Modulated structures formed in defect fluorite-type (Y2O3)1-x(Nb2O5) x (0.21 ≤ x ≤ 0.27) solid solutions have been investigated by electron diffraction.  diffraction patterns showed a pair of diffuse spots in the  direction at both sides of the 1/21/21/2 reciprocal-lattice point. The distance between the diffuse spots decreased from 0.064 to 0.045 Å-1 with increasing x from 0.21 to 0.27. High-resolution electron microscopy images revealed the existence of small domains with an antiphase structure. The two-dimensional antiphase structure projected on the (110) plane is described by compositional waves of Y3+/Nb5+ and O2-/vacancy and displacive waves of Y3+ + Nb5+ and O2- along the  direction. The composition at cation sites is expressed by a sinusoidal wave with occupation changes between Y and 0.58Y + 0.42Nb. The occupation probability of O at anion sites is also expressed by a sinusoidal wave with occupation changes between 0.806 and 0.904. Amplitudes of the displacive waves for anions and cations were determined to be about 0.3 and 0.02 Å, respectively.
|Number of pages||8|
|Journal||Journal of Applied Crystallography|
|Publication status||Published - 1997 Jun 1|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)