The Experts below are selected from a list of 2142 Experts worldwide ranked by ideXlab platform
Bo B Iversen - One of the best experts on this subject based on the ideXlab platform.
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new insight on tuning electrical transport properties via chalcogen doping in n type mg3sb2 based thermoelectric materials
Advanced Energy Materials, 2018Co-Authors: Jiawei Zhang, Lirong Song, Kasper A Borup, Mads R V Jorgensen, Bo B IversenAbstract:n-type Mg3Sb1.5Bi0.5 has recently been discovered to be a promising thermoelectric material, yet the effective n-type dopants are mainly limited to the chalcogens. This may be attributed to the limited chemical insight into the effects from different n-type dopants. By comparing the effects of different chalcogen dopants Q (Q = S, Se, and Te) on thermoelectric properties, it is found that the chalcogen dopants Q become more efficient with decreasing Electronegativity Difference between Q and Mg, which is mainly due to the increasing carrier concentration and mobility. Using density functional theory calculations, it is shown that the improving carrier concentration originates from the increasing doping limit induced by the stabilizing extrinsic defect. Moreover, the increasing electron mobility with decreasing Electronegativity Difference between Q and Mg is attributed to the smaller effective mass resulting from the enhancing chemical bond covalency, which is supported by the decreasing theoretical density of states. According to the above trends, a simple guiding principle based on Electronegativity is proposed to shed new light on n-type doping in Zintl antimonides. (Less)
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New Insight on Tuning Electrical Transport Properties via Chalcogen Doping in n‐type Mg3Sb2‐Based Thermoelectric Materials
Advanced Energy Materials, 2018Co-Authors: Jiawei Zhang, Lirong Song, Kasper A Borup, Mads R V Jorgensen, Bo B IversenAbstract:n-type Mg3Sb1.5Bi0.5 has recently been discovered to be a promising thermoelectric material, yet the effective n-type dopants are mainly limited to the chalcogens. This may be attributed to the limited chemical insight into the effects from different n-type dopants. By comparing the effects of different chalcogen dopants Q (Q = S, Se, and Te) on thermoelectric properties, it is found that the chalcogen dopants Q become more efficient with decreasing Electronegativity Difference between Q and Mg, which is mainly due to the increasing carrier concentration and mobility. Using density functional theory calculations, it is shown that the improving carrier concentration originates from the increasing doping limit induced by the stabilizing extrinsic defect. Moreover, the increasing electron mobility with decreasing Electronegativity Difference between Q and Mg is attributed to the smaller effective mass resulting from the enhancing chemical bond covalency, which is supported by the decreasing theoretical density of states. According to the above trends, a simple guiding principle based on Electronegativity is proposed to shed new light on n-type doping in Zintl antimonides. (Less)
Miquel Sola - One of the best experts on this subject based on the ideXlab platform.
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x2y2 isomers tuning structure and relative stability through Electronegativity Differences x h li na f cl br i y o s se te
Inorganic Chemistry, 2013Co-Authors: Majid Elhamdi, Jordi Poater, F Bickelhaupt, Miquel SolaAbstract:We have studied the XYYX and X2YY isomers of the X2Y2 species (X = H, Li, Na, F, Cl, Br, I; Y = O, S, Se, Te) using density functional theory at the ZORA-BP86/QZ4P level. Our computations show that, over the entire range of our model systems, the XYYX isomers are more stable than the X2YY forms except for X = F and Y = S and Te, for which the F2SS and F2TeTe isomers are slightly more stable. Our results also point out that the Y–Y bond length can be tuned quite generally through the X–Y Electronegativity Difference. The mechanism behind this electronic tuning is the population or depopulation of the π* in the YY fragment.
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X2Y2 Isomers: Tuning Structure and Relative Stability through Electronegativity Differences (X = H, Li, Na, F, Cl, Br, I; Y = O, S, Se, Te)
Inorganic chemistry, 2013Co-Authors: Majid El-hamdi, Jordi Poater, F Bickelhaupt, Miquel SolaAbstract:We have studied the XYYX and X2YY isomers of the X2Y2 species (X = H, Li, Na, F, Cl, Br, I; Y = O, S, Se, Te) using density functional theory at the ZORA-BP86/QZ4P level. Our computations show that, over the entire range of our model systems, the XYYX isomers are more stable than the X2YY forms except for X = F and Y = S and Te, for which the F2SS and F2TeTe isomers are slightly more stable. Our results also point out that the Y-Y bond length can be tuned quite generally through the X-Y Electronegativity Difference. The mechanism behind this electronic tuning is the population or depopulation of the π* in the YY fragment.
W J Botta - One of the best experts on this subject based on the ideXlab platform.
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topological instability average Electronegativity Difference and glass forming ability of amorphous alloys
Intermetallics, 2009Co-Authors: Marcelo Falcão De Oliveira, F S Pereira, C Bolfarini, C S Kiminami, W J BottaAbstract:Abstract In this paper, we report the remarkable agreement of the glass forming ability of binary alloys with a new criterion that combines the topological instability parameter (λ) and the average Electronegativity Difference among the elements of an alloy, assuming both exert a synergetic effect. The best glass forming compositions for Zr–Cu and Ti–Ni systems are well predicted by this new approach. Although the new criterion needs further refinement, it is concluded that the proposed approach is a promising and simple tool to guide and reduce the tedious and labour intensive work to find good glass former compositions in metallic systems.
