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Javier Gainza - One of the best experts on this subject based on the ideXlab platform.
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substantial thermal conductivity reduction in mischmetal skutterudites mmxco4sb12 prepared under High Pressure Conditions due to uneven distribution of the rare earth elements
Journal of Materials Chemistry C, 2019Co-Authors: Federico Serranosanchez, Jesus Pradogonjal, Norbert M Nemes, N Biskup, O J Dura, J L Martinez, Javier Gainza, F FauthAbstract:Thermoelectric mischmetal-filled MmxCo4Sb12 (Mm: natural cocktail of rare-earth elements, mostly Ce and La) skutterudites have been synthesized and sintered in one step under High-Pressure Conditions at 3.5 GPa in a piston–cylinder hydrostatic press. Synchrotron X-ray diffraction patterns display a splitting of the diffraction peaks ascribed to purely Ce-, and Mm-filled skutterudite phases, which have been analyzed and confirmed by High-resolution TEM and EELS. A total thermal conductivity (κ) of 1.51 W m−1 K−1 is measured at 773 K for Mm0.5Co4Sb12, below that of other filled skutterudites, which is promoted by the enhanced phonon scattering over a broad range of the phonon spectrum due to the inhomogeneous and nanoscale mischmetal inclusion. Compared to undoped CoSb3 skutterudite synthesized by conventional methods, κ is reduced by a factor of 3, while the power factor is also substantially enhanced.
F Fauth - One of the best experts on this subject based on the ideXlab platform.
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substantial thermal conductivity reduction in mischmetal skutterudites mmxco4sb12 prepared under High Pressure Conditions due to uneven distribution of the rare earth elements
Journal of Materials Chemistry C, 2019Co-Authors: Federico Serranosanchez, Jesus Pradogonjal, Norbert M Nemes, N Biskup, O J Dura, J L Martinez, Javier Gainza, F FauthAbstract:Thermoelectric mischmetal-filled MmxCo4Sb12 (Mm: natural cocktail of rare-earth elements, mostly Ce and La) skutterudites have been synthesized and sintered in one step under High-Pressure Conditions at 3.5 GPa in a piston–cylinder hydrostatic press. Synchrotron X-ray diffraction patterns display a splitting of the diffraction peaks ascribed to purely Ce-, and Mm-filled skutterudite phases, which have been analyzed and confirmed by High-resolution TEM and EELS. A total thermal conductivity (κ) of 1.51 W m−1 K−1 is measured at 773 K for Mm0.5Co4Sb12, below that of other filled skutterudites, which is promoted by the enhanced phonon scattering over a broad range of the phonon spectrum due to the inhomogeneous and nanoscale mischmetal inclusion. Compared to undoped CoSb3 skutterudite synthesized by conventional methods, κ is reduced by a factor of 3, while the power factor is also substantially enhanced.
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low thermal conductivity in la filled cobalt antimonide skutterudites with an inhomogeneous filling factor prepared under High Pressure Conditions
arXiv: Materials Science, 2018Co-Authors: Federico Serranosanchez, Jesus Pradogonjal, Norbert M Nemes, N Biskup, M Varela, O J Dura, J L Martinez, M T Fernandezdiaz, F Fauth, J A AlonsoAbstract:La-filled skutterudites LaxCo4Sb12 (x : 0.25 and 0.5) have been synthesized and sintered in one step under High-Pressure Conditions at 3.5 GPa in a piston-cylinder hydrostatic press. The structural properties of the reaction products were characterized by synchrotron X-ray powder diffraction, clearly showing an uneven filling factor of the skutterudite phases, confirmed by transmission electron microscopy. The non-homogeneous distribution of La filling atoms is adequate to produce a significant decrease in lattice thermal conductivity, mainly due to strain field scattering of High-energy phonons. Furthermore, the lanthanum filler primarily acts as an Einstein-like vibrational mode having a strong impact on the phonon scattering. Extra-low thermal conductivity values of 2.39 W/mK and 1.30 W/mK are measured for La0.25Co4Sb12 and La0.5Co4Sb12 nominal compositions at 780 K, respectively. Besides this, lanthanum atoms have contributed to increase the charge carrier concentration in the samples. In the case of La0.25Co4Sb12, there is an enhancement of the power factor and an improvement of the thermoelectric properties.
