Evolution of structure and electrical properties with lanthanum content in [(Bi1/2Na1/2)0.95Ba0.05]1-xLaxTiO3 ceramics

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2014-01-01
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Liu, Xiaoming
Guo, Hanzheng
Tan, Xiaoli
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Tan, Xiaoli
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Materials Science and Engineering
Materials engineers create new materials and improve existing materials. Everything is limited by the materials that are used to produce it. Materials engineers understand the relationship between the properties of a material and its internal structure — from the macro level down to the atomic level. The better the materials, the better the end result — it’s as simple as that.
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Lead-free perovskite [(Bi1/2Na1/2)0.95Ba0.05]1-xLaxTiO3 (x = 0.00 ~ 0.10) ceramics were fabricated via the solid state reaction method and their crystal structures and electrical properties were systematically studied. Transmission electron microscopy examination reveals a transition from a rhombohedral R3c phase with micron-sized complex domains to a mixture of rhombohedral R3c and tetragonal P4bm phases with nanodomains as La content was increased. X-ray diffraction analysis on bulk samples, however, indicates a pseudocubic structure in La-doped compositions. Electrical poling seems to transform the pseudocubic structure to a rhombohedral phase in compositions with 0.00 < x < 0.03. With La addition, the depolarization temperature (Td) is observed to decrease and the dielectric constant (εr) within 100 ~ 350 oCbecomes more temperature independent, promising for applications in high-temperature capacitors. Electric field-induced polarizations and strains display complex changes with respect to La concentration, with the highest strain of 0.35 % achieved in the composition x = 0.04 under 70 kV/cm at room temperature. The piezoelectric coefficient d33 initially increases with La content, reaching a maximum value of 151 pC/N in the composition x = 0.02, and then diminishes.

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NOTICE: this is the author’s version of a work that was accepted for publication in Journal of the European Ceramic Society. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of the European Ceramic Society, [34, 2997, (2014)] DOI:10.1016/j.jeurceramsoc.2014.03.017

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Wed Jan 01 00:00:00 UTC 2014
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