Formation and evolution of local and crystalline structure of Tb_2O_3-HfO_2 compounds

摘要

The process of Tb_2Hf_2O_7 nanocrystals formation upon calcinations up to 1600°C has been investigated by means of X-ray absorption fine structure (XAFS) spectroscopy combined with X-ray diffraction (XRD) and analysis of pair distribution function (PDF). The structure ordering and the growth of nanocrystals upon calcination were estimated independently from XRD patterns and PDF. The probable content of Tb~(4+) cations in Tb_2Hf_2O_7 was estimated from XANES. All studies indicate a high disorder and a large number of local structure defects in Tb_2Hf_2O_7 pyrochlore structure.