Structural, optical and transport properties of Al doped BiFeO3 nanopowder synthesized by solution combustion method

Aluminum doped Bismuth ferrite (BFO) nanopowders (grain size 13-20 nm) having composition Bi_1−xAl_2xFe_1−xO₃ (x = 0.00, 0.025, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) were successfully synthesized by solution combustion method using citric acid as fuel at a temperature as low as 200 °C. As-prepared samples were examined by powder XRD for phase identification and crystallite size determination. The d.c. resistivity as a function of temperature was measured by standard two probe setup which exhibits clear metal to insulator transition for all samples. FTIR analysis was carried out to identify the chemical bonds present in the system. The optical band gap was calculated from the UV-vis absorbance spectra using classical Tauc relation which was found to vary from 2.78 eV to 2.93 eV for different Al³⁺ concentrations. The activation energies calculated from the slopes of ln(ρ) versus 10³/T plots are in the range 0.54-0.73 eV.