Achieving high energy density, ultralow dielectric loss and ultrahigh hardness in environmentally friendly Ba_0.39Sr_0.61Nb₂O₆-based glass ceramics

In this study, Ba2O-Na2O-SrO-Nb2O5-TeO2-B2O3 (BNSN-TB) glass ceramics (GCs) were prepared using the meltannealing and heat treatment methods. The sample was crystallized at 670 degrees C for 2 h to obtain the Ba0.39Sr0.61Nb2O6 GCs, exhibiting an ultrahigh hardness (Hv) of 8.82 GPa. The first-principles calculations demonstrate that Ba0.39Sr0.61Nb2O6 has a lager band gap compared to BaNb2O6, which could favor the increase in the high breakdown strength (BDS). The simulation model explains how the small grains can withstand high BDS. GCs sample heated at 670 degrees C can achieve a large recoverable energy storage density (Wrec) of 2.38 J/cm3 and an ultrahigh energy efficiency (eta) of 90.2%. Additionally, the GCs sample can attain an actual discharge energy density (Wd) of 1.78 J/cm3 and a power density (Pd) of 268 MW/cm3. These results demonstrate that the GCs possess a great potential for pulsed energy-storage capacitor applications.