Nitrogen saturation, phase transitions

Nenitzescu reaction 100 Neumann principle, tensor properties 201 neural networks 810 neutron scattering 680-698 Newton equations, molecular modelling 74 nickel, X ray absorption curve 622 nitro, terminal substituents 147 nitrogen saturation, phase transitions 357... 

Abstract. Gas interstitial fullerenes was produced by precipitation of C6o from the solution in 1,2 dichlorobenzene saturated by O2, N2, or Ar. The structure and chemical composition of the fullerenes was characterized by X-ray powder diffraction analysis, FTIR spectroscopy, thermal desorption mass spectrometry, differential scanning calorimetric and chemical analysis. The images of fullerene microcrystals were analyzed by SEM equipped with energy dispersive X-ray spectroscopy (EDS) attachment. Thermal desorption mass spectroscopy and EDS analysis confirmed the presence of Ar, N and O in C60 specimens. From the diffraction data it has been shown that fullerite with face centered cubic lattice was formed as a result of precipitation. The lattice parameter a was found to enhance for precipitated fullerene microcrystals (a = 14.19 -14.25 A) in comparison with that for pure C60 (a = 14.15 A) due to the occupation of octahedral interstices by nitrogen, oxygen or argon molecules. The phase transition temperature and enthalpy of transition for the precipitated fullerene microcrystals decreased in comparison with pure Cgo- Low temperature wet procedure described in the paper opens a new possibility to incorporate chemically active molecules like oxygen to the fullerene microcrystals. 

For instance, nitrogenation modulates the crystal structures, saturation magnetization (Ms), and Curie temperature (7c) of Fe films [4, 5], substantially. An addition of a small amount of N raises the Ms value of the a"-FeiftN2 phase by 25 % of that of pure Fe (2.22 b)- Further doping of N lowers the Ms value associated with crystal structure transition from s, y, to the paramagnetic phase of amorphous FeN [6]. Nitrogenation also raises the Ms value and the Tc of rare earth I-ferromagnet (Co and Fe) considerably [7]. The Ms of the R(Fe, Co) alloys is increased by 30-40 % relative to their parent alloys [7]. 

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