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cityengle2609至尊木虫 (著名写手)
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【Nature communication】传统铁电体中的热致相界 已有1人参与
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http://www.nature.com/ncomms/201 ... ull/ncomms4172.html High-performance piezoelectrics are lead-based solid solutions that exhibit a so-called morphotropic phase boundary, which separates two competing phases as a function of chemical composition; as a consequence, an intermediate low-symmetry phase with a strong piezoelectric effect arises. In search for environmentally sustainable lead-free alternatives that exhibit analogous characteristics, we use a network of competing domains to create similar conditions across thermal inter-ferroelectric transitions in simple, lead-free ferroelectrics such as BaTiO3 and KNbO3. Here we report the experimental observation of thermotropic phase boundaries in these classic ferroelectrics, through direct imaging of low-symmetry intermediate phases that exhibit large enhancements in the existing nonlinear optical and piezoelectric property coefficients. Furthermore, the symmetry lowering in these phases allows for new property coefficients that exceed all the existing coefficients in both parent phases. Discovering the thermotropic nature of thermal phase transitions in simple ferroelectrics thus presents unique opportunities for the design of ‘green’ high-performance materials. 在高性能含铅的压电材料中，具有低对称度的准同型相界存在于相互竞争两相中间，并且具有很强的压电效应。在寻找环境友好型不含铅压电材料的过程中，一些不含铅的铁电体也表现出了类似的性质。在 BaTiO3 and KNbO3中发现了热致相界，这些相界表现出了很好的非线性光学和压电效应。 在传统的铁电体中发现并研究这种热致相变的本质将会提供一条寻找和设计新的具有环境友好性质的高性能材料的途径。 |
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2楼2014-01-26 14:46:15
