Fyzikální ústav Akademie věd ČR

We investigate materials with globally or locally broken center of inversion, such as piezoelectric, ferroelectric, antiferroelectric, relaxor or incommensurate dielectrics in form of crystals, ceramics, films as well as complex nanostructures. The team focuses on developing preparation methods, by characterization of structural phase transitions by calorimetric, structural and nonlinear optic methods, and by theoretical modeling of their physical properties.

(More about this group.)

Research Activities

• preparation of novel ceramic materials, e.g. EuTiO₃
• single crystal growth, e.g. piezoelectric KIO₃
• soft chemistry technology, e.g. filling nanoporous materials with ferroelectrics,...
• indentification and thermodynamical and structural characterization of novel phase transitions
• developing crystallographic databases
• investigation of ferroelectric heterostructures
• effective medium theory for dielectric and piezoelectric properties
• theoretical studies of ferroelectric phase transitons
• studying of domain walls and domain structures (link to ferrodomains)

Equipment

• Differential scanning calorimeters Perkin-Elmer DSC 7 and Pyris Diamond -180°C – +725°C
  (contact: P. Vaněk, ext. 2909, room 149)
  
• Apparatus for second harmonic generation, pulsed Nd:YAG laser, wedge or Maker-fringe methods, temperature range 5-800 K
  (contact: J. Kroupa, ext. 2655, room 53)
  
• Planetary ball micro mill Fritsch Pulverisette 7
  (contact: P. Vaněk, ext. 2909, room 122)
  
• Ion sputter coater Bal-Tec SCD 050
  (contact: P. Vaněk, ext. 2909, room 122)
  
• Muffle furnace Linn High Therm, up to 1200°C
  (contact: P. Vaněk, ext. 2909, room 122)
  

Some recent results

Sythesis of LaNiO₃ nanocrystalline powder

LaNiO₃ is oxide with perovskite structure and metallic electric conductivity. The agglomerated LaNiO₃ nanocrystalline powder was prepared by water-solution sol-gel technique from nitrates with addition of malic acid. (more...)

Mechanochemical activation for solid-state synthesis

Mechanochemical activation (intensive ultrafine milling) in a planetary ball micro mill puts deformation energy into components and starts the solid-state reaction. Following calcination (solid-state synthesis at enhanced temperature) is easier, usually only one calcination step is necessary, processing temperature can be reduced and resulting product is more homogeneous. E.g. multiferroic oxides EuTiO₃ and (Eu_0.5Ba_0.5)TiO₃ were prepared by this technique. (more...)