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Effect of space charge on the polarization hysteresis characteristics of monolithic and compositionally graded ferroelectrics / M.B. Okatan in Acta materialia, Vol. 58 N° 1 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 39–48 Titre : Effect of space charge on the polarization hysteresis characteristics of monolithic and compositionally graded ferroelectrics Type de document : texte imprimé Auteurs : M.B. Okatan, Auteur ; J.V. Mantese, Auteur ; S. P. Alpay, Auteur Année de publication : 2010 Article en page(s) : pp. 39–48 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Dielectrics  Multilayers  Perovskites  Ferroelectricity  Interface  defects Résumé : A non-linear thermodynamic analysis of ferroelectric systems with localized space charges for monolithic and compositionally graded materials is described wherein the electrostatic interlayer interactions are specifically accounted for. The electrostatic coupling is established through the built-in polarization due to the space charges and the intrinsic polarization variations between the ferroelectric layers. The findings show that the polarization hysteresis response of monolithic stress-free barium strontium titanate (BST) ferroelectrics with asymmetrically distributed space charges result in a displacement of the hysteresis loop along the applied electric field axis. In compositionally graded BST multilayers, the hysteresis response is characterized by off-sets along both the polarization and the electric field axes, yet with magnitudes of displacement that are markedly larger than those for monolithic ferroelectrics. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005679 [article] Effect of space charge on the polarization hysteresis characteristics of monolithic and compositionally graded ferroelectrics [texte imprimé] / M.B. Okatan, Auteur ; J.V. Mantese, Auteur ; S. P. Alpay, Auteur . - 2010 . - pp. 39–48. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 39–48 Mots-clés : Dielectrics  Multilayers  Perovskites  Ferroelectricity  Interface  defects Résumé : A non-linear thermodynamic analysis of ferroelectric systems with localized space charges for monolithic and compositionally graded materials is described wherein the electrostatic interlayer interactions are specifically accounted for. The electrostatic coupling is established through the built-in polarization due to the space charges and the intrinsic polarization variations between the ferroelectric layers. The findings show that the polarization hysteresis response of monolithic stress-free barium strontium titanate (BST) ferroelectrics with asymmetrically distributed space charges result in a displacement of the hysteresis loop along the applied electric field axis. In compositionally graded BST multilayers, the hysteresis response is characterized by off-sets along both the polarization and the electric field axes, yet with magnitudes of displacement that are markedly larger than those for monolithic ferroelectrics. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005679

Misfit strain–film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films / Q. Y. Qiu in Acta materialia, Vol. 58 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 823-835 Titre : Misfit strain–film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films Type de document : texte imprimé Auteurs : Q. Y. Qiu, Auteur ; R. Mahjoub, Auteur ; S. P. Alpay, Auteur Article en page(s) : pp. 823-835 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Ferroelectricity  Thin  films  Phase  transformations  Electroceramics  Dielectrics Index. décimale : 669 Métallurgie Résumé : The phase stability of ultra-thin (0 0 1) oriented ferroelectric PbZr1–xTixO3 (PZT) epitaxial thin films as a function of the film composition, film thickness, and the misfit strain is analyzed using a non-linear Landau–Ginzburg–Devonshire thermodynamic model taking into account the electrical and mechanical boundary conditions. The theoretical formalism incorporates the role of the depolarization field as well as the possibility of the relaxation of in-plane strains via the formation of microstructural features such as misfit dislocations at the growth temperature and ferroelastic polydomain patterns below the paraelectric–ferroelectric phase transformation temperature. Film thickness–misfit strain phase diagrams are developed for PZT films with four different compositions (x = 1, 0.9, 0.8 and 0.7) as a function of the film thickness. The results show that the so-called rotational r-phase appears in a very narrow range of misfit strain and thickness of the film. Furthermore, the in-plane and out-of-plane dielectric permittivities ε11 and ε33, as well as the out-of-plane piezoelectric coefficients d33 for the PZT thin films, are computed as a function of misfit strain, taking into account substrate-induced clamping. The model reveals that previously predicted ultrahigh piezoelectric coefficients due to misfit-strain-induced phase transitions are practically achievable only in an extremely narrow range of film thickness, composition and misfit strain parameter space. We also show that the dielectric and piezoelectric properties of epitaxial ferroelectric films can be tailored through strain engineering and microstructural optimization. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Misfit strain–film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films [texte imprimé] / Q. Y. Qiu, Auteur ; R. Mahjoub, Auteur ; S. P. Alpay, Auteur . - pp. 823-835. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 823-835 Mots-clés : Ferroelectricity  Thin  films  Phase  transformations  Electroceramics  Dielectrics Index. décimale : 669 Métallurgie Résumé : The phase stability of ultra-thin (0 0 1) oriented ferroelectric PbZr1–xTixO3 (PZT) epitaxial thin films as a function of the film composition, film thickness, and the misfit strain is analyzed using a non-linear Landau–Ginzburg–Devonshire thermodynamic model taking into account the electrical and mechanical boundary conditions. The theoretical formalism incorporates the role of the depolarization field as well as the possibility of the relaxation of in-plane strains via the formation of microstructural features such as misfit dislocations at the growth temperature and ferroelastic polydomain patterns below the paraelectric–ferroelectric phase transformation temperature. Film thickness–misfit strain phase diagrams are developed for PZT films with four different compositions (x = 1, 0.9, 0.8 and 0.7) as a function of the film thickness. The results show that the so-called rotational r-phase appears in a very narrow range of misfit strain and thickness of the film. Furthermore, the in-plane and out-of-plane dielectric permittivities ε11 and ε33, as well as the out-of-plane piezoelectric coefficients d33 for the PZT thin films, are computed as a function of misfit strain, taking into account substrate-induced clamping. The model reveals that previously predicted ultrahigh piezoelectric coefficients due to misfit-strain-induced phase transitions are practically achievable only in an extremely narrow range of film thickness, composition and misfit strain parameter space. We also show that the dielectric and piezoelectric properties of epitaxial ferroelectric films can be tailored through strain engineering and microstructural optimization. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]

Misfit strain–film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films / Q. Y. Qiu in Acta materialia, Vol. 58 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 823–835 Titre : Misfit strain–film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films Type de document : texte imprimé Auteurs : Q. Y. Qiu, Auteur ; R. Mahjoub, Auteur ; S. P. Alpay, Auteur Année de publication : 2011 Article en page(s) : pp. 823–835 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Ferroelectricity  Thin  films  Phase  transformations  Electroceramics  Dielectrics Résumé : The phase stability of ultra-thin (0 0 1) oriented ferroelectric PbZr1–xTixO3 (PZT) epitaxial thin films as a function of the film composition, film thickness, and the misfit strain is analyzed using a non-linear Landau–Ginzburg–Devonshire thermodynamic model taking into account the electrical and mechanical boundary conditions. The theoretical formalism incorporates the role of the depolarization field as well as the possibility of the relaxation of in-plane strains via the formation of microstructural features such as misfit dislocations at the growth temperature and ferroelastic polydomain patterns below the paraelectric–ferroelectric phase transformation temperature. Film thickness–misfit strain phase diagrams are developed for PZT films with four different compositions (x = 1, 0.9, 0.8 and 0.7) as a function of the film thickness. The results show that the so-called rotational r-phase appears in a very narrow range of misfit strain and thickness of the film. Furthermore, the in-plane and out-of-plane dielectric permittivities ε11 and ε33, as well as the out-of-plane piezoelectric coefficients d33 for the PZT thin films, are computed as a function of misfit strain, taking into account substrate-induced clamping. The model reveals that previously predicted ultrahigh piezoelectric coefficients due to misfit-strain-induced phase transitions are practically achievable only in an extremely narrow range of film thickness, composition and misfit strain parameter space. We also show that the dielectric and piezoelectric properties of epitaxial ferroelectric films can be tailored through strain engineering and microstructural optimization. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409006661 [article] Misfit strain–film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films [texte imprimé] / Q. Y. Qiu, Auteur ; R. Mahjoub, Auteur ; S. P. Alpay, Auteur . - 2011 . - pp. 823–835. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 823–835 Mots-clés : Ferroelectricity  Thin  films  Phase  transformations  Electroceramics  Dielectrics Résumé : The phase stability of ultra-thin (0 0 1) oriented ferroelectric PbZr1–xTixO3 (PZT) epitaxial thin films as a function of the film composition, film thickness, and the misfit strain is analyzed using a non-linear Landau–Ginzburg–Devonshire thermodynamic model taking into account the electrical and mechanical boundary conditions. The theoretical formalism incorporates the role of the depolarization field as well as the possibility of the relaxation of in-plane strains via the formation of microstructural features such as misfit dislocations at the growth temperature and ferroelastic polydomain patterns below the paraelectric–ferroelectric phase transformation temperature. Film thickness–misfit strain phase diagrams are developed for PZT films with four different compositions (x = 1, 0.9, 0.8 and 0.7) as a function of the film thickness. The results show that the so-called rotational r-phase appears in a very narrow range of misfit strain and thickness of the film. Furthermore, the in-plane and out-of-plane dielectric permittivities ε11 and ε33, as well as the out-of-plane piezoelectric coefficients d33 for the PZT thin films, are computed as a function of misfit strain, taking into account substrate-induced clamping. The model reveals that previously predicted ultrahigh piezoelectric coefficients due to misfit-strain-induced phase transitions are practically achievable only in an extremely narrow range of film thickness, composition and misfit strain parameter space. We also show that the dielectric and piezoelectric properties of epitaxial ferroelectric films can be tailored through strain engineering and microstructural optimization. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409006661