Vidya Vihar Institute of Technology

This work presents a comprehensive investigation of the structural, magnetic, optical, and dielectric properties of praseodymium-doped barium hexaferrite nanomaterials, BaPrxFe12−xO19 (x = 0.00 and 1), synthesized via a heat treatment method at 850 °C. Fourier transform infrared (FTIR) spectroscopy confirms the formation of the hexaferrite phase through characteristic metal–oxygen vibrational modes and enables the evaluation of force constants, bond lengths, and functional groups. X-ray diffraction (XRD) analysis reveals the formation of M-type hexaferrite with a hexagonal structure, accompanied by a minor BaFe2O4 secondary phase, while providing detailed crystallographic parameters influenced by Pr3+ substitution. Thermogravimetric analysis (TGA) demonstrates excellent thermal stability of the samples beyond 780 °C, indicating their suitability for high-temperature applications. Magnetic characterization using vibrating sample magnetometry (VSM) shows a notable enhancement in magnetic behavior with Pr incorporation, attