Dielectric and Piezoelectric Properties of PZT Composite Thick Films with Variable Solution to Powder Ratios.

The use of PZT films in sliver-mode high-frequency ultrasonic transducers applications requires thick, dense, and crack-free films with excellent piezoelectric and dielectric properties. In this work, PZT composite solutions were used to deposit PZT films >10 μm in thickness. It was found that the functional properties depend strongly on the mass ratio of PZT sol-gel solution to PZT powder in the composite solution.

Influence of TiCl4 treatment on surface defect photoluminescence in pure and mixed-phase nanocrystalline TiO2.

Room-temperature UV-excited photoluminescence spectra are reported for nanocrystalline films of anatase, rutile, and mixed-phase TiO2 (Degussa P25) before and after treatment with TiCl4 solution. The surface defect luminescence of anatase in the visible region is suppressed by TiCl4 treatment, indicating a decrease in surface traps. A similar anatase surface-defect emission is observed in the mixed-phase nanoparticles but is completely quenched following TiCl4 treatment and replaced by emission characteristic of rutile.

Room-temperature preparation of nanocrystalline TiO2 films and the influence of surface properties on dye-sensitized solar energy conversion.

An extremely easy method is presented for producing surfactant-free films of nanocrystalline TiO2 at room temperature with excellent mechanical stability when deposited on glass or plastic electrodes for dye-sensitized solar energy conversion. Prolonged magnetic stirring of commercial TiO2 nanoparticles (Degussa P25) in either ethanol or water results in highly homogeneous dispersions which are used to prepare TiO2 films with surface properties which depend on the solvent used for dispersing the particles, even after sintering. The optical and mechanical properties of films cast from ethanol and water dispersions are compared, and differences in the extent of surface defects and dye binding are observed.

Solvent effects on interfacial electron transfer from Ru(4,4'-dicarboxylic acid-2,2'-bipyridine)2(NCS)2 to nanoparticulate TiO2: spectroscopy and solar photoconversion.

Resonance Raman spectra are reported for Ru(4,4'-dicarboxylic acid-2,2'-bipyridine)2(NCS)2 (commonly called "N3") in ethanol solution and adsorbed on nanoparticulate colloidal TiO2 in ethanol (EtOH) and in acetonitrile (ACN), at wavelengths within the visible absorption band of the dye. Raman cross sections of free N3 in EtOH are found to be similar to those of N3 adsorbed on colloidal TiO2 in EtOH, and are generally lower than those of N3 on TiO2 in ACN. Strong electronic coupling mediated by surface states results in red-shifted absorption spectra and enhanced Raman signals for N3 adsorbed on nanocolloidal TiO2 in ACN compared to EtOH.