The Effect of Niobium Doping on the Electrical Properties of 0.4(Bi0.5K0.5)TiO3-0.6BiFeO3 Lead-Free Piezoelectric Ceramics

Abstract

Ceramics in the system (Bi0.5K0.5)TiO3-BiFeO3 have good electromechanical properties and temperature stability. However, the high conductivity inherent in BiFeO3-based ceramics complicates measurement of the ferroelectric properties. In the present work, doping with niobium (Nb) is carried out to reduce the conductivity of (Bi0.5K0.5)TiO3-BiFeO3. Powders of composition 0.4(K0.5Bi0.5)Ti1−xNbxO3-0.6BiFe1−xNbxO3 (x = 0, 0.01 and 0.03) are prepared by the mixed oxide method and sintered at 1050 °C for 1 h. The effect of Nb doping on the structure is examined by X-ray diffraction. The microstructure is examined by scanning electron microscopy. The variation in relative permittivity with temperature is measured using an impedance analyzer. Ferroelectric properties are measured at room temperature using a Sawyer Tower circuit. Piezoelectric properties are measured using a d33 meter and a contact type displacement sensor. All the samples have high density, a rhombohedral unit cell and equiaxed, micron-sized grains. All the samples show relaxor-like behavior. Nb doping causes a reduction in conductivity by one to two orders of magnitude at 200 °C. The samples have narrow P-E loops reminiscent of a linear dielectric. The samples all possess bipolar butterfly S-E loops characteristic of a classic ferroelectric material. Nb doping causes a decrease in d33 and Smax/Emax.

Solid state crystal growth of single crystals of 0.75(Na1/2Bi1/2)TiO3-0.25SrTiO3 and their characteristic electrical properties

“…The low frequency data for ε' r and loss tangent are not shown as it is very noisy. As previously reported [15,43,[49][50][51], from the AC conductivity curves (Figure 4(c,f)), activation energies of 1.65 eV and 1.19 eV above ~600°C at the low frequency limit can be estimated for the single crystal and polycrystalline samples respectively (calculated from the data measured at 39.8 Hz) [52,53].…”

Large difference between the magnetic properties of Ba and Ti co-doped BiFeO3bulk materials and their corresponding nanoparticles prepared by ultrasonication

“…The leakage current density and ferroelectric polarization of the pellet shaped samples of bulk and nanoparticles were carried out using a ferroelectric loop tracer in conjunction with external amplifier (10 kV) (Marine India). [31,35]. During the solid sate synthesis of bulk undoped BiFeO 3 and cations substituted BiFeO 3 the formation of these secondary phases were observed in a number of previous investigations [31,[35][36][37].…”

“…[31,35]. During the solid sate synthesis of bulk undoped BiFeO 3 and cations substituted BiFeO 3 the formation of these secondary phases were observed in a number of previous investigations [31,[35][36][37]. In a previous investigation, it was observed that the specific reaction pathway has good influence on the final distribution of the secondary phases [38], however, the mechanism leading to the formation of those secondary phases is still unknown.…”

Structural, Dielectric, Electrical, and Magnetic Characteristics of Bi0.8Ba0.1Er0.1Fe0.96Cr0.02Mn0.02O3 Nanoparticles

“…The presence of the triclinic Bi 4 O 7 (P-1 space group) and Ba 2 FeO 4 (P12/c1 space group) secondary phases were identified. These impurities emanate from the volatility of bismuth ions that were identified in doped BiFeO 3 materials [38,39]. To further analyze the substitution effect on structural properties, we executed a Rietveld refinement using FullProf software.…”