Effect of Zn2+ → Li+Fe3+ substitution on electromagnetic properties in lithium zinc ferrite

In this investigation, to tailor functional properties we explore a partial Zn²⁺ → Li⁺Fe³⁺ substitution in a series Li_0.5(1-x)Zn_xFe_(2.5-x/2)O₄ (x = 0.3, 0.5, 0.8) via a citrate-gel combustion method using metal nitrates, citric acid, and ethylene glycol at a low temperature ~90 °C. A typical sample, at x = 0.3, annealed at 400 °C for 2 h offers a ferrimagnetic hysteresis loop with a high saturation magnetization of 52.4 emu/g and a large coercivity of 138 Oe at 100 K in a low magnetic field ± 500 Oe. The magnetization value has decreased to ~17.8 emu/g (with 4 Oe coercivity) in a sample with higher Zn²⁺-content (x = 0.8). FESEM images describe homogeneous distribution of crystallites average 26 nm diameter. A high dielectric constant of 15117 with a low dielectric loss of 1.49 is observed at 10 kHz at x = 0.3.