http://dspace.aiub.edu:8080/jspui/handle/123456789/7 Thu, 02 Apr 2026 02:31:40 GMT 2026-04-02T02:31:40Z http://dspace.aiub.edu:8080/jspui/handle/123456789/2906 Title: Structure-based magnetic, electrical and transport properties of Ni–Zn–Co ferrite by V5+ substitution Authors: Hossain, M.D.; Khan, M.N.I.; Hossain, Md Sarowar; Ahned, S. J.; Alam, M. K.; Liba, S. I.; Hakim, M. A.; Jamil, A.T.M.K. Abstract: This article presents the modification of structure-based magnetic, electronic and transport properties along with the conduction mechanism and its relaxation process in a Ni–Zn–Co ferrite tailored by V5+substitution at B-site replacing Fe3+ions. The composition Ni0.7Zn0.2Co0.1Fe2-xVxO4 (0≤x≤0.12) was synthesized by standard solid- state reaction method and all samples were crystallized with a single-phase cubic spinel structure belonging to the Fd3m space group. The lattice constants decreased gradually from 8.3673 Å to 8.3602 Å and the average grain sizes (DSEM)are also decreased from 6.92 μm to 1.99 μm due to V5+ ions substitution at Fe3+ of B-site. However, more than 25% of Fe3+ ions migrate to A-site from B-site due to V5+ substitution at Fe3+of B-site. In all samples θD does not strictly follow the Anderson’s prediction, rather it monotonically decreases to a low value until x= 0.12. Magnetic phase transition temperature shifted to the lower temperature and the net magnetization (n_B^e ) decreases due to V5+ substitution in Ni–Zn–Co ferrite. Apart this, during conduction charge carriers should require more energy to jump from one cationic site to other for V5+ substitution in the Ni–Zn–Co ferrite and the activation energy (Ea) is much more higher in V5+ substituted sample. Moreover, long-range interaction with localized relaxation mechanism is observed in V5+ doped samples. The resistance at the grain (Rg) is maximum (243.09 Ω) for the sample x=0.10 while grain boundary resistance (Rgb) is maximum (5.98×105 Ω) for the sample x=0.07. However, the higher value of ρ_DC for x=0.12 sample ensures to be suitable for electromagnets, transformers, electronic inductors, and at high-frequency applications. Moreover, x=0.07 sample displays high value of TCR (8.6 %/K at 418 K) which may be utilized as an infrared detector for night vision bolometer material. Thu, 11 Aug 2022 00:00:00 GMT http://dspace.aiub.edu:8080/jspui/handle/123456789/2906 2022-08-11T00:00:00Z http://dspace.aiub.edu:8080/jspui/handle/123456789/2894 Title: Structure-based magneto-dielectric response in Zn and V Co-doped NiFe2O4 for magnetic and spintronic applications Authors: Hossain, Md. Sarowar; Dutta, Sagar; Hassan, Md. Rabiul; Tarif, Ejaj; Bhuyan, M. D. I.; Tama, Angkita Mistry; Hossain, M. D.; Roy, Gourab Kumar Abstract: This study implemented the sol-gel method to synthesize NiFe2O4 (NFO) and Ni0.6Zn0.4Fe1.94V0.06O4 (NZFVO) nanoparticles. X-ray diffraction (XRD) with Rietveld refinement confirmed cubic spinel structures, while FESEM and TEM showed that dopants caused lattice distortion, leading to larger grains and crystallites in NZFVO. First- principles calculations show a reduced direct bandgap and conduction band splitting in NZFVO, attributed to strong d–p orbital hybridization. Mulliken population analysis indicates off-center cationic displacements and increased covalency, further supporting the observed dielectric and magnetic behavior. Dielectric measurements confirmed lower permittivity and loss in NZFVO, indicating its suitability for low-loss spintronic devices. Magnetic characterization shows enhanced saturation magnetization, lower coercivity, and reduced Curie temperature (Tc) in NZFVO, resulting from optimized cation distribution and weakened anisotropy. Therefore, NZFVO, with high saturation magnetization (~72.4 emu/g) and low coercivity (~6.6 Oe), is well-suited for low-field detection, magnetic biosensing, and room-temperature sensing. Its reduced bandgap and strong d-p hybridization enable spin-dependent conduction, while moderate conductivity and low resistivity make