Antiferroelectric (AFE) material possesses excellent electrical properties, such as high energy density, fast discharge time, good fatigue resistance and abundant structural phase transitions under the external electric field, temperature or stress. Therefore, AFE has become a research hotspot in new energy sources and devices. However, the preparation of AFE single crystal remains a longstanding challenge.
Pb(Lu1/2Nb1/2)O3 (PLN) system possesses high energy storage characteristic with ultrahigh phase transition electric field. In order to solve the problems of high electric field and poor quality of PLN system, new types of large-size, high-quality AFE crystals with low critical field and excellent electrical properties are expected to be obtained by means of phase boundary control.
In a study published in ACS Appl. Mater. Inter., a group led by Prof. LONG Xifa from Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences, reported a PLN AFE single crystal by electric field-induced secondary phase transition via Na/La co-doping.
The researchers obtained the enhanced recoverable energy storage density of 4.81 J/cm3 with a high energy efficiency of 82.36% . A secondary ferroelectric (FE) phase transition is induced after Na/La co-doping, resulting in a sharp improvement of polarization (12.5 μC/cm2), which contributes to the enormous enhancement of energy storage density.
By X-ray diffraction and selected area electron diffraction，they identified two superlattice reflections which stem from the A-site Pb2+ ions and the ordered B-site ions. The domain structures demonstrated high temperature stability of AFE phase.
Besides, the researchers explained this multi-phase transition by using the modified Ginzburg-Landau-Devonshire (GLD) phenomenology.The contour plots of the free energy for Na/La co-doping Pb(Lu1/2Nb1/2)O3 (NLPLN) single crystal system exhibits multiple minima free energy contour, corresponding the AFE-FEa-FEb phase transition.
This study presents a paradigm for researches on AFE phase transition and energy storage properties via AFE single crystals.
Schematic illustration of the AFE-FEa-FEb phase transition and phenomenology (Image by Prof. LONG’s group)
Contact:
Prof. LONG Xifa
Fujian Institute of Research on the Structure of Matter
Chinese Academy of Sciences
Email: lxf@fjirsm.ac.cn
