COMPRES
Crystallography Lab
    Why Neutrons?

    Neutron scattering offers some unique advantages for quantitative characterization of material properties and therefore provides the ideal method for studying many natural materials. Some of the advantages and potential applications are listed below, but a more detailed summary of the properties of neutrons and their application to Earth sciences can be found in the excellent series of articles on "Neutron Scattering Techniques in Mineral and Earth Sciences", European Journal of Mineralogy (http://www.schweizerbart.de/j/ejm), Vol. 14, 2002.


    Neutrons have energies that are similar to the energies of atomic and electronic processes
    • molecular translations, rotations, vibrations and lattice modes, to eV transitions within the electronic structure of materials can be probed
    • phonon dispersion curves and phonon densities of states can be determined using inelastic neutron scattering techniques

    Neutrons provide a highly penetrating probe
    • makes the use of complex sample environments such as cryostats, furnaces and pressure cells routine
    • penetrating power and availability of wide beams allow investigation of texture (preferred orientation) and residual stress analysis of geological materials

    Neutron absorption cross-sections are not electron dependent
    • site occupancies and order-disorder distributions of atoms or ions with equal or similar numbers of electrons, such as Al3+/Si4+ and Fe2+/Mn2+, can be determined directly with neutron diffraction
    • Neutron diffraction can detect hydrogen and other light atoms as easily as heavy atoms, whereas hydrogen atoms are virtually invisible in X-ray diffraction

    Neutron scattering lengths do not change with scattering vector
    • collection of diffraction data up to large scattering vectors possible, making the precise determination of bonding geometry more reliable with neutrons

    Neutrons provide the best probe to study microscopic magnetism and magnetic structures