Advances in Nanoalumina Ceramic Particle Fabrication Using Sonofragmentation
TL;DR: In this article, the effects of various parameters such as ultrasonic frequency, feed concentration, sonication time, surfactant, and applied ultrasonic power on sonofragmentation were investigated.
Abstract: The present study is focused on fabrication of high-purity submicrometer alumina ceramic particles (predominantly in sub-100 nm range) from micrometer-sized feed (e.g., 70-80 mum) using sonofragmentation. The effects of various parameters such as ultrasonic frequency, feed concentration, sonication time, surfactant, and applied ultrasonic power on sonofragmentation were investigated. Sub-100 nm particle production by sonofragmentation was validated via three metrics, i.e., laser particle size analysis, high-resolution transmission electron microscopy, and turbidimetry. There is a significant change in color and shape of alumina ceramic particles as a result of sonofragmentation. Higher size reduction ratios are obtained at lower frequencies and at higher input power. Submicrometer particle generation increases as concentration of the feed particles increases, indicating that attrition by interparticle collision is a significant mechanism. The shape of the particles changes from angular to spherical as sonofragmentation time increases. Probe-type sonication produces fragmentation effects that are less uniform than those induced by tank-type ultrasonics. Surfactant plays a significant role in preventing agglomeration, especially as finer fragments are produced with prolonged sonication.
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TL;DR: The individual and mutual effect of important input parameters on the nanomaterial synthesis process as a start to help understand the underlying mechanism is discussed and an objective discussion of the diversely synthesizednanomaterial follows to divulge the easiness imparted by sonochemistry.
239 citations
Cites background from "Advances in Nanoalumina Ceramic Par..."
...Like power, ultrasound frequency and surfactants affect the process such that low frequency and addition of relevant surfactant enhances cavitation and promotes sonofragmentation [197]....
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...require stabilizers and unnecessary power and post-processing [197]....
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...Sonication of aqueous slurry of micrometer-sized alumina showed a decrease in particle size while increasing power and decreasing frequency, and a uniform size distribution when continued for prolonged time [83][197]....
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04 Jul 2018
TL;DR: In this paper, the effects of ultrasound on the crystallization of organic molecules are discussed and the effect of various experimental parameters and empirical products of sonocrystallization have been reported, but the mechanisms of sonomerization and sonofragmentation have not been confirmed clearly.
Abstract: When ultrasound is applied to a solution for crystallization, it can affect the properties of the crystalline products significantly. Ultrasonic irradiation decreases the induction time and metastable zone and increases the nucleation rate. Due to these effects, it generally yields smaller crystals with a narrower size distribution when compared with conventional crystallizations. Also, ultrasonic irradiation can cause fragmentation of existing crystals which is caused by crystal collisions or sonofragmentation. The effect of various experimental parameters and empirical products of sonocrystallization have been reported, but the mechanisms of sonocrystallization and sonofragmentation have not been confirmed clearly. In this review, we build upon previous studies and highlight the effects of ultrasound on the crystallization of organic molecules. In addition, recent work on sonofragmentation of molecular and ionic crystals is discussed.
81 citations
TL;DR: Conventional chemical-based soaking and stirring methods are compared here to ultrasonic methods of de-sulfurization, which have the main advantages of ultrasonic de-Sulfurized over conventional methods, the mechanism involved in ultrasonicDe-solfurization and the difference between aqueous-based and solvent-based (2N HNO(3), 3-volume percentage H(2)O(2)) de-magnifying methods are investigated experimentally.
58 citations
TL;DR: In this article, the authors investigated utilization of ultrasound in reagent-based coal de-ashing and de-sulfurization and derived an empirical model for the prediction of total sulfur removal.
Abstract: The present work investigates utilization of ultrasound in reagent-based coal de-ashing and de-sulfurization. The coal under study was received from Girald mine, Rajasthan, India. Three different ultrasonic frequencies (25 kHz, Dual (58/192 kHz) and 430 kHz) and three reagents (HCl, HNO 3 and H 2 O 2 ) were used. The study employed a Taguchi fractional-factorial L 27 DOE. Experimental data were used to derive an empirical model for the prediction of total sulfur removal. The model incorporates cavitational intensity, reagent concentration, sonication time, coal particle size and coal concentration as key parameters. Effects of above factors on reagent-based ultrasonic coal-desulfurization are presented here. An optimum set of process parameters are identified and validated. Larger-scale trial with high-ash and high-sulfur coals is strongly recommended.
45 citations
TL;DR: This sonication technique may be considered as a simple and promising route to prepare ultrafine nanoparticles for functional applications to synthesize ultra fine nanoparticles directly from bulk multiferroic perovskite powder.
Abstract: We present a simple technique to synthesize ultrafine nanoparticles directly from bulk multiferroic perovskite powder. The starting materials, which were ceramic pellets of the nominal compositions Bi0.9Gd0.1Fe1−xTixO3 (x = 0.00–0.20), were prepared initially by a solid state reaction technique, then ground into micrometer-sized powders and mixed with isopropanol or water in an ultrasonic bath. The particle size was studied as a function of sonication time with transmission electron microscopic imaging and electron diffraction that confirmed the formation of a large fraction of single-crystalline nanoparticles with a mean size of 11–13 nm. A significant improvement in the magnetic behavior of Bi0.9Gd0.1Fe1−xTixO3 nanoparticles compared to their bulk counterparts was observed at room temperature. This sonication technique may be considered as a simple and promising route to prepare ultrafine nanoparticles for functional applications.
