Chemistry

Successful Publications

20.05.2021

Our Department Instructor Research  Asst. Dr. Ayşe DEMİR KORKMAZ's studies published in ACS Omega, Materials Science and Engineering B and Nano-Structures & Nano-Objects journals is given below.. We congratulate her, and wish her continued success.

1. Influence of Dy3+ Ions on the Microstructures and Magnetic, Electrical, and Microwave Properties of [Ni0.4Cu0.2Zn0.4](Fe2−xDyx)O4 (0.00 ≤ x ≤ 0.04) Spinel Ferrites

Journal: ACS Omega

Author(s): Almessiere, Munirah Abdullah; Slimani, Yassine; Güngüneş, Hakan ; Korkmaz, Ayse Demir; Zubar, Tatiana; Trukhanov, Sergei; Trukhanov, Alex; Manikandan, Ayyar; Alahmari, Fatimah; Baykal, Abdulhadi
[Ni0.4Cu0.2Zn0.4](Fe2–xDyx)O4 spinel ferrite nanoparticles with different Dy3+ concentrations (0.00 ≤ x ≤ 0.04) were prepared by a citrate sol–gel auto-combustion technique. A strong correlation among Dy concentration, structural parameters, and magnetic, electrical, and microwave properties was established. An increase in the Dy3+ concentration is the reason for a rise in the crystal structure parameters (due to different ionic radii of Fe and Dy ions) and a slight increase in the average particle size with a minor reduction in the specific surface area. It was observed that Dy3+ ions prefer to occupy the octahedral B site due to their large ionic radius (0.91 Å). The explanation of the electrical and magnetic properties was given in terms of the features of Dy3+–O2––Fe3+ dysprosium–oxygen–iron indirect exchange. The occurrence of the intensive changes in amplitude–frequency characteristics was observed from 1.6 to 2.7 GHz. The explanation of electromagnetic absorption was given in terms of the peculiarities of the microstructure (resonance of domain boundaries). The results open perspectives in the utilization of [Ni0.4Cu0.2Zn0.4](Fe2–xDyx)O4 spinel ferrite nanoparticles as functional materials for targeted drug delivery and hyperthermia applications.

2. Title: Correlation between chemical composition, electrical, magnetic and microwave properties in Dy-substituted Ni-Cu-Zn ferrites

Journal: Materials Science and Engineering:B
Authors: MA Almessiere, Y Slimani, H Güngüneş, A Demir Korkmaz, SV Trukhanov, S Guner, F Alahmari, AV Trukhanov, A Baykal
Dy3+ ion-substituted nanoferrites Ni0.4Cu0.2Zn0.4Fe2−xDyxO4 (x ≤ 0.04) were produced via sol-gel method. Correlation between chemical composition, crystal structure, electrical, magnetic and microwave properties was investigated. All samples were characterized by single-phase state. It was observed that the increase of the Dy content leads to a decrease in the average crystallite size. The bandgap (Eg) was deduced to be between 1.83 and 1.86 eV. The measurements of magnetization versus applied magnetic field (M-H) and magnetization versus temperature (M-T) were investigated by vibrating sample magnetometer (VSM). Magnetic measurements revealed superparamagnetic character at room temperature. The magnetization was increased initially with doping Dy3+ in the ratio of x = 0.01 compering to the un-doped sample and thereafter dropped as Dy3+ ions content further increases. Microwave properties were discussed in terms of electromagnetic absorption in the frequency range 1–20 GHz. The occurrences of the intensive electromagnetic absorption in the frequency ranged from 1.6 to 2.7 GHz were observed. The changes in the amplitude-frequency characteristics correlated well with the level of chemical substitution (x) with Dy ions concentration.

3. Review on functional bi-component nanocomposites based on hard/soft ferrites: Structural, magnetic, electrical and microwave absorption properties

Journal: Nano-Structures & Nano-Objects

Authors: M.A. Almessiere, Y. Slimani, A.V. Trukhanov , A. Sadaqat , A. Demir Korkmaz, N.A. Algarou , H. Aydın , A. Baykal , Muhammet S. Toprak

Bi-component hard (H) (hexaferrite) and soft (S) (spinel) ferrites nanocomposites are gaining interest scientifically and technically, not only for combining the high magnetization of spinel ferrite nanomaterials and the high coercivity of hexaferrite magnetic nanomaterials but also for the outstanding exchange-coupling behavior among hard and soft magnetic phase. The improved magnetic features lead to produce a new nanocomposite with higher microwave absorption capacity in comparison with ferrites with a single absorption mechanism. Exchange-coupled effect has a potential application based on microwave absorption, recording media, permanent magnets, biomedical and other applications. Intensive studies have been conducted on this topic to produce hard/soft (H/S) ferrite nanocomposites with establishment of exchange coupled effect between the two phases. Preparation methods, microstructure, magnetics features, microwave and dielectric properties, and applications are elaborated. Consequently, a comprehensive effort has been made to contain an original reference investigating in detail the precise outcomes of the published papers.