Enhanced energy storage of lead-free mixed oxide core double-shell barium strontium zirconate titanate@magnesium aluminate@zinc oxide-boron trioxide-silica ceramic nanocomposites

Ba0.8Sr0.2Zr0.1Ti0.9O3@MgO-Al2O3@ZnO-B2O3-SiO2 (BSZT@MgO-Al2O3@ZBSO) core double-shell lead-free nanoceramic is prepared by facile protocol. The protocol involves three steps of (a) BSZT synthesis by co-precipitation, (b) coating of MgO-Al2O3 layer through co-precipitation, and (c) ZBSO deposition via sol-precipitation method. The diameter of the resultant BSZT@MgO-Al2O3@ZBSO core double-shell nanoparticles is about 280 nm, and the average thicknesses of the MgO-Al2O3 and ZBSO layers are about 8 and 13 nm, respectively. The physical and chemical properties of BSZT@MgO-Al2O3@ZBSO are tuned by varying the ratio between MgO and Al2O3 of MgO-Al2O3 layer. The results reveal that the grain size increases with the decrease in the MgO/Al2O3 ratio, while the dielectric properties initially increase and then decrease with increase of Al2O3 content. After sintering at 1150 °C for 2 h, the MgO-Al2O3 in the interlayer self-assembled into a MgAl2O4 spinel phase. Thus, fine-grained relaxor ferroelectric BSZT@MgAl2O4@ZBSO core double-shell ceramic nanoceramics (grain size ≤ 300 nm) were obtained. The lead-free core double-shell nanoparticles with Mg/Al ratio of 4:2 exhibit the maximum energy storage density of 0.91 J/cm3 under a maximum polarization field of 28.08 kV/mm.Graphical abstractEnhanced energy storage was observed in the lead-free mixed oxide core double-shell barium strontium zirconate titanate@magnesium aluminate@zinc oxide-boron trioxide-silica nanoceramics.