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Dielectric relaxation and polar structures of BaTi1−xSnxO3 ceramics, x=0.10–0.20, are investigated by means of dielectric spectroscopy and piezoresponse force microscopy. A transition regime between “normal” ferroelectric and relaxor behaviors is encountered. In the compositions with x=0.10, a complex domain pattern confirming the ferroelectric state is observed. Strong dielectric relaxation around Tm is attributed to domain wall motion. On the other hand, the dielectric spectra in the sample with x=0.20 are very similar to those observed in relaxor ferroelectrics. Analysis of the relaxation spectra at the intermediate concentration, x=0.15, reveals both domain wall response and an additional contribution related to mesoscale polar structures. The appearance of relaxor behavior in BaTi1−xSnxO3 is discussed within the framework of the random field model.

The origin of high piezoelectric response in (Na0.52K0.48−x)(Nb0.92−xSb0.08)O3-xLiTaO3 lead-free ceramics was investigated by looking into the composition-dependent domain morphology by means of transmission electron microscopy. Nanodomains of alternate orthorhombic and tetragonal domains with a width of 20–50 nm were surprisingly observed but only for compositions near polymorphic phase coexistence zone. The formation of nanodomain morphology was considered to result from the reduction of the domain wall energy owing to the vanishing of the polar anisotropy, which ultimately induced enhanced piezoelectric properties. The result indicated that nanodomains are not proprietary features of traditional Pb-based piezoelectric ceramics with a morphotropic phase boundary.

Computer simulation showed that catalytic distillation is an attractive process for the removal of dilute acetic acid from wastewater. Selection of catalysts and kinetic data have been obtained for the design of the catalytic distillation column. Kinetic measurements were conducted in a batch reactor. Methanol was added to the dilute acetic acid solutions and reacted with the acid in water to form methyl acetate and water. The reaction can be catalyzed by solid acid catalysts. It was found that Amberlyst 15 was an effective catalyst for this reaction. The effects of stirrer speed, reaction temperature, reactant concentration and catalyst loading on reaction rate were investigated. A complete kinetic equation for describing the reaction catalyzed by Amberlyst 15 was developed. This equation can be used in the simulation and design of the catalytic distillation column for removing acetic acid from wastewater.