Phase Transitions, Glass Transitions

Landau free energy contour plot showing 4 minima corresponding to 4 different domain states. White lines indicate domain wall trajectories.

We perform fundamental research on synthetic crystals and minerals undergoing ferroelectric, ferroelastic or multiferroic phase transitions. Materials include: Ferroelastics (e.g. SrTiO3, LaAlO3), Ferroelectrics (PbTiO3) and Antiferroelectrics (PbZrO3), Multiferroics (EuTiO3), etc.

Selected Publications

  1. Puchberger, S., et al. "Domain wall motion and precursor dynamics in PbZrO3." Physical Review B 94.21 (2016): 214101.
  2. Böhmer, A. E., et al. "Nematic Susceptibility of Hole-Doped and Electron-Doped BaFe2As2 Iron-Based Superconductors from Shear Modulus Measurements." Physical review letters 112.4 (2014): 047001.
  3. Cordero, F., et al. "Elastic response of (1 − x)Ba(Ti0.8 Zr0.2)O3 − x(Ba0.7Ca0.3)TiO3(x = 0.45 – 0.55) and the role of the intermediate orthorhombic phase in enhancing the piezoelectric coupling." Applied Physics Letters 105.23 (2014): 232904.
  4. Goian, V., et al. "Antiferrodistortive phase transition in EuTiO3." Physical Review B 86.5 (2012): 054112.

Scheme, describing two different pathways, i.e. disorder - crystalline vs. disorder - glass, in different materials. Adapted from X. Ren, Phys. Stat. Sol. 251, 1982 (2014).

In contrast to structural phase transitions, glass transitions occur without symmetry breaking. One of the central questions in glasses is concerned with the tremendous slowing down of dynamics, i.e. increase of viscosity when the glass transition is approached. To study dynamic correlations in glass forming liquids we confine the material in nanoporous silica and measure dynamic susceptibilities as a function of temperature, frequency and pore diameter.

Selected Publications

  1. Waitz, T., W. Schranz, and A. Tröster. "Nanoscale Phase Transformations in Functional Materials." Mesoscopic Phenomena in Multifunctional Materials. Springer Berlin Heidelberg, 2014. 23-56.
  2. Soprunyuk, Viktor, Wilfried Schranz, and Patrick Huber. "Dynamic mechanical analysis of supercooled water in nanoporous confinement." EPL (Europhysics Letters) 115.4 (2016): 46001.
  3. Soprunyuk, V., M. Reinecker, and W. Schranz. "On the behaviour of supercooled liquids and polymers in nano-confinement." Phase Transitions 89.7-8 (2016): 695-707.
  4. Koppensteiner, J., W. Schranz, and M. A. Carpenter. "Revealing the pure confinement effect in glass-forming liquids by dynamic mechanical analysis." Physical Review B 81.2 (2010): 024202.