it a promising channel material for spin-based transistors and logic devices. Mon, 01 Sep 2025 00:00:00 GMT http://dspace.aiub.edu:8080/jspui/handle/123456789/2894 2025-09-01T00:00:00Z http://dspace.aiub.edu:8080/jspui/handle/123456789/2893 Title: Investigation on structure, thermodynamic and multifunctional properties of Ni–Zn–Co ferrite for Gd3+ substitution Authors: Hossain, M. D.; Jamil, A. T. M. K.; Hossain, Md. Sarowar; Ahmed, S. J.; Das, H. N.; Rashid, R.; Hakim, M. A.; Khan, M. N. I. Abstract: This study presents a modification of structure-dependent elastic, thermodynamic, magnetic, transport and magneto-dielectric properties of a Ni–Zn–Co ferrite tailored by Gd3+ substitution at the B-site replacing Fe3+ ions. The synthesized composition of Ni0.7Zn0.2Co0.1Fe2-xGdxO4 (0≤x≤0.12) crystallized with a single-phase cubic spinel structure that belongs to the Fd3m space group. The average particle size decreases due to Gd3+ substitution at Fe3+. Raman and IR spectroscopy studies illustrate phase purity, lattice dynamics with cation disorders and thermodynamic conditions inside the studied samples at room temperature (RT=300 K). Ferromagnetic to paramagnetic phase transition was observed in all samples where Curie temperature (TC) decreases from 731 to 711 K for Gd3+ substitution in Ni–Zn–Co ferrite. In addition, Gd3+ substitution reinforces to decrease the A-B exchange interaction. Temperature dependent DC electrical resistivity (ρ_DC ) and temperature coefficient of resistance (TCR) have been surveyed with the variation of the grain size. The frequency-dependent dielectric properties and electric modulus at RT for all samples were observed from 20 Hz to 100 MHz and the conduction relaxation processes were found to spread over an extensive range of frequencies with the increase in the amount of Gd3+ in the Ni–Zn–Co ferrite. The RLC behavior separates the zone of frequencies ranging from resistive to capacitive regions in all the studied samples. Finally, the matching impedance (Z/η_0) for all samples was evaluated over an extensive range of frequencies for the possible miniaturizing application. Mon, 07 Feb 2022 00:00:00 GMT http://dspace.aiub.edu:8080/jspui/handle/123456789/2893 2022-02-07T00:00:00Z http://dspace.aiub.edu:8080/jspui/handle/123456789/2892 Title: Development of a simulated blood-like solution for medical experiments Authors: Hossain, Md. Sarowar; Ferdous, Humayra; Tarif, Ejaj; Islam, Md Aminul; Md Abdullah, Shamvi; Heaven Mondol, Frank Abstract: Real human blood presents several challenges that hinder long-term and large-scale studies, such as rapid degradation and clotting of real blood, which restricts its usability and necessitates frequent procurement of fresh supplies and complex storage solutions. This study develops a stable, long-lasting blood-mimicking fluid (BMF) to replicate human blood. This BMF has been synthesized from Agar-Agar (C12H18O9), Iron(II) Tetraphenylporphyrin (C44H28ClFeN4), Ringer’s solution, and red food color (C20H6I4Na2O5). The microstructure and size of the particles inside the BMF have been studied using a field effect scanning electron microscope (FESEM). Additionally, the dynamic light scattering (DLS) method has been employed to analyze the particle distribution in BMF at various solution concentrations. The other physical and chemical properties of the studied BMF, such as pH, density, viscosity, glucose level, particle size, and conductance were measured. The synthesized BMF shows a viscosity of 3.24 mPa·s, density of 1.013 g/cm3, and average particle size of ∼1.4-2.0 μm, closely resembling real blood. Moreover, the BMF demonstrates the conductivity of 3.56 mS/cm and does not show phase separation, confirming its hydrophilic behavior. In addition, a 24-hour circulation test confirmed its stability, making it suitable for biomedical device testing, especially in diagnostics and hemodynamic studies. Fri, 04 Jul 2025 00:00:00 GMT http://dspace.aiub.edu:8080/jspui/handle/123456789/2892 2025-07-04T00:00:00Z