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9. High Performance and Durable Anode with 10‐Fold Reduction of Iridium Loading for Proton Exchange Membrane Water Electrolysis

Author

Torrero, Jorge, primary, Morawietz, Tobias, additional, García Sanchez, Daniel, additional, Galyamin, Dmitry, additional, Retuerto, Maria, additional, Martin‐Diaconescu, Vlad, additional, Rojas, Sergio, additional, Alonso, José Antonio, additional, Gago, Aldo Saul, additional, and Friedrich, Kaspar Andreas, additional

Published
2023
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13. Study of catalyst bed composition for the direct synthesis of dimethyl ether from CO 2 -rich syngas

Author

Peinado, Cristina, Liuzzi, Dalia, Retuerto, Maria, Boon, Jurriaan, Peña, Miguel A., and Rojas, Sergio

Subjects
Biofuels, H2O-sorption, SEDMES, Dimethyl ether, CO2-rich syngas
Abstract

In this work, we study the direct synthesis of DME using CO2 -rich syngas, with a CO2/CO ratio similar to that obtained from the gasification of biomass, i.e. , 1.9. We used catalytic beds consisting of physical mixtures of the benchmark catalysts used for the synthesis of methanol from syngas and for methanol dehydration to DME, namely Cu/ZnO/Al2O3 and 𝛾-Al2O3 , respectively. Our results show that the ratio between each catalytic phase determines the productivity and selectivity to DME, as well CO and CO2 conversions. Thus, higher total carbon conversions were obtained with the catalytic bed with the highest content of the Cu/Zn/Al2O3 phase. The presence of 𝛾-Al2O3 allows to exceed the equilibrium conversion of CO for the syngas to methanol synthesis. The highest DME productivity is obtained with the catalytic bed containing equal amounts of both catalytic phases. In addition, we also show that other reaction variables such as temperature, pressure, and contact time also play an important role in terms of DME productivity. The presence of a high fraction of CO2 in the syngas results in a high production of H2O, which after long times on stream result in the deactivation of the Cu/ZnO/Al2O3 catalytic phase due to the sintering of the copper particles. The in situ removal of H2O via the addition of an H2O sorbent, zeolite 3A, into the catalytic bed, results in a significant enhancement of both carbon conversion and DME productivity.

Published
2020

14. How oxidation state and lattice distortion influence the oxygen evolution activity in acid of iridium double perovskites

Author

Retuerto, Maria, Pascual, Laura, Pique, Oriol, Kayser González, Paula, Abdel Salam, Mohamed, Mokhtar, Mohamed, Alonso, Jose Antonio, Peña, Miguel, Calle-Vallejo, Federico, Rojas, Sergio, Retuerto, Maria, Pascual, Laura, Pique, Oriol, Kayser González, Paula, Abdel Salam, Mohamed, Mokhtar, Mohamed, Alonso, Jose Antonio, Peña, Miguel, Calle-Vallejo, Federico, and Rojas, Sergio

Abstract

In view of iridium's scarceness and high cost, Ir-containing catalysts for water electrolyzers should have low loadings and maximal utilization. Here, we studied low-Ir-content, highly active, double perovskites (Sr2MIrO6, M = Ni, Co, Sc and Fe) for the oxygen evolution reaction (OER) in acid combining electrochemical experiments, DFT, and advanced characterization techniques. The initial OER performance depends on Ir's oxidation state and the geometric features of IrO6 frameworks, which are tuned by the choice of M. Higher oxidation states, particularly Ir6+, enhance the OER activity: Sr2NiIrO6 and Sr2CoIrO6 display potentials of ∼1.53 V at 10 mA cm−2, comparable to the best Ir-based catalysts in the literature. However, because of their less symmetric structures, perovskites with Ir6+ are less stable, prone to surface reconstruction and their cations leach under OER conditions. These results show that improved iridium-based OER electrocatalysts in acid can be designed by balancing their activity and stability., Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Investigación y Universidades (España), Generalitat de Catalunya, Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub

