TITLE:
Densification of Lithium Disilicate under High Pressure Investigated by XPS
AUTHORS:
Silvio Buchner, Cláudio Radtke, Naira Maria Balzaretti
KEYWORDS:
XPS; Glass Ceramic; Lithium Disilicate; High Pressure; Binding Energy
JOURNAL NAME:
Open Journal of Inorganic Non-metallic Materials,
Vol.3 No.2,
April
30,
2013
ABSTRACT:
The aim of this work was to investigate by X-ray photoelectron
spectroscopy the effect of high pressure on the chemical environments of Si 2p,
O 1s and Li 1s in lithium disilicate glass ceramic with stoichiometric
composition Li2O·2SiO2 (LS2). A group of
samples was processed at 2.5 GPa, 4 GPa and 7.7 GPa at room temperature and a
second group was crystallized under high pressure and high temperature. Large
shifts of the binding energy toward higher energies were observed in the X-ray
photoelectron spectroscopy spectra for samples of the first group after
densification at 2.5 and 4 GPa. For samples processed at 7.7 Gpa, the
major component of the binding energy for the Si 2p environment remained
practically unchanged compared to the pristine sample but new components, with
smaller intensities, appeared in the spectra, indicating the existence of
distinct Q-species induced by high pressure. This behavior may be related to
changes in the number of bridged and non-bridged oxygen atoms in the glass
structure. The results for the second group of samples, crystallized
under high pressure, showed evidences of three binding energies for the O
atoms, one of them related to non-bridged and two of them to bridged O atoms.