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Ceramic processing strategies for thick films on copper foils / Aiying Wu in Acta materialia, Vol. 58 N° 6 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2282–2290 Titre : Ceramic processing strategies for thick films on copper foils Type de document : texte imprimé Auteurs : Aiying Wu, Auteur ; Paula M. Vilarinho, Auteur ; Angus I. Kingon, Auteur Année de publication : 2011 Article en page(s) : pp. 2282–2290 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Electroceramics  Perovkskites  Copper  Sintering  Ferroelectricity Résumé : Functional oxides on Cu have multiple applications. For thick films the required high sintering temperatures present a challenge for processing on base metal substrates. In this study it is shown that it is possible to adapt well-known ceramic processing strategies to the fabrication of thick lead zirconate titanate (PZT) films on Cu with useful ferroelectric properties. PZT powders with optimized particle sizes are used to fabricate thick films by electrophoretic deposition in combination with a post-deposition isostatic pressing step. This approach to maximize green packing is sufficient to dramatically lower the required sintering temperatures. 25 μm thick PZT films on Cu sintered at 900 °C have a dielectric permittivity of 585, a loss tangent at 10 kHz of 0.03, a remanent polarization of 19 μC cm−2 and a coercive field of 22 kV cm−1. This significant improvement in the dielectric response opens the possibility of using thick PZT films on Cu for a wide range of devices where cost, yield and reliability are concerns. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008581 [article] Ceramic processing strategies for thick films on copper foils [texte imprimé] / Aiying Wu, Auteur ; Paula M. Vilarinho, Auteur ; Angus I. Kingon, Auteur . - 2011 . - pp. 2282–2290. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2282–2290 Mots-clés : Electroceramics  Perovkskites  Copper  Sintering  Ferroelectricity Résumé : Functional oxides on Cu have multiple applications. For thick films the required high sintering temperatures present a challenge for processing on base metal substrates. In this study it is shown that it is possible to adapt well-known ceramic processing strategies to the fabrication of thick lead zirconate titanate (PZT) films on Cu with useful ferroelectric properties. PZT powders with optimized particle sizes are used to fabricate thick films by electrophoretic deposition in combination with a post-deposition isostatic pressing step. This approach to maximize green packing is sufficient to dramatically lower the required sintering temperatures. 25 μm thick PZT films on Cu sintered at 900 °C have a dielectric permittivity of 585, a loss tangent at 10 kHz of 0.03, a remanent polarization of 19 μC cm−2 and a coercive field of 22 kV cm−1. This significant improvement in the dielectric response opens the possibility of using thick PZT films on Cu for a wide range of devices where cost, yield and reliability are concerns. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008581

Sr- and Ti-site substitution, lattice dynamics, and octahedral tilt transition relationship in SrTiO3: Mn ceramics / Alexander Tkach in Acta materialia, Vol. 58 N° 2 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 577-582 Titre : Sr- and Ti-site substitution, lattice dynamics, and octahedral tilt transition relationship in SrTiO3: Mn ceramics Type de document : texte imprimé Auteurs : Alexander Tkach, Auteur ; Paula M. Vilarinho, Auteur ; Dmitry Nuzhnyy, Auteur Article en page(s) : pp. 577-582 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : SrTiO3  Dopants  Structural  phase  transition  Phonon  dynamics  Infrared  and  terahertz  spectroscopy Index. décimale : 669 Métallurgie Résumé : SrTiO3:Mn ceramics, prepared according to the chemical formulae Sr1–xMnxTiO3 and SrTi1–yMnyO3, are studied by Fourier transform infrared and time-domain terahertz spectroscopy in the temperature range of 10–300 K to support the incorporation of Mn ions into the perovskite lattice of SrTiO3, and to ascertain their different lattice site locations. The polar soft mode of the incipient ferroelectric SrTiO3 is found to be hardened in the whole temperature range by the substitution of Mn ions on Ti sites, and only in the low-temperature range by the Sr site substitution. Activation of the mode, associated with the R point condensation of the Brillouin zone due to the doubling of the unit cell by antiphase rotations of the O-octahedra below the structural transition temperature Ta, shows that the substitution of Mn ions on the Sr sites increases Ta, whereas the Ti-site substitution suppresses Ta with respect to the undoped SrTiO3. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Sr- and Ti-site substitution, lattice dynamics, and octahedral tilt transition relationship in SrTiO3: Mn ceramics [texte imprimé] / Alexander Tkach, Auteur ; Paula M. Vilarinho, Auteur ; Dmitry Nuzhnyy, Auteur . - pp. 577-582. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 577-582 Mots-clés : SrTiO3  Dopants  Structural  phase  transition  Phonon  dynamics  Infrared  and  terahertz  spectroscopy Index. décimale : 669 Métallurgie Résumé : SrTiO3:Mn ceramics, prepared according to the chemical formulae Sr1–xMnxTiO3 and SrTi1–yMnyO3, are studied by Fourier transform infrared and time-domain terahertz spectroscopy in the temperature range of 10–300 K to support the incorporation of Mn ions into the perovskite lattice of SrTiO3, and to ascertain their different lattice site locations. The polar soft mode of the incipient ferroelectric SrTiO3 is found to be hardened in the whole temperature range by the substitution of Mn ions on Ti sites, and only in the low-temperature range by the Sr site substitution. Activation of the mode, associated with the R point condensation of the Brillouin zone due to the doubling of the unit cell by antiphase rotations of the O-octahedra below the structural transition temperature Ta, shows that the substitution of Mn ions on the Sr sites increases Ta, whereas the Ti-site substitution suppresses Ta with respect to the undoped SrTiO3. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]