December 1995 issue
The asymmetric unit of K3Nb3Ti2O11F4 contains two STX6 octahedra where X = O, F or OF (= 1/4 F + 3/4 O) and ST = (3/5 Nb + 2/5 Ti). The K-atom environment is similar to that in ferroelectric phases, but the weak distortion of the octahedra and the occupation of their centres by Nb5+ and Ti4+ cations result in paraelectric behaviour.
Dicerium pentanickel dizinc, Ce2Ni5Zn2, crystallizes as a new ordered substitution variant of the Er2Co7 structure type, and cerium dinickel zinc, CeNi2Zn, crystallizes with the YRh2Si structure type.
H9Tb7Ce6(SO4)27.72.2H2O is isomorphous with the Nd compound reported previously, but is less stable and features unexpectedly long Tb-O distances.
Pr3(SiO4)2Cl is isostructural with La3(SiO4)2Cl. The structure comprises layers of Pr(2)(SiO4)4Cl2 octahedra separated in the a direction by Pr(1) cations occupying Pr(1)O7Cl polyhedral sites.
The structure of S4N4Cl2 has been redetermined at 120K. The results are compared with those of an earlier study using photographic data obtained at ambient temperature.