Significant improvement in morphological, dielectric, ferroelectric and piezoelectric characteristics of Ba_0.9Sr_0.1Ti_0.9Zr_0.1O₃–BaNb₂O₆ nanocomposites

Multifunctional composite with material composition (1 − x)Ba_0.9Sr_0.1Ti_0.9Zr_0.1O₃–xBaNb₂O₆ (x = 0.0, 0.05, 0.1, 0.2 and 0.3) has been successfully synthesized using mechano-chemical activation process. The co-existence of perovskite tetragonal phase of BSTZ and niobate orthorhombic phase of BNO was detected by X-ray diffraction measurement and confirmed by Rietveld analysis. All the BSTZ–BNO composites show a polygonal grain type morphology with clearly visible grain boundaries. BSTZ–BNO composites possessed a thermally stable dielectric constant within a broad range of temperature. The obtained results show a strong influence of BNO addition on the microstructural, dielectric, ferroelectric, piezoelectric and breakdown strength of bare BSTZ ceramic. For x = 0.10, the composite exhibit optimum properties with high dielectric constant ε_m = 5842, large remnant polarization P_r = 9.25 µC/cm², improved piezoelectric constant d₃₃ = 296 pC/N and high breakdown strength E_bd = 304 kV/cm. The high dielectric constant accompanied by very low dielectric loss and large piezoelectric constant make BSTZ–BNO a suitable material for ceramic capacitors and electromechanical device applications.