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Neutrons High Pressure crystallographic structure and magnetic Study of the Fe-Cr-Hx Phase Diagram.


  Amir Broide [1,2]  ,  Itzhak Halevy [1,2]  ,  Silvie Maskova [3]  ,  Oleg Rivin [2]  ,  Matthew S. Lucas [4]  ,  Amir Hen [2,5]  ,  Itzhak Orion [2]  ,  Shai Salhov [1]  ,  Michael Shandalov [1]  ,  Antonio F Moreira Dos Santos [6]  ,  Jamie Molaison [6]  
 [1] Dept. of physics, NRCN, P.O.Box 9001, Beer-Sheva, ISRAEL
[2] Nuclear engineering Department, Ben Gurion Univ., Beer-Sheva, ISRAEL
[3] Department of Condensed Matter Physics, Charles University Prague, The Czech Republic
[4] Air Force Research Laboratory, OH, USA
[5] 5European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe, Germany
[6] BL3, Spallation Neutron Source, Oak Ridge National Laboratory Oak Ridge, TN, USA

Neutron diffraction reviles crystallographic structure, symmetry and unit cell parameters combined with the magnetic structure. High Pressure X-Ray diffraction performed in the NSLS gave the crystallographic structure, symmetry and the unit cell parameters as function of pressure. Those techniques can give an insight to the Fe-Cr phase diagram. There is a known crystallographic phase transition from bcc to hcp structure at 13GPa in  elemental iron. In measurements made on disordered bcc solid solutions of Fe-Cr we noticed a correlation between the Cr concentration and the unit cell parameter. The phase transition point measured by neutron high pressure diffraction is increasing with the increase of the Cr concentration, an example of parental sample and hydrogenated one, Fe80Cr20, is given Fig 1 & 2. Mössbauer effect spectra of Fe-Cr at various concentrations are given in Fig. 3. Fig. 4 shows the SQUID magnetization measurements of Fe-Cr at various temperatures demontrating a magnetic phase transition in the form of an Arrotte plot.