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1 + 1 = 3: Coupling μ-XRD2 and DTA New insights in temperature-dependent phase transitions

The gypsum–bassanite–anhydrite system as an example


The article shows how additional information can be obtained from coupling a self constructed DTA-system with a commercially available BRUKER D8 DISCOVER GADDS XRD2-microdiffractometer. The dehydration process of gypsum to anhydrite in the temperature range from room temperature up to 723 K is used as an example. Due to the short measurement times of 10 s for each diffraction pattern the three phase transformations from gypsum to anhydrite (anhydrite II) via the hemihydrate bassanite, a water-free bassanite structure (γ-anhydrite, anhydrite III) were resolved in detail by recording the thermal signal and the diffraction pattern simultaneously. To the best of our knowledge, this is the first observation of a completely reversible dehydration/rehydration process of the bassanite/γ-anhydrite-structure around 373 K which is studied by coupled XRD and differential thermal analysis (DTA) measurements.

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We thank the workshop team of the Institute for Geoscience Tübingen (IFG) for manufacturing the DTA block and modification of the furnace. Dr. A. Bjeoumikhov from the IFG-Adlershof is kindly acknowledged for providing the X-ray optics and valuable discussions. V. Presser gratefully acknowledges financial support from the Alexander-von-Humboldt foundation.

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Correspondence to Christoph Berthold.

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Berthold, C., Presser, V., Huber, N. et al. 1 + 1 = 3: Coupling μ-XRD2 and DTA New insights in temperature-dependent phase transitions. J Therm Anal Calorim 103, 917–923 (2011).

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  • DTA
  • Thermal analysis
  • Capillary optics
  • Microdiffraction
  • Gypsum
  • Anhydrite
  • Bassanite