Energy storage and dielectric properties of a novel Bi1.5MgNb1.5O7-Bi2Mg2/3Nb4/3O7 thin film

Lead-free Bi1.5MgNb1.5O7-Bi2Mg2/3Nb4/3O7 (BMN1.5-BMN2) thin films have been deposited on Pt/Ti/SiO2/Si substrates by RF magnetron sputtering. A very low loss tangent of-0.005 with a high dielectric constant of 158 is achieved in a BMN1.5-BMN2 thin film annealed in an oxygen pressure of 0.03 MPa. The BMN1.5-BMN2 thin film possesses superior energy storage properties due to its slim P-E loops, large maximum polarization (P-max similar to 36.97 mu C/cm(2)) and high charge storage density (P-max-P-r similar to 32.25 mu C/cm(2)), with an energy storage density of 40.59 J/cm(3) and an energy conversion efficiency of 61.67% at 2.91 MV/cm. The energy storage density is superior to other the reference ferroelectric thin films. In addition, the BMN1.5-BMN2 thin film exhibits a large power density of 16.34 MW/cm(3) due to the low dielectric loss. More importantly, BMN1.5-BMN2 as a new system provides new ideas for the design of lead-free linear dielectrics with ultrahigh energy storage density, indicating it is a very promising candidate for electrostatic energy storage capacitors.