Preparation et structure cristalline de I0.33NbSe4(I4Nb12Se48)

Single crystals with I_0.33NbSe₄ composition are grown, along with NbSe₂ crystals, by iodine vapor transport from NbSe₃. Single phase powder is obtained by heating the elements in corresponding proportions at 700°C. The structure has been studied by X-ray diffraction on a single crystal. The symmetry is tetragonal with the following parameters of the unit cell a = 9.489 Å, c = 19.13 Å. The space group is $\text{P4}\text{mnc}$ with Z = 12. The structure is built up with chains of rectangular NbSe₈]-antiprisms. Iodine atoms are located between these chains.