Published
2021

15. Universal A-Cation Splitting in LiNbO3-Type Structure Driven by Intrapositional Multivalent Coupling

Author

Han, Yifeng, primary, Zeng, Yijie, additional, Hendrickx, Mylène, additional, Hadermann, Joke, additional, Stephens, Peter W., additional, Zhu, Chuanhui, additional, Grams, Christoph P., additional, Hemberger, Joachim, additional, Frank, Corey, additional, Li, Shufang, additional, Wu, MeiXia, additional, Retuerto, Maria, additional, Croft, Mark, additional, Walker, David, additional, Yao, Dao-Xin, additional, Greenblatt, Martha, additional, and Li, Man-Rong, additional

Published
2020
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16. Structural, magnetic, and spin dynamical properties of the polar antiferromagnets Ni\(_{3−x}\)Co\(_x\)TeO\(_6\)(x=1,2)

Author

Skiadopoulou, Stella, Retuerto, Maria, Borodavka, Fedir, Kadlec, Christelle, Kadlec, Filip, Míšek, Martin, Prokleška, Jan, Deng, Zheng, Tan, Xiaoyan, Frank, Corey, Alonso, Jose A., Fernandez-Diaz, Maria Tereza, Croft, Mark, Orlandi, Fabio, Manuel, Pascal, McCabe, Emma E., Legut, Dominik, Greenblatt, Martha, and Kamba, Stanislav

Subjects
Condensed Matter::Strongly Correlated Electrons
Abstract

We present results of a multimethod investigation of the polar antiferromagnets Ni\(_2\) CoTeO\(_6\) and NiCo\(_2\) TeO\(_6\), inspired by the colossal magnetoelectric effect present in Ni\(_3\) TeO\(_6\). Both compounds crystalize in the same polar space group R3 as Ni\(_3\) TeO\(_6\), preserving the crystal symmetry at least from room temperature down to 2 K. Ni\(_2\) CoTeO\(_6\) and NiCo\(_2\) TeO\(_6\) undergo antiferromagnetic phase transitions at T\(_N\) = 55 and 52 K, and spin-flop transitions at an external magnetic field of approximately 8 and 4 T, respectively. Both compounds present an incommensurate antiferromagnetic helical structure with spins lying in the a b plane, in contrast to the collinear one along the c axis in Ni\(_3\) TeO\(_6\). Moreover, dielectric anomalies are observed at their antiferromagnetic phase transitions, suggesting a magnetoelectric behavior. Spin and lattice dynamics studies by a combination of infrared, Raman, and terahertz spectroscopies were performed. Below T\(_N\), in both Ni\(_2\) CoTeO\(_6\) and NiCo\(_2\) TeO\(_6\), low-frequency spin excitations extremely sensitive to external magnetic field were observed. At least one of these magnons was simultaneously seen in Raman and THz spectra of both compounds, therefore we propose to assign them to electromagnons.

Published
2020

17. Universal A-Cation Splitting in LiNbO3-Type Structure Driven by Intrapositional Multivalent Coupling

Author

Han, Yifeng, Zeng, Yijie, Hendrickx, Mylene, Hadermann, Joke, Stephens, Peter W., Zhu, Chuanhui, Grams, Christoph P., Hemberger, Joachim, Frank, Corey, Li, Shufang, Wu, MeiXia, Retuerto, Maria, Croft, Mark, Walker, David, Yao, Dao-Xin, Greenblatt, Martha, Li, Man-Rong, Han, Yifeng, Zeng, Yijie, Hendrickx, Mylene, Hadermann, Joke, Stephens, Peter W., Zhu, Chuanhui, Grams, Christoph P., Hemberger, Joachim, Frank, Corey, Li, Shufang, Wu, MeiXia, Retuerto, Maria, Croft, Mark, Walker, David, Yao, Dao-Xin, Greenblatt, Martha, and Li, Man-Rong

