Hein, F.; Albert, P. W., Zeitschrift fur Anorganische und Allgemeine Chemie
摘要:
DOI:
作为产物:
描述:
三乙醇胺 、 aluminum tri-sec-butoxide 以
not given 为溶剂,
生成 次氮基三乙氧化铝
参考文献:
名称:
Combinatorial Nanopowder Synthesis Along the ZnO-Al2O3Tie Line Using Liquid-Feed Flame Spray Pyrolysis
摘要:
Liquid‐feed flame spray pyrolysis (LF‐FSP) of mixtures of alumatrane [Al(OCH2CH2)3N]/zinc acetate dihydrate [Zn(O2CCH3)2·2(H2O)] or zinc propionate [Zn(O2CCH2CH3)2]/aluminum acetylacetonate [Al(Acac)3] dissolved in EtOH in known molar ratios can be used to combinatorially generate nanopowders along the ZnO–Al2O3tie‐line. LF‐FSP was used to produce (ZnO)x(Al2O3)1−xpowders withx=0–1.0. Powders were characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, thermal gravimetric analysis, differential thermal analysis, and BET. The resulting powders had average particle sizes (APSs) <100 nm with the majority being <50 nm. Analytical data suggest that at concentrations of interest for transparent conducting oxides, <10 mol% Al2O3the particle morphologies are combinations of plates and rods that grow withc/aratios close to 1. The spinel phase dominates at (ZnO)x(Al2O3)1−x(x=0.5 and 0.3). In the latter case, the currently accepted phase diagram for the ZnO–Al2O3couple indicates that phase separation should occur to form zinc spinel (ZnAl2O4) and α‐alumina. It appears that the rapid quenching during LF‐FSP helps to preserve the spinel phase at ambient temperature giving rise to kinetic nanopowder products along the ZnO2–Al2O3tie‐line. Finally, the solubility of ZnO in Al2O3and vice versa in the materials produced by LF‐FSP suggest apparent flame temperatures reached before quenching are 1700°–1800°C. Efforts to re‐pass the spinel phase powders, (ZnO)x(Al2O3)1−x,x=0.5 and 0.3 through the LF‐FSP system were made with the hope of generating core shell materials. However, instead thex=0.5 material generated materials closer to thex=0.3 composition and pure ZnO nanoparticles that coat the former materials. These results suggest that at LF‐FSP flame temperatures ZnO remains in the vapor phase for sufficient times that Al3+oxy‐ions generated promote nucleation of finer particles leaving essentially phase pure ZnO still in the vapor phase to condense giving the two distinct particle morphologies observed.
Flame Spray Pyrolysis of Precursors as a Route to Nano-mullite Powder: Powder Characterization and Sintering Behavior
作者:Rita Baranwal、Maria P. Villar、Rafael Garcia、Richard M. Laine
DOI:10.1111/j.1151-2916.2001.tb00774.x
日期:2001.5
The flamespraypyrolysis of alcohol-soluble precursors allows the synthesis of mullite-composition nanopowders (average size of ;60 ‐100 nm) that, when annealed carefully, provide processable nano-mullite powders. The powders have been characterized using several spectroscopic and microscopy methods, including thermal gravimetric analysis, differential thermal analysis, diffuse reflectance infrared
Synthesis and Characterization of Mixed-Metal Oxide Nanopowders Along the CoOx-Al2O3 Tie Line Using Liquid-Feed Flame Spray Pyrolysis
作者:Jose Azurdia、Julien Marchal、Richard M. Laine
DOI:10.1111/j.1551-2916.2006.01155.x
日期:——
We report here the use of liquid‐feed flame spray pyrolysis (LF‐FSP) to produce a series of nanopowders along the CoOx–Al2O3 tie line. The process is a general aerosol combustion synthesis route to a wide range of lightly agglomerated oxide nanopowders. The materials reported here were produced by aerosolizing ethanol solutions of alumatrane [Al(OCH2CH2)3N] and a cobalt precursor, made by reacting Co(NO3)2·6H2O crystals with propionic acid. The compositions of the as‐produced nanopowders were controlled by selecting the appropriate ratios of the precursors. Nine samples with compositions (CoO)y(Al2O3)1−y, y=0−1 along the CoOx–Al2O3 tie line were prepared and studied. The resulting nanopowders were characterized by X‐ray fluorescence, BET, scanning electron microscopy, high‐resolution transmission electron micrographs, X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and FTIR. The powders typically consist of single‐crystal particles <40 nm diameter and specific surface areas (SSAs) of 20–60 m2/g. XRD studies show a gradual change in powder patterns from δ‐Al2O3 to Co3O4. The cobalt aluminate spinel phase is observed at stoichiometries (21 and 37 mol%) not seen in published phase diagrams, likely because LF‐FSP processing involves a quench of >1000°C in microseconds frequently leading to kinetic rather than thermodynamic products. Likewise, the appearance of Co3O4 rather than CoO as the end member in the tie line is thought to be a consequence of the process conditions. TGA studies combined with diffuse reflectance FTIR spectroscopic studies indicate that both physi‐ and chemi‐sorbed H2O are the principal surface species present in the as‐processed nanopowders. The only sample that differs is Co3O4, which has some carbonate species present that are detected and confirmed by a sharp mass loss event at ∼250°C. The thermal behavior of the high cobalt content samples differs greatly from the low cobalt content samples. The latter behave like most LF‐FSP‐derived nanopowders exhibiting typical 1%–4% mass losses over the 1400°C range due mostly to loss of water and some CO2. The high cobalt content samples exhibit a sharp mass loss event that can be attributed to the decomposition of Co3O4 to CoO.
Pressureless Sintering<i>t</i>-zirconia@δ-Al<sub>2</sub>O<sub>3</sub>(54 mol%) Core-Shell Nanopowders at 1120°C Provides Dense<i>t</i>-Zirconia-Toughened α-Al<sub>2</sub>O<sub>3</sub>Nanocomposites
作者:Min Kim、Richard M. Laine
DOI:10.1111/j.1551-2916.2009.03498.x
日期:2010.3
Zirconia‐toughened alumina (ZTA) is of growing importance in a wide variety of fields exemplified by ZTA prosthetic implants. Unfortunately, ZTA composites are generally difficult to process because of the need to preserve the tetragonal zirconia phase in the final dense ceramic, coincident with the need to fully densify the α‐Al2O3 component. We report here that liquid‐feed flame spray pyrolysis of mixtures of metalloorganic precursors of alumina and zirconia at varying compositional ratios provide access in one step to core–shell nanoparticles, wherein the shell is δ‐Al2O3 and the core is a perfect single crystal of tetragonal (t‐) zirconia. Pressureless sintering studies provided parameters whereby these nanopowder compacts could be sintered to full density (>99%) at temperatures just above 1100°C converting the shell component to α‐Al2O3 but preserving the t‐ZrO2 without the need for any dopants. The final average grain sizes of these sintered compacts are ≤200 nm. The resulting materials exhibit the expected response to mechanical deformation with the subsequent production of monoclinic ZrO2. These materials appear to offer a low‐temperature, low‐cost route to fine‐grained ZTA with varied Al2O3:t‐ZrO2 compositions.