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topological instability and Electronegativity effects on the glass forming ability of metallic alloys
Philosophical Magazine Letters, 2008Co-Authors: W J Botta, C Bolfarini, F S Pereira, C S Kiminami, Marcelo Falcão De OliveiraAbstract:The glass-forming ability (GFA) of metallic alloys is associated with a topological instability criterion combined with a new parameter based on the average Electronegativity Difference of an element and its surrounding neighbours. In this model, we assume that during solidification the glassy phase competes directly with the supersaturated solid solution having the lowest topological instability factor for a given composition. This criterion is combined with the average Electronegativity Difference among the elements in the alloy, which reflects the strength of the liquid. The GFA is successfully correlated with this combined criterion in several binary glass-forming systems.
Marcelo Falcão De Oliveira - One of the best experts on this subject based on the ideXlab platform.
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A new correlation between electronic parameters and glass forming ability of metallic alloys
Philosophical Magazine Letters, 2011Co-Authors: Marcelo Falcão De OliveiraAbstract:A quantitative correlation between the glass forming ability and the electronic parameters of metallic alloys is presented. It is found that the critical cooling rate for glass formation (R c) correlates well with the average work function Difference (Δφ) and the average electron density Difference ( ) among the constituent elements of the investigated alloys. A correlation coefficient (R 2) of 0.77 was found for 68 alloys in 30 metallic systems, which is better than the previous proposed correlation between the glass forming ability and the average Pauling Electronegativity Difference.
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topological instability average Electronegativity Difference and glass forming ability of amorphous alloys
Intermetallics, 2009Co-Authors: Marcelo Falcão De Oliveira, F S Pereira, C Bolfarini, C S Kiminami, W J BottaAbstract:Abstract In this paper, we report the remarkable agreement of the glass forming ability of binary alloys with a new criterion that combines the topological instability parameter (λ) and the average Electronegativity Difference among the elements of an alloy, assuming both exert a synergetic effect. The best glass forming compositions for Zr–Cu and Ti–Ni systems are well predicted by this new approach. Although the new criterion needs further refinement, it is concluded that the proposed approach is a promising and simple tool to guide and reduce the tedious and labour intensive work to find good glass former compositions in metallic systems.
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topological instability and Electronegativity effects on the glass forming ability of metallic alloys
Philosophical Magazine Letters, 2008Co-Authors: W J Botta, C Bolfarini, F S Pereira, C S Kiminami, Marcelo Falcão De OliveiraAbstract:The glass-forming ability (GFA) of metallic alloys is associated with a topological instability criterion combined with a new parameter based on the average Electronegativity Difference of an element and its surrounding neighbours. In this model, we assume that during solidification the glassy phase competes directly with the supersaturated solid solution having the lowest topological instability factor for a given composition. This criterion is combined with the average Electronegativity Difference among the elements in the alloy, which reflects the strength of the liquid. The GFA is successfully correlated with this combined criterion in several binary glass-forming systems.
Jiawei Zhang - One of the best experts on this subject based on the ideXlab platform.
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new insight on tuning electrical transport properties via chalcogen doping in n type mg3sb2 based thermoelectric materials
Advanced Energy Materials, 2018Co-Authors: Jiawei Zhang, Lirong Song, Kasper A Borup, Mads R V Jorgensen, Bo B IversenAbstract:n-type Mg3Sb1.5Bi0.5 has recently been discovered to be a promising thermoelectric material, yet the effective n-type dopants are mainly limited to the chalcogens. This may be attributed to the limited chemical insight into the effects from different n-type dopants. By comparing the effects of different chalcogen dopants Q (Q = S, Se, and Te) on thermoelectric properties, it is found that the chalcogen dopants Q become more efficient with decreasing Electronegativity Difference between Q and Mg, which is mainly due to the increasing carrier concentration and mobility. Using density functional theory calculations, it is shown that the improving carrier concentration originates from the increasing doping limit induced by the stabilizing extrinsic defect. Moreover, the increasing electron mobility with decreasing Electronegativity Difference between Q and Mg is attributed to the smaller effective mass resulting from the enhancing chemical bond covalency, which is supported by the decreasing theoretical density of states. According to the above trends, a simple guiding principle based on Electronegativity is proposed to shed new light on n-type doping in Zintl antimonides. (Less)
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New Insight on Tuning Electrical Transport Properties via Chalcogen Doping in n‐type Mg3Sb2‐Based Thermoelectric Materials
Advanced Energy Materials, 2018Co-Authors: Jiawei Zhang, Lirong Song, Kasper A Borup, Mads R V Jorgensen, Bo B IversenAbstract:n-type Mg3Sb1.5Bi0.5 has recently been discovered to be a promising thermoelectric material, yet the effective n-type dopants are mainly limited to the chalcogens. This may be attributed to the limited chemical insight into the effects from different n-type dopants. By comparing the effects of different chalcogen dopants Q (Q = S, Se, and Te) on thermoelectric properties, it is found that the chalcogen dopants Q become more efficient with decreasing Electronegativity Difference between Q and Mg, which is mainly due to the increasing carrier concentration and mobility. Using density functional theory calculations, it is shown that the improving carrier concentration originates from the increasing doping limit induced by the stabilizing extrinsic defect. Moreover, the increasing electron mobility with decreasing Electronegativity Difference between Q and Mg is attributed to the smaller effective mass resulting from the enhancing chemical bond covalency, which is supported by the decreasing theoretical density of states. According to the above trends, a simple guiding principle based on Electronegativity is proposed to shed new light on n-type doping in Zintl antimonides. (Less)