Abstract

Understanding the electric dipole switching in multiferroic materials requires deep insight of the atomic-scale local structure evolution to reveal the ferroelectric mechanism, which remains unclear and lacks a solid experimental indicator in high-pressure prepared LiNbO3-type polar magnets. Here, we report the discovery of Zn-ion splitting in LiNbO3-type Zn2FeNbO6 established by multiple diffraction techniques. The coexistence of a high-temperature paraelectric-like phase in the polar Zn2FeNbO6 lattice motivated us to revisit other high-pressure prepared LiNbO3-type A(2)BB'O-6 compounds. The A-site atomic splitting (similar to 1.0-1.2 angstrom between the split-atom pair) in B/B'-mixed Zn2FeTaO6 and O/N-mixed ZnTaO2N is verified by both powder X-ray diffraction structural refinements and high angle annular dark field scanning transmission electron microscopy images, but is absent in single-B-site ZnSnO3. Theoretical calculations are in good agreement with experimental results and suggest that this kind of A-site splitting also exists in the B-site mixed Mn-analogues, Mn2FeMO6 (M = Nb, Ta) and anion-mixed MnTaO2N, where the smaller A-site splitting (similar to 0.2 angstrom atomic displacement) is attributed to magnetic interactions and bonding between A and B cations. These findings reveal universal A-site splitting in LiNbO3-type structures with mixed multivalent B/B', or anionic sites, and the splitting-atomic displacement can be strongly suppressed by magnetic interactions and/or hybridization of valence bands between d electrons of the A- and B-site cations.

Published
2020

19. La1.5Sr0.5NiMn0.5Ru0.5O6 Double Perovskite with Enhanced ORR/OER Bifunctional Catalytic Activity

Author

Retuerto, Maria, primary, Calle-Vallejo, Federico, additional, Pascual, Laura, additional, Lumbeeck, Gunnar, additional, Fernandez-Diaz, María Teresa, additional, Croft, Mark, additional, Gopalakrishnan, Jagannatha, additional, Peña, Miguel A., additional, Hadermann, Joke, additional, Greenblatt, Martha, additional, and Rojas, Sergio, additional

Published
2019
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20. Contributors

Author

Boruah, Tribani, Cai, Weiwei, Cui, Xun, Das, Dipak Kumar, Doan, Thi Luu Luyen, Gao, Likun, García, Álvaro, Gautam, Sonali, Goyal, Charu, Gupta, Ram K., Hatshan, Mohammad Rafe, Honorato, Ana Maria Borges, Hu, Guangzhi, Ibraheem, Shumaila, Ingsel, Tenzin, Iqbal, Rashid, Khalid, Mohd, Kim, Nam Hoon, Kumar, Anuj, Kumar, Bijandra, Lee, Joong Hee, Li, Jing, Lin, Zhiqun, Mushtaq, Muhammad Asim, Nguyen, Dinh Chuong, Nguyen, Tuan Anh, Retuerto, María, Rojas, Sergio, Saleem, Adil, Sulaiman, Muhammad Rizwan, Sundriyal, Shashank, Tabish, Mohammad, Torrero, Jorge, Tran, Duy Thanh, Varela, Hamilton, Xiao, Shenglin, Yang, Yingkui, Yang, Zehui, Yasin, Ghulam, Ye, Zihao, Zhang, Lei, Zhang, Quan, Zhao, Xue, and Zhu, Yuan-Xin

Published
2022
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22. Dynamic Ferrimagnetic Order in a Highly Distorted Double Perovskite Y2CoRuO6

