Preparation, Characterization, Thermal Stability, Optical, and Dielectric Behavior of Fe3+-Doped Al3+ in Mg–Al Layered Double Hydroxides Containing Nitrates

In this work, Fe3+-doped Al3+ in Mg–Al layered double hydroxides (LDHs) containing nitrates were synthesized through the coprecipitation with different molar fractions of Fe3+ (0, 0.25, 0.5, 0.75, and 1). The LDHs were then subjected to a series of characterization techniques, including X-ray diffraction, Fourier transform infrared, diffuse reflectance spectroscopy and impedance spectroscopy. Thermal stability of LDHs was monitored using X-ray diffraction. It was demonstrated that increasing the iron composition allows for enhancing the process of absorbing light, increasing the refractive index, and inducing a red shift at the absorption edge. In addition, a correlation was found between increased iron composition and a reduction in optical gap energy. However, at high frequencies, the electrical conductivity and dielectric constant increased with decreasing iron content, while the dielectric loss parameters were found to be relatively dependent on both frequency and iron doping.