydrides are in direct contact with each other and each in the form of a nanocrystalline powder or layer. This composite is particularly useful as a hydrogen supply source for hydrogen-fueled vehicles.

Abstract: Disclosed is a method for inducing desorption of hydrogen for a metal hydride by applying thereto sufficient energy to induce hydrogen desorption by endothermic reaction. The energy that is so-applied is non-thermal and selected from the group consisting of mechanical energy, ultrasonic energy, microwave energy, electric energy, chemical energy and radiation energy.

Abstract: A powder of an alloy of Ni and Mg, La, Be or Li, consisting of crystallites having a grain size lower than 100 nm and a crystalline structure allowing hydrogen absorption. This powder which is preferably obtained by mechanical grinding, may consist of cristallites of Mg.sub.2 Ni, LaNi.sub.5 or of Ni-based alloys of Be or Li having a grain size lower than 100 nm. The powder may also consist of cristallites of formula Mg.sub.2-x Ni.sub.1+x, x ranging from -0.3 to +0.3, which have a grain size lower than 100 nm, and preferably lower than 30 nm. This crystalline powder is particularly useful for storing and transporting hydrogen. Indeed, it has been discovered that such Ni-based nanocrystalline powder requires no or only one single activation treatment at low temperature to absorb hydrogen. It has also been discovered that the kinetic of absorption and diffusion of hydrogen within the powder is much faster. This can be explained by the presence of a large number of grain boundaries.