Jesus Pradogonjal - One of the best experts on this subject based on the ideXlab platform.
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substantial thermal conductivity reduction in mischmetal skutterudites mmxco4sb12 prepared under High Pressure Conditions due to uneven distribution of the rare earth elements
Journal of Materials Chemistry C, 2019Co-Authors: Federico Serranosanchez, Jesus Pradogonjal, Norbert M Nemes, N Biskup, O J Dura, J L Martinez, Javier Gainza, F FauthAbstract:Thermoelectric mischmetal-filled MmxCo4Sb12 (Mm: natural cocktail of rare-earth elements, mostly Ce and La) skutterudites have been synthesized and sintered in one step under High-Pressure Conditions at 3.5 GPa in a piston–cylinder hydrostatic press. Synchrotron X-ray diffraction patterns display a splitting of the diffraction peaks ascribed to purely Ce-, and Mm-filled skutterudite phases, which have been analyzed and confirmed by High-resolution TEM and EELS. A total thermal conductivity (κ) of 1.51 W m−1 K−1 is measured at 773 K for Mm0.5Co4Sb12, below that of other filled skutterudites, which is promoted by the enhanced phonon scattering over a broad range of the phonon spectrum due to the inhomogeneous and nanoscale mischmetal inclusion. Compared to undoped CoSb3 skutterudite synthesized by conventional methods, κ is reduced by a factor of 3, while the power factor is also substantially enhanced.
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low thermal conductivity in la filled cobalt antimonide skutterudites with an inhomogeneous filling factor prepared under High Pressure Conditions
arXiv: Materials Science, 2018Co-Authors: Federico Serranosanchez, Jesus Pradogonjal, Norbert M Nemes, N Biskup, M Varela, O J Dura, J L Martinez, M T Fernandezdiaz, F Fauth, J A AlonsoAbstract:La-filled skutterudites LaxCo4Sb12 (x : 0.25 and 0.5) have been synthesized and sintered in one step under High-Pressure Conditions at 3.5 GPa in a piston-cylinder hydrostatic press. The structural properties of the reaction products were characterized by synchrotron X-ray powder diffraction, clearly showing an uneven filling factor of the skutterudite phases, confirmed by transmission electron microscopy. The non-homogeneous distribution of La filling atoms is adequate to produce a significant decrease in lattice thermal conductivity, mainly due to strain field scattering of High-energy phonons. Furthermore, the lanthanum filler primarily acts as an Einstein-like vibrational mode having a strong impact on the phonon scattering. Extra-low thermal conductivity values of 2.39 W/mK and 1.30 W/mK are measured for La0.25Co4Sb12 and La0.5Co4Sb12 nominal compositions at 780 K, respectively. Besides this, lanthanum atoms have contributed to increase the charge carrier concentration in the samples. In the case of La0.25Co4Sb12, there is an enhancement of the power factor and an improvement of the thermoelectric properties.
I P Tsypysheva - One of the best experts on this subject based on the ideXlab platform.
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inversion of diastereoselectivity under High Pressure Conditions diels alder reactions of 12 n substituted derivatives of cytisine with n phenylmaleimide
ChemInform, 2015Co-Authors: I P Tsypysheva, Sophia S Borisevich, Alexander N. Lobov, A V Kovalskaya, Vadim V Shamukaev, R L Safiullin, Sergey L. KhursanAbstract:The High Pressure Diels-Alder title reaction yields products with inverted diastereoselectivity compared to thermal Conditions.
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inversion of diastereoselectivity under High Pressure Conditions diels alder reactions of 12 n substituted derivatives of cytisine with n phenylmaleimide
Tetrahedron-asymmetry, 2015Co-Authors: I P Tsypysheva, Sophia S Borisevich, A V Kovalskaya, Vadim V Shamukaev, R L Safiullin, A N Lobov, Sergey L. KhursanAbstract:Abstract Diels–Alder adducts of 12- N -substituted derivatives of (−)-cytisine with N -phenylmaleimide were synthesized. The Conditions of effective diastereodifferentiation were found: the thermal Diels–Alder reaction of 12- N -substituted derivatives of (−)-cytisine with N -phenylmaleimide leads to 3a S , 4 R , 12a R , 12b S adducts, while under High Pressure, adducts with 3a R , 4 S , 12a S , 12b R configurations of new asymmetric centers are formed. The effect of High Pressure on the diastereoselectivity of Diels–Alder reaction was rationalized by theoretical DFT calculations.