Author

Deng, Zheng, primary, Retuerto, Maria, additional, Liu, Sizhan, additional, Croft, Mark, additional, Stephens, Peter W., additional, Calder, Stuart, additional, Li, Wenmin, additional, Chen, Bijuan, additional, Jin, Changqing, additional, Hu, Zhiwei, additional, Li, Man-Rong, additional, Lin, Hong-Ji, additional, Chan, Ting-Shan, additional, Chen, Chien-Te, additional, Kim, Sun Woo, additional, and Greenblatt, Martha, additional

Published
2018
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24. Structural and spectroscopic properties of the polar antiferromagnet Ni2MnTeO6

Author

Retuerto, Maria, primary, Skiadopoulou, Stella, additional, Borodavka, Fedir, additional, Kadlec, Christelle, additional, Kadlec, Filip, additional, Prokleška, Jan, additional, Deng, Zheng, additional, Alonso, Jose A., additional, Fernandez-Diaz, Maria T., additional, Saouma, Felix O., additional, Jang, Joon I., additional, Legut, Dominik, additional, Kamba, Stanislav, additional, and Greenblatt, Martha, additional

Published
2018
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25. Chemical tunnel-splitting-engineering in a dysprosium-based molecular nanomagnet

Author

Sørensen, Mikkel A., primary, Hansen, Ursula B., additional, Perfetti, Mauro, additional, Pedersen, Kasper S., additional, Bartolomé, Elena, additional, Simeoni, Giovanna G., additional, Mutka, Hannu, additional, Rols, Stéphane, additional, Jeong, Minki, additional, Zivkovic, Ivica, additional, Retuerto, Maria, additional, Arauzo, Ana, additional, Bartolomé, Juan, additional, Piligkos, Stergios, additional, Weihe, Høgni, additional, Doerrer, Linda H., additional, van Slageren, Joris, additional, Rønnow, Henrik M., additional, Lefmann, Kim, additional, and Bendix, Jesper, additional

Published
2018
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26. Magnetostriction-polarization coupling in multiferroic Mn2MnWO6

Author

Li, Man-Rong, primary, McCabe, Emma E., additional, Stephens, Peter W., additional, Croft, Mark, additional, Collins, Liam, additional, Kalinin, Sergei V., additional, Deng, Zheng, additional, Retuerto, Maria, additional, Sen Gupta, Arnab, additional, Padmanabhan, Haricharan, additional, Gopalan, Venkatraman, additional, Grams, Christoph P., additional, Hemberger, Joachim, additional, Orlandi, Fabio, additional, Manuel, Pascal, additional, Li, Wen-Min, additional, Jin, Chang-Qing, additional, Walker, David, additional, and Greenblatt, Martha, additional

Published
2017
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27. Magnetoelectric excitations in multiferroic Ni3TeO6

Author

Skiadopoulou, Stella, primary, Borodavka, Fedir, additional, Kadlec, Christelle, additional, Kadlec, Filip, additional, Retuerto, Maria, additional, Deng, Zheng, additional, Greenblatt, Martha, additional, and Kamba, Stanislav, additional

Published
2017
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28. Magnetostriction-polarization coupling in multiferroic Mn2MnWO6

Author

Li, Man-Rong, McCabe, Emma E., Stephens, Peter W., Croft, Mark, Collins, Liam, Kalinin, Sergei V., Deng, Zheng, Retuerto, Maria, Sen Gupta, Arnab, Padmanabhan, Haricharan, Gopalan, Venkatraman, Grams, Christoph P., Hemberger, Joachim, Orlandi, Fabio, Manuel, Pascal, Li, Wen-Min, Jin, Chang-Qing, Walker, David, Greenblatt, Martha, Li, Man-Rong, McCabe, Emma E., Stephens, Peter W., Croft, Mark, Collins, Liam, Kalinin, Sergei V., Deng, Zheng, Retuerto, Maria, Sen Gupta, Arnab, Padmanabhan, Haricharan, Gopalan, Venkatraman, Grams, Christoph P., Hemberger, Joachim, Orlandi, Fabio, Manuel, Pascal, Li, Wen-Min, Jin, Chang-Qing, Walker, David, and Greenblatt, Martha

