Effect on dielectric, magnetic, optical and structural properties of Nd–Co substituted barium hexaferrite nanoparticles

M-type barium hexaferrite [Ba1−x Nd x Co x Fe12−x O19 (x = 0.0–0.5) (BNCM)] powders, synthesized using citrate precursor method, were heat treated at 900 °C for 5 h. The pattern of powders, when subjected to X-ray diffraction, shows the formation of M-type hexaferrite phase. The formation of BNCM, from thermogravimetric analysis/differential thermal analysis/derivative thermogravimetry, is observed to be at 440 °C. The presence of two prominent peaks near 430 and 580 cm−1 in Fourier transform infrared spectroscopy spectra indicates the formation of M-type hexaferrites. The M–H curves obtained from vibrating sample magnetometer were used to calculate saturation magnetization (M S), retentivity (M R), squareness ration and coercivity (H C). UV–Vis NIR spectroscopy reveals that band gap depends on size of the crystallites. The dielectric constant is found to be high at low frequency and decreases with increase in frequency. This kind of behaviour is explained on the basis of Koop’s phenomenological theory and Maxwell–Wagner theory.