High pressure powder X-ray diffraction of sillenites Bi{sub 12}MO{sub 20} (M=Si, Ge, Ti) and Bi{sub 4}Ti{sub 3}O{sub 12}
- Institut für Geowissenschaften, Goethe Universität Frankfurt, Altenhöferallee 1, D-60438 Frankfurt a.M. (Germany)
- ESRF, BP 220, F-38043 Grenoble Cedex (France)
Powder X-ray diffraction experiments of sillenites Bi{sub 12}M O{sub 20} (M=Si, Ge, Ti) were performed with synchrotron radiation at the ESRF, Grenoble, at pressures up to 39 GPa (M=Si), 50 GPa (M=Ge), and 37 GPa (M=Ti), respectively. These three sillenites were investigated for the first time over such a large pressure range and they show no phase transition up to the highest pressures achieved. Birch–Murnaghan equations of state of third order were fitted to the pressure dependence of the lattice parameters. The resulting bulk moduli B{sub 0} and their pressure derivatives B′ are B{sub 0}=63(1)GPa with B′=6.6(3) (M=Si), B{sub 0}=63.0(5)GPa with B′=5.90(7) (M=Ge), and B{sub 0}=48(1)GPa with B′=9.4(5) (M=Ti). In the case of Bi{sub 12}SiO{sub 20} and Bi{sub 12}TiO{sub 20} the equation of state fits were restricted to pressures below 15 GPa, because the experimental data were affected by non-hydrostatic stress at higher pressures. The equation of state of neon was redetermined (V{sub 0}=11.7(6)cm{sup 3}/mol, B{sub 0}=5(1)GPa, B′=5.5(3)GPa) and its use as an internal pressure standard for diffraction experiments is discussed. A second cubic phase could be identified in our Bi{sub 12}TiO{sub 20} sample. This was attributed to eulytite-type Bi{sub 4}Ti{sub 3}O{sub 12}, which has B{sub 0}=50.9(8)GPa and B′=6.9(3). - Graphical abstract: X-ray diffraction at high pressure → Equation of state. - Highlights: • Powder X-ray diffraction experiments of sillenites were performed at high pressures. • Equations of state of sillenites Bi{sub 12}MO{sub 20} (M=Si, Ge, Ti) were determined. • The sillenite structure was shown to be stable at high hydrostatic pressure. • Sillenites are sensitive to non-hydrostatic pressure conditions in neon-loaded DACs. • An eulytite-type Bi{sub 4}Ti{sub 3}O{sub 12} phase was found to exist up to 10 GPa.
- OSTI ID:
- 22309063
- Journal Information:
- Journal of Solid State Chemistry, Vol. 208; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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