Journal of Material and Metamaterial Sciences

Synthesis and characterization of strontium hexaferrite composite magnetic materials: A review

Meiyuli Simanullang — Sat, 31 May 2025 00:00:00 +0700

SrCo_xFe_12-xO₁₉is a composite magnetic material that has wide applications in the field of modern technology. This study aims to synthesize and characterize SrCo_xFe_12-xO₁₉ (x=0–0.3) using coprecipitation technique and high temperature sintering. The results showed that increasing cobalt (Co) concentration enhanced the magnetic properties of the composite, including saturation magnetization (M_s) up to a peak value of 42.5 emu/g at x = 0.3, as well as higher coercivity (H_c) due to morphological anisotropy and valence change of Fe³⁺ to Fe²⁺. XRD characterization revealed a magnetoplumbite-type crystal structure with a hexagonal M phase, while FTIR analysis identified Fe–O and Co–O bond vibrations that became more intense with the addition of Co. SEM showed morphological changes from lamellar shapes to small spherical particles as Co increased. VSM analysis confirmed the strong interaction between the hard (SrFe₁₂O₁₉) and soft (CoFe₂O₄) magnetic phases, which supports the application of this composite as a microwave absorbing material. These findings highlight the potential of SrCo_xFe_12-xO₁₉ as an advanced magnetic material with characteristics that can be optimized for high-tech applications.

Physical and electrochemical properties of activated carbon derived from bamboo charcoal utilizing diverse electrolytes for supercapacitor applications: A review

Seli Novalina Sawitri — Sat, 31 May 2025 00:00:00 +0700

Activated carbon is a highly porous material that is widely used in energy applications, such as supercapacitors, as it has a large specific surface area and good electrical conductivity. Bamboo, as one of the abundant biomasses, can be processed into high-quality activated carbon through chemical activation process. With its natural carbon-rich structure and pores, bamboo provides a great opportunity to improve the energy storage performance of supercapacitors. This study analyzes the physical and electrochemical properties of activated carbon synthesized from bamboo charcoal using KOH activation for supercapacitor applications. Structural characterization was performed using X-ray diffraction and field emission scanning electron microscopy, which showed an amorphous structure with high porosity. Electrochemical studies via cyclic voltammetry and galvanostatic charge-discharge revealed that the electrolyte mixture (Na₂SO₄ 1 M and KOH 0.5 M) yielded the best performance with a maximum specific capacitance of 290 F/g at a current density of 1 A/g. These results indicate that bamboo-based activated carbon has great potential for environmentally friendly energy storage applications.

Hypothetical multi-detection ultra-sensitive sensors using ZnO thin films and metamaterials: A review

Yan Soerbakti — Sat, 31 May 2025 00:00:00 +0700

This study aims to observe the ability of a thin layer of zinc oxide (ZnO) which is applied to sensor technology. Currently, the low detection limit of the sensor is a problem in its use. Metamaterials offer resonant properties in increasing sensitivity, but their performance is still below the current high modern technology. The high engineering properties of metamaterials provide opportunities for realizing renewable metamaterials. ZnO thin layer semiconductor material as a transparent conductive oxide can provide a wide detection potential. The ability of ZnO thin films to be adapted to metamaterial sensors can be further investigated and improved for the future.