Neutron-diffraction patterns have been obtained for quenched and annealed samples of MnPt. The magnetic structure was found to be antiferromagnetic with the spins on the Mn atoms aligned normal to the [001] direction. The moments on the Mn and Pt atoms were determined to be (4.0±0.4) μB and (0.4±0.4) μB, respectively. These values for the moments are in good agreement with those obtained in earlier investigations. However, we do not find the previously claimed change in spin direction as a function of alloy composition.

Reçu le 1 S juillet 1971)Résumé. -Nous donnons les caractéristiques électro-optiques, les conditions de fonctionnement et les performances actuelles d'un microscope électronique supraconducteur 400 kV.Abstract. -Electron-optical features, working conditions and present performances of a 400 kV superconducting electron microscope are given.

Amorphous Fe87B11Au2 ribbons that are stable above 300 K displayed saturation magnetization Ms of 223 emu/g at 4.2 K. The deduced average Fe atomic moment μ̄Fe was 2.46 μB, which is relatively high compared to μ̄Fe=2.13 μB in Fe87B13. The higher Fe moment is attributed to a quenched-in, high-volume Fe lattice (similar to that found in amorphous Fe-Au films) stabilized by Au and B atoms. Upon annealing, three crystallization stages were observed. First, a α-Fe phase with about 3 at.% Au emerged at around 620 K followed by a Fe2B phase at ≊745 K. At ≊790 K, a Au-rich phase emerged. There were decreases in Ms (4.2 K) as the isothermal annealing temperature was increased, with the largest decrease coinciding with the precipitation of Fe2B.

Substitution of Be for B in the amorphous binary alloy Fe82B18 was observed to cause an initial increase in saturation magnetization (Ms) to a maximum of 200 emu/g at 4.2K, followed by a decrease for alloys with more than 4 at.% Be. Meanwhile, the Curie temperature of the Fe82B18−y Bey alloys decreased progressively with the Be content. These changes in Ms and TC differ from those observed in the Fe-B-M′ metallic glasses, where M′ is another metalloid (P, C, Si or Ge). Results from Auger electron spectroscopy and Mössbauer experiments confirmed the reversal trend detected in the magnetization measurements. Combining all these results enables us to attribute the initial increase in Ms to a smaller charge transfer from the Be atoms than that from the B atoms to Fe and the subsequent decrease in Ms to a possible clustering of the Be atoms at higher concentrations. The annealing behavior for the present alloys is described in terms of crystallization stages and the phases formed.