Reactive Laser Ablation Synthesis of Nanosize Alumina Powder

Johnston, Gregory; Muenchausen, R. E.; Smith, Douglas M.; Fahrenholtz, William G.; Foltyn, S. R.

doi:10.1111/j.1151-2916.1992.tb04424.x

Cited by 85 publications

(31 citation statements)

References 13 publications

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“…Syntheses of nanocrystalline oxides often produce crystal structures that are not thermodynamically stable. Cubic BaTiO 3 , [10] tetragonal ZrO 2 , [11] monoclinic Y 2 O 3 , [12] and g-Al 2 O 3 [13,14] are some examples of stabilization of metastable forms in the finely divided form. It is important to establish whether the stabilization is caused by the lower surface Gibbs energy of the metastable form relative to stable variety, as suggested by the molecular dynamics simulations of Blonski and Garofalini [15] on a and g-Al 2 O 3 .…”

Section: ±1mentioning

confidence: 99%

Nanocrystalline MgAl ₂ O ₄ : Measurement of Thermodynamic Properties Using a Solid State Cell

et al. 2000

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Most materials in their nanocrystalline state exhibit unusual properties. The tremendous enhancement of mechanical, physical, and chemical properties caused by the fine admixture of order (inside the crystallites) and disorder (in the grain boundary regions) is being exploited in a number of frontier technologies. A concern in the use of nanocrystalline materials is their stability during high temperature exposure, either while processing or in service. There is no experimental data in the literature on the Gibbs energy of formation of any nanocrystalline material and no standard technique is available for measurement, especially at elevated temperatures. Quantitative information on the thermodynamic driving force for degradation to the microcystalline state and mechanistic understanding of the degradation processes would be useful in the design and processing of nanocrystalline materials for new applications. Reliable information on surface and interfacial properties of ceramic materials, which provide important guidelines for understanding nanocrystalline materials, are not available in the literature, even for model systems. Magnesium aluminate, which is used as an adsorbent for removing surfactants from aqueous solutions, as a support material for transition metal and lanthanide phosphors, and as a catalyst, was selected as a model compound in this study.Reported in this communication is a novel application of the solid state electrochemical technique for probing the thermodynamic state of nanocrystalline MgAl 2 O 4 at high temperatures. The method has been used recently for the measurement of the Gibbs energy of microcrystalline MgAl 2 O 4 .[1] Although the principle of this method for thermodynamic measurements was outlined in the classic papers of Kiukkola and Wagner, [2,3] the technique has not been applied to nanocrystalline materials. The reversible electromotive force (emf) of the cell was measured as a function of temperature in the range 900 to 1250 K. The cell is written such that the right-hand electrode is positive. Single crystal CaF 2 was used as the solid electrolyte and the cell was operated under dry oxygen. The reference electrode consisted of an intimate equimolar mixture of MgO and MgF 2 powders, compacted at a pressure of 250 MPa. Similarly, the working electrode was a compacted equimolar mixture of MgAl 2 O 4 , a-Al 2 O 3 , and MgF 2 . The particle size of the powders used to prepare the reference and working electrodes usually vary from 2 to 10 mm. In a recent study of the Gibbs energy of formation of MgAl 2 O 4 , [1] the average size of the aluminate particles used, as determined by scanning electron microscopy (SEM), was 3 mm. In the present study, the measurements were made using nanocrystalline MgAl 2 O 4 powders, keeping all other conditions the same.To obtain constant and reversible emf at any given temperature, it was necessary to remove moisture completely in the ceramic enclosure surrounding the cell. Formation of CaO on the surface of CaF 2 , by the reaction of water vapor wi...

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Section: ±1mentioning

confidence: 99%

Nanocrystalline MgAl ₂ O ₄ : Measurement of Thermodynamic Properties Using a Solid State Cell

et al. 2000

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“…Metal oxide particles can be generated by ablating metal oxide targets in an inert gas or pure metals in an oxidizing gas. For example, ablation of aluminum in the presence of oxygen can produce alumina nanoparticles of very high purity (Johnston et al 1992). Several studies have focused on the operating parameters that control particle size and morphology in laser ablation systems (Sasaki et al 1998;Camata et al 2000;Ogawa et al 2000).…”

Section: Laser Ablationmentioning

confidence: 99%

Generation and Sizing of Particles for Aerosol-Based Nanotechnology

Biskos

Vons

Yurteri

et al. 2008

KONA

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“…Until now, a large variety of methods such as sol-gel synthesis from calcination of boehmite [9], poly hydroxo aluminum-poly vinyl alcohol [10], laser ablation of an aluminum target in an oxygen atmosphere [13], hydrolysis of alumina alkoxide [14], thermal decomposition of aluminum sulfate [15], metal organic chemical vapor deposition with Al(CH 3 ) 3 [16] have been used to prepare γ-alumina.…”

Section: Introductionmentioning

confidence: 99%

Production of γ-Al<sub>2</sub>O<sub>3</sub> from Kaolin

Hosseini¹,

Niaei²,

Salari³

2011

OJPC

100

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The paper reports a process for synthesis of γ-alumina from kaolin. Kaolin was transformed to meta-kaolin by calcination at 800˚C for 2h. γ-alumina powder was synthesized through extracting alumina from metakaolin via H 2 SO 4 and meta-kaolin reactions and consequently precipitation in ethanol, which led to form the aluminum sulfate. The precipitated aluminum sulfate was dried and calcined at 900˚C for 2h, which resulted the formation of γ-alumina. The structure of γ-alumina was confirmed by XRD and FTIR and the mean particles size of γ-alumina was determined by SEM to be 0.5 -0.9 µm. The study revealed the kaolin could be promising material for preparation of γ-alumina.

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Reactive Laser Ablation Synthesis of Nanosize Alumina Powder

Cited by 85 publications

References 13 publications

Nanocrystalline MgAl ₂ O ₄ : Measurement of Thermodynamic Properties Using a Solid State Cell

Nanocrystalline MgAl ₂ O ₄ : Measurement of Thermodynamic Properties Using a Solid State Cell

Generation and Sizing of Particles for Aerosol-Based Nanotechnology

Production of γ-Al<sub>2</sub>O<sub>3</sub> from Kaolin

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Reactive Laser Ablation Synthesis of Nanosize Alumina Powder

Cited by 85 publications

References 13 publications

Nanocrystalline MgAl 2 O 4 : Measurement of Thermodynamic Properties Using a Solid State Cell

Nanocrystalline MgAl 2 O 4 : Measurement of Thermodynamic Properties Using a Solid State Cell

Generation and Sizing of Particles for Aerosol-Based Nanotechnology

Production of γ-Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; from Kaolin

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Nanocrystalline MgAl ₂ O ₄ : Measurement of Thermodynamic Properties Using a Solid State Cell

Nanocrystalline MgAl ₂ O ₄ : Measurement of Thermodynamic Properties Using a Solid State Cell

Production of γ-Al<sub>2</sub>O<sub>3</sub> from Kaolin