Study of XRD, dielectric properties and DC electrical conductivity of Li-Zn-Al ferrite synthesized by sol–gel combustion method

Abstract

A series of nanocrystalline aluminum (Al3+) doped Lithium-Zinc ferrites (LZA) having general chemical formula Li0.5(1- x )Zn x Fe2.5- y Al y -0.5 x O4 with x = 0.1 and y = 0.2 (S1C1), 0.4 (S1C2), 0.6 (S1C3) and 0.8 (S1C4) were synthesized by citrate sol-gel combustion method. The structural characterizations of the samples were carried out by X-Ray Diffraction (XRD) studies. Morphological investigations were performed using Scanning Electron and Transmission Electron Microscopies. XRD analysis confirmed the formation of single phase of the reported samples. All the samples crystallized in spinel cubic crystal structure with Fd-3m (227) space group. Crystallite size was estimated in the range of 19 nm to 21 nm using Scherrer formula. The variation of D.C. electrical conductivity as a function of temperature of as-prepared samples revealed the semiconducting nature. The dielectric constant (ε'), dielectric loss factor (ε") and the dielectric loss tangent (tan δ) were studied in the frequency range of 1 KHz to 1 MHz at room temperature by using LCR Meter. The values of dielectric constant, dielectric loss factor and dielectric loss tangent were found to decrease with addition of Al3+ content as well as with the increase in the frequency. The observed dielectric dispersion at lower frequency is attributed to Maxwell-Wagner type of interfacial polarization due to hopping of charge between Fe+2 and Fe+3. High value of resistivity (≈106 Ω-cm) and low value of dielectric constant and dielectric loss are the prime achievements of the present research work which make these investigated nanoferrites useful for the microwave devices.