Enhanced Energy Storage Density of Lead Lutetium Niobate Crystals by Electric Field-Induced Secondary Phase Transition via Na/La Co-doping.

As emerging materials for capacitor applications, antiferroelectric (AFE) materials possess high energy storage density. AFE single crystals have conducive to study of physical mechanism of AFE response. However, preparation of AFE single crystal is a huge and longstanding challenge. Herein, we report the effect of Na/La co-doping on energy storage properties and phase transition of Pb(Lu1/2Nb1/2)O3 (PLN) AFE single crystals. The enhanced recoverable energy storage density of 4.81 J/cm3 with a high energy efficiency of 82.36% is obtained, which is much larger than that of the PbZrO3(PZ) and PLN based AFE crystals. Two superlattice reflections, which stem from the A-site Pb2+ ions and the ordered B-site ions, are identified by X-ray diffraction and selected area electron diffraction. The domain structures demonstrated high temperature stability of AFE phase. A secondary ferroelectric (FE) phase transition is induced after co-doping, resulting in a sharp improvement of polarization (12.5 μC/cm2), which contributes to the enormous enhancement of energy storage density. This multi-phase transition is explained using the modified Ginzburg-Landau-Devonshire (GLD) phenomenology.