Nanomaterials (NMs) with structural, optical, and dielectric properties are called functional or smart materials and have favorable applications in various fields of material science and nanotechnology. Pure and Co-doped MgAl₂O₄ were synthesized by using the sol-gel combustion method. A systematic investigation was carried out to understand the effects of the Co concentration on the crystalline phase, morphology, and optical and dielectric properties of Co-doped MgAl₂O₄. X-ray diffraction confirmed the cubic spinel structure with the Fd3̅m space group, and there was no impurity phase, while the surface morphology of the samples was investigated by scanning electron microscopy. The dielectric properties of the synthesized material are investigated using an LCR meter with respect to the variation in frequency (1-2 GHz), and their elemental composition has been examined through the energy-dispersive X-ray technique. The existence of the metal-oxygen Mg-Al-O bond has been confirmed by Fourier transform infrared spectroscopy. The value of the dielectric constant decreases with the increasing frequency and Co concentration. The optical behaviors of the Co²⁺-doped MgAl₂O₄ reveal that the optical properties were enhanced by increasing the cobalt concentration, which ultimately led to a narrower band gap, which make them exquisite and suitable for energy storage applications, especially for super capacitors. This work aims to focus on the effect of cobalt ions in different concentrations on structural, optical, and dielectric properties.

The current research examines the impact of Ca²⁺ substitution on the phase and electrical properties of (Ba_1−xCa_x)Ti₄O₉, (x = 0.0, 0.3, 0.6, and 0.9) sintered pellets synthesized by solid-state reaction method. The as-synthesized samples were analyzed using X-ray diffraction (XRD) and impedance spectroscopy. The emergence of orthorhombic phase fit into space group Pnmm was revealed by XRD, and the addition of Ca resulted in a considerable shift in grain size. Dielectric properties were determined using an impedance spectroscopy in a wide frequency range from 1MHz to 3 GHz. The dielectric properties i.e., dielectric constant (ε_r) and dielectric loss ($tan\sigma$), were measured at 3 GHz frequency. The frequency-dependent parameters such as conductivity, dielectric constant, and dielectric loss indicated that the relaxation process is a Maxwell–Wagner type of interfacial polarization. The improved dielectric properties and low energy loss have made (Ba_1−xCa_x)Ti₄O₉ a prominent energy storage material. This study provides the possibility to improve its dielectric properties and reduce energy loss, making it an excellent energy storage material.

The new ceramic composite of Ca(Zr_xTi_1-x)O₃ had been prepared using the conventional mixed oxide solid state reaction method. The effects of Zr⁴⁺ ions substation over Ti⁴⁺ ions on the microwave dielectric properties of the CaTiO₃ ceramics were investigated. The phase analysis showed that the specimens Ca(Zr_xTi_1-x)O₃ presented single phase with orthorhombic structure in the range of x = 0.0–0.7 when sintered at 1300 °C for 3 h. The addition of Zr⁴⁺ facilitated the formation of large round-like grains with porous microstructure. The solid solution with x = 0.7 sintered at 1300 °C for 3 h showed a good combination of dielectric properties: ${\mathrm{\epsilon }}_{\mathrm{r}}=64,\text{ Q*f}=3937\mathrm{GHz}$ and ${\rho }_{\mathit{rel}}=81.08\mathrm{\%}$ (at 2.5 GHz).

The structural, microstructural, and microwave dielectric properties of Ba_1–xSr_xTi₄O₉, (0.0 ≤ x ≤ 0.06) ceramics samples synthesized by a conventional route were investigated. These structural, microstructural, and dielectric properties were recorded using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) and impedance analyzer spectroscopies. Ti–O octahedral distortion was observed due to Sr²⁺ addition. The microwave dielectric properties were interrelated with various Sr²⁺ concentrations. Excellent microwave dielectric properties, i.e., high relative permittivity (ϵ_r = 71.50) and low dielectric loss (tan δ = 0.0006), were obtained.

Slate is a naturally available aluminous silicate based material and can be used as a good source for silica extraction. In the current investigation, the slate sample was passed through calcination and acid leaching processes to decrease alumina contents and other major constituents. Silica extraction was performed by alkaline hydrothermal treatment of a given slate sample followed by acidic precipitation. Different steps, including the effect of concentration of sodium hydroxide solution, reaction time, the ratio of the mass of sample to volume of alkaline solution, the temperature of dispersion, and pH of the filtrate, were investigated to extract the maximum amount of pure amorphous silica. The extracted silica was physicochemically analyzed through XRF, XRD, FT-IR spectroscopy, and SEM techniques. The amorphous nature of the extracted silica is evident from XRD and SEM studies, while FT-IR studies support its purity, showing peaks of only Si–O–Si bonds. The purity of the extracted silica was further confirmed via XRF spectroscopic analysis and a hydrofluoric acid test.