Iranian Journal of Materials Science and Engineering

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The densification behavior, structural and microstructural evolution and microwave dielectric properties of Li₂TiO₃ + xZnO (x = 0, 0.5, 1, 1.5, 2, 3, and 5 mol%) ceramics have been investigated using X-ray diffraction, Field Emission Scanning Electron Microscopy, Raman spectroscopy and microwave resonant measurement. The Maximum density of 3.33 g/cm³ was obtained in Li₂TiO₃ + 2ZnO ceramic at low sintering temperature of 1100˚C. SEM investigations revealed good close packing of grains when x = 2 and preferential grain growth when x ≥ 3. The maximum values of Q × f = 31800 GHz and ε_r = 22.5 were obtained in Li₂TiO₃ + 3ZnO and Li₂TiO₃ + 2ZnO compositions, respectively. The observed properties are attributed to the microstructural evolution and grain growth (first case) or high density of the obtained ceramic (second case).
 

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In present work Ni_0.7Cd_0.3Nd_xFe_2-xO₄ ferrite samples (0≤x≤0.03) were prepared by using oxalate co-precipitation technique. The different characterization techniques were achieved using X-ray diffraction (XRD), FT-infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), DC electrical resistivity and dielectric measurements. The crystallographic parameters such as crystal structure, crystallite size, lattice constant, unit cell volume and theoretical density have been systematically analysed. The XRD and FT-IR measurements confirmed the formation of single phase spinel ferrite structure. The cation distribution among the octahedral and tetrahedral sites has been proposed on the basis of analysis of XRD patterns by employing Rietveld refinement analysis. The samples exist as a mixed type spinel with cubic structure. The DC electrical resistivity confirms the semiconducting behaviour and the Curie temperature decreases with increase in Nd³⁺ content. The dielectric constant and loss tangent decreases with frequency and higher frequencies remain constant, which shows the usual dielectric dispersion due to space charge polarization. The AC conductivity reveals that the small type polarons responsible for conduction process.

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This study investigates the effect of sintering temperature on the structural, dielectric and magnetic properties of cobalt ferrite nanoparticles (CoFe₂O₄ NPs) synthesized by the sol–gel method. The samples were sintered at 400°C–1000°C for 2 h and characterized using XRD, FTIR, SEM, AFM, dielectric and VSM measurements. XRD confirmed the formation of a stable cubic spinel structure, with crystallite size increasing from 10.71 to 16.09 nm and porosity decreasing with increasing sintering temperature. SEM and AFM showed progressive grain growth and improved grain connectivity, with the sample at 800°C exhibiting the most uniform morphology before excessive grain growth occurred at 1000°C. The dielectric response showed decreasing real and imaginary permittivity with increasing frequency, while the sample at 800°C exhibited the lowest dielectric loss (tan δ ≈ 2 at 1 kHz). Magnetic measurements revealed ferrimagnetic behavior, with saturation magnetization increasing from 27.5 emu/g at 400°C to 68 emu/g at 1000°C, whereas coercivity reached a maximum of 715 Oe at 800°C. Overall, sintering at 800°C provided the best balance between microstructural uniformity, low dielectric loss and magnetic performance, making it a strong candidate for further evaluation in high-frequency and multifunctional magnetic applications.