Laser Ablation Condensation, Coalescence, and Phase Change of Dense γ-Al<sub>2</sub>O<sub>3</sub>Particles

Pan, Chiennan; Chen, Shuei-Yuan; Shen, Pouyan

doi:10.1021/jp064843+

Cited by 33 publications

(51 citation statements)

References 25 publications

(51 reference statements)

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“…Hence, in recent years, PLAL has become a successful nanomaterial fabrication tool for the formation of the novel nanostructures. 19,[21][22][23][24][25] However, compared to large investigations on fabrication of TiO 2 by laser ablation in vacuum, 7,[26][27][28][29][30][31] there were few studies on the preparation of TiO 2 nanoparticles by PLAL.…”

Section: 5mentioning

confidence: 99%

Simple Preparation of Anatase TiO₂Nanoparticles via Pulsed Laser Ablation in Liquid

Hong¹,

Lee²,

Jung³

et al. 2013

Bulletin of the Korean Chemical Society

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The physical and chemical properties of TiO 2 have been of great interest due to the potential application in photocatalytic, photovoltaic, lithium-ion battery and dye-sensitized solar cell systems.1-3 Especially, its characteristic properties in optical and electronic properties, nontoxicity, chemical inertness, and high melting temperatures have drawn extensive research on the ability of semiconductor photocatalyst to promote the photodegradation of various pollutants. 4,5Anatase, brookite, and rutile are the major crystalline structures of TiO 2 , of which rutile phase is most stable; whereas anatase and brookite phases are metastable and easily transformed to rutile phase when heated above about 600-8006,7 As demonstrated in other experimental studies, the anatase form of TiO 2 has shown much higher photoactivity than that of rutile. 3,5,8,9 In the meantime, a number of methods have been explored and developed for the synthesis of TiO 2 nanoparticles, such as hydrolysis of Ti(IV) ions, 10 hydrolysis of titanium alkoxides 11 or titanium tetrachloride 12 in gas phase, sol-gel, 13hydrothermal hydrolysis, 14 and precipitation, 15 of which many studies were devoted to the synthesis of rutile phase, while fewer investigations on the anatase phase. This naively supports that synthesis of pure anatase phase is more challenging than that of rutile. Furthermore, the major products from the above techniques are typically amorphous and require post-calcination for better crystallinity and morphology of the product, which inevitably results in the formation of larger sizes of TiO 2 nanoparticles. Therefore, it is demanding to explore a method that overcomes the problems mentioned above.In order to fabricate small-sized TiO 2 nanoparticles with good crystallinity at room temperature, we have applied a pulsed laser to ablate a Ti plate immersed in deionized water and methanol. Pulsed laser ablation in liquid (PLAL) 16 was introduced by Patil and co-workers in 1987 and has been demonstrated to be an effective, simple, and versatile method for synthesizing nanomaterials starting from an appropriate choice of solids and liquids.17-20 Because of relatively simple and clean preparation of nanoparticles using PLAL, coupled with its versatility, many different metal nanostructures providing desired functions have been fabricated. One of the main advantages of PLAL compared to other methods is that it can generate nanomaterials without the need of any catalysts or organic additives. Hence, in recent years, PLAL has become a successful nanomaterial fabrication tool for the formation of the novel nanostructures.19,21-25 However, compared to large investigations on fabrication of TiO 2 by laser ablation in vacuum, 7,26-31 there were few studies on the preparation of TiO 2 nanoparticles by PLAL.32-34 Furthermore in the previous PLAL studies, the synthesis of rutile and mixture of anatase and rutile phase was mostly employed. 34,35In the present note, we report a one-step synthesis of pure anatase TiO 2 nanoparticles by PLA of Ti pla...

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Section: 5mentioning

confidence: 99%

Simple Preparation of Anatase TiO₂Nanoparticles via Pulsed Laser Ablation in Liquid

Hong¹,

Lee²,

Jung³

et al. 2013

Bulletin of the Korean Chemical Society

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“…Lattice parameters and Birch-Murnaghan equation of state (EOS) were used for the estimation of residual stress up to several GPa for the condensates thus formed. Recently, dense g-Al 2 O 3 condensates with a residual compressive stress up to 3 GPa and an unexpected micrometer size were synthesized by the same laserablation technique [11]. Residual stress and {1 1 1}/{1 0 0} surface were suggested to suppress the transformation of abnormal large-sized g-condensates to the stable a-Al 2 O 3 form [11].…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence and transformation of dense Al2O3:Cr3+ condensates synthesized by laser-ablation route

