The impact of nanocrystallite size and shape on phase transformation: Application to the boehmite/alumina transformation

Karouia, Fathi; Boualleg, Malika; Digne, Mathieu; Alphonse, Pierre

doi:10.1016/j.apt.2016.06.014

Cited by 27 publications

(18 citation statements)

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“…While the previous studies have shown that the heating for more than ~2 h above 300 ºC does not cause significant changes in the degree of phase transformation and/or dehydration (e.g., Xu and Smith, 2012;Kim and Lee, 2013a, b; Ryu, 2018 and references therein), the effect of annealing time on the dehydration in the low-temperature range remains to be explored. Furthermore, the stability fields of metastable aluminas are dependent on their physical properties (i.e., particle sizes, permeability, and surface area) (Sun et al, 2008;Kim and Lee, 2013b;Karouia et al, 2016).…”

Section: Quantification Of Coexisting Phases In the Heat-treated Alummentioning

confidence: 99%

“…The phase transformation paths from aluminum (oxy)hydroxides to stable -Al 2 O 3 via metastable aluminas have been extensively explored (e.g., Levin and Brandon, 1998;Digne et al, 2002;Chandran et al, 2019 and references therein). The transformation temperatures are also affected by various factors such as particle size (IngramJones et al, 1996;Tsukada et al, 1999;Bokhimi et al, 2007;Kim and Lee, 2013b), morphology (Lee et al, 2015;Karouia et al, 2016), and synthesis conditions (Kim et al, 2005;Chen et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Diverse experimental techniques such as differential thermal analysis (DTA), infrared (IR) spectroscopy, X-ray diffraction (XRD), and solid-state nuclear magnetic resonance (NMR) have observed phase transformation from aluminum (oxy)hydroxides into metastable aluminas (e.g., Bastow et al, 1994;Tsukada et al, 1999;Alphonse and Courty, 2005;Karouia et al, 2016;Chen et al, 2018;Chandran et al, 2019). In particular, 27 Al NMR has revealed the Al coordination environments in diverse disordered crystalline (i.e., metastable)/amorphous Al 2 O 3 and Al-(oxy)hydroxides (e.g., Lippmaa et al, 1986;Boissiere et al, 2006;Shen et al, 2007;Lee et al, 2009b;Lee et al, 2010;Sabarinathan et al, 2010;Kim and Lee, 2013b;Cui et al, 2018;Lee and Ryu, 2018;He et al, 2019 and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Kim

Lee

2021

American Mineralogist

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Detailed knowledge of the structural evolution of diverse aluminum (oxy)hydroxides with varying temperatures up to ~300 °C provides insights into the dehydration processes involving transitions among metastable phases in Earth's surface and crust. Here, we report the high-resolution solid-state 27 Al NMR spectra for three different types of aluminum (oxy)hydroxides (i.e., boehmite, bayerite, and gibbsite) with varying annealing temperatures up to 300 °C, revealing the effect of distinct precursor minerals on the stability of metastable alumina. 27 Al MAS NMR results allow us to obtain the quantitative fractions and NMR parameters for each phase during transformation. The results demonstrate that each aluminum (oxy)hydroxide phase follows the unique transformation path to metastable alumina. The 27 Al MAS and 3QMAS NMR spectra of boehmite show that a minor but observable [4] Al signal (~2%) is detected at ~50 °C, and the [4] Al fraction gradually increases up to 300 °C (~16%), indicating that the phase transformation from boehmite to -/-Al 2 O 3 occurs at a temperature as low as ~50 °C, significantly lower than earlier estimations based on XRD. Together with the [4] Al fraction, the [5] Al fraction increases from < 1% at 50 °C to ~2.3% at 300 °C, whereas the NMR results of bayerite and gibbsite do not show the presence of [5] Al. In addition, the 27 Al 3QMAS NMR spectra resolved the [6] Al site in boehmite and that in -/-Al 2 O 3 , which could not be uniquely determined from 1D NMR spectra. The population of bayerite abruptly decreases from 100% (at 150 ºC), through ~47% (at 200 ºC), to 0% (at 250 ºC), indicating that the phase transition from bayerite to boehmite + -/-Al 2 O 3 occurs within a narrow temperature range. As for gibbsite, while [4] Al is not observed in the spectra up to 200 °C, the [4] Al fraction of ~2% is observed in the spectra for gibbsite annealed at 250 °C, and the [4] Al fraction increases rapidly to ~15% as the annealing temperature increases to 300 °C, suggesting that the phase transformation into -/-Al2O3 occurs at ~250 ºC. The results confirm that the phase transformation paths (gradual vs. dramatic) depend on the type of precursor minerals. Particularly, the threshold temperature at which the onset of the phase transformation from boehmite to metastable alumina (~50 ºC) is lower than those from other precursor minerals (>150 ºC). Furthermore, the phase transformation from boehmite to -/-Al 2 O 3 occurs gradually within broad temperature ranges from ~50 °C. This is due to This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Section: Quantification Of Coexisting Phases In the Heat-treated Alummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Kim

