The Experts below are selected from a list of 1068 Experts worldwide ranked by ideXlab platform
Pratap Raychaudhuri - One of the best experts on this subject based on the ideXlab platform.
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phase diagram and hall effect of the electron doped manganite la1 xcexmno3
Journal of Applied Physics, 2003Co-Authors: Pratap Raychaudhuri, Chandrima Mitra, P D A Mann, S WirthAbstract:We report on the electronic, transport, and magnetic properties of the Ce-doped manganite, La1−xCexMnO3. This material is remarkably similar to the heavily investigated hole doped manganite La1−xCaxMnO3; e.g., both materials show Curie temperatures of TC∼250 K for x=0.3. The main difference which makes the Ce-doped material highly interesting for basic research as well as for possible applications (e.g., in spintronics) is the fact that Ce doping drives the manganese in a mixture of Mn2+ and Mn3+ induced by electron doping. We present conclusive evidence for electron doping by x-ray absorption spectroscopy and Hall measurements on single phase epitaxial thin films. From transport measurements on a series of La1−xCexMnO3, the magnetic phase diagram of La1−xCexMnO3 is established.
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observation of minority spin character of the new electron doped manganite la0 7ce0 3mno3 from tunneling magnetoresistance
Physical Review Letters, 2003Co-Authors: Chiranjib Mitra, K. Dörr, Pratap Raychaudhuri, Kh Muller, Ludwig Schultz, P M Oppeneer, S WirthAbstract:Observation of minority spin character of the new electron-doped manganite La0.7Ce0.3MnO3 from tunneling magnetoresistance
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observation of minority spin character of the new electron doped manganite la0 7ce0 3mno3 from tunneling magnetoresistance
Physical Review Letters, 2003Co-Authors: Chiranjib Mitra, K. Dörr, Pratap Raychaudhuri, Kh Muller, L Schultz, P M Oppeneer, S WirthAbstract:We report the magnetotransport characteristics of a trilayer ferromagnetic tunnel junction built of an electron doped manganite (${\mathrm{L}\mathrm{a}}_{0.7}{\mathrm{C}\mathrm{e}}_{0.3}{\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$) and a hole doped manganite (${\mathrm{L}\mathrm{a}}_{0.7}{\mathrm{C}\mathrm{a}}_{0.3}{\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$). At low temperatures the junction exhibits a large positive tunneling magnetoresistance (TMR), irrespective of the bias voltage. At intermediate temperatures below ${T}_{C}$ the sign of the TMR is dependent on the bias voltage across the junction. The magnetoresistive characteristics of the junction strongly suggest that ${\mathrm{L}\mathrm{a}}_{0.7}{\mathrm{C}\mathrm{e}}_{0.3}{\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$ is a minority spin carrier ferromagnet with a high degree of spin polarization, i.e., a transport half-metal.
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p n diode with hole and electron doped lanthanum manganites
Applied Physics Letters, 2001Co-Authors: Chiranjib Mitra, K. Dörr, Pratap Raychaudhuri, G Kobernik, Kh Muller, L Schultz, R PintoAbstract:The hole-doped (p-) manganite La0.7Ca0.3MnO3 and the electron-doped (n-) manganite La0.7Ce0.3MnO3 undergo an insulator-to-metal transition at around 250 K, above which both behave as a polaronic semiconductor. We have fabricated an epitaxial trilayer (La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3), where SrTiO3 is an insulator. At room temperature, i.e., in the semiconducting regime, it exhibits asymmetric current–voltage (I–V) characteristics akin to a p–n diode. The observed asymmetry in the I–V characteristics disappears at low temperatures where both the manganite layers are metallic. These results indicate that using the polaronic semiconducting regime of doped manganites, a p–n diode can be constructed.
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a p n diode with hole and electron doped lanthanum manganite
arXiv: Strongly Correlated Electrons, 2001Co-Authors: Chiranjib Mitra, K. Dörr, Pratap Raychaudhuri, G Kobernik, R Pinto, Kh Muller, L SchultzAbstract:The hole-doped manganite La0.7Ca0.3MnO3 and the electron-doped manganite La0.7Ce0.3MnO3 undergo an insulator to metal transition at around 250 K, above which both behave as a polaronic semiconductor. We have successfully fabricated an epitaxial trilayer (La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3), where SrTiO3 is an insulator. At room temperature, i.e. in the semiconducting regime, it exhibits asymmetric current-voltage (I-V) characteristics akin to a p-n diode. The observed asymmetry in the I-V characteristics disappears at low temperatures where both the manganite layers are metallic. To the best of our knowledge, this is the first report of such a p-n diode, using the polaronic semiconducting regime of doped manganites.
S Wirth - One of the best experts on this subject based on the ideXlab platform.
