Titanium oxide compounds TiO, Ti2O3, and TiO2 with a considerable extent of nonstoichiometry were fabricated by pulsed laser ablation in water and characterized by X-ray/electron
diffraction, X-ray photoelectron spectroscopy and electron energy loss spectroscopy. The titanium oxides were found to occur
as nanoparticle aggregates with a predominant 3+ charge and amorphous microtubes when fabricated under an average power density
of ca. 1 × 108 W/cm2 and 1011 W/cm2, respectively followed by dwelling in water. The crystalline colloidal particles have a relatively high content of Ti2+ and hence a lower minimum band gap of 3.4 eV in comparison with 5.2 eV for the amorphous state. The protonation on both crystalline
and amorphous phase caused defects, mainly titanium rather than oxygen vacancies and charge and/or volume-compensating defects.
The hydrophilic nature and presumably varied extent of undercoordination at the free surface of the amorphous lamellae accounts
for their rolling as tubes at water/air and water/glass interfaces. The nonstoichiometric titania thus fabricated have potential
optoelectronic and catalytic applications in UV–visible range and shed light on the Ti charge and phase behavior of titania-water
binary in natural shock occurrence. 相似文献
The influence of the target material, fluence, laser wavelength, and nitrogen pressure on the synthesis of AlN nanosized powders via reactive laser ablation has been investigated. Using infrared laser radiation and fluences of ≥11 J/cm2, pure AlN nanosized powders were produced at nitrogen pressures of ≥1.3 kPa via ablation of an AlN target and ≥13.3 kPa via ablation of an aluminum target. With ultraviolet laser radiation, AlN powders could be synthesized at a lower fluence (9 J/cm2 at a pressure of 8 kPa). The mean powder size was 7.5−15 nm. 相似文献
An overview of pulsed laser-assisted methods for nanofabrication, which are currently developed in our Institute (LP3), is presented. The methods compass a variety of possibilities for material nanostructuring offered by laser–matter interactions and imply either the nanostructuring of the laser-illuminated surface itself, as in cases of direct laser ablation or laser plasma-assisted treatment of semiconductors to form light-absorbing and light-emitting nano-architectures, as well as periodic nanoarrays, or laser-assisted production of nanoclusters and their controlled growth in gaseous or liquid medium to form nanostructured films or colloidal nanoparticles. Nanomaterials synthesized by laser-assisted methods have a variety of unique properties, not reproducible by any other route, and are of importance for photovoltaics, optoelectronics, biological sensing, imaging and therapeutics. 相似文献
In this article we report the preparation of new arylazophosphonate‐containing polymers, poly(arylazophosphonates), via polycondensation reactions of bifunctional hydroxy functionalized arylazophosphonate‐containing monomers with isocyanate or acid chloride comonomers. The polyurethanes and polyesters were characterized by common methods such as 1H, 13C, 31P NMR, FTIR, UV/visible spectroscopy, DSC, and GPC measurements. In addition, a number of polymer structuring experiments (macro and micro experiments) by means of laser ablation with a XeCl excimer laser were performed. In macro experiments, pulse number and fluence were investigated systematically and their influence on the ablation depth was discovered. In micro experiments, structures of high quality were obtained which possess clear contours without any debris on the polymer surface. Structures in the sub micron range were created by applying a phase mask. These high quality results indicate that the poly(arylazophosphonates) are well suited materials for laser ablation structuring with XeCl excimer lasers (e.g. for microstructuring or microlithography).
SEM image of sub micro structures of polymer APU 5 generated in experiments using a phase mask (line width: 0.3–0.5 μm, trench width: 0.3–0.5 μm, fluence: 3 J/cm2). 相似文献
