Giant polarization in super-tetragonal thin films through interphase strain

Strain engineering has emerged as a powerful tool to enhance the performance of known functional materials. Here we demonstrate a general and practical method to obtain super-tetragonality and giant polarization using interphase strain. We use this method to create an out-of-plane–to–in-plane lattice parameter ratio of 1.238 in epitaxial composite thin films of tetragonal lead titanate (PbTiO3), compared to 1.065 in bulk. These thin films with super-tetragonal structure possess a giant remanent polarization, 236.3 microcoulombs per square centimeter, which is almost twice the value of known ferroelectrics. The super-tetragonal phase is stable up to 725°C, compared to the bulk transition temperature of 490°C. The interphase-strain approach could enhance the physical properties of other functional materials.

Source: ScienceNOW - August 2, 2018 Category: Science Authors: Zhang, L., Chen, J., Fan, L., Dieguez, O., Cao, J., Pan, Z., Wang, Y., Wang, J., Kim, M., Deng, S., Wang, J., Wang, H., Deng, J., Yu, R., Scott, J. F., Xing, X. Tags: Materials Science, Physics reports Source Type: news