Reduced dielectric loss and enhanced piezoelectric properties of Mn modified 0.71BiFeO3–0.29BaTiO3 ceramics sintered under oxygen atmosphere

Abstract

0.71BiFeO3–0.29BaTiO3 piezoelectric ceramics with Mn modification (BF–BT–x %Mn) sintered in air and O2 atmospheres have been investigated to understand the effects of sintering atmosphere on structure, dielectric, ferroelectric and piezoelectric properties. All ceramics exhibited the pseudo-cubic phase, while the O2 sintered ceramics possessed larger grain sizes and more homogeneous distribution. Dielectric, ferroelectric and piezoelectric properties of BF–BT–xMn ceramics were improved obviously after O2 atmospheres sintering, especially for the compositions with Mn contents less than 1.2 mol%. The evidence of impedance spectroscopy indicated that the concentration of oxygen vacancies decreased significantly by the introduction of O2 atmosphere. The dielectric loss tanδ was decreased down to 1/2 and the resistivity ρ enhanced 11 times for BF–BT–0 %Mn ceramics by the introduction of O2 atmosphere. The strains of BF–BT–0.5 %Mn increased from 0.09 to 0.22 and the d33* increased from 119 to 284 pm/V after sintering in O2 atmosphere. The Curie temperature and piezoelectric constant of O2 sintered BF–BT–1.2 %Mn reached up to 500 °C and 353 pm/V, respectively. This work suggests that sintering in the O2 oxygen atmosphere is an effective way to improve the dielectric and piezoelectric properties of BiFeO3–BaTiO3 solid solutions.