Synthesis of β″-Alumina Polymer Precursor and Ultrafine β″-Alumina Composition Powders

Treadwell, David R.; Sutorik, Anthony C.; Neo, Siew Siang; Laine, Richard M.; Svedberg, Robert C.

doi:10.1021/bk-1998-0681.ch014

Cited by 5 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This process has the potential to produce composite mixed-metal oxide powders in the size range of 1 to 200 nm from low cost precursors [90] with production rates up to 250 g/h, as was summarized recently by Laine et al [19,91]. Typical products synthesized are titania [92] and MgAl 2 O 4 [93], gamma-Fe 2 O 3 [94], alumina [93], manganese oxide, zirconia, and zirconia-ceria [87, 95±97] particles, or very specific functional particles such as beta¢¢-alumina for high temperature solid electrolytes [98,99], to name a few. These processes clearly differ from the conventional spray pyrolysis [100] as the precursor is released from the droplet environment undergoing gas phase reaction and subsequent particle growth by coagulation, surface growth and sintering.…”

Section: Nanoparticles By Combustion Of Liquid Dropletsmentioning

confidence: 99%

Flame Synthesis of Nanoparticles

Kammler

Mädler

Pratsinis³

2001

Chem. Eng. Technol.

394

208

View full text Add to dashboard Cite

An overview of recent advances in the synthesis of nanoparticles by flame aerosol processes is given. In flame processes with gaseous precursors emphasis is placed on reactant mixing and composition, additives, and external electric fields for control of product characteristics. Thermophoretic sampling can monitor the formation and growth of nanoparticles, while the corresponding temperature history can be obtained by non-intrusive Fourier transform infrared spectroscopy. Furthermore, synthesis of composite nanoparticles for various applications is addressed such as in reinforcement or catalysis as well as for scale-up from 1 to 700 g/h of silica-carbon nanostructured particles. In flame processes with liquid precursors using the so-called flame spray pyrolysis (FSP), emphasis is placed on reactant and fuel composition. The FSP processes are quite attractive as they can employ a wide array of precursors, so a broad spectrum of new nanosized powders can be synthesized. Computational fluid dynamics (CFD) in combination with gas-phase particle formation models offer unique possibilities for improvement and possible new designs for flame reactors.

show abstract

Section: Nanoparticles By Combustion Of Liquid Dropletsmentioning

confidence: 99%

Flame Synthesis of Nanoparticles

Kammler

Mädler

Pratsinis³

2001

Chem. Eng. Technol.

394

208

View full text Add to dashboard Cite

show abstract

“…[33][34][35] Because we can control compositional make-up to ppm levels, it is possible to also dope pure materials for photonic, electronic, and catalytic applications. LF-FSP also provides access to complex mixed-metal oxide materials including mullite, Y 3 Al 5 O 12 , SrSi 2 Al 2 O 8 , and b 00 Al 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

“…LF-FSP also provides access to complex mixed-metal oxide materials including mullite, Y 3 Al 5 O 12 , SrSi 2 Al 2 O 8 , and b 00 Al 2 O 3 . [33][34][35] Because we can control compositional make-up to ppm levels, it is possible to also dope pure materials for photonic, electronic, and catalytic applications. 36,37 In the latter arena, we have recently demonstrated that we can process materials along the TiO 2 -Al 2 O 3 , NiO-Al 2 O 3 , ZnO-Al 2 O 3 , and MgO-Al 2 O 3 tie lines with the discovery of several unusual phase compositions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Mixed‐Metal Oxide Nanopowders Along the CoO_x–Al₂O₃ Tie Line Using Liquid‐Feed Flame Spray Pyrolysis

Azurdia

Marchal

Laine

2006

Journal of the American Ceramic Society

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…Apenas um aluminato de manganês com estrutura semelhante à fase espinélio galaxita pôde ser observado. A ausência dos picos de cristalização de γ-Al 2 O 3 e transformação para α-Al 2 O 3 na ATD é coerente com os dados de difração de raios X e indica a cristalização do espinélio em temperaturas mais baixas, assim como para a formação de β-aluminas [17,18]. Para a Al 2 O 3 contendo 5 mol% Mn é observado efeito semelhante (Fig.…”

Section: Resultsunclassified

Efeito do vapor d'água na síntese pelo método do precursor polimérico da alumina contendo aditivos

Castro

Gouvêa

2005

Cerâmica

View full text Add to dashboard Cite

A presença de H2O nos processos de síntese e transformação de fase da alumina tem usualmente função catalisadora, diminuindo as temperaturas dos processos e facilitando os possíveis rearranjos atômicos. Neste trabalho mostrou-se que o vapor de H2O durante a síntese pode não apenas acelerar os processos diminuindo as energias de ativação, mas também induzir diferentes formas de ação de aditivos. O estudo foi possível utilizando-se o método dos precursores poliméricos para a síntese dos pós, que permite um controle absoluto do teor de H2O na etapa de cristalização do material. Alumina contendo Mn ou Mg como aditivos foram sintetizadas na ausência de H2O e na presença de excesso controlado desta e fases diferentes para cada situação foram observadas. Uma explicação do fenômeno é descrita em função da dependência da cristalização da gama-Al2O3 na presença de H+ para compensação das vacâncias catiônicas.

show abstract

Synthesis of β″-Alumina Polymer Precursor and Ultrafine β″-Alumina Composition Powders

Cited by 5 publications

References 0 publications

Flame Synthesis of Nanoparticles

Flame Synthesis of Nanoparticles

Synthesis and Characterization of Mixed‐Metal Oxide Nanopowders Along the CoO_x–Al₂O₃ Tie Line Using Liquid‐Feed Flame Spray Pyrolysis

Efeito do vapor d'água na síntese pelo método do precursor polimérico da alumina contendo aditivos

Contact Info

Product

Resources

About

Synthesis of β″-Alumina Polymer Precursor and Ultrafine β″-Alumina Composition Powders

Cited by 5 publications

References 0 publications

Flame Synthesis of Nanoparticles

Flame Synthesis of Nanoparticles

Synthesis and Characterization of Mixed‐Metal Oxide Nanopowders Along the CoOx–Al2O3 Tie Line Using Liquid‐Feed Flame Spray Pyrolysis

Efeito do vapor d'água na síntese pelo método do precursor polimérico da alumina contendo aditivos

Contact Info

Product

Resources

About

Synthesis and Characterization of Mixed‐Metal Oxide Nanopowders Along the CoO_x–Al₂O₃ Tie Line Using Liquid‐Feed Flame Spray Pyrolysis