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phase diagram and hall effect of the electron doped manganite la1 xcexmno3
Journal of Applied Physics, 2003Co-Authors: Pratap Raychaudhuri, Chandrima Mitra, P D A Mann, S WirthAbstract:We report on the electronic, transport, and magnetic properties of the Ce-doped manganite, La1−xCexMnO3. This material is remarkably similar to the heavily investigated hole doped manganite La1−xCaxMnO3; e.g., both materials show Curie temperatures of TC∼250 K for x=0.3. The main difference which makes the Ce-doped material highly interesting for basic research as well as for possible applications (e.g., in spintronics) is the fact that Ce doping drives the manganese in a mixture of Mn2+ and Mn3+ induced by electron doping. We present conclusive evidence for electron doping by x-ray absorption spectroscopy and Hall measurements on single phase epitaxial thin films. From transport measurements on a series of La1−xCexMnO3, the magnetic phase diagram of La1−xCexMnO3 is established.
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observation of minority spin character of the new electron doped manganite la0 7ce0 3mno3 from tunneling magnetoresistance
Physical Review Letters, 2003Co-Authors: Chiranjib Mitra, K. Dörr, Pratap Raychaudhuri, Kh Muller, Ludwig Schultz, P M Oppeneer, S WirthAbstract:Observation of minority spin character of the new electron-doped manganite La0.7Ce0.3MnO3 from tunneling magnetoresistance
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observation of minority spin character of the new electron doped manganite la0 7ce0 3mno3 from tunneling magnetoresistance
Physical Review Letters, 2003Co-Authors: Chiranjib Mitra, K. Dörr, Pratap Raychaudhuri, Kh Muller, L Schultz, P M Oppeneer, S WirthAbstract:We report the magnetotransport characteristics of a trilayer ferromagnetic tunnel junction built of an electron doped manganite (${\mathrm{L}\mathrm{a}}_{0.7}{\mathrm{C}\mathrm{e}}_{0.3}{\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$) and a hole doped manganite (${\mathrm{L}\mathrm{a}}_{0.7}{\mathrm{C}\mathrm{a}}_{0.3}{\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$). At low temperatures the junction exhibits a large positive tunneling magnetoresistance (TMR), irrespective of the bias voltage. At intermediate temperatures below ${T}_{C}$ the sign of the TMR is dependent on the bias voltage across the junction. The magnetoresistive characteristics of the junction strongly suggest that ${\mathrm{L}\mathrm{a}}_{0.7}{\mathrm{C}\mathrm{e}}_{0.3}{\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$ is a minority spin carrier ferromagnet with a high degree of spin polarization, i.e., a transport half-metal.
Minjoon Park - One of the best experts on this subject based on the ideXlab platform.
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Seed-mediated atomic-scale reconstruction of silver Manganate nanoplates for oxygen reduction towards high-energy aluminum-air flow batteries
Nature Communications, 2018Co-Authors: Haeseong Jang, Joohyuk Park, Minjoon ParkAbstract:Aluminum-air batteries are lightweight and cost effective, but performance is limited by corrosion and solid by-products. Here the authors catalyze oxygen reduction with silver Manganate nanoplates and develop an aluminum-air flow battery that delivers high energy density and alleviates side reactions. Aluminum–air batteries are promising candidates for next-generation high-energy-density storage, but the inherent limitations hinder their practical use. Here, we show that silver nanoparticle-mediated silver Manganate nanoplates are a highly active and chemically stable catalyst for oxygen reduction in alkaline media. By means of atomic-resolved transmission electron microscopy, we find that the formation of stripe patterns on the surface of a silver Manganate nanoplate originates from the zigzag atomic arrangement of silver and manganese, creating a high concentration of dislocations in the crystal lattice. This structure can provide high electrical conductivity with low electrode resistance and abundant active sites for ion adsorption. The catalyst exhibits outstanding performance in a flow-based aluminum–air battery, demonstrating high gravimetric and volumetric energy densities of ~2552 Wh kg_Al^−1 and ~6890 Wh l_Al^−1 at 100 mA cm^−2, as well as high stability during a mechanical recharging process.
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Seed-mediated atomic-scale reconstruction of silver Manganate nanoplates for oxygen reduction towards high-energy aluminum-air flow batteries
Nature Publishing Group, 2018Co-Authors: Jaechan Ryu, Haeseong Jang, Joohyuk Park, Minjoon Park, Youngshin Yoo, Jaephil ChoAbstract:Aluminum-air batteries are lightweight and cost effective, but performance is limited by corrosion and solid by-products. Here the authors catalyze oxygen reduction with silver Manganate nanoplates and develop an aluminum-air flow battery that delivers high energy density and alleviates side reactions
Khalil Amine - One of the best experts on this subject based on the ideXlab platform.
