High-resolution studies of cubic perovskites by elastic neutron diffraction: CsPbCl3

A programme of elastic neutron-diffraction experiments has been undertaken to derive (and compare) atomic distribution functions, with high spatial resolution, for the antiferroelectric perovskites SiTiO 3 , KMnF 3 , RbCaF 3 and CsPbCl 3 in their cubic phase. The study of cubic CsPbCl 3 is presented. Data were collected out to a resolution limit of sin theta lambda =1.2AA -1 , and used in least-squares refinements of parameters describing anharmonic distributions for the Cs, Pb and Cl ions. Two different techniques yield essentially the same conclusions: anharmonicity is very much more significant for the Cl ion than for the metals and, the inharmonic parameters for Cl correspond to a small bulging of its distribution in the directions along which Cl is known to displace on passing to the low-temperature phase.