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.
T. T. Lummen et al., "Thermotropic Phase Boundaries in Classic Ferroelectrics," Nature Communications, vol. 5, Nature Research, Jan 2014.
The definitive version is available at https://doi.org/10.1038/ncomms4172
Materials Science and Engineering
Keywords and Phrases
chemical composition; lead; nonlinearity; performance assessment; piezoelectricity, article; electric field; electrical parameters; electricity; experimental study; ferroelectrics; fluorescence imaging; phase transition; piezoelectricity
International Standard Serial Number (ISSN)
Article - Journal
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01 Jan 2014