Showing 2 results for Jabbar
Rihab Jabbar, Mohammed Alluaibi, Sara Shahatha, Dhuha Hasan,
Volume 21, Issue 0 (IN PRESS 2024)
Abstract
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.
Sibbt Jabbar, Dalya Hameed, Imad Disher,
Volume 23, Issue 2 (June 2026 2026)
Abstract
Geopolymer/nano carbon black composite is a promising electrically conductive smart material that can be used in self-heating and self-sensing applications. This paper studies the effect of adding nano carbon black to the physical, mechanical, electrical, and electrothermal performance of metakaolin-based geopolymer. Carbon black was added at the percent of 5%, 10%, 15%, and 20% by weight of metakaolin; the compressive strength was tested at various ages of 7, 14, 28, and 90 days, and the electrothermal performance was tested using AC and DC voltages. The results showed that a compromise between suitable compressive strength and high electrothermal conversion could be achieved when a specific balance between the carbon black percent and the lowest water content is established. A composite with a compressive strength of 27 MPa and stable electrothermal performance reaching 142°C at 9V DC can be prepared using 20 wt% of carbon black and a water-to-metakaolin ratio of 0.549, which is used as a smart material in construction applications.
