Powder Diffraction Studies in the YONO3-Y2O3 System

The crystal structure of yttrium oxide nitrate and the microstructure of the oxide obtained from its thermal decomposition have been investigated by modern powder diffraction methods. Sequential high-temperature diffraction studies of the thermal decomposition of two precursors of yttrium oxide nitrate, i.e., neutral yttrium nitrate and yttrium hydroxide nitrate, are reported. The structure of YONO3 has been determined ab initio from conventional powder diffractometry using monochromatic X-rays. The pattern was indexed by the successive dichotomy method yielding tetragonal unit cell dimensions: a = 3.8590(1) Å and c = 9.7161(6) Å. The space group is P4/nmm and Z = 2. Most of the atoms were located by direct methods and the remaining ones from a Fourier map. Refinement of the complete diffraction profile parameters converged to final agreement factors Rp = 0.12, Rwp = 0.16 and RF = 0.039. The structure is closely related to the matlockite PbFCl-type structure. The microstructure of ex-oxide-nitrate yttrium oxide has been analysed by total pattern fitting techniques, from which strain-free coherently diffracting nanodomains with a rectangular parallelepipedic shape have been obtained.