We report the properties of a new class of high-performance permanent magnets prepared from Nd-Fe-B and Pr-Fe-B alloys. Magnetic hardening is achieved by rapid solidification. Energy products of these isotropic materials can exceed 14 MGOe with intrinsic coercivities of ∼15 kOe. X-ray and microstructural analyses indicate that the alloys exhibiting optimum characteristics are comprised of roughly spherical crystallites, strongly suggesting that the coercivity mechanism is of the single-domain particle type. The crystallites are composed of an equilibrium R-Fe-B intermetallic phase having tetragonal symmetry, and the stability of this phase with respect to other rare earths and other metalloids has been investigated.

Mobile applications of hydrogen power have long demanded new solid hydride materials with large hydrogen storage capacities. We report synthesis of a new quaternary hydride having the approximate composition Li(3)BN(2)H(8) with 11.9 wt % theoretical hydrogen capacity. It forms by reacting LiNH(2) and LiBH(4) powders in a 2:1 molar ratio either by ball milling or by heating the mixed powders above 95 degrees C. This new quaternary hydride melts at approximately 190 degrees C and releases > or =10 wt % hydrogen above approximately 250 degrees C. A small amount of ammonia (2-3 mol % of the generated gas) is released simultaneously. Preliminary calorimetric measurements suggest that hydrogen release is exothermic and, hence, not easily reversible.

Supporting information Sample preparation and measurement details:Samples for volumetric measurements were prepared in the dehydrogenated state, i.e., the right-hand side of reaction (3a). Mixed powders having the composition LiH + ½ MgB 2 + 0.03 TiCl 3 were ball milled for one hour in a Fritsch P6 planetary mill to homogenize the mixture and reduce the particle size; x-ray diffraction (XRD) confirmed that the powders did not react during milling. Samples of the milled powder were hydrogenated in a Sieverts apparatus by heating to 300 °C at 2 °C/min in a sealed

Determination of the crystal structure of Nd2Fe14B, a new ternary phase, is reported. It has recently been demonstrated that permanent magnets having large co ercivities and energy products can be formed from this phase, underscoring its potential technological impor tance. We relate the crystal structure and intrinsic mag netic properties by considering analogies with previously known rare earth transition metal materials.