Структурные преобразования порядок-беспорядок в нанокристаллических высоко дефектных флюорит производных Gd2MO5 (M − Zr, Hf)
Order–disorder phenomena in nanocrystalline Gd2ZrO5 and Gd2HfO5 with highly imperfect fluorite- derived structures in the range 1000–1600°C have been studied using monochromatic synchrotron X-ray diffraction and Raman spectroscopy. The results demonstrate that the synthesis process leads to the formation of two coherent phases identical in composition: a nanocrystalline disordered fluorite-like (F) phase (Fm3m) and a nanoparticulate ordered fluorite derivative (C1) (Ia3). Their lattice parameters have been determined. In the range 1000–1600°C, the Raman spectra of the Gd2ZrO5 and Gd2HfO5 materials contain broad bands in low- and high-frequency regions, at ~118 (108), 362 (353), and 670 (665) cm–1, which characterize the C1 and F phases, respectively.