Combined structural, electrical, magnetic and optical characterization of bismuth ferrite nanoparticles synthesized by auto-combustion route

Abstract

a b s t r a c tPhase-pure multiferroic bismuth ferrite (BFO) nanoparticles were synthesized by energy efficient, simple and low temperature sol-gel followed by auto-combustion route. Highly crystalline and well-shaped BFO nanoparticles of size about 50 nm were observed in TEM. Thermal analysis was used to optimize the calcination temperature as 500 • C. An endothermic peak at 834 • C has been detected in the DTA curve, representing the Curie temperature. The dielectric anomaly around Neel temperature (T N ) was observed signifying the magnetoelectric coupling. The BFO nanoparticles were found to be highly resistive ( ∼ 3 × 10 9 -cm) and had very low leakage current of the order of A/cm 2 , which resulted from phase purity. A significantly enhanced weak ferromagnetism was observed due to smaller particles size and remnant magnetization and coercive field were 0.067 emu/g and 185 Oe, respectively. P-E loop confirmed the ferroelectric behavior of BFO nanoparticles. The direct band gap energy was calculated to be 2.2 eV from UV-vis studies.

Effect of Ba–Nb co-doping on the structural, dielectric, magnetic and ferroelectric properties of BiFeO3 nanoparticles

“…3(b) (inset) shows the SAED pattern for 10BaNb sample, in which bright diffraction spots indicate crystalline nature of as-synthesized nanoparticles. Table 2, increase gradually with doping concentration and are found to be remarkably enhanced than undoped BFO and comparable to previously reported Ba-doped BFO [13,26]. Doping of non-magnetic ions has no direct consequence in the enhancement of magnetic properties of BFO like other magnetically active dopants (e.g.…”

“…In this way, the leakage current has been reduced up to 3 orders of magnitude for 10BaNb sample as compared to previously reported undoped sample [26]. The resistivity (ȡ) values calculated from J-E plots are given in Table 2, where ȡ is found to increase on Ba-doping, which is further enhanced on Ba-Nb co-doping.…”

“…The solution concentration was kept as 0.1 molar for each composition. Complete procedure followed for sample synthesis has been reported earlier [26]. The synthesized powder was ground finely and was calcined at 550 o C for 2 h to get pure phase BFO nanoparticles with desired composition.…”

“…For Ba-doped samples, a clear splitting of peaks reveals that Ba 2+ ions are incorporated in BFO lattice. However, separation between peaks is found to decrease with increasing doping concentration as compared to pure BFO sample[26]. On the other hand, (104) & (110) peaks merge to a single broad peak for Ba-Nb co-doped samples, indicating a decrease in the degree of 6 structural distortion of BFO and rhombohedral structure may have changed slightly to pseudocubic on Nb substitution to Ba-doped BFO[9].…”

“…The refined lattice parameters and structure fitting factors for all doped samples (for undoped BFO NPs: a hex = 5.5820 Å, c hex = 13.8758 Å and V = 374.43 Å 3[26]). …”