Thermotropic phase boundaries in classic ferroelectrics

Tom T.A. Lummen, Yijia Gu, Jianjun Wang, Shiming Lei, Fei Xue, Amit Kumar, Andrew T. Barnes, Eftihia Barnes, Sava Denev, Alex Belianinov, Martin Holt, Anna N. Morozovska, Sergei V. Kalinin, Long Qing Chen, Venkatraman Gopalan

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


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 BaTiO 3 and KNbO 3. 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.

Original languageEnglish (US)
Article number3172
JournalNature communications
StatePublished - Jan 20 2014

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Biochemistry, Genetics and Molecular Biology
  • General Physics and Astronomy


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