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Experimental frequency-dependent conductivity relaxation spectra of a number of molten, glassy, and crystalline ionic conductors that show both the presence of the near constant loss (NCL) and the cooperative ion hopping contribution are analyze[...]texto impreso
Díaz Guillén, M. R. ; Moreno, K. J. ; Díaz Guillén, J. A. ; Fuentes, A .F. ; Naval, K. L. Ngai ; Garcia Barriocanal, Javier ; Santamaría Sánchez-Barriga, Jacobo ; León Yebra, Carlos | American Physical Society | 2008-09In this work we evaluate the effect of cation size on the dc activation energy needed for oxygen ion migration, E_(dc), in highly disordered pyrochlore-type ionic conductors A_(2)B_(2)O_(7). Twenty six compositions with the general formula, Ln_([...]texto impreso
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Salafranca, Juan ; Rincón, Julián ; Tornos Castillo, Javier ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo ; Dagotto, Elbio ; Pennycook, Stephen J. ; Varela del Arco, María | American Physical Society | 2014-05-14Here we study the electronic properties of cuprate-manganite interfaces. By means of atomic resolution electron microscopy and spectroscopy, we produce a subnanometer scale map of the transition metal oxidation state profile across the interface[...]texto impreso
Peña, V. ; Rivera Calzada, Alberto Carlos ; Garcia Barriocanal, Javier ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo ; García González, E. ; González Calbet, J. M. | Sociedad Española de Cerámica y Vidrio | 2004-01Presentamos medidas de la conductividad eléctrica del sistema BIFEVOX Bi_(4)V_(2-x)Fe_(x)O_(11-y)(0?x?0.9;0?y?1), en el que se realiza la sustitución de iones V (IV) por Fe (III) de forma sistemática. La conductividad muestra un comportamiento p[...]texto impreso
Hernández Martín, David ; Gallego Toledo, Fernando ; Tornos Castillo, Javier ; Rouco Gómez, Víctor ; Beltrán Finez, Juan Ignacio ; Munuera, C. ; Sánchez Manzano, David ; Cabero Piris, Mariona ; Cuéllar Jiménez, Fabián Andrés ; Arias Serna, Diego ; Sánchez Santolino, Gabriel ; Mompean, F. J. ; Gárcia Hernández, M. ; Rivera Calzada, Alberto Carlos ; Pennycook, S. J. ; Varela del Arco, María ; Muñoz, M. C. ; Sefrioui, Zouhair ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2020-12-30The persistence of ferroelectricity in ultrathin layers relies critically on screening or compensation of polarization charges which otherwise destabilize the ferroelectric state. At surfaces, charged defects play a crucial role in the screening[...]texto impreso
Moreno, K. J. ; Mendoza-Suárez, G. ; Fuentes, A. F. ; Garcia Barriocanal, Javier ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2005-04-22We report on dispersive conductivity measurements in the oxygen ion conductor Gd_(2)(Ti_(2?y)Zr_(y))O_(7). Increasing Zr content leads to higher concentration of oxygen vacancies and results in higher activation energies for long-range ion trans[...]texto impreso
León Yebra, Carlos ; Lucía Mulas, María Luisa ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 1997-01-01A study of the effect of correlated ion motion on the electrical conductivity relaxation in single-crystalline yttria-stabilized zirconia is presented. Complex admittance in the radio frequency range show power-law dependencies in the real part[...]texto impreso
León Yebra, Carlos ; Ngai, K. L. ; Rivera Calzada, Alberto Carlos | American Physical Society | 2004-04-16For ionic conductivity relaxation in ionically conducting materials we predict in the framework of the coupling model that the magnitude of the ubiquitous near constant loss correlates with the activation energy E_(a) for independent ion hopping[...]texto impreso
Peña, V. ; Sefrioui, Zouhair ; Arias Serna, Diego ; León Yebra, Carlos ; Santamaría Sánchez-Barriga, Jacobo ; Varela del Arco, María ; Pennycook, S. J. ; Martínez, J. L. | American Physical Society | 2004-06-08Here we examine the ferromagnetic/superconducting proximity effect in half-metallic ferromagnetic La_(0.7)Ca_(0.3)MnO_(3) and high-T_(c) superconducting YBa_(2)Cu_(3)O_(7) artificial structures. We have found experimental evidence for the coupli[...]texto impreso
Rivera Calzada, Alberto Carlos ; León Yebra, Carlos ; Sanz, J. ; Santamaría Sánchez-Barriga, Jacobo ; Moynihan, C. T. ; Ngai, K. L. | American Physical Society | 2002-06-10Electrical conductivity measurements of the fast ionic conductor Li_(0.18)La_(0.61)TiO_(3) have been conducted at temperatures ranging from 8 to 300 K and frequencies between 20 Hz and 5 MHz. A detailed analysis of the ac conductivity shows the [...]texto impreso
Sefrioui, Zouhair ; Arias Serna, Diego ; Varela del Arco, María ; Villegas, J. E. ; López de la Torre, M. A. ; León Yebra, Carlos ; Loos, G. D. ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 1999-12-01Current-voltage (I-V) characteristics were used to investigate the response of the vortex-glass (VG) phase transition in high-quality epitaxial YBa_(2)Cu_(3)O_(7-?) films in magnetic fields up to 7 T. We show that varying the oxygen content, the[...]texto impreso
Díaz Guillén, M. R. ; Díaz Guillén, J. A. ; Fuentes, A. F. ; Santamaría Sánchez-Barriga, Jacobo ; León Yebra, Carlos | American Physical Society | 2010-11-18We report on ac conductivity measurements of oxide ion conductors with composition Gd_(2)(Zr_(y)Ti_(1?y)_(2)O_(7), at temperatures between 170 and 500 K and in the frequency range 1 Hz–3MHz, and show that a crossover from a sublinear power law t[...]texto impreso
Varela del Arco, María ; Arias Serna, Diego ; Sefrioui, Zouhair ; León Yebra, Carlos ; Ballesteros, C. ; Pennycook, S. J. ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2002-10-01We report the effects of epitaxial strain and deoxygenation on high quality [YBa_(2)Cu_(3)O_(7-x)(YBCO)_(N) /PrBa_(2)Cu_(3)O_(7)(PBCO)_(5)]_(1000 Å) superlattices, with 1texto impreso
Varela del Arco, María ; Grogger, W. ; Arias Serna, Diego ; Sefrioui, Zouhair ; León Yebra, Carlos ; Ballesteros, C. ; Frishnan, K.M. ; Santamaría Sánchez-Barriga, Jacobo | American Physical Society | 2001-05-28Charge neutrality and stoichiometry impose severe restrictions on the mechanisms of epitaxial growth of complex oxides. The fundamental question arises of what is the minimum growth unit when sample thickness is reduced beyond the size of the un[...]
