Crystal chemistry and magnetic structures of Tb(IV) fluorides

This paper reviews the particular crystal-chemical properties of fluorides containing tetravalent terbium and emphasises the special case of the half-filled shell 4f7 of the Tb4+ ion. To this end the crystal-chemical properties of Zr4+, Tb4+ and U4+ are compared. The way according to which the thermal decomposition of TbF4 is turn to account to synthesise mixed valence (III/IV) terbium fluorides is presented. The study of the magnetic interactions involving Tb4+ ions has been taken up through magnetic structures determination from neutron diffraction. The broad outlines of further work will be presented in the light of our recent results concerning the crystal chemistry of Tb(IV) fluorides.