Phase evolution from Ln2Ti2O7 (Ln=Y and Gd) pyrochlores to brannerites in glass with uranium incorporation

다국어 초록 (Multilingual Abstract)

Ln2Ti2O7 (Ln=Y and Gd) pyrochlore glass‐ceramics have been fabricated successfully via internal crystallization. Subsequently, the phase evolution from Ln2Ti2O7 pyrochlores to Ln0.5U0.5Ti2O6 brannerites in glass with uranium (U) substitutions on the Ln‐site of Ln2Ti2O7 has been investigated using X‐ray diffraction, scanning electron microscope‐electron dispersive spectroscopy, transmission electron microscopy, Raman and diffuse reflectance spectroscopy. Combined characterization by XRD, SEM‐EDS and TEM SAED confirms the structures and phase evolution while Raman spectroscopy reveals characteristic vibration modes for both pyrochlore and brannerite. In addition, DRS of the U5+ ion has been used to probe the phase evolution, with the corresponding f‐f transition band of 2F7/2 energy level significantly shifting to longer wavenumbers due to the local coordination environment changing from eightfold coordination in pyrochlore to sixfold coordination in brannerite.