40 citations
References
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TL;DR: In this article, a sonication procedure was performed on talc with sizes in the submicrometer range and the resulting materials presented a narrow particle size distribution and retained the crystalline structure of the parent mineral, as assayed by X-ray diffraction and FTIR spectroscopy experiments.
94 citations
"Advances in Nanoalumina Ceramic Par..." refers background in this paper
...reduction of talc powder [13], showing that the sonicated talc powder had significantly finer mean and median particle sizes, narrower particle-size distributions, and less angular morpholo-...
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TL;DR: In this paper, a semi-empirical expression that relates fragmentation rate to particle size, suspension volume and ultrasonic power was derived for both eroding and non-eroding powders.
68 citations
"Advances in Nanoalumina Ceramic Par..." refers background in this paper
...Ultrasonic fragmentation of alumina particles [8], [9] to produce a fine fraction of crystalline materials to produce particles in the 10-μm-size range, and of kaolinite [10] in the 1–2-μm-size range are examples of studies reported in literature....
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...fragmentation of powders [9], the energy consumption per unit mass is less compared to ball milling for eroding particles (like silica and zirconia)....
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25 Aug 2004-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, Magnesia-doped alumina nano-powders were synthesized using sucrose as a chelating agent and template material from the aqueous solutions of aluminium nitrate, magnesium oxide, ytrrium nitrate and zirconyl nitrate.
Abstract: Magnesia–doped alumina and yttria–doped zirconia nano-powders were synthesized using sucrose as a chelating agent and template material from the aqueous solutions of aluminium nitrate, magnesium nitrate, ytrrium nitrate and zirconyl nitrate, respectively. Synthesis parameters were optimized with varying sucrose to metal ion ratio, calcinations time, and temperature to produce these nano-powders. As-synthesized powders were characterized by room temperature X-ray diffraction, BET surface area analyzer and transmission electron microscopy. Y 2 O 3 –ZrO 2 nano-powders had particle size in the range of 80–200 nm with specific average surface area of 119 m 2 /g and for MgO–Al 2 O 3 powders, particle sizes were 30–200 nm with the specific average surface area of 250 m 2 /g. Our results indicate that this synthesis method is a versatile one and can be applied to a variety of oxide-based materials to form nano-powders. Nano-powders were compacted uniaxially and densified in a muffle furnace. Sintered discs were used for hardness testing and density measurements, as well as for microstructural characterization.
65 citations
TL;DR: In this article, a solid state reduction reaction of ZnO and Al powder mixtures induced by mechanical alloying has been investigated, and it is revealed that the reduction product consists of crystalline zinc and amorphous alumina particles with nanometer sizes of 10-50 nm.
60 citations
"Advances in Nanoalumina Ceramic Par..." refers background in this paper
...Fragmentation by conventional attritional means such as grinding or milling is reported widely in literature, but contamination from the milling material, as well as energy efficiency, are definite drawbacks [2]–[6]; comminution by high-intensity ultrasound has also been studied [7]–[14], but to a lesser extent....
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TL;DR: Both sonoluminescence and passive cavitation detection were used to examine the acoustic cavitation field generated at different acoustic pulse lengths in the presence of an anionic surfactant, sodium dodecyl sulfate (SDS), and a decrease in the SL intensity was observed.
Abstract: It has previously been reported that the addition of low concentrations of ionic surfactants enhances the steady-state sonoluminescence (SL) intensity relative to water (Ashokkumar; et al. J. Phys. Chem. B 1997, 101, 10845). In the current study, both sonoluminescence and passive cavitation detection (PCD) were used to examine the acoustic cavitation field generated at different acoustic pulse lengths in the presence of an anionic surfactant, sodium dodecyl sulfate (SDS). A decrease in the SL intensity was observed in the presence of low concentrations of SDS and short acoustic pulse lengths. Under these conditions, the inhibition of bubble coalescence by SDS leads to a population of smaller bubbles, which dissolve during the pulse "off time". As the concentration of surfactant was increased at this pulse length, an increase in the acoustic cavitation activity was observed. This increase is partly attributed to enhanced growth rate of the bubbles by rectified diffusion. Conversely, at long pulse lengths acoustic cavitation activity was enhanced at low SDS concentrations as a larger number of the smaller bubbles could survive the pulse "off time". The effect of reduced acoustic shielding and an increase in the "active" bubble population due to electrostatic repulsion between bubbles are also significant in this case. Finally, as the surfactant concentration was increased further, the effect of electrostatic induced impedance shielding or reclustering dominates, resulting in a decrease in the SL intensity.
44 citations
"Advances in Nanoalumina Ceramic Par..." refers background in this paper
...It has been reported in [15] that addition of low concentra-...
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