Effect of Mg and Mn co-doping on the high electrical properties of BiFe 1-2x Mg x Mn x O 3 −BaTiO 3 lead-free ceramics prepared by sol–gel method and two-step sintering method

Lead-free 0.7BiFe 1−2 x Mg x Mn x O 3 –0.3BaTiO 3 (BFMM x O–BTO) piezoceramics were prepared through the sol–gel method followed by a two-step sintering process and the crystal structure and the surface morphology, dielectric, polarization, and piezoelectric properties of lead-free BFMM x O–BTO ceramics were investigated. Through the synergistic effects of Mn and Mg ions to reduce the oxygen vacancies and prevent the formation of defect complexes, the electric performance of lead-free BFMM x O–BTO ceramics was improved. A large remnant polarization (2 P r = 93.8 μC/cm 2 ), low leakage current (4.93 × 10 −7 A/cm 2 ), excellent piezoelectric constant ( d 33 = 193 pC/N), high unipolar strain (0.202