Influence of cerium substitution on structural and dielectric properties of the modified BiFeO₃-PbTiO₃ ceramics

Abstract

In this communication, cerium modified Bi_0.65Fe_0.65Pb_0.35Ti_0.2Ce_0.15O₃ ceramics was synthesized by the high-temperature metal oxides method. It has a rhombohedral crystal structure with R-3c space group. The average crystalline of the sample is 79.4 nm. The Raman spectrum suggests that when the Ce is doped into BF-PT ceramic; then A₁ and E-symmetry normal modes for R3c symmetry including A₁-1, A₁-2, A₁-3, A₁-4, E-1, E-4, E-6, E-7, E-8, and E-9 at around 273, 334, 460, 537, 631, 829, 1425, 1698, and 2018 cm⁻¹, respectively are observed. A band gap of 1.6 eV in modified BF-BT ceramics is calculated from UV vis study; suitable for photovoltaic applications. The dielectric study suggests bulk resistance of the material decreases with increasing temperature showing negative temperature showing a typical semiconducting property, i.e., negative temperature coefficient of resistance (NTCR) behavior. The complex impedance graph exhibited one impedance semicircle arc at all reported temperatures, which indicates that the impedance response is a Cole-Cole type relaxation. The shape of the electric field- polarization loop confirms the ferroelectric character of the sample. The calculated activation energies are 781.2 meV, 777.6 meV, 675.8 meV, 579.9 meV, and 302.1 meV at 1 kHz, 10 kHz, 100 kHz, 1 MHz and 5 MHz with a rise of the temperature suggest a thermally activated conducting process in the sample.

Keywords:

• rhombohedral
• bandgap
• NTCR
• photovoltaic
• NTCR
• activation energy

Acknowledgment

The authors would like to extend their gratitude and sincere thanks to our host Institute for providing XRD and electrical characterization.