Hot neutron four-circle diffractometer

Study of an unconventional material

Single-crystal neutron-diffraction is a conventional technique used to determine the crystallographic or magnetic structure of a compound. The results become innovative when studying unconventional materials.
This is the case for Pr0.6Ca0.4MnO3 with the perovskite structure and where the charge, spin, and lattice degrees of freedom are closely interrelated, leading to unusual physical phenomena. This compound shows a transition where charges localize and this change in the electronic behaviour is accompanied by a structural phase transition. The 2D-detector of D9 is a valuable advantage for the correct measurement of Bragg-intensities in this case.
An example of the manifestation of twinning in the observed diffraction peaks is shown in figure (Fig. left column), together with the temperature evolution through the change of lattice parameters. The refinement of the obtained data reveals a new structural model which suggests the formation and ordering of ferromagnetic pairs of Mn atoms (Fig. right side) giving rise to a new interpretation of the electronic localization and the magnetic ordering in similar manganites. A D9-like diffractometer is the best tool for this purpose.

Ref.: A. Daoud-Aladine et al.; Appl. Phys A, 74, S1758-S1760 (2002).