Electrical and Structural Properties of LiNi0.5Fe2O4 Nanoparticles Synthesized by Sol-Gel Self-Combustion Technique under Different Calcination Temperatures

Abstract

Lithium nitrate, nickel nitrate, and ferric nitrate are utilized as precursors, with citric acid acting as a chelating agent. Li-Ni ferrite nanoparticles (LiNi_0.5Fe₂O₄) were manufactured via the sol-gel auto-combustion method. The synthesis technique was followed by calcination at temperatures of 400°C, 600°C, and 800°C. The impact of calcination temperatures on the crystalline structure, surface morphology, and dielectric properties of LiNi₀.₅Fe₂O₄ nanoparticles was methodically examined. XRD examination verified the existence of a single-phase cubic spinel structure. The crystallite size was ascertained from the dominant peak (311). An augmentation in crystallite size was noted with elevated calcination temperatures (i.e., from as-burnt to 800°C), varying from 28.314 nm to 40.940 nm. The lattice constant attained its maximum value of 8.292 Å at 400°C, which suggests structural relaxation (i.e., partial cation redistribution) during early-stage crystallization. FTIR spectra exhibited three unique absorption bands indicative of the nanoparticles' chemical nature. Moreover, electrical experiments revealed that both the dielectric constant and dielectric loss diminished with rising frequency at the calcination temperature of 800°C. For instance, ε' decreased from 30 ± 0.5 (100 Hz) to 0.2 ± 0.05 (1 MHz), while tanδ reduced from 4 ± 0.1 to 1.5 ± 0.05 over the same range.