Mechanism of enhanced energy storage density in AgNbO3-based lead-free antiferroelectrics

• DOI: 10.1016/j.nanoen.2020.105423
• Publication Date: 2020-09-30T07:11:24Z
• Authors: Zhilun Lu; Weichao Bao; Ge Wang; Shi-Kuan Sun; Linhao Li; Jinglei Li; Huijing Yang; Hongfen Ji; Antonio Feteira; Dejun Li; Fangfang Xu; Annette K. Kleppe; Dawei Wang; Shi-Yu Liu; Ian M. Reaney
• Keywords: Antiferroelectrics; Energy storage capacitors, Antiferroelectrics, In-situ synchrotron X-ray diffraction, Silver niobate; In-situ synchrotron X-ray diffraction; Energy storage capacitors; 02 engineering and technology; Silver niobate; 0210 nano-technology; 7. Clean energy

The mechanisms underpinning high energy storage density in lead-free Ag1–3xNdxTayNb1-yO3 antiferroelectric (AFE) ceramics have been investigated. Rietveld refinements of in-situ synchrotron X-ray data reveal that the structure remains quadrupled and orthorhombic under electric field (E) but adopts a non-centrosymmetric space group, Pmc21, in which the cations exhibit a ferrielectric configuration. Nd and Ta doping both stabilize the AFE structure, thereby increasing the AFE-ferrielectric switching field from 150 to 350 kV cm−1. Domain size and correlation length of AFE/ferrielectric coupling reduce with Nd doping, leading to slimmer hysteresis loops. The maximum polarization (Pmax) is optimized through A-site aliovalent doping which also decreases electrical conductivity, permitting the application of a larger E. These effects combine to enhance energy storage density to give Wrec = 6.5 J cm−3 for Ag0.97Nd0.01Ta0.20Nb0.80O3.