High energy-storage performance of lead-free BacoSr(0.6)TiO(3)-Sr0.7Bi0.2TiO3 relaxor-ferroelectric ceramics with ultrafine grain size

Relaxor-ferroelectric (RFE) ceramics possess slender ferroelectric hysteresis loop and low remnant polarization (P-r). They have great potential to provide excellent energy-storage performance as dielectric energy-storage materials. Herein, a lead-free 0.8Ba(0.4)Sr(0.6)TiO(3)-0.2Sr(0.7)Bi(0.2)TiO(3) (0.8BST-0.2SBT) RFE ceramic with high energy-storage performance has been realized successfully. The addition of Bi3+ and increase in Sr2+ content at the A site of the BST can effectively inhibit the growth of grains for high breakdown strength (E-b). As a result, an ultrafine average grain size of 0.7 mu m was obtained in 0.8BST-0.2SBT RFE ceramic, affording a high E-b of 300 kV/cm. Further investigation revealed that the mutual conversion of short-range polar nanoregions and long-range-ordered ferroelectric domains upon application and withdrawal of a 300 kV/cm applied electric field resulted in a high maximum polarization (P-max) of 31 mu C/cm(2) and a low P-r of 2.5 mu C/cm(2). Hence, the 0.8BST-0.2SBT RFE ceramic simultaneously exhibited a high recoverable energy-storage density of 3.3 J/cm(3) and a high energy-storage efficiency of 85% at 300 kV/cm. Additionally, a good energy-storage performance was reported over a temperature range of 50 degrees C-120 degrees C and frequency from 10 to 1000 Hz, making the 0.8BST-0.2SBT RFE ceramic a potential lead-free dielectric energy-storage material.