Lee

2021

American Mineralogist

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“…Experimental studies of structural and chemical transformations in the systems containing a large substance proportion in the nonautonomous phases, as well as of physical-chemical, mechanical, thermal physical, electrophysical, magnetic and other properties of materials based on these systems are of independent interest. Since these materials contain nanoscale elements, not only their properties but also their geometric characteristics, as well as the geometric parameters of their fragments, can be determined only based on the analysis of a set of complementary methods [51][52][53][54]. The synthesis of such materials requires the development of special approaches and methods, and represents a standalone target [55][56][57][58][59][60][61][62][63][64][65].…”

Section: Introductionmentioning

confidence: 99%

Flintstone as a nanocomposite material for photonics

Федоров¹,

Maslov²,

Voronov³

et al. 2018

Nanosystems: Phys. Chem. Math.

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The scope of the journal includes all areas of nano-sciences. Papers devoted to basic problems of physics, chemistry, material science and mathematics inspired by nanosystems investigations are welcomed. Both theoretical and experimental works concerning the properties and behavior of nanosystems, problems of its creation and application, mathematical methods of nanosystem studies are considered. The journal publishes scientific reviews (up to 30 journal pages), research papers (up to 15 pages) and letters (up to 5 pages). All manuscripts are peer-reviewed. Authors are informed about the referee opinion and the Editorial decision.

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“…[15], 25 g of aluminum tri-sec-butoxide precursor was hydrolyzed in 100 mL of distilled water at 353 K for 1 h, under vigorous stirring to form a white precipitate. Then 7 mL of nitric acid was added and the temperature raised to 363 K for 20 h. At the end of this process, a sol containing 9 wt % at at 473 K for 2h.…”

mentioning

confidence: 99%

Influence of boehmite intermediate layer as covalent linker on synthesis of LTA zeolite coatings

Rodríguez-Castro

Urbiztondo-Castro

Pina-Iritia

2020

Rev.Fac.Ing.Univ.Antioquia

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La incorporación de materiales nanoestructurados como la zeolita tipo LTA en las obleas de silicio, abre una puerta muy interesante para el uso de estos materiales dentro de las tecnologías de microfabricación basadas en silicio. En este trabajo, se estudió la deposición y el entrecruzamiento de la capa de zeolita tipo LTA libre de defectos en obleas de silicio de 3 pulgadas con una capa de SiO2 sometida a pretratamiento. La principal desventaja asociada con la síntesis de la capa de zeolita es la formación de grietas y la obtención de una capa uniforme. Al modificar los soportes con boehmita, se observó una mejora sustancial en términos de continuidad de capa y crecimiento de cristales en comparación con los recubrimientos preparados en polímero catiónico, poli (cloruro de dialildimetilamonio). Se sintetizó una capa de zeolita de tipo LTA entre un rango de 350 y 1300 nm mediante un método hidrotermal ex situ, a 363 K durante 12 h. Se usó hidróxido de tetrametilamonio (TMAOH) como molde y se usaron isopropóxido de aluminio y sílice coloidal como fuentes de Al y Si, respectivamente.

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The impact of nanocrystallite size and shape on phase transformation: Application to the boehmite/alumina transformation

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 27 publications

References 34 publications

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Flintstone as a nanocomposite material for photonics

Influence of boehmite intermediate layer as covalent linker on synthesis of LTA zeolite coatings

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