Structural and electrical properties of NaNbO3 modified BiFeO3

Polycrystalline (Bi
_0.5
Na
_0.5
)(Fe
_0.5
Nb
_0.5
)O
₃
material has been prepared using a mixed-oxide route at 800°C. The preliminary structural analysis shows that addition of equal amount of NaNbO
₃
into BiFeO
₃
induces a structural phase transformation from rhombohedral (BiFeO
₃
) to orthorhombic. X-ray peak broadening analysis was used to evaluate the crystalline sizes and lattice strain by the Williamson-Hall (W-H) analysis. The appearance of P-E hysteresis loop confirms the ferroelectric properties of the new system with remnant polarization (2P
_r
) of 3.58 μC/cm
²
and coercive field (2E
_c
) of 42.8 kV/cm. The remnant polarization and coercive fields are found to be strongly field and frequency dependent. The electrical behaviour of the material was studied over a wide frequency (1 kHz-1MHz) and temperature (25°C-500°C) ranges. The activation energy calculated from dc conductivity signifies the conduction behaviour due to Bi cation and oxygen vacancies. Frequency dependence of ac conductivity suggests that that the material obeys Jonscher's power law. The linear variation of the conductivity pattern is attributed to Arrhenius type thermally activated electrical transport phenomena. Addition of NaNbO
₃
causes appearance of weak ferromagnetic moment.