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aza michael reaction of 12 n carboxamide of cytisine under High Pressure Conditions
Natural Product Research, 2015Co-Authors: I P Tsypysheva, Sophia S Borisevich, A V Kovalskaya, R L Safiullin, A N Lobov, Polina R Petrova, S P Ivanov, Shamil A Rameev, M S YunusovAbstract:The first example of aza-Michael reaction of 12-N-carboxamide of quinolizidine alkaloid (–)-cytisine with α,β-unsaturated ketones, dimethyl acetylenedicarboxylate and β-nitrostyrene under High Pressure condition has been described. It has been shown that the [4+2]-cycloaddition takes place in the case with N-phenylmaleimide.
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Aza-Michael reaction of 12-N-carboxamide of (–)-cytisine under High Pressure Conditions
2014Co-Authors: I P Tsypysheva, Sophia S Borisevich, Alexander N. Lobov, A V Kovalskaya, R L Safiullin, Polina R Petrova, S P Ivanov, Shamil A Rameev, M S YunusovAbstract:The first example of aza-Michael reaction of 12-N-carboxamide of quinolizidine alkaloid (–)-cytisine with α,β-unsaturated ketones, dimethyl acetylenedicarboxylate and β-nitrostyrene under High Pressure condition has been described. It has been shown that the [4+2]-cycloaddition takes place in the case with N-phenylmaleimide.
Hiyoshizo Kotsuki - One of the best experts on this subject based on the ideXlab platform.
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enantioselective synthesis of quaternary carbon stereogenic centers through the primary amine catalyzed michael addition reaction of α substituted cyclic ketones at High Pressure
European Journal of Organic Chemistry, 2015Co-Authors: Ryo Horinouchi, Kouhei Kamei, Riki Watanabe, Nobushige Hieda, Naoki Tatsumi, Keiji Nakano, Yoshiyasu Ichikawa, Hiyoshizo KotsukiAbstract:The enantioselective Michael addition reaction of α-substituted cyclic ketones with acrylates was efficiently promoted by a primary amine chiral catalyst under High-Pressure Conditions (1.0 GPa) in tetrahydrofuran. This method was Highly successful for the construction of an all-carbon-substituted quaternary-carbon stereogenic center at the α-position of cyclic ketones in High enantiomeric excess, and could be conveniently applied to the formal synthesis of (+)-aspidospermidine.
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efficient bronsted acid catalyzed aza michael reaction of amides and ureas with α β unsaturated enones under High Pressure Conditions
Tetrahedron Letters, 2009Co-Authors: Saleha Azad, Keiji Nakano, Yoshiyasu Ichikawa, Tomohiro Kobayashi, Hiyoshizo KotsukiAbstract:Abstract A new strategy for the aza-Michael reaction of amides and ureas with α,β-unsaturated enones, which uses p -TsOH·H 2 O as an efficient and inexpensive catalyst under High-Pressure Conditions, has been developed.
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a new practical method for the synthesis of unsymmetrical ureas via High Pressure promoted condensation of 2 2 2 trichloroethyl carbamates troc carbamates with amines
Tetrahedron Letters, 2006Co-Authors: Saleha Azad, Yoshiyasu Ichikawa, Koji Kumamoto, Kaoru Uegaki, Hiyoshizo KotsukiAbstract:A new practical method for the synthesis of unsymmetrical ureas was achieved by condensation between 2,2,2-trichloroethyl carbamates (Troc-carbamates) and primary or secondary amines under High-Pressure Conditions.
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synthesis of novel chiral diazole ligands for enantioselective addition of diethylzinc to benzaldehyde
ChemInform, 1996Co-Authors: Hiyoshizo Kotsuki, Masahiro Wakao, Hiroyuki Hayakawa, Tomoyasu Shimanouchi, Masamitsu OchiAbstract:Abstract A variety of chiral pyrazole and imidazole derivatived ligands have been prepared under High Pressure Conditions and their catalytic efficiency in the enantioselective addition of diethylzinc to benzaldehyde has been examined.