Exploring determinants of lattice structure and high energy storage properties of Fe-doped SBN ceramics

(Sr _0.5 Ba _0.5 ) _1+x Nb _2-x Fe _x O ₆ (SBNF-x, 0 ≤ x ≤ 0.20) ceramics were prepared using the conventional solid-state reaction method. With the increase in x, the tungsten bonze structure of the ceramics will transform from “unfilled” to “filled.” The crystallographic parameters obtained using the Rietveld method on XRD patterns were used to explore the determinants of the lattice structure. Lattice parameter a is dominated by the distance of the A1- and A2-sites via the Coulomb interaction. The average bond length of Nb1–O4 controls the change of c due to the symmetrical environment around the Nb1O ₆ octahedron. High energy storage properties appear in low doping samples. The discharge energy density of SBNF-0.02 is 0.595 J/cm ³ , with a storage efficiency of 91.3%, and of SBNF-0.04 is 0.680 J/cm ³ , 5.3 times the value of SBNF-0, with a storage efficiency of 83.6%. SBNF-x (0.02 ≤ x ≤ 0.04) ceramics with high discharge energy density and high storage efficiency are promising candidates for producing high energy density capacitors.