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effectively suppressing dissolution of manganese from spinel lithium Manganate via a nanoscale surface doping approach
Nature Communications, 2014Co-Authors: Yang-kook Sun, Chun Zhan, Xinping Qiu, Jianguo Wen, Yu Lei, Jeremy A Kropf, D J Miller, Jeffrey W Elam, Khalil AmineAbstract:The capacity fade of lithium Manganate-based cells is associated with the dissolution of Mn from cathode/electrolyte interface due to the disproportionation reaction of Mn(III), and the subsequent deposition of Mn(II) on the anode. Suppressing the dissolution of Mn from the cathode is critical to reducing capacity fade of LiMn2O4-based cells. Here we report a nanoscale surface-doping approach that minimizes Mn dissolution from lithium Manganate. This approach exploits advantages of both bulk doping and surface-coating methods by stabilizing surface crystal structure of lithium Manganate through cationic doping while maintaining bulk lithium Manganate structure, and protecting bulk lithium Manganate from electrolyte corrosion while maintaining ion and charge transport channels on the surface through the electrochemically active doping layer. Consequently, the surface-doped lithium Manganate demonstrates enhanced electrochemical performance. This study provides encouraging evidence that surface doping could be a promising alternative to improve the cycling performance of lithium-ion batteries.
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Mn(II) deposition on anodes and its effects on capacity fade in spinel lithium Manganate-carbon systems
Nature Communications, 2013Co-Authors: Chun Zhan, A. Jeremy Kropf, Yang-kook Sun, Xinping Qiu, Tianpin Wu, Andrew N Jansen, Jun Lu, Khalil AmineAbstract:Dissolution and migration of manganese from cathode lead to severe capacity fading of lithium Manganate-carbon cells. Overcoming this major problem requires a better understanding of the mechanisms of manganese dissolution, migration and deposition. Here we apply a variety of advanced analytical methods to study lithium Manganate cathodes that are cycled with different anodes. We show that the oxidation state of manganese deposited on the anodes is +2, which differs from the results reported earlier. Our results also indicate that a metathesis reaction between Mn(II) and some species on the solid-electrolyte interphase takes place during the deposition of Mn(II) on the anodes, rather than a reduction reaction that leads to the formation of metallic Mn, as speculated in earlier studies. The concentration of Mn deposited on the anode gradually increases with cycles; this trend is well correlated with the anodes rising impedance and capacity fading of the cell.
Chun Zhan - One of the best experts on this subject based on the ideXlab platform.
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effectively suppressing dissolution of manganese from spinel lithium Manganate via a nanoscale surface doping approach
Nature Communications, 2014Co-Authors: Yang-kook Sun, Chun Zhan, Xinping Qiu, Jianguo Wen, Yu Lei, Jeremy A Kropf, D J Miller, Jeffrey W Elam, Khalil AmineAbstract:The capacity fade of lithium Manganate-based cells is associated with the dissolution of Mn from cathode/electrolyte interface due to the disproportionation reaction of Mn(III), and the subsequent deposition of Mn(II) on the anode. Suppressing the dissolution of Mn from the cathode is critical to reducing capacity fade of LiMn2O4-based cells. Here we report a nanoscale surface-doping approach that minimizes Mn dissolution from lithium Manganate. This approach exploits advantages of both bulk doping and surface-coating methods by stabilizing surface crystal structure of lithium Manganate through cationic doping while maintaining bulk lithium Manganate structure, and protecting bulk lithium Manganate from electrolyte corrosion while maintaining ion and charge transport channels on the surface through the electrochemically active doping layer. Consequently, the surface-doped lithium Manganate demonstrates enhanced electrochemical performance. This study provides encouraging evidence that surface doping could be a promising alternative to improve the cycling performance of lithium-ion batteries.
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Mn(II) deposition on anodes and its effects on capacity fade in spinel lithium Manganate-carbon systems
Nature Communications, 2013Co-Authors: Chun Zhan, A. Jeremy Kropf, Yang-kook Sun, Xinping Qiu, Tianpin Wu, Andrew N Jansen, Jun Lu, Khalil AmineAbstract:Dissolution and migration of manganese from cathode lead to severe capacity fading of lithium Manganate-carbon cells. Overcoming this major problem requires a better understanding of the mechanisms of manganese dissolution, migration and deposition. Here we apply a variety of advanced analytical methods to study lithium Manganate cathodes that are cycled with different anodes. We show that the oxidation state of manganese deposited on the anodes is +2, which differs from the results reported earlier. Our results also indicate that a metathesis reaction between Mn(II) and some species on the solid-electrolyte interphase takes place during the deposition of Mn(II) on the anodes, rather than a reduction reaction that leads to the formation of metallic Mn, as speculated in earlier studies. The concentration of Mn deposited on the anode gradually increases with cycles; this trend is well correlated with the anodes rising impedance and capacity fading of the cell.