Abstract

Double corundum-related polar magnets are promising materials for multiferroic and magnetoelectric applications in spintronics. However, their design and synthesis is a challenge, and magnetoelectric coupling has only been observed in Ni3TeO6 among the known double corundum compounds to date. Here we address the high-pressure synthesis of a new polar and antiferromagnetic corundum derivative Mn2MnWO6, which adopts the Ni3TeO6-type structure with low temperature first-order field-induced metamagnetic phase transitions (T-N = 58 K) and high spontaneous polarization (similar to 63.3 mu C.cm(-2)). The magnetostrictionpolarization coupling in Mn2MnWO6 is evidenced by second harmonic generation effect, and corroborated by magnetic-field-dependent pyroresponse behavior, which together with the magnetic-field-dependent polarization and dielectric measurements, qualitatively indicate magnetoelectric coupling. Piezoresponse force microscopy imaging and spectroscopy studies on Mn2MnWO6 show switchable polarization, which motivates further exploration on magnetoelectric effect in single crystal/ thin film specimens.

Published
2017

29. Mn2FeWO6: A New Ni3TeO6-Type Polar and Magnetic Oxide

Author

Li, Man-Rong, Croft, Mark, Stephens, Peter W., Ye, Meng, Vanderbilt, David, Retuerto, Maria, Deng, Zheng, Grams, Christoph P., Hemberger, Joachim, Hadermann, Joke, Li, Wen-Min, Jin, Chang-Qing, Saouma, Felix O., Jang, Joon I., Akamatsu, Hirofumi, Gopalan, Venkatraman, Walker, David, and Greenblatt, Martha

Subjects
magnetic phase diagrams, Mn2FeWO6, multiferroics, first-principles calculations, polar magnets
Published
2015

30. Pb2MnTeO6 Double Perovskite : An Antipolar Anti-ferromagnet

Author

Retuerto, Maria, Skiadopoulou, Stella, Li, Man-Rong, Abakumov, Artem M., Croft, Mark, Ignatov, Alexander, Sarkar, Tapati, Abbett, Brian M., Pokorny, Jan, Savinov, Maxim, Nuzhnyy, Dmitry, Prokleska, Jan, Abeykoon, Milinda, Stephens, Peter W., Hodges, Jason P., Vanek, Premysl, Fennie, Craig J., Rabe, Karin M., Kamba, Stanislav, Greenblatt, Martha, Retuerto, Maria, Skiadopoulou, Stella, Li, Man-Rong, Abakumov, Artem M., Croft, Mark, Ignatov, Alexander, Sarkar, Tapati, Abbett, Brian M., Pokorny, Jan, Savinov, Maxim, Nuzhnyy, Dmitry, Prokleska, Jan, Abeykoon, Milinda, Stephens, Peter W., Hodges, Jason P., Vanek, Premysl, Fennie, Craig J., Rabe, Karin M., Kamba, Stanislav, and Greenblatt, Martha

Abstract

Pb2MnTeO6, a new double perovskite, was synthesized. Its crystal structure was determined by synchrotron X-ray and powder neutron diffraction. Pb2MnTeO6 is monoclinic (I2/m) at room temperature with a regular arrangement of all the cations in their polyhedra. However, when the temperature is lowered to similar to 120 K it undergoes a phase transition from I2/m to C2/c structure. This transition is accompanied by a displacement of the Pb atoms from the center of their polyhedra due to the 6s2 lone-pair electrons, together with a surprising off-centering of Mn2+ (d5) magnetic cations. This strong first-order phase transition is also evidenced by specific heat, dielectric, Raman, and infrared spectroscopy measurements. The magnetic characterizations indicate an anti-ferromagnetic (AFM) order below TN approximate to 20 K; analysis of powder neutron diffraction data confirms the magnetic structure with propagation vector k = (0 1 0) and collinear AFM spins. The observed jump in dielectric permittivity near similar to 150 K implies possible anti-ferroelectric behavior; however, the absence of switching suggests that Pb2MnTeO6 can only be antipolar. First-principle calculations confirmed that the crystal and magnetic structures determined are locally stable and that anti-ferroelectric switching is unlikely to be observed in Pb2MnTeO6.

