Tuning of structural, magnetic and dielectric properties of M0.45La0.10Fe2.45O4; (M = Mn, Co, Cu, Mg and Zn) nanoparticles: effect of particle size and porosity

M0.45La0.10Fe2.45O4; (M = Mn, Co, Cu, Mg and Zn) nanoparticles are prepared by the citrate combustion method. The sharpness and dilation of XRD peaks of all nanoferrites emphasize its nanocrystalline nature, with average crystallites size in the range (37-31 nm). FTIR spectra manifest the two finger print ferrite bands. HR-TEM micrographs along with SAED patterns reveal the polycrystalline spherical nature of M0.45Fe2.45La0.10O4 samples with some agglomerations. FESEM micrographs demonstrate the presence of many pores owing to the combustion temperature during the preparation. Double factors; the magnetic moment of substituting cations and crystallite size govern the saturation magnetization behavior. The attitude of dielectric and impedance parameters; in temperature and frequency ranges (298-788K) and (4 Hz-5 MHz) have been studied. The behavior of epsilon ', tan delta and sigma(ac) of the investigated nanoferrites is governed by porosity and particle size. Nyquist plots have a distinct arc; meanwhile the second one is wholly unseen, confirmed the grain boundaries contribution. The nanoferrite Co0.45Fe2.45La0.10O4 has the highest coercivity (1613.10 G) and high magnetization level (46.86 emu g(-1)) which can be an appropriate for all hard magnetic material applications as permanent magnet in audio and video recorders and computer peripherals. The nanoferrite Mn0.45Fe2.45La0.10O4 has the highest magnetization (47.27 emu g(-1)), dielectric constant (1914), conductivity (2.17E-4 ohm m(- 1)), besides lowest coercivity (150.53G), losses (43.25) and relaxation time (53.03 ns), which can be suitable candidate as soft magnetic material and for microwave applications.