A unique combination of acid treatment, aqueous colloidal processing, and spark-plasma sintering (SPS) has been used to fabricate high-density Al2O3 /single-wall carbon nanotube (SWNT) composites with well-distributed SWNTs and other carbon nanostructures ('nano-onions', diamond) at Al2O3 grain boundaries. This approach could be used to obtain well-controlled microstructures of ceramic/SWNT composites for tailored mechanical, electrical, and thermal properties. In addition, the colloidal approach for dispersing SWNTs presented here could be used for the controlled manipulation of SWNTs.

Sol-gel derived polycrystalline La-doped ${\mathrm{PbTiO}}_3$ films are investigated by scanning force microscopy (SFM) in a piezoelectric contact mode. The SFM signal proportional to the effective piezoelectric coefficient, $d_{\mathrm{eff}},$ is measured inside individual domains as a function of the mechanical force exerted by the SFM tip on the film’s surface. It is found that the piezoelectric signal can be fully suppressed under sufficiently high force (∼20–22 μN). The suppression is qualitatively different for domains of opposite polarities where $d_{\mathrm{eff}}$ may change its sign depending on the orientation of polarization vector. The piezoelectric hysteresis loops acquired under increasing force gradually shrink with an asymmetric decrease of the piezoelectric coefficients. This leads to a pronounced vertical shift of the loops ${\mathrm{(d}}_{\mathrm{eff}}$ offset). The obtained results are discussed in terms of the competing electrostatic and piezoelectric contributions to the measured signal and stress-induced polarization instabilities in the vicinity of the SFM tip.