Structure-microstructure-property Correlation Study in Chemically Modified Lead Free BZT-BCT Solutions

In this project, we have synthesized a non-Pb piezoelectric system BZT-BCT, which exhibits a very high piezoelectric coefficient (d33) of 512 pC/N at MPB, which is comparable even with high-end PZT. Lead-free BZT-xBCT samples were prepared using the solid-state reaction technique. Structural analysis shows the presence of orthorhombic and tetragonal phases in the prepared samples. We observed that with an increase in x content, the tetragonal phase increases which further results in higher d33. Sintering temperature plays a very important role to achieve desired density, which further leads to good piezoelectric properties.

Meanwhile, we have also introduced a novel method to obtain high piezoelectric coefficient and electromechanical coupling coefficient in BZT-BCT by introducing a novel synthesis procedure. We observed high d33~ 520 pC/N and electromechanical coupling coefficient ~ 57.5% in 0.5BZT-0.5BCT synthesized by novel synthesis procedure.

For energy storage efficiency, we prepared BZT-BCT by sol-gel technique. The different parameters like dielectric constant, dielectric loss, polarization, coercive field, the efficiency of energy storage were found to be optimum for the (1-x)BZT-xBCT ceramics at x =0.55. We estimated the energy storage density W~ 189 mJ/cm3 and high efficiency η ~ 75.6% for BZT-0.55BCT ceramic composition. Therefore, this work suggested that 0.45BZT-0.55BCT ceramics are potential candidates for energy storage capacitor.

Furthermore, we investigated the temperature stability of 5% (Mg1/3Nb2/3)4+ doped BZT-BCT composition at 50kV/cm. We observed Wrec ~ 235 mJ/cm3and ultra-high η~ 94.3% at room temperature. The η of ceramic increases to 94.6% and Wrec to 187 mJ/cm3 as the temperature rises to 110°C.