Thermotropic phase boundaries in classic ferroelectrics.
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.
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Tom T A
TT
Lummen
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Yijia
Y
Gu
1] Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Department of Physics, University of Science and Technology Beijing, Beijing 100083, China.
Jianjun
J
Wang
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Shiming
S
Lei
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Fei
F
Xue
1] Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Amit
A
Kumar
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Andrew T
AT
Barnes
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Eftihia
E
Barnes
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Sava
S
Denev
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Alex
A
Belianinov
Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Martin
M
Holt
Institute of Physics, National Academy of Sciences of Ukraine, 46, Nauki, 03028 Kiev, Ukraine.
Anna N
AN
Morozovska
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Sergei V
SV
Kalinin
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Long-Qing
LQ
Chen
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Venkatraman
V
Gopalan