Structural, dielectric and magnetic characteristics of Mn-substituted Bi0.80Nd0.20FeO3 multiferroics

Recently, investigations have been focused on modified BiFeO3 multiferroics for obtaining improved physical properties. Keeping this in view, multiferroics having composition Bi0.80Nd0.20Fe1 - xMnxO3 (x = 0.01, 0.03 and 0.05) have been synthesized using solid-state reaction method. The crystal structure was examined by X-ray diffraction technique and Rietveld refinement. All unit cells were described by a combination of rhombohedral (R3c) and orthorhombic (Pbnm) phase. Increasing Mn content results in phase transformation with increasing orthorhombic character and major contribution by rhombohedral symmetry for all samples. Dielectric measurements carried out by impedance/gain phase analyzer in the frequency range from 10 Hz to 1 MHz. Dielectric constant (eMODIFIER LETTER PRIME) and loss tangent (tan delta) show dispersion in the lower frequency range. The characteristics of the Nyquist plot confirmed the non-Debye type of relaxation processes with negative temperature coefficient behaviour of resistance (NTCR) in the ceramics. A strong variation in impedance is observed with Mn content also confirmed by conductivity analysis. The variation of 's' with temperature described that conduction mechanism is overlapping of large polaron tunnelling for x = 0.01, 0.03 and for x = 0.05 the appropriate mechanism is small polaron tunnelling. Magnetic measurements indicate the change in ferromagnetic character which might be due to a small change in structural parameters and maximum remanent magnetization is M-r = 0.023 emu/g and coercive field is H-c = 0.760 kOe for x = 0.05. These prepared materials with improved multiferroic properties may lead to many technical applications, such as sensors, transducers and memory devices, etc.