Fabrication of lanthanum copper oxide nanofibers by electrospinning.

摘要

For about 75 years electrospinning has been explored as a simple and versatile method to produce nanofibers. Since electrospinning was introduced in the 1930s, most researchers have focused on fabrication and theoretical work for polymer nanofibers. Recently, more than 40 ceramic nanofibers were produced by electrospinning. However, few theoretical works have been performed on ceramic electrospinning.; The objectives of this dissertation were to study the relationships among variables and responses using response surface methodology and to applying this to ceramic electrospinning theory.; The theory was applied in the fabrication of ceramic nanofibers. Lanthanum nitrate/copper nitrate/polyacrylamide composite nanofibers were prepared by combining a sol-gel process and electrospinning. Porous lanthanum copper oxide nanofibers with diameters ranging from 75 nm to 175 nm were obtained by calcination of composite fibers.; Responses dependent on experimental conditions were studied in polymer electrospinning and ceramic electrospinning, independently. In both types of electrospinning, solution parameters were found to be more important than process parameters in determining responses (fiber diameters, bead density). With varying ceramic precursor concentrations, fiber diameters decrease first, then increase though the conductivities increase continuously. Bead density shows the opposite trend. Regression analysis shows that bead density is inversely proportional to (fiber diameter)3 (sigmaBead ∝ 1h3 where sigmaBead is the bead density and h is the fiber diameter); Polymer (polyacrylamide) electrospinning and ceramic (lanthanum copper oxide) electrospinning was compared using the same parameters (pH, voltage). Ceramic electrospinning showed similar trends compared to polymer electrospinning although the electrospinning solution contained ceramic precursors. A higher conductivity of ceramic electrospinning solution produced thinner fibers. Additionally, it was verified experimentally that the proposed model in the polymer system could be applied to a ceramic system.; Using the lanthanum copper oxide nanoparticles, three planar sensors were fabricated over tape-cast yttria-stabilized zirconia substrate with screen-printed electrodes. Sensing characteristics such as sensitivity, stability, signal to noise ratio, and response time were studied with varying NO gas concentration and temperature. At 450°C, sensitivity was 6.44 mV/log (ppm) and response time was 29.2 seconds. Electrospinning was found to be an effective route for the preparation of dispersible nanoparticles.