A compilation of accurate structural parameters for KDP and DKDP, and a users' guide to their crystal structures

Abstract

Abstract Accurate fractional coordinates, (harmonic) thermal parameters and lattice parameters are presented for KDP (KH2PO4) at 293 K, Tc + 5 K and Tc - 20 K, and for ∼95% deuterated DKDP (KD2PO4) at 293 K, Tc + 5 K and Tc - 10 K; and also for KDP and DKDP at 16.5 kbar (at 293 K). The fractional coordinates and thermal parameters have all been obtained from high-resolution neutron-diffraction data. Details are given of the experiments, the data analysis and refinement, and also of the derivation of the lattice parameters. The paper includes a “users' guide” to the conventional descriptions of the tetragonal (above Tc ) and orthorhombic (below Tc ) crystal structures, and the relationship between them.