Structural, dielectric and conductivity studies of PbFe0.5Nb0.5O3 - BiFeO3 multiferroic solid solution

Abstract

Single step solid state reaction method was adopted to synthesize (1-x) PbFe0.5Nb0.5O3 (PFN) - (x) BiFeO3 (BFO) (PFN - BFO) multiferroic solid solution with x = 0.1, 0.2, 0.3 and 0.4. Structural analysis of PFN - BFO solid solution was carried out by X Ray Diffraction (XRD) and confirmed the single phase in all solid solutions with negligible amount of pyrochlore (x = 0.2 and 0.4). The Rietveld refined XRD data was well fitted with monoclinic structure (Cm space group). The TEM analysis showed good crystallinity and the average particle size was found to be 100 nm. Dielectric constant (ε′), loss tangent (tan δ) and AC conductivity (σac) of PFN - BFO solid solution were carried out over a wide range of frequency (100 Hz–1 MHz) and temperature (303 K–600 K). The dielectric constant and loss tangent showed the temperature and frequency dependent nature in all solid solutions. The temperature dependent dielectric constant exhibits broad diffuse ferroelectric to paraelectric phase transition with systematic shift in ferroelectric to paraelectric transition temperature (TC). The TC value gets shifted to 423 K, 473 K, 523 K and 563 K for x = 0.1, 0.2, 0.3 and 0.4 respectively and was well supported by differential scanning calorimetric (DSC) measurements. Frequency dependent AC conductivity of PFN - BFO solid solution obeys Johnscher's power law and the conduction mechanism follows Correlated Barrier Hopping (CBH) model. AC conductivity exhibits negative temperature coefficient resistance (NTCR) kind of behaviour.