Investigation of sintering methodologies and its influence on magnetic and electric properties of NiFe2O4: a comparative study

Abstract

Nickel ferrite samples are synthesized by three different processing routes viz. (i) normal press and sintering (NPS), (ii) magnetic field press and sintering (MFPS), and (iii) Spark plasma sintering (SPS), followed by their magnetic and dielectric properties characterizations. The comparison of these properties pertaining to their different synthesis routes worked out for the first time is presented here. The average grain sizes of the samples are found to be 5 μm and ∼3 μm for NPS and MFPS samples respectively. The grains of SPS samples are found to be very fine than NPS and MFPS samples. Coercivity (Hc), obtained from the M-H curves is noted to be high for SPS samples (90 Oe) and low for NPS samples (2 Oe) which can be attributed to the finer grains in SPS samples. The squareness ratio of the samples is found to be in the range of 0.002–0.16, indicating the multi-domain nature of the samples. Besides, dielectric properties, impedance measurement, and AC conductivity studies, carried out on these samples at room temperature as a function of frequency are also discussed here.