Elasticity of Earth Materials

Elasticity of Earth Materials Elastic properties determine the response of materials to stress within the elastic limit. They reflect the nature of atomic bonding (strength) and carry crucial information about materials’ physical behavior. This motivates the strong interest in elasticity of several scientific disciplines, including materials sciences, solid state physics, geosciences and chemistry. Elastic properties also govern the propagation speed of elastic waves (and seismic waves). A quantitative understanding of elastic properties and elastic wave velocities in the minerals that likely compose the deep Earth is of central importance for geosciences as it facilitates the interpretation of seismological observations in terms of composition, evolution, dynamics and thermal state of the Earth’s interior.

Determination of elastic properties of spinels at high pressure by means of GHz-ultrasonic interferometry

Spinels (AB2O4) are among the most common non-silicate minerals in the Earth's crust and uppermost mantle. A characteristic feature of spinels is the ability to host a wide range of cations. Moreover, spinel structured ringwoodite γ-(MgFe)2SiO4 is believed to be the most abundant phase in the transition zone (410 - 660 km depth). The aim of this project is to understand the effect of the transition elements on the elastic properties of spinels. We determined the high pressure behavior of the elastic properties of gahnite (ZnAl2O4), franklinite (ZnFe2O4) and magnetite (Fe3O4) in a diamond anvil cell. Because the opaque Fe-bearing spinels magnetite and franklinite are not accessible to optical methods like Brillouin spectroscopy, we utilized GHz-ultrasonic interferometry. Those spinels hosting two transition elements on the [4]A and [6]B sites show a distinctive different elastic behavior than those bearing only one or no transition metal.

Bulk sound velocity VΦ=(K/ρ)1/2 versus density ρ of spinel structured minerals

Contact person:

  • Dr. Hans Josef Reichmann

Cooperation:

  • Steven D. Jacobsen, Northwestern University USA
  • Tiziana Boffa Ballaran, Bayerischen Geoinstitut (BGI) Forschungsinstitut für Experimentelle Geochemie und Geophysik

Elastic properties of spinels in the series MgAl2O4-FeAl2O4 and MgAl2O4-MnAl2O4

The elasticity systematics in the series spinel-hercynite and spinel-galaxite is investigated by Brillouin scattering and crystal structure characterization as a function of composition and equilibration temperature.

Ansprechpartner:

  • Dr. Sergio Speziale

Kooperation:

  • Dr. Enrico Bruschini and Prof. Giovanni B. Andreozzi, Sapienza,Università di Roma, Italien

Elasticity of cement crystalline and amorphous phases

We are systematically exploring the mechanical properties of primary and secondary crystalline (sulfates, hydroxides, silicates) and amorphous (alkali-Si gel) phases of cement in order to develop quantitative models able to predict the behavior and properties of concrete as complex multi-component system.

Contact persons:

  • Dr. Sergio Speziale
  • Dr. Hans Josef Reichmann

Cooperation:

  • Paulo J. M. Monteiro and Hans-Rudolf Wenk, University of California, Berkeley, USA

Fe spin transition in the lower mantle phases

We are investigating the effects of electronic spin-pairing transition of Fe on the mechanical properties of the main minerals of the lower mantle. This is essential to model the structure and dynamics of the deep Earth interiors based on global geophysical data.

Contact persons:

  • Dr. Sergio Speziale
  • Dr. Hans Josef Reichmann

Cooperation:

  • Prof. Dan J. Frost, Bayerischen Geoinstitut (BGI), Forschungsinstitut für Experimentelle Geochemie und Geophysik, Universität Bayreuth

The elastic properties of portlandite at high pressures

The elastic properties of portlandite, which is an important compound of cement and a prototype of strongly anisotropic layered materials. We investigate stress-induced amorphization, the effects of experimental geometries and possible strategies to optimize the approach to analyze volume and axial strains for equation of state studies of anisotropic materials. We perform elasticity and equation of state measurements at high pressure in the diamond anvil cell and multi anvil apparatus measurement.

Contact persons:

  • Dr. Sergio Speziale
  • Dr. Hans Josef Reichmann

Cooperation:

  • Prof. Frank Schilling, Karlsruher Institut für Technologie (KIT)

Silicate glasses at high pressures

Structural and elastic properties of silicate glasses with compositions of the most important components of the Earth mantle are investigated at the relevant deep Earth pressures. Sound velocity measurements are used to determine in situ high-pressure density.

Contact person:

  • Dr. Sergio Speziale

Cooperation:

  • Sang-Heon (Dan) Shim, Arizona State University, USA

Elasticity of antigorite at high pressures and temperatures

The high-pressure polymorph of serpentine, Antigorite, is a candidate mineral to transport “water” into subduction zones. In order to map hydration in subduction zone environments, laboratory data on the (anisotropic) sound wave velocities of serpentine minerals are needed. We are measuring high-pressure/high-temperature acoustic wave velocities within special crystallographic plane of natural antigorite single-crystals by Brillouin scattering. Preparation of the desired samples for Brillouin Spectroscopy is possible by using the focused ion beam technique.

Contact persons:

  • Prof. Monika Koch-Müller
  • Dr. Sergio Speziale
  • Dr. Hans Josef Reichmann

Cooperation:

  • Dr. Hanns-Peter Liermann, Deutsches Elektronen-Synchrotron (DESY) - Ein Forschungszentrum der Helmholtz-Gemeinschaft, Hamburg

Elasticity and Equation of State of Argon to high-pressure and high-temperature

We measure bulk elastic properties of polycrystalline solid fcc-argon at high-pressures and high temperatures by a combination of Brillouin scattering and synchrotron x-ray diffraction. This combination of methods allows a detailed analysis of the derived acoustic velocities and enables us to put constraints on the single-crystal elastic constants.

Contact person:

  • Dr. Sergio Speziale

Cooperation:

  • Dr. Vitali Prakapenka, The University of Chicago, CARS, and Argonne National Laboratory, USA
  • Dr. Stanislav V. Sinogeikin, Carnegie Institution for Science, Washington, and Argonne National Laboratory, USA

The equation of state and sound velocity in Nanocrystalline-MgO

We compare high-pressure synchrotron x-ray diffraction data to high-pressure sound wave velocity measurements on nanocrystalline materials using Brillouin to gain insight into the elastic response of nano materials larges stresses.

Contact person:

  • Dr. Sergio Speziale

Cooperation:

  • Dr. Hanns-Peter Liermann and Zusana Konopka, Deutsches Elektronensynchrotron DESY - Ein Forschungszentrum der Helmholtz-Gemeinschaft, Hamburg
  • Wolfgang Morgenroth, Institut für Geowissenschaften, Goethe Universität Frankfurt a. Main
  • Arianna E. Gleason, Stanford University, USA

Elastic properties and phase transition in zircon (ZrSiO4)

Natural zircon is a host of uranium and thorium and an important tool of geological dating. We examine the elastic properties as well as the phase transitions of natural (metamict) zircon by means of Raman and Brillouin scattering to obtain a better understanding of the behavior of this mineral in the Earth’s crust.

Contact person:

  • Dr. Hans Josef Reichmann