Computer simulations based on Ginzburg-Landau-Devonshire theory are used to investigate piezoelectric response of tetragonal BaTiO₃ crystals. We have shown that piezoelectric response of twinned BaTiO₃ increases with increasing density of 90° domain walls. A considerable enhancement of piezoelectric coefficients is predicted below 50 nm. We have also shown that main contribution to the longitudinal piezoelectric coefficient comes from volume of domain, rather than from the domain wall region.

Recently, we are strongly involved in research of environment-friendly, lead-free piezoelectric single crystals. For example, polarized streamline Raman spectroscopy was used to visualize inhomogenity of the preferential polarization direction across the surface of Na_1/2Bi_1/2TiO₃-BaTiO₃ single crystals that are investigated in collaboration with Prof. Haosu Luo from Shanghai Institute of Ceramics, Chinese Academy of Sciences. Spectral analysis reveals local anisotropy of the crystal structure!

The dependences of occurrences of the six most frequent space-group types on reduced unit-cell volumes were investigated for organic and metal-organic compounds with 1-3 different molecular constituents residues. It can be inferred that ability for crystallization of organic and metal-organic molecules ceases for the structures with the reduced unit-cell volumes above 8000 angstroms³. This volume corresponds roughly to 450 non-hydrogen atoms in a molecule.

LaNiO₃ is oxide with perovskite structure and metallic electric conductivity. The agglomerated LaNiO₃ nanocrystalline powder shown in the micrograph was prepared by water-solution sol-gel technique from nitrates with addition of malic acid. It is suitable for the preparation of porous oxide electrodes with application in electronics. Such application has been tested in the company AVX Czech Republic.

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, the mixture of Eu₂O₃ and Ti₂O₃ after milling in a ZrO₂ bowl is shown in the photograph. These oxides are interesting by simultaneous antiferromagnetic and ferroelectric properties at low temperature, multiferroic properties can be applied in electronics.