Structural and electrical properties of zirconium doped yttrium oxide nanostructures

A synthetic process for the formation of Zr x Y 1-x O y nanostructures is demonstrated by the reaction of yttrium nitrate hexahydrate with zirconium propoxide. The reactions are carried out at temperature 60°C and pressure 0.1 MPa. The energy dispersive X-ray (EDX) spectroscopy measurements confirm formation of Zr x Y 1-x O y nanostructures and the presence of carbonate and hydroxide species which are removed after high temperature anneals. It was found that the oxygen pressure during synthesis plays a determinant role on the structural properties of the nanostructure. This effect is further studied by atomic force microscopy (AFM) measurements and scanning electron microscope (SEM), which showed the formation of an isotopically organized structure. X-ray diffraction (XRD) measurement reveals that these changes in the nanostructural efficiency are associated with structural and compositional changes among the substrate. The dielectric constant as measured by the capacitance–voltage (C–V) technique is estimated to be around 39.05. C–V measurements taken at 1 MHz show the maximum capacitance for the Zr 0.05 Y 0.95 O y film. The leakage current densities were below 10-5 A/cm2 for the Zr 0.05 Y 0.95 O y film.

Fabrication of Al2O3/ZrO2 Micro/Nano Composites Using Powder Alkoxide Mixtures

Al2O3/ZrO2 composites have been investigated as the bio-inert material. In the present work Al2O3/ZrO2 Micro/Nano composites were prepared by colloidal method. The effects of the concentration of zirconium propoxide and the sintering temperature were studied on the distribution of ZrO2 nano-grainsin Al2O3 matrix and mechanical properties of composites. XRD patterns for all compositions showed a single phase of a-Al2O3, and the tetragonal and monoclinic ZrO2 phases. Samples sintered at 1650°C demonstrated the high bulk density with value of 86-92% of theoretical density. ZrO2 nano-grains were dispersed within Al2O3 grain and the grain boundary. The sample of the highest flexural strength of 710 MPa was synthesized using 100% Zr propoxide solution and sintered at 1650o C. The flexural strength was found to increase with increasing the concentration of Zr propoxide and sintering temperature.

Micropatterned lead zirconium titanate thin films

Micropatterning of Pb(Zr0.52Ti0.48)O3 (PZT) thin films with line features as small as 350 nm was demonstrated through capillary molding of organometallic solutions within the continuous channels of an elastomeric mold. Despite the large stresses that develop during the evaporation of the solvent, pyrolysis of the organics, and the densification and crystallization of the inorganic gel, the patterned crystalline PZT films were crack-free and mechanically robust. Flawless regions as large as 1 cm2 were obtained. The cross-sectional shape of the patterned PZT lines was trapezoidlike. Single perovskite PZT grains that formed during annealing at 600–700 °C completely filled the cross-sectional area of the patterned lines. Lead acetate, zirconium propoxide, and titanium isopropoxide were used as the starting materials. Substrates used included silver tape, stainless steel plate, silicon wafer, and platinum-coated silicon wafer.

One-pot sol-gel synthesis of sulfated ZrO2-SiO2 catalysts for alcohol dehydration

Sulfated ZrO2–SiO2 catalysts were synthesized by one-pot sol-gel method using ammonium sulfate, zirconium propoxide, and tetraethyl orthosilicate as precursors. The catalysts were characterized by N2 adsorption and DRIFTS. On calcining the gel at elevated temperature, the ammonium sulfate decomposed, giving a sulfated zirconia–silica catalyst. By adding ammonium sulfate to the sol-gel synthesis system, the surface area, pore size, and pore volume of the resultant catalyst were increased. The one-pot sol-gel synthesized catalyst with an optimum loading of SO42– 14 mol% showed significantly higher catalytic activity, with a selectivity of 100%, for isopropanol dehydration when compared to the impregnated catalyst. The one-pot sol-gel synthesis method is an effective way to prepare sulfated zirconia catalyst.Key words: sulfated zirconia, sol-gel synthesis, acid catalyst, alcohol dehydration, N2 adsorption, DRIFT.