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Electromechanical properties of ternary BiFeO3?0.35BaTiO3–BiGaO3 piezoelectric ceramics
摘要： In the present work, composition dependent crystal structure, ferroelectric, piezoelectric, and temperature dependent dielectric properties of the BiGaO3-modified (1–x)(0.65Bi1.05FeO3–0.35BaTiO3) (BFBT35–xBG, where x = 0.00–0.03) lead-free ceramics were systematically investigated by solid-state reaction method, followed by water quenching process. The substitution of BG successfully diffuses into the lattice of the BFBT ceramics, without changing the pseudo-cubic structure of the samples. The scanning electron microscopy (SEM) results revealed that the average grain size was increased with BG-content in BFBT system. The BFBT–xBG ceramics showed a maximum in permittivity (?max) at temperatures (Tmax) above 500 °C in the compositional range of 0.00 ≤ x ≤ 0.03. The electro-strain is measured to be 0.125% (d*33 ~ 250 pm/V) under unipolar fields (5 kV/mm) for BFBT–0.01BG ceramics. The same composition (x = 0.01), large static piezoelectric constant (d33 ~ 165 pC/N) and electromechanical coupling factor (kp ~ 25%) were obtained. The above investigated characterizations suggests that BFBT–BG material is favorable for piezoelectric and high temperature applications.
关键词： Lead-free,Dielectric,Piezoelectric,Ferroelectric,BiFeO3–BaTiO3
更新于2025-09-09 09:28:46
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Structural and electrical properties of Gd-doped BiFeO3:BaTiO3 (3:2) multiferroic ceramic materials
摘要： Gadolinium doped BiFeO3:BaTiO3 (3:2) polycrystalline multiferroic ceramics have been prepared by high-temperature solid state reaction technique. X-ray diffraction (XRD) analysis at room temperature of the prepared materials confirmed the formation of the compounds with rhombohedral crystal structure. The average particle size of as prepared samples have been found in the range of 35 nm to 55 nm for different doping concentrations. The average grain size of as prepared samples are less than 100 nm which is confirmed from SEM study. The SEM of annealed compounds showed the uniform distribution of grains and the formation of dense ceramic with average grain size in the order of 4 μm. Dielectric studies of the materials reveals that the dielectric constant ( εr ) and tangent loss (tan δ) decreases with doping concentrations at room temperature. The variation of εr and tan δ with temperature was explained on the basis of Maxwell–Wagner mechanism. The values of grain resistance ( Rb ) and grain capacitance (Cb) were obtained from Nyquist plots for the different doping concentrations at 300 °C. The activation energy ( Ea ) was calculated from the curve of frequency dependent ac conductivity ( σac ) within the range 0.19 eV to 0.45 eV. The remnant polarization of the samples (0.53 μC/cm2) was measured from polarization versus electric field (P–E) hysteresis curves. The ferromagnetic behaviour of the Gd-doped BiFeO3:BaTiO3 (3:2) sample has been studied by SQUID for the lowest doping concentration. The value of remnant magnetization was found 0.0235 emu/g at room temperature.
关键词： multiferroic ceramics,dielectric properties,ferroelectric properties,Gd-doped BiFeO3:BaTiO3,ferromagnetic properties
更新于2025-09-09 09:28:46