TY - JOUR A1 - Rosa, A. D. A1 - Pohlenz, Julia A1 - de Grouchy, C. A1 - Cochain, B. A1 - Kono, Y. A1 - Pasternak, S. A1 - Mathon, O. A1 - Irifune, T. A1 - Wilke, Max T1 - In situ characterization of liquid network structures at high pressure and temperature using X-ray absorption spectroscopy coupled with the Paris-Edinburgh press JF - High pressure research N2 - We review recent progress in studying structural properties of liquids using X-ray absorption spectroscopy coupled with the Paris-Edinburgh press at third-generation synchrotron facilities. This experimental method allows for detecting subtle changes in atomic arrangements of melts over a wide pressure-temperature range. It has been also employed to monitor variations of the local coordination environment of diluted species contained in glasses, liquids and crystalline phases as a function of the pressure and temperature. Such information is of great importance for gaining deeper insights into the physico-chemical properties of liquids at extreme condition, including the understanding of such phenomena as liquid-liquid phase transitions, viscosity drops and various transport properties of geological melts. Here, we describe the experimental approach and discuss its potential in structural characterization on selected scientific highlights. Finally, the current ongoing instrumental developments and future scientific opportunities are discussed. KW - X-ray absorption KW - Paris-Edinburgh press KW - liquid structure KW - high pressure and temperature KW - EXAFS Y1 - 2016 U6 - https://doi.org/10.1080/08957959.2016.1199693 SN - 0895-7959 SN - 1477-2299 VL - 36 SP - 332 EP - 347 PB - American Geophysical Union CY - Abingdon ER - TY - JOUR A1 - Pohlenz, Julia A1 - Rosa, A. D. A1 - Mathon, O. A1 - Pascarelli, S. A1 - Belin, S. A1 - Landrot, G. A1 - Murzin, V. A1 - Veligzhanin, A. A1 - Shiryaev, A. A1 - Irifune, T. A1 - Wilke, Max T1 - Structural controls of CO2 on Y, La and Sr incorporation in sodium-rich silicate - carbonate melts by in-situ high P-T EXAFS JF - Chemical geology : official journal of the European Association for Geochemistry N2 - Carbonate-rich silicate and carbonate melts play a crucial role in deep Earth magmatic processes and their melt structure is a key parameter, as it controls physical and transport properties. Carbon-rich melts can be strongly enriched in trace elements, but the structural incorporation mechanisms of these elements are difficult to study because such melts generally cannot be quenched to glasses. In this contribution we investigate the influence of CO2 on the local environments of trace elements contained in silicate glasses with variable CO2 concentrations and in silicate and carbonate melts. The melts were studied in-situ at high pressure and temperature conditions using the Paris-Edinburgh press (2.2 to 2.6 GPa and 1200 to 1500 degrees C). The compositions studied include sodium-rich peralkaline silicate melts and glasses and carbonate melts similar to those occurring naturally at Oldoinyo Lengai volcano. The local environments of yttrium (Y), lanthanum (La) and strontium (Sr) were investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy. Main findings of the study suggest: (1) In peralkaline silicate glasses the local structure of Y is unaffected by the CO2 content. Contrary, a slight increase of oxygen bond lengths of Sr and La is inferred with increasing CO2 content in peralkaline glasses, while they remain constant in glasses of even higher peralkalinity independent of the CO2 content. (2) In silicate melts of different CO2 contents Y-O bond lengths are constant, while a slight increase within carbonate melt compositions is deduced. On the other hand, a steady bond lengths increase over the whole compositional range is inferred for La-O and Sr-O. This may well be explained by distinct preferences of these elements for specific local environments. Based on these new data, we suggest potential mechanisms for the structural incorporation of these elements, a key step towards understanding their partitioning behavior in natural magmatic systems. KW - Silicate- carbonate melts/glasses KW - Local structure Yttrium, Strontium, Lanthanum KW - EXAFS KW - Paris-Edinburgh press Y1 - 2018 U6 - https://doi.org/10.1016/j.chemgeo.2017.12.023 SN - 0009-2541 SN - 1872-6836 VL - 486 SP - 1 EP - 15 PB - Elsevier CY - Amsterdam ER -