Pan

Chen

Shen

2008

Journal of Crystal Growth

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“…10 Owing to the general availability and unique characteristics, such as good structural, chemical and thermal stability at elevated temperatures, high electrical resistivity, low gate leakage, and excellent behavior in optics and electronics, Al 2 O 3 in both amorphous and polymorphs (material with similar composition but different crystal structure) forms are registered among the technologically most crucial ceramic materials. [11][12][13][14][15][16][17]27,28 In this Letter, we evaluated the effects of ordered/disordered structures of Al 2 O 3 NPs, volume fraction, and temperatures on the TC enhancement in EG nanofluid for different volume concentrations. As described in a previous work, three different structures of NPs, i.e., amorphous and crystalline c-, and a-Al 2 O 3 , were synthesized by sol-gel method.…”

Section: O 3 Nanoparticlesmentioning

confidence: 99%

“…The long-range order in nano-crystalline may resist to the liquid-particle interface and resulted in the lower enhanced TC of the crystalline c-and a-Al 2 O 3 /EG nanofluids. Moreover, the amorphous structure of Al 2 O 3 has random distribution of Al 3þ and vacancies over tetrahedral (AlO 4 ), polyhedral (AlO 5 ), and octahedral (AlO 6 ) sites with the prominent tetrahedral and octahedral units; whereas the crystal structure of c-Al 2 O 3 is composed of a mixture of tetrahedral and 12,15,27,28 We infer that the predominant fractions of a-Al 2 O 3 NPs may highly interact with the base-fluid and enhance the TC of nanofluids. The lower TC enhancement achieved by the crystalline c-and a-Al 2 O 3 /EG nanofluids can be ascribed due to the presence of short-range interfacing between solid-particle and liquidphase as compared to the a-Al 2 O 3 /EG nanofluids.…”

mentioning

confidence: 99%

Strong enhancement in thermal conductivity of ethylene glycol-based nanofluids by amorphous and crystalline Al2O3 nanoparticles

Gangwar

Srivastava

Tripathi

et al. 2014

Applied Physics Letters

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In the present work, the temperature and concentration dependence of thermal conductivity (TC) enhancement in ethylene glycol (EG)-based amorphous and crystalline Al2O3 nanofluids have been investigated at temperatures ranging from 0 to 100 °C. In our prior study, nanometer-sized particles of amorphous-, γ-, and α-Al2O3 were prepared via a simple sol-gel process with annealing at different temperatures and characterized by various techniques. Building upon the earlier study, we probe here the crystallinity, microstructure, and morphology of the obtained α-Al2O3 nanoparticles (NPs) by using X-ray powder diffraction with Rietveld full-profile refinement, scanning electron microscopy, and high-resolution transmission electron microscopy, respectively. In this study, we achieved a 74% enhancement in TC at higher temperature (100 °C) of base fluid EG by incorporating 1.0 vol. % of amorphous-Al2O3, whereas 52% and 37% enhancement is accomplished by adding γ- and α-Al2O3 NPs, respectively. The amorphous phase of NPs appears to have good TC enhancement in nanofluids as compared to crystalline Al2O3. In a nutshell, these results are demonstrating the potential consequences of Al2O3 NPs for applications of next-generation efficient energy transfer in nanofluids.

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Laser Ablation Condensation, Coalescence, and Phase Change of Dense γ-Al₂O₃Particles

Cited by 33 publications

References 25 publications

Simple Preparation of Anatase TiO₂Nanoparticles via Pulsed Laser Ablation in Liquid

Simple Preparation of Anatase TiO₂Nanoparticles via Pulsed Laser Ablation in Liquid

Photoluminescence and transformation of dense Al2O3:Cr3+ condensates synthesized by laser-ablation route

Strong enhancement in thermal conductivity of ethylene glycol-based nanofluids by amorphous and crystalline Al2O3 nanoparticles

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Laser Ablation Condensation, Coalescence, and Phase Change of Dense γ-Al2O3Particles

Cited by 33 publications

References 25 publications

Simple Preparation of Anatase TiO2Nanoparticles via Pulsed Laser Ablation in Liquid

Simple Preparation of Anatase TiO2Nanoparticles via Pulsed Laser Ablation in Liquid

Photoluminescence and transformation of dense Al2O3:Cr3+ condensates synthesized by laser-ablation route

Strong enhancement in thermal conductivity of ethylene glycol-based nanofluids by amorphous and crystalline Al2O3 nanoparticles

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Product

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Laser Ablation Condensation, Coalescence, and Phase Change of Dense γ-Al₂O₃Particles

Simple Preparation of Anatase TiO₂Nanoparticles via Pulsed Laser Ablation in Liquid

Simple Preparation of Anatase TiO₂Nanoparticles via Pulsed Laser Ablation in Liquid