Polar Dielectrics

Polar dielectrics (ferroelectrics, piezoelectrics, pyroelectrics) are key materials for modern electronics, telecommunication systems, microwave technology, sensors and actuators due to their unique properties like high piezoelectric and pyroelectric coefficients, strong electromechanical coupling, existence of temperature stable directions for SAW velocity, high dielectric constant together with very low loss factor. Along with the measurements of all these properties important for applications, the study of ferroelectric phase transitions is one of the most important basic problems in solid state physics

Our interests are mainly concentrated on the following directions:

• New promising piezoelectric single crystals for SAW devices and sensors applications:
  • Sr₃NbGa₃Si₂O₁₄ (SNGS), Ca₃NbGa₃Si₂O₁₄ (CNGS), Ca₃TaGa₃Si₂O₁₄ (CTGS), and Sr₃TaGa₃Si₂O₁₄ (STGS)
• higher (as compared to quartz) electromechanical coupling coefficient
• low acoustic loss
• possible existence of temperature stable cuts for SAW velocity
• absence of phase transition
  (as a result, principal possibility to operate at very high temperature up to 1000° C)
• growth by conventional Czochralski technique and therefore reduced crystal cost
• AIN
  • very promising piezoelectric properties
  • high value of SAW velocity which is very important for high-frequency SAW applications
  • no phase transitions on heating from room temperature up to melting point (> 2000° C)
• Ferroelectrics and related materials:
  • Solid solutions on the base of incipient ferroelectric SrTiO₃
    • impurity induced ferroelectric phase transitions
  • interrelation of ferroelectric and antiferrodistortive instabilities
  • Ferroelectric relaxors
• Multiferroics - materials with simultaneous magnetic and ferroelectric ordering (in cooperation with other scientific groups of IFF)

Contact:

Dr. Andrei Sotnikov
IFW Dresden e.V.
'Magnetic and acoustic resonances' (Dept. 15)
Surface Dynamics Group
P.O.Box 270116
D-01171 Dresden, Germany
phone: ++49/351/4659 689
fax: ++49/351/4659 313
e-mail: a.sotnikov + @ifw-dresden.de (Sorry, but we try to prevent automatic SPAM)