Person: Martínez De Irujo Labalde, Xabier
Loading...
First Name
Xabier
Last Name
Martínez De Irujo Labalde
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Inorgánica
Area
Química Inorgánica
Identifiers
9 results
Search Results
Now showing 1 - 9 of 9
Item Structural Ordering Supremacy on the Oxygen Reduction Reaction of Layered Iron-Perovskites(Inorganic Chemistry, 2020) Martínez De Irujo Labalde, Xabier; Marín Gamero, Rafael; Urones Garrote, Esteban; García Martín, Susana; ACS PublicationsItem Multiferroism induced by spontaneous structural ordering in antiferromagnetic iron perovskites(Chemistry of Materials, 2019) Martínez De Irujo Labalde, Xabier; Goto, Masato; Urones-Garrote, Esteban; Amador, Ulises; Ritter, Clemens; Amano Patino, Midori ; Koedtruad, Anucha; Tan, Zhenhong; Shimakawa, Yuichi; García Martín, SusanaRoom-temperature multiferroism in polycrystalline antiferromagnetic Fe perovskites is reported for the first time. In the perovskite-type oxides RE1.2Ba1.2Ca0.6Fe3O8 (RE = Gd, Tb), the interplay of layered ordering of Gd(Tb), Ba, and Ca atoms with the ordering of FeO4-tetrahedra (T) and FeO6-octahedra (O) results in a polar crystal structure. The layered structure consists of the stacking sequence of RE/Ca-RE/Ca-Ba-RE/Ca layers in combination with the TOOT sequence in a unit cell. A polar moment of 33.0 μC/cm2 for the Gd-oxide (23.2 μC/cm2 for the Tb one) is determined from the displacements of the cations, mainly Fe, and oxygen atoms along the b-axis. These oxides present antiferromagnetic ordering doubling the c-axis, and the magnetic structure in the Tb-compound remains up to 690 K, which is one of the highest transition temperatures reported in Fe perovskites.Item Complex modulation of the crystal structure of a layered perovskite. A promising solid-oxide-fuelcell cathode(Journal of Materials Chemistry A, 2016) Martínez De Irujo Labalde, Xabier; Muñoz Gil, Daniel; Urones Garrote, Esteban; Ávila Brande, David; García Martín, SusanaLayered-type perovskites have been the focus of research in the last few years due to their outstanding properties as solid oxide fuel cell oxygen electrodes. The synthesis of a new (GdBa)0.8Ca0.4Co0.6Fe1.4O6-d layered perovskite as a single phase as well as the crystal structure determination and catalytic activity for oxygen reduction is reported. Highly advanced methods of transmission electron microscopy have been used for structure determination at atomic resolution. The oxide shows a complex modulation of the crystal structure associated with layered-type ordering of the Gd, Ba and Ca atoms in combination with formation of different coordination polyhedra of the Fe and Co atoms. Location of the anion vacancies within particular highly ion-conducting layers of the crystal structure has been achieved by phase image reconstruction. This material exhibits excellent electrochemical behaviour and thermal stability for use as an air electrode in IT-SOFCs.Item YBaCuO-type perovskites as potential air electrodes for SOFCs. The case of YSr2Cu2FeO7+δ(Journal of Materials Chemistry A, 2021) López Paz, Sara Almudena; Marín Gamero, Rafael; Martínez De Irujo Labalde, Xabier; Sánchez Marcos, Jorge; Perez Coll, Domingo; Alario y Franco, Miguel Ángel; García Martín, SusanaThe electrochemical properties of YSr2Cu2FeO7+d with YBaCuO-type structure have been studied. The temperature dependent oxygen content of this oxide has a marked influence on its p-type conducting behavior, since topochemical oxygen release occurs on heating above 673 K while reversible oxygen uptake takes place on cooling. Mixed valence Fe3+/Fe4+ and Cu2+/Cu3+ in combination with anion vacancies within the oxygen-sublattice suggest mixed (electronic and ionic) conductivity in this oxide. Electrochemical measurements indicate that YSr2Cu2FeO7+d shows high oxygen reduction reaction activity at intermediate temperatures, revealing its potential applications as an air electrode in SOFCs.Item 3D to 2D Magnetic Ordering of Fe3+ Oxides Induced by Their Layered Perovskite Structure(Inorganic Chemistry, 2021) García Martín, Susana; Martínez De Irujo Labalde, Xabier; Amador, Ulises; Ritter, Clemens; Goto, Masato; Patino, Midori Amano; Shimakawa, YuichiThe antiferromagnetic behavior of Fe3+ oxides of composition RE1.2Ba1.2Ca0.6Fe3O8, RE2.2Ba3.2Ca2.6Fe8O21, and REBa2Ca2Fe5O13 (RE = Gd, Tb) is highly influenced by the type of oxygen polyhedron around the Fe3+ cations and their ordering, which is coupled with the layered RE/Ba/Ca arrangement within the perovskite-related structure. Determination of the magnetic structures reveals different magnetic moments associated with Fe3+ spins in the different oxygen polyhedra (octahedron, tetrahedron, and square pyramid). The structural aspects impact on the strength of the Fe-O-Fe superexchange interactions and, therefore, on the Neel temperature ( ́ TN) of the compounds. The oxides present an interesting transition from three-dimensional (3D) to two-dimensional (2D) magnetic behavior above TN. The 2D magnetic interactions are stronger within the FeO6 octahedra layers than in the FeO4 tetrahedra layers.Item Efectos del orden estructural en las propiedades eléctricas y magnéticas de óxidos multi-catiónicos con estructura derivada de la perovskita(2019) Martínez De Irujo Labalde, Xabier; García Martín, Susana; Alario Franco, Miguel ÁngelLos óxidos mixtos con estructura tipo perovskita, de fórmula general ABO3, forman familias de compuestos de gran interés tanto desde el punto de vista científico como tecnológico. Esta estructura ofrece una gran variedad de posibilidades de sustitución de cationes en las posiciones A y/o B para formar sistemas complejos con dos o más tipos de cationes en ambas posiciones. Esta flexibilidad composicional está asociada a una flexibilidad estructural que permite acomodar la variedad de tamaños y estados de oxidación de los diferentes cationes. En este sentido, el orden de los cationes en posiciones A y B de óxidos con estructura derivada del tipo perovskita ha generado un gran interés en los últimos años debido a su gran impacto sobre las propiedades eléctricas y magnéticas, lo que los convierte en materiales con un gran interés funcional. Entre los diferentes modelos de orden que se pueden establecer, el orden de tipo laminar de los cationes en las posiciones A ha sido poco explorado por su mayor dificultad de estabilización. Un método eficaz para inducir este tipo de orden consiste en la co-existencia de vacantes aniónicas, que también pueden llegar a ordenarse, estableciendo un orden laminar adicional dentro de la subred aniónica con interesantes implicaciones en las propiedades de estos óxidos. El objetivo general de este trabajo ha consistido en preparar óxidos con estructura derivada de la perovskita, con orden laminar en ambas subredes, catiónica y aniónica, y estudiar los efectos del orden estructural en sus propiedades eléctricas y magnéticas...Item Influence of Structural (Cation and Anion) Order in the Superconducting Properties of Ozone-Oxidized Mo0.3Cu0.7Sr2RECu2Oy (RE = Yb, Tm, Gd, Nd, and Pr)(Inorganic Chemistry, 2018) Martínez De Irujo Labalde, Xabier; García-Martín, Susana; Urones-Garrote, Esteban; Alario-Franco, Miguel ÁngelThe influence of rare earth (RE) elements on superconducting properties of the transition element (TE)-substituted TExCu1−xSr2RECu2Oy cuprates has not been sufficiently emphasized so far. In the case of molibdocuprates with the general formula Mo0.3Cu0.3Sr2RECu2Oy, all the RE element containing compounds except La, Ce, and Lu can be prepared at room pressure. The influence of the crystal structure on the superconducting properties after ozone oxidation of the present system is reported selecting three groups of RE elements attending to their different atom sizes: small (Yb and Tm), medium (Gd), and big (Nd and Pr). Advanced transmission electron microscopy, various diffraction techniques, and spectroscopic analysis have been used to demonstrate that the increase of structural disorder complemented with a decrease in the hole content play a major role in the vanishing of superconductivity within the present system.Item Multiferroism Induced by Spontaneous Structural Ordering in Antiferromagnetic Iron Perovskites(Chemistry of Materials, 2019) García-Martín, Susana; Martínez De Irujo Labalde, Xabier; Goto, Masato; Urones-Garrote, Esteban; Amador, Ulises; Ritter, Clemens; Amano Patino, Midori E; Koedtruad, Anucha; Tan, Zhenhong; Shimakawa, YuichiRoom-temperature multiferroism in polycrystalline antiferromagnetic Fe perovskites is reported for the first time. In the perovskite-type oxides RE1.2Ba1.2Ca0.6Fe3O8 (RE = Gd, Tb), the interplay of layered ordering of Gd(Tb), Ba, and Ca atoms with the ordering of FeO4-tetrahedra (T) and FeO6-octahedra (O) results in a polar crystal structure. The layered structure consists of the stacking sequence of RE/Ca-RE/Ca-Ba-RE/Ca layers in combination with the TOOT sequence in a unit cell. A polar moment of 33.0 μC/cm2 for the Gd-oxide (23.2 μC/cm2 for the Tb one) is determined from the displacements of the cations, mainly Fe, and oxygen atoms along the b-axis. These oxides present antiferromagnetic ordering doubling the c-axis, and the magnetic structure in the Tb compound remains up to 690 K, which is one of the highest transition temperatures reported in Fe perovskites.Item Structural and dielectric properties of ultra-fast microwave-processed La_0.3Ca_0.7Fe_0.7Cr_0.3O3-delta ceramics(Journal of solid state chemistry, 2022) Sánchez Ahijón, Elena; Schmidt, Rainer; Martínez De Irujo Labalde, Xabier; Haris Masood, Ansari; Fernández Díaz, María Teresa; Morán, Emilio; Molero Sánchez, Beatriz; Prado Gonjal, Jesús De La PazPerovskite La_0.3Ca_0.7Fe_0.7Cr_0.3O_(3-delta) (LCFCr) is a mixed ionic and electronic conductor (MIEC) that can be employed as an electrode material in reversible solid oxide fuel cells (RSOFCs). In this work, an ultra-fast (15 min) one-step microwave (MW)-assisted combustion synthesis route has been developed to obtain phase pure and highly crystalline LCFCr powder. The synthesized powders exhibited a sponge-like microstructure with increased electrochemical reaction sites. Neutron thermodiffraction analysis revealed a structural transition above 500 degrees C from the room temperature (RT) orthorhombic Pnma to a rhombohedral R3c perovskite phase. The oxygen vacancy concentration was found to increase from delta = 0.272(7) at RT to delta = 0.333(5) at 900 degrees C. Furthermore, a 3-dimensional G-type antiferromagnetic structure was detected at RT. MW-sintering of pressed green ceramic pellets was carried out at 950 degrees C for 1 h, using a MW-transparent quartz fiber crucible or alternatively a SiC crucible acting as a MW-absorber. Impedance spectroscopy data on sintered ceramic pellets revealed electronic inhomogeneity as demonstrated by the occurrence of three dielectric relaxation processes associated with two grain boundary (GB)-like contributions and one bulk. The dielectric inhomogeneity encountered may be restricted to the extrinsic GB areas, which may be rather thin. More homogeneous dielectric properties of the GBs were found in the pellet that was sintered in the SiC crucible.