MAX200x: In-situ X-ray Measurements at High Pressure and High Temperatures.
Twenty years ago geoscientists from all over the world launched in-situ X-ray diffraction experiments under extreme pressure and temperature conditions at synchrotron beamlines. One of the first apparatus was installed at HASYLAB, MAX80, a single-stage multi-anvil system. MAX80 allows in-situ diffraction studies in conjunction with the simultaneous measurement of elastic properties up to 12 GPa and 1600 K. This very successful experiment, unique in Europe, is operated by Helmholtz Centre Potsdam and is used by more than twenty groups from different countries every year. Experiments for both, applied and basic research are conducted, ranging from life-sciences, chemistry, physics, over material sciences to geosciences. Today new materials and the use of high brilliant synchrotron sources allow constructing double-stage multi-anvil systems for X-ray diffraction to reach much higher pressures. The newly designed high-flux hard wiggler (HARWI-II) beamline is an ideal X-ray source for this kind of experiments. As only the uppermost few kilometres of the Earth (less than 0.1% of its radius) are accessible for direct observations (e.g. deep drilling), sophisticated techniques are required to observe and to understand the processes in the deep interior of our planet. In-situ studies are an excellent tool to investigate ongoing geodynamic processes within the laboratory. One of the fundamental regions to study geodynamic processes seems to be the so-called transition zone, the boundary between upper and lower Earth's mantle between 410 and 670 km depth. Mineral reactions, phase transitions, as wheel as fluid rock interaction in this area might have the potential to strongly influence and control the dynamic motions within our whole planet. Around 25 GPa and 2 000 K are required to simulate these processes in the laboratory. The new MAX200x will be an excellent tool for these ambitious experiments.
Recent development on measurement of anelasticity of minerals at high pressures
Anelasticity defines the frequency dependence of acoustic velocities of minerals. It is an important property to bridge high pressure acoustic measurement at high P-T to seismic observations. The recent technical development allows us to determine these properties using multi-anvil high pressure devices and synchrotron X-ray radiation. The stress-strain relation measured as a function of time defines the elastic modulus at seismic frequencies (1mHz-1Hz) and quality factor (Q-1). This paper reports the recent results on the effect of phase transitions on the elastic modulus, in which elastic weakening of ringwoodite-olivine was found when the kinetics of the phase transition is comparable to the frequency of the applied stresses. Furthermore, we observed stress-driven domain-wall motion in neighborite (NaMgF3) at high P-T as a result of the ferroelastic phase transitions. Finally, we report the results on partial-molten peridotite, for which partial-melting was not found to have significant effect on quality factor. Experimental data and sample microstructures will be presented.