Electron energy-loss spectroscopy at incommensurately modulated crystalline and glassy Ba2TiGe2O8

Based on cluster molecular orbital calculations, high-energy resolution (ΔE?～ 0.4?eV) Ti–L_2,3 electron energy loss near-edge structures of single-crystalline and glassy Ba₂TiGe₂O₈ are interpreted. The finding that the Ti–L_2,3 near-edge structure of the Ba₂TiGe₂O₈ single crystal possesses less pronounced peaks than the glass under identical experimental conditions can be attributed to distinct distortions of the titanium environment caused by the very strong one-dimensional structural modulation hosted by the Ba₂TiGe₂O₈ crystal lattice. As lattice periodicity is absent in the glass, the titanium environment is more regular in the vitreous surroundings. Moreover, the modulation in crystalline Ba₂TiGe₂O₈ is responsible for the virtually indiscernible O–K near-edge structures of the glassy and crystalline samples.