@article{SchultzeWirthWunderetal.2021,
  author    = {Schultze, Dina and Wirth, Richard and Wunder, Bernd and Loges, Anselm and Wilke, Max and Franz, Gerhard},
  title     = {Corundum-quartz metastability},
  series = {Contributions to mineralogy and petrology},
  volume    = {176},
  journal   = {Contributions to mineralogy and petrology},
  number    = {4},
  publisher = {Springer},
  address   = {Berlin ; Heidelberg},
  issn      = {0010-7999},
  doi       = {10.1007/s00410-021-01786-5},
  pages     = {13},
  year      = {2021},
  abstract  = {The metastable paragenesis of corundum and quartz is rare in nature but common in laboratory experiments where according to thermodynamic predictions aluminum-silicate polymorphs should form. We demonstrate here that the existence of a hydrous, silicon-bearing, nanometer-thick layer (called "HSNL") on the corundum surface can explain this metastability in experimental studies without invoking unspecific kinetic inhibition. We investigated experimentally formed corundum reaction products synthesized during hydrothermal and piston-cylinder experiments at 500-800 degrees C and 0.25-1.8 GPa and found that this HSNL formed inside and on the corundum crystals, thereby controlling the growth behavior of its host. The HSNL represents a substitution of Al with Si and H along the basal plane of corundum. Along the interface of corundum and quartz, the HSNL effectively isolates the bulk phases corundum and quartz from each other, thus apparently preventing their reaction to the stable aluminum silicate. High temperatures and prolonged experimental duration lead to recrystallization of corundum including the HSNL and to the formation of quartz + fluid inclusions inside the host crystal. This process reduces the phase boundary area between the bulk phases, thereby providing further opportunity to expand their coexistence. In addition to its small size, its transient nature makes it difficult to detect the HSNL in experiments and even more so in natural samples. Our findings emphasize the potential impact of nanometer-sized phases on geochemical reaction pathways and kinetics under metamorphic conditions in one of the most important chemical systems of the Earth's crust.},
  language  = {en}
}
@article{GruenebergerSchmidtJahnetal.2016,
  author    = {Gr{\"u}neberger, Anja Maria and Schmidt, Christian and Jahn, Sandro and Rhede, Dieter and Loges, Anselm and Wilke, Max},
  title     = {Interpretation of Raman spectra of the zircon-hafnon solid solution},
  series = {European journal of mineralogy},
  volume    = {28},
  journal   = {European journal of mineralogy},
  publisher = {Schweizerbart},
  address   = {Stuttgart},
  issn      = {0935-1221},
  doi       = {10.1127/ejm/2016/0028-2551},
  pages     = {721 -- 733},
  year      = {2016},
  abstract  = {Zircon (ZrSiO4), hafnon (HfSiO4) and five intermediate compositions were synthesized from a Pb silicate melt. The resulting crystals were 20-300 mu m in size and displayed sector and growth zoning. Raman spectra were acquired at locations in the sample for which preceding electron microprobe (EMP) analyses revealed sufficient compositional homogeneity. The dataset documents shifts of Raman bands with changing composition. In this study, bands that have previously not been reported were found for the intermediate compositions and for pure hafnon, in particular at wavenumbers less than 200 cm(-1). For these external modes, the dataset provides new insight into the compositional dependence of their frequencies. Density-functional theory calculations support the observations and are used for a detailed interpretation of the spectra. The pitfalls of the EMP analysis along the zircon-hafnon join are highlighted.},
  language  = {en}
}
@article{KlemmeFeldhausPotapkinetal.2021,
  author    = {Klemme, Stephan and Feldhaus, Michael and Potapkin, Vasily and Wilke, Max and Borchert, Manuela and Louvel, Marion and Loges, Anselm and Rohrbach, Arno and Weitkamp, Petra and Welter, Edmund and Kokh, Maria A. and Schmidt, Christian and Testemale, Denis},
  title     = {A hydrothermal apparatus for x-ray absorption spectroscopy of hydrothermal fluids at DESY},
  series = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  volume    = {92},
  journal   = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  number    = {6},
  publisher = {AIP Publishing},
  address   = {Melville},
  issn      = {0034-6748},
  doi       = {10.1063/5.0044767},
  pages     = {6},
  year      = {2021},
  abstract  = {We present a new autoclave that enables in situ characterization of hydrothermal fluids at high pressures and high temperatures at synchrotron x-ray radiation sources. The autoclave has been specifically designed to enable x-ray absorption spectroscopy in fluids with applications to mineral solubility and element speciation analysis in hydrothermal fluids in complex compositions. However, other applications, such as Raman spectroscopy, in high-pressure fluids are also possible with the autoclave. First experiments were run at pressures between 100 and 600 bars and at temperatures between 25 degrees C and 550 degrees C, and preliminary results on scheelite dissolution in fluids of different compositions show that the autoclave is well suited to study the behavior of ore-forming metals at P-T conditions relevant to the Earth's crust.},
  language  = {en}
}