The Structure of Ferroelectric DCsDA

In further neutron scattering experiments on the (orthorhombic) ferroelectric phase of DCsDA and CsDA, a study has been made of the scattering arising at wavevectors along the a* direction at positions away from Bragg reflections. It is shown that this most probably arises from Bragg scattering in which two different ferroelectric domains are involved.

Below Tc each Bragg reflection can split into four separate spots corresponding to the different domain types. Surprisingly in DCsDA a central Bragg spot from the (tetragonal) paraelectric phase persists with decreasing intensity over a 60K temperature range. This effect has been observed with both neutron and X-ray scattering techniques and is independent of crystal size.