Sequential Synthesis Methodology Yielding Well-Defined Porous _75%SrTiO₃/_25%NiFe₂O₄ Nanocomposite

In this research, we reported on the formation of highly porous foam SrTiO₃/NiFe₂O₄ (_100-xSTO/_xNFO) heterostructure by joint solid-state and sol-gel auto-combustion techniques. The colloidal assembly process is discussed based on the weight ratio x (x = 0, 25, 50, 75, and 100 wt %) of NiFe₂O₄ in the _100-xSTO/_xNFO system. We proposed a mechanism describing the highly porous framework formation involving the self-assembly of SrTiO₃ due to the gelation process of the nickel ferrite. We used a series of spectrophotometric techniques, including powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N₂ adsorption isotherms method, UV-visible diffuse reflectance spectra (UV-Vis DRS), vibrating sample magnetometer (VSM), and dielectric measurements, to investigate the structural, morphological, optical, magnetic, and dielectric properties of the synthesized samples. As revealed by FE-SEM analysis and textural characteristics, SrTiO₃-NiFe₂O₄ nanocomposite self-assembled into a porous foam with an internally well-defined porous structure. HRTEM characterization certifies the distinctive crystalline phases obtained and reveals that SrTiO₃ and NiFe₂O₄ nanoparticles were closely connected. The specific magnetization, coercivity, and permittivity values are higher in the ₇₅STO/₂₅NFO heterostructure and do not decrease proportionally to the amount of non-magnetic SrTiO₃ present in the composition of samples.