Enhanced dielectric and structural properties of iron-doped magnesium aluminate (MgAl2−xFexO4) synthesized via citrate sol–gel method

The growing demand for high-frequency electronic components has intensified the search for dielectric materials with improved polarization and conduction behavior. Although, Magnesium aluminate (MgAl₂O₄) spinels offer excellent thermal and mechanical stability, their limited dielectric response restricts wider technological use. This study investigates whether iron substitution can effectively enhance the structural and dielectric characteristics of MgAl₂O₄, addressing the need for tunable materials suitable for advanced electronic applications. A series of iron-doped compositions with the general formula MgAl_2−xFe_xO₄ (x = 0.0, 0.1, 0.15, 0.2, and 0.25) were prepared using an economical citrate sol–gel method. The formation of the spinel phase was confirmed through X-ray diffraction. FTIR spectroscopy revealed characteristic AlO₆ vibrational bands near 500 and 700 cm^-1. Dielectric analysis showed a progressive increase in dielectric constant (from 4 × 10² to 9 × 10²), dielectric loss (from 6.5  ×  10² to 1.6  ×  10³), and tangent loss (from 1.2 to 1.5) with increasing iron content. Impedance and Cole–Cole analyses further demonstrated reduced resistance and improved relaxation dynamics in Fe-substituted samples. The findings establish iron doping as an effective strategy for tailoring the dielectric behavior of MgAl₂O₄, underscoring its potential for high-frequency electronics, sensors, and energy-related devices.