Published
2016
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31. Frontispiz: Low‐Temperature Cationic Rearrangement in a Bulk Metal Oxide

Author

Li, Man‐Rong, primary, Retuerto, Maria, additional, Stephens, Peter W., additional, Croft, Mark, additional, Sheptyakov, Denis, additional, Pomjakushin, Vladimir, additional, Deng, Zheng, additional, Akamatsu, Hirofumi, additional, Gopalan, Venkatraman, additional, Sánchez‐Benítez, Javier, additional, Saouma, Felix O., additional, Jang, Joon I., additional, Walker, David, additional, and Greenblatt, Martha, additional

Published
2016
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32. Low-Temperature Cationic Rearrangement in a Bulk Metal Oxide

Author

Li, Man-Rong, primary, Retuerto, Maria, additional, Stephens, Peter W., additional, Croft, Mark, additional, Sheptyakov, Denis, additional, Pomjakushin, Vladimir, additional, Deng, Zheng, additional, Akamatsu, Hirofumi, additional, Gopalan, Venkatraman, additional, Sánchez-Benítez, Javier, additional, Saouma, Felix O., additional, Jang, Joon I., additional, Walker, David, additional, and Greenblatt, Martha, additional

Published
2016
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33. Mn2MnReO6: Synthesis and Magnetic Structure Determination of a New Transition-Metal-Only Double Perovskite Canted Antiferromagnet

Author

Li, Man-Rong, primary, Hodges, Jason P., additional, Retuerto, Maria, additional, Deng, Zheng, additional, Stephens, Peter W., additional, Croft, Mark C., additional, Deng, Xiaoyu, additional, Kotliar, Gabriel, additional, Sánchez-Benítez, Javier, additional, Walker, David, additional, and Greenblatt, Martha, additional

Published
2016
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34. Pb2MnTeO6 Double Perovskite: An Antipolar Anti-ferromagnet

Author

Retuerto, Maria, primary, Skiadopoulou, Stella, additional, Li, Man-Rong, additional, Abakumov, Artem M., additional, Croft, Mark., additional, Ignatov, Alexander, additional, Sarkar, Tapati, additional, Abbett, Brian M., additional, Pokorný, Jan, additional, Savinov, Maxim, additional, Nuzhnyy, Dmitry, additional, Prokleška, Jan, additional, Abeykoon, Milinda, additional, Stephens, Peter W, additional, Hodges, Jason P., additional, Vaněk, Přemysl, additional, Fennie, Craig J., additional, Rabe, Karin M., additional, Kamba, Stanislav, additional, and Greenblatt, Martha, additional

Published
2016
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36. Mn2 FeWO6 : A New Ni3 TeO6 -Type Polar and Magnetic Oxide

Author

Li, Man-Rong, primary, Croft, Mark, additional, Stephens, Peter W., additional, Ye, Meng, additional, Vanderbilt, David, additional, Retuerto, Maria, additional, Deng, Zheng, additional, Grams, Christoph P., additional, Hemberger, Joachim, additional, Hadermann, Joke, additional, Li, Wen-Min, additional, Jin, Chang-Qing, additional, Saouma, Felix O., additional, Jang, Joon I., additional, Akamatsu, Hirofumi, additional, Gopalan, Venkatraman, additional, Walker, David, additional, and Greenblatt, Martha, additional

Published
2016
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37. Diseño de una metodología innovadora para evaluar y mejorar la comprensión lectora en Primaria

Author

Louzao-Retuerto, Maria del Carmen

Subjects
educación primaria, comprensión lectora, Grado en Maestro en Educación Primaria, lectoescritura, estrategias cognitivas, interacción
Abstract

La latente preocupación del sistema educativo por los deficitarios niveles de comprensión lectora de nuestro alumnado justifican la presente propuesta de intervención que, basada en una metodología lúdico-creativa y centrada en el trabajo constructivista y cooperativo, conjuga todos sus esfuerzos en ofrecer una herramienta didáctica para mejorar y evaluar la comprensión lectora. Se trata de una propuesta metodológica que busca explorar, conceptuar, estructurar y aplicar los fundamentos de la comprensión lectora a través de la creación literaria de cuentos. El objetivo es crear un espacio en el que lectura y escritura se aúnen para aportar una herramienta de diálogo y reflexión crítica alrededor de las estrategias cognitivas de comprensión. El resultado permitirá observar como el tratamiento conceptual y procedimental de dichas estrategias ofrece una interacción lector-texto-escritor que favorece el proceso de comprensión, así como un instrumento de autoevaluación para las capacidades de escritura y comprensión del alumnado.

Published
2014

38. Designing Polar and Magnetic Oxides: Zn2FeTaO6 - in Search of Multiferroics

Author

Li, Man-Rong, Stephens, Peter W., Retuerto, Maria, Sarkar, Tapati, Grams, Christoph P., Hemberger, Joachim, Croft, Mark C., Walker, David, and Greenblatt, Martha

Subjects
Chemistry, Microchemistry, Oxides, Crystals, Materials, Materials science, Chemistry, Physical and theoretical
Abstract

Polar oxides are technically of great interest but difficult to prepare. Our recent discoveries predicted that polar oxides can be synthesized in the corundum-derivative A2BB′O6 family with unusually small cations at the A-site and a d0 electron configuration ion at B′-site. When magnetic transition-metal ions are incorporated more interesting polar magnetic oxides can form. In this work we experimentally verified this prediction and prepared LiNbO3 (LN)-type polar magnetic Zn2FeTaO6 via high pressure and temperature synthesis. The crystal structure analysis indicates highly distorted ZnO6 and (Fe/Ta)O6 octahedra, and an estimated spontaneous polarization (PS) of ∼50 μC/cm2 along the c-axis was obtained from point charge model calculations. Zn2Fe3+Ta5+O6 has a lower magnetic transition temperature (TN ∼ 22 K) than the Mn2FeTaO6 analogue but is less conductive. The dielectric and polarization measurements indicate a potentially switchable component.

Published
2014
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41. La1.5Sr0.5NiMn0.5Ru0.5O6Double Perovskite with Enhanced ORR/OER Bifunctional Catalytic Activity

Author

Retuerto, Maria, Calle-Vallejo, Federico, Pascual, Laura, Lumbeeck, Gunnar, Fernandez-Diaz, María Teresa, Croft, Mark, Gopalakrishnan, Jagannatha, Peña, Miguel A., Hadermann, Joke, Greenblatt, Martha, and Rojas, Sergio

Abstract

Perovskites (ABO3) with transition metals in active B sites are considered alternative catalysts for the water oxidation to oxygen through the oxygen evolution reaction (OER) and for the oxygen reduction through the oxygen reduction reaction (ORR) back to water. We have synthesized a double perovskite (A2BB′O6) with different cations in A, B, and B′ sites, namely, (La1.5Sr0.5)A(Ni0.5Mn0.5)B(Ni0.5Ru0.5)B′O6(LSNMR), which displays an outstanding OER/ORR bifunctional performance. The composition and structure of the oxide has been determined by powder X-ray diffraction, powder neutron diffraction, and transmission electron microscopy to be monoclinic with the space group P21/nand with cationic ordering between the ions in the B and B′ sites. X-ray absorption near-edge spectroscopy suggests that LSNMR presents a configuration of ∼Ni2+, ∼Mn4+, and ∼Ru5+. This bifunctional catalyst is endowed with high ORR and OER activities in alkaline media, with a remarkable bifunctional index value of ∼0.83 V (the difference between the potentials measured at −1 mA cm–2for the ORR and +10 mA cm–2for the OER). The ORR onset potential (Eonset) of 0.94 V is among the best reported to date in alkaline media for ORR-active perovskites. The ORR mass activity of LSNMR is 1.1 A g–1at 0.9 V and 7.3 A g–1at 0.8 V. Furthermore, LSNMR is stable in a wide potential window down to 0.05 V. The OER potential to achieve a current density of 10 mA cm–2is 1.66 V. Density functional theory calculations demonstrate that the high ORR/OER activity of LSNMR is related to the presence of active Mn sites for the ORR- and Ru-active sites for the OER by virtue of the high symmetry of the respective reaction steps on those sites. In addition, the material is stable to ORR cycling and also considerably stable to OER cycling.

Published
2019
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42. Polar and Magnetic Mn2FeMO6 (M = Nb, Ta) with LiNbO3-type Structure - High Pressure Synthesis

Author

Li, Man-Rong, Walker, David, Retuerto, Maria, Sarkar, Tapati, Hadermann, Joke, Stephens, Peter W., Croft, Mark, Ignatov, Alexander, Grams, Christoph P., Hemberger, Joachim, Nowik, Israel, Halasyamani, P. Shiv, Tran, T. Thao, Mukherjee, Swarnakamal, Dasgupta, Tanusri Saha, and Greenblatt, Martha

Subjects
Chemistry, Chemical engineering, Geochemistry, FOS: Earth and related environmental sciences, FOS: Chemical engineering
Abstract

Polar oxides are of much interest in materials science and engineering. Their symmetry-dependent properties such as ferroelectricity/multiferroics, piezoelectricity, pyroelectricity, and second-order harmonic generation (SHG) effect are important for technological applications. However, polar crystal design and synthesis is challenging, because multiple effects, such as steric or dipole-dipole interactions, typically combine to form non-polar structures; so the number of known polar materials, especially polar magnetoelectric materials, is still severely restricted. Therefore, it is necessary for the material science community to develop new strategies to create these materials.

Published
2013
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47. New polar and magnetic corundum - type oxides, A2BB ' O6:High pressure synthesis

Author

Greenblatt, Martha, Li, Manrong, Retuerto, Maria, Deng, Zheng, Croft, Mark, Vanderbilt, David, Ye, Meng, Stephens, Peter, Hadermann, Joke, Walker, David, Hemberger, Joachim, Grams, Christoph, Jin, Chang-Qing, Li, Wen-Min, Jang, Joon, Saouma, Felix, Gopalan, Venkatraman, Akamatsu, Hirofumi, Greenblatt, Martha, Li, Manrong, Retuerto, Maria, Deng, Zheng, Croft, Mark, Vanderbilt, David, Ye, Meng, Stephens, Peter, Hadermann, Joke, Walker, David, Hemberger, Joachim, Grams, Christoph, Jin, Chang-Qing, Li, Wen-Min, Jang, Joon, Saouma, Felix, Gopalan, Venkatraman, and Akamatsu, Hirofumi

Published
2015

50. Giant Magnetoresistance in the Half-Metallic Double-Perovskite Ferrimagnet Mn2FeReO6

Author

Li, Man-Rong, primary, Retuerto, Maria, additional, Deng, Zheng, additional, Stephens, Peter W., additional, Croft, Mark, additional, Huang, Qingzhen, additional, Wu, Hui, additional, Deng, Xiaoyu, additional, Kotliar, Gabriel, additional, Sánchez-Benítez, Javier, additional, Hadermann, Joke, additional, Walker, David, additional, and Greenblatt, Martha, additional

Published
2015
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