{"id":99434,"date":"2018-03-11T10:20:34","date_gmt":"2018-03-11T10:20:34","guid":{"rendered":"https:\/\/www.deberes.net\/tesis\/sin-categoria\/materiales-con-alta-constante-dielectrica-multiferroicos-magnetoelectricos-y-magnetodielectricos\/"},"modified":"2018-03-11T10:20:34","modified_gmt":"2018-03-11T10:20:34","slug":"materiales-con-alta-constante-dielectrica-multiferroicos-magnetoelectricos-y-magnetodielectricos","status":"publish","type":"post","link":"https:\/\/www.deberes.net\/tesis\/propiedades-magneticas-de-los-solidos\/materiales-con-alta-constante-dielectrica-multiferroicos-magnetoelectricos-y-magnetodielectricos\/","title":{"rendered":"Materiales con alta constante diel\u00e9ctrica, multiferroicos magnetoel\u00e9ctricos y magnetodiel\u00e9ctricos"},"content":{"rendered":"<h2>Tesis doctoral de <strong> Susana Y\u00e1\u00f1ez <\/strong><\/h2>\n<p>Esta tesis doctoral se centra en la b\u00fasqueda y estudio de materiales con alta constante diel\u00e9ctrica, basados en \u00f3xidos mixtos con orden de carga, y en la posibilidad de modificar y controlar las propiedades diel\u00e9ctricas de distintos materiales mediante la aplicaci\u00f3n de un campo magn\u00e9tico. como punto de partida se escoge el compuesto pr0.79na0.21mno3 (toc= 220 k) donde se observa la aparici\u00f3n de un m\u00e1ximo en la constante diel\u00e9ctrica a la temperatura a la que se produce el fen\u00f3meno de orden de carga. Este comportamiento se relaciona con la formaci\u00f3n de entidades polares debido a una distribuci\u00f3n de carga asim\u00e9trica. a continuaci\u00f3n se ha estudiado el compuesto la2mncoo6 (toc= 400 k) que se ha preparado con diferente grado de orden cati\u00f3nico en la posici\u00f3n b obteniendo una muestra pr\u00e1cticamente ordenada que presenta un comportamiento diel\u00e9ctrico intr\u00ednseco, mientras que las muestras m\u00e1s desordenadas presentan elevadas constantes diel\u00e9ctricas que aumentan al incrementarse el tama\u00f1o de part\u00edcula y variar el tipo de contactos. El inconveniente son los elevados valores de tangente de p\u00e9rdidas que presentan y que se pueden reducir preparando materiales compuestos tipo n\u00facleo-corteza la2mncoo6@sio2. adem\u00e1s, en el compuesto camn7o12 (toc= 440 k) se ha encontrado una anomal\u00eda en la constante diel\u00e9ctrica en torno a tn2= 50 k adem\u00e1s de un peque\u00f1o efecto magnetoel\u00e9ctrico del orden del 1% a t= 10 k y h= 10 t. Este efecto es debido a la aparici\u00f3n de polarizaci\u00f3n inducida por la magnetostricci\u00f3n que presenta este sistema a 50 k.  tambi\u00e9n se han preparado monocristales de la serie lnm2o5 (ln= y, pr, nd, sm, eu, gd, tb, dy, ho y er) mediante s\u00edntesis hidrotermal encontrando una serie de anomal\u00edas en la constante diel\u00e9ctrica que coinciden con las transiciones el\u00e9ctricas, adem\u00e1s de un efecto magnetoel\u00e9ctrico del 2 % a 5 k y h= 14 t para los compuestos lnmn2o5 (ln= y, tb, dy y er). en nanopart\u00edculas de la0.67ca0.33mno3 se observa un comportamiento magnetodiel\u00e9ctrico considerable del orden del 20 % a 280 k y h= 0.5 t debido a la coexistencia del fen\u00f3meno de polarizaci\u00f3n interfacial maxwell-wagner, magnetorresistencia y segregaci\u00f3n de fases. finalmente en nanopart\u00edculas de mfe2o4 (m= fe y ni) se ha encontrado un efecto magnetodiel\u00e9ctrico que especialmente importante en fe3o4 (md=6 % a 300 k y 5 koe) y superior al descrito en la bibliograf\u00eda para otras nanopart\u00edculas magn\u00e9ticas.<\/p>\n<p>&nbsp;<\/p>\n<h3>Datos acad\u00e9micos de la tesis doctoral \u00ab<strong>Materiales con alta constante diel\u00e9ctrica, multiferroicos magnetoel\u00e9ctricos y magnetodiel\u00e9ctricos<\/strong>\u00ab<\/h3>\n<ul>\n<li><strong>T\u00edtulo de la tesis:<\/strong>\u00a0 Materiales con alta constante diel\u00e9ctrica, multiferroicos magnetoel\u00e9ctricos y magnetodiel\u00e9ctricos <\/li>\n<li><strong>Autor:<\/strong>\u00a0 Susana Y\u00e1\u00f1ez <\/li>\n<li><strong>Universidad:<\/strong>\u00a0 A coru\u00f1a<\/li>\n<li><strong>Fecha de lectura de la tesis:<\/strong>\u00a0 26\/02\/2010<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Direcci\u00f3n y tribunal<\/h3>\n<ul>\n<li><strong>Director de la tesis<\/strong>\n<ul>\n<li>Mar\u00eda Antonia Se\u00f1ar\u00eds  Rodr\u00edguez<\/li>\n<\/ul>\n<\/li>\n<li><strong>Tribunal<\/strong>\n<ul>\n<li>Presidente del tribunal: Miguel angel Alarios franco <\/li>\n<li>nevenko Biskup (vocal)<\/li>\n<li>purificaci\u00f3n Escribano l\u00f3pez (vocal)<\/li>\n<li>Jorge Mira p\u00e9rez (vocal)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Tesis doctoral de Susana Y\u00e1\u00f1ez Esta tesis doctoral se centra en la b\u00fasqueda y estudio de materiales con alta constante [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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