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

• Published in: Philosophical magazine (Abingdon, England) England), 2004-10, Vol.84 (29), p.3117-3132
• Main Authors: Höche †, Thomas, van Aken, Peter A., Grodzicki, Michael, Heyroth, Frank, Keding, Ralf, Uecker, Reinhard
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electron and ion emission by liquids and solids; impact phenomena; Electron energy loss spectra; Electron energy loss spectroscopy; Exact sciences and technology; Impact phenomena (including electron spectra and sputtering); Inorganic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Water, oxides, hydroxides, peroxides
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430410001716953

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 Ba 2 TiGe 2 O 8 are interpreted. The finding that the Ti-L 2,3 near-edge structure of the Ba 2 TiGe 2 O 8 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 Ba 2 TiGe 2 O 8 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 Ba 2 TiGe 2 O 8 is responsible for the virtually indiscernible O-K near-edge structures of the glassy and crystalline samples.