Optical band gap tuning of Barium Titanate by incorporation of iron ion | Othman Ali Hussein
Summary :
In this research work, the energy band gap of Bi & Li doped BaTiO3 has been reduced by the incorporation of metal ion (Fe+3). The results show that the lattice distortion as well as the defect formation in the perovskite unit cell gives rise to a narrower band gap which is useful for photovoltaic applications. Solid state reaction method was followed to prepare the samples. Five samples were prepared with different Fe concentrations Ba0.96Bi0.02Li0.02Ti1-xFexO3, where x = 0.00, 0.02, 0.04, 0.06, and 0.08. The powders were weighed and ground using ball milling for 4 hours. The powders were kept for calcination at 1100 ˚C for 6 hours. Afterwards, the calcined powders were axially pressed to form circular pellets which kept for sintering at 1250 ˚C for 4 hours using conventional furnace. The structural investigations were confirmed via XRD and Raman analyses. Measurements showed crystal structure transition from tetragonal to hexagonal phase with respect to the Fe concentration. Rietveld refinement was performed to obtain the structural information. The octahedral distortion and the average bond length variation have been calculated to interpret the variation in the energy band gap. This material has shown the Jahn-Teller effect which gives rise to 3d orbital splitting leading to narrower band gap. The optical band gaps were calculated using Tauc-plot and Kubelka-Munk function from the DRS spectra. To confirm the existence of oxygen vacancies, ESR measurement has been carried out and analyzed. The energy band gap of the sample x = 0.08 showed the narrowest band gap of 2 eV, which paves the way for this composition to be used for visible range photovoltaic applications.
About Author :
My name is Othman Ali, Iraqi national. I have completed my BSc. from School of Physics, Tikrit University, Iraq. Afterwards, I studied MSc. in Physics, Department of Studies in Physics, Mysore University, India. Now I am pursuing my Ph.D. in Physics, School of Physics, University of Hyderabad, India.
