Abstract
Intensive phase transformations of alumina are known to occur at temperatures above 1000 °C. In the present work, high temperature behaviour of pure Al2O3 and the carbon coated Al2O3@C sample with core-shell structure was comparatively studied using low-temperature nitrogen adsorption, transmission electron microscopy, powder X-ray diffraction (XRD) analysis and solid-state nuclear magnetic resonance (NMR). The solid-state NMR 27Al method has allowed us to identify and estimate the concentration of all phases appeared during the transformation of pseudoboehmite γ-Al2O3 into corundum α-Al2O3. The data obtained correlate well with the results of XRD analysis and low-temperature nitrogen adsorption. It is shown that the deposition of carbon coating with formation of core-shell Al2O3@C system stabilizes the size of oxide core and prevents the formation of corundum phase until the temperatures of 1350–1400 °C, which are close to the temperature of carbothermal reduction of alumina. The stabilization of the size of the oxide core nanoparticles was considered as a main factor preventing the formation of corundum phase at high temperatures. At the same time, the carbon coating does not affect the phase transformation of γ-Al2O3 to δ-Al2O3.
| Original language | English |
|---|---|
| Pages (from-to) | 4801-4806 |
| Number of pages | 6 |
| Journal | Ceramics International |
| Volume | 44 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 1 Apr 2018 |
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Keywords
- Alumina
- Carbon coating
- Core-shell structure
- Phase transformations
- Solid-state NMR
- Stabilization effect
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Process Chemistry and Technology
- Surfaces, Coatings and Films
- Materials Chemistry
Cite this
Stabilizing effect of the carbon shell on phase transformation of the nanocrystalline alumina particles. / Yakovlev, Ilya V.; Volodin, Alexander M.; Zaikovskii, Vladimir I.; Stoyanovskii, Vladimir O.; Lapina, Olga B.; Vedyagin, Aleksey A.
In: Ceramics International, Vol. 44, No. 5, 01.04.2018, p. 4801-4806.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Stabilizing effect of the carbon shell on phase transformation of the nanocrystalline alumina particles
AU - Yakovlev, Ilya V.
AU - Volodin, Alexander M.
AU - Zaikovskii, Vladimir I.
AU - Stoyanovskii, Vladimir O.
AU - Lapina, Olga B.
AU - Vedyagin, Aleksey A.
PY - 2018/4/1
Y1 - 2018/4/1
N2 - Intensive phase transformations of alumina are known to occur at temperatures above 1000 °C. In the present work, high temperature behaviour of pure Al2O3 and the carbon coated Al2O3@C sample with core-shell structure was comparatively studied using low-temperature nitrogen adsorption, transmission electron microscopy, powder X-ray diffraction (XRD) analysis and solid-state nuclear magnetic resonance (NMR). The solid-state NMR 27Al method has allowed us to identify and estimate the concentration of all phases appeared during the transformation of pseudoboehmite γ-Al2O3 into corundum α-Al2O3. The data obtained correlate well with the results of XRD analysis and low-temperature nitrogen adsorption. It is shown that the deposition of carbon coating with formation of core-shell Al2O3@C system stabilizes the size of oxide core and prevents the formation of corundum phase until the temperatures of 1350–1400 °C, which are close to the temperature of carbothermal reduction of alumina. The stabilization of the size of the oxide core nanoparticles was considered as a main factor preventing the formation of corundum phase at high temperatures. At the same time, the carbon coating does not affect the phase transformation of γ-Al2O3 to δ-Al2O3.
AB - Intensive phase transformations of alumina are known to occur at temperatures above 1000 °C. In the present work, high temperature behaviour of pure Al2O3 and the carbon coated Al2O3@C sample with core-shell structure was comparatively studied using low-temperature nitrogen adsorption, transmission electron microscopy, powder X-ray diffraction (XRD) analysis and solid-state nuclear magnetic resonance (NMR). The solid-state NMR 27Al method has allowed us to identify and estimate the concentration of all phases appeared during the transformation of pseudoboehmite γ-Al2O3 into corundum α-Al2O3. The data obtained correlate well with the results of XRD analysis and low-temperature nitrogen adsorption. It is shown that the deposition of carbon coating with formation of core-shell Al2O3@C system stabilizes the size of oxide core and prevents the formation of corundum phase until the temperatures of 1350–1400 °C, which are close to the temperature of carbothermal reduction of alumina. The stabilization of the size of the oxide core nanoparticles was considered as a main factor preventing the formation of corundum phase at high temperatures. At the same time, the carbon coating does not affect the phase transformation of γ-Al2O3 to δ-Al2O3.
KW - Alumina
KW - Carbon coating
KW - Core-shell structure
KW - Phase transformations
KW - Solid-state NMR
KW - Stabilization effect
UR - http://www.scopus.com/inward/record.url?scp=85039045644&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85039045644&partnerID=8YFLogxK
U2 - 10.1016/j.ceramint.2017.12.066
DO - 10.1016/j.ceramint.2017.12.066
M3 - Article
VL - 44
SP - 4801
EP - 4806
JO - Ceramics International
JF - Ceramics International
SN - 0272-8842
IS - 5
ER -