Investigation of the structural, dielectric, magnetic properties and NTC-thermistor response of CaBiFeMnO6 double perovskites

Abstract

To modify the physical properties through the cationic substitution of distinct elements at both the A and B sites, a novel polycrystalline double perovskite CaBiFeMnO₆ was synthesized using an economical solid-state technique. According to Rietveld refinement analysis, the material crystallized in two orthorhombic phases. Field emission scanning electron microscopy images demonstrate that the mean crystalline size of the specimen is 754.265 nm and it has some porosity and a non-uniform distribution of grains on the surface. The unique transmittance, as observed in the Fourier transform infrared spectroscopy (FTIR) graph, suggests its perovskite background. The dielectric property analysis supported the exclusive negative temperature coefficient of resistance (NTCR) behaviour, confirmed by the impedance measurements in a defined temperature range for a specific electric field. The complex modulus analysis confirms the potential existence of a non-Debye-type relaxation mechanism. All of the characterizations, together with the high room temperature dielectric constant of 4023.194 with little tangent loss, suggested that the material could be a viable contender for use in different energy storage devices and supercapacitors. To illustrate the NTCR characteristic for NTC thermistor applications, the temperature coefficient of resistance (TCR) and thermistor constant (β) were calculated. The ferromagnetic nature of the prepared sample was verified through the M–H hysteresis loop.