Fe2O3@BaTiO3 Core−Shell Particles as Reactive Precursors for the Preparation of Multifunctional Composites Containing Different Magnetic Phases

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• 作者：Maria Teresa Buscaglia ; Vincenzo Buscaglia ; Lavinia Curecheriu ; Petronel Postolache ; Liliana Mitoseriu ; Adelina C. Ianculescu ; Bogdan S. Vasile ; Zhao Zhe ; Paolo Nanni
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：August 24, 2010
• 年：2010
• 卷：22
• 期：16
• 页码：4740-4748
• 全文大小：1021K
• 年卷期：v.22,no.16(August 24, 2010)
• ISSN：1520-5002

文摘

Well-designed reactive precursors and templates allow for careful control of solid-state reactions at the nanoscale level, thus enabling the fabrication of materials with specific microstructures and properties. In this study, Fe₂O₃@BaTiO₃ core−shell particles have been used as precursors for the in situ fabrication of multifunctional composites containing a dielectric/ferroelectric phase and two magnetic phases with contrasting coercivities (Fe₂O₃/Fe₃O₄, BaFe₁₂O₁₉/Ba₁₂Fe₂₈Ti₁₅O₈₄). The formation of new magnetic phases occurs during sintering or post-annealing via reaction between BaTiO₃ and Fe₂O₃. The starting powders have been prepared using a multistep process that combines colloidal chemistry methods and a solid-state reaction. The nature and the amount of the magnetic phases and, consequently, the final magnetic properties of the composite can be controlled by varying the relative amount of Fe₂O₃ (30 or 50 vol%), the densification method (conventional or spark plasma sintering), and the processing temperature. The composites show constricted magnetic hysteresis loops with a coercivity of 0.1−2.5 kOe and a saturation magnetization of 5−16 emu/g. Composites obtained from powders containing 30 vol% Fe₂O₃ show, at temperatures of 20−80 °C and frequencies between 10 kHz and 1 MHz, a relative dielectric constant of 50 and dielectric losses of <10%.