The anomalous behaviour of the neutron reflexion of fluorite

Abstract

At room temperature the neutron intensities of the Bragg reflexions of CaF 2 cannot be interpreted satisfactorily by the ideal fluorite model, with calcium atoms at the 000, ~1 1 0, 2101,2 0~1 1 positions of the cubic cell, fluorine atoms at _1_:ll 1 1 a etc. and with all atoms executing isotropic thermal