TY  - JOUR
A1  - Petitgirard, Sylvian
A1  - Sahle, C. J.
A1  - Weis, C.
A1  - Gilmore, K.
A1  - Spiekermann, Georg
A1  - Tse, J. S.
A1  - Wilke, Max
A1  - Cavallari, C.
A1  - Cerantola, V
A1  - Sternemann, Christian
T1  - Magma properties at deep Earth’s conditions from electronic structure of silica
JF  - Geochemical perspectives letters
N2  - SiO(2 )is the main component of silicate melts and thus controls their network structure and physical properties. The compressibility and viscosities of melts at depth are governed by their short range atomic and electronic structure. We measured the O K-edge and the Si L-2,L-3-edge in silica up to 110 GPa using X-ray Raman scattering spectroscopy, and found a striking match to calculated spectra based on structures from molecular dynamic simulations. Between 20 and 27 GPa, Si-[4] species are converted into a mixture of Si-[5] and Si-[6] species and between 60 and 70 GPa, Si-[6] becomes dominant at the expense of Si-[5] with no further increase up to at least 110 GPa. Coordination higher than 6 is only reached beyond 140 GPa, corroborating results from Brillouin scattering. Network modifying elements in silicate melts may shift this change in coordination to lower pressures and thus magmas could be denser than residual solids at the depth of the core-mantle boundary.
Y1  - 2019
U6  - https://doi.org/10.7185/geochemlet.1902
SN  - 2410-339X
SN  - 2410-3403
VL  - 9
SP  - 32
EP  - 37
PB  - Association of Geochemistry
CY  - Paris
ER  - 
TY  - JOUR
A1  - Ketenoglu, Didem
A1  - Spiekermann, Georg
A1  - Harder, Manuel
A1  - Oz, Erdinc
A1  - Koz, Cevriye
A1  - Yagci, Mehmet C.
A1  - Yilmaz, Eda
A1  - Yin, Zhong
A1  - Sahle, Christoph J.
A1  - Detlefs, Blanka
A1  - Yavas, Hasan
T1  - X-ray Raman spectroscopy of lithium-ion battery electrolyte solutions in a flow cell
JF  - Journal of synchrotron radiation
N2  - The effects of varying LiPF6 salt concentration and the presence of lithium bis(oxalate)borate additive on the electronic structure of commonly used lithium-ion battery electrolyte solvents (ethylene carbonate-dimethyl carbonate and propylene carbonate) have been investigated. X-ray Raman scattering spectroscopy (a non-resonant inelastic X-ray scattering method) was utilized together with a closed-circle flow cell. Carbon and oxygen K-edges provide characteristic information on the electronic structure of the electrolyte solutions, which are sensitive to local chemistry. Higher Li+ ion concentration in the solvent manifests itself as a blue-shift of both the pi* feature in the carbon edge and the carbonyl pi* feature in the oxygen edge. While these oxygen K-edge results agree with previous soft X-ray absorption studies on LiBF4 salt concentration in propylene carbonate, carbon K-edge spectra reveal a shift in energy, which can be explained with differing ionic conductivities of the electrolyte solutions.
KW  - non-resonant inelastic X-ray scattering
KW  - lithium-ion battery electrolyte
KW  - C and O K-edge spectra
Y1  - 2018
U6  - https://doi.org/10.1107/S1600577518001662
SN  - 0909-0495
SN  - 1600-5775
VL  - 25
SP  - 537
EP  - 542
PB  - International Union of Crystallography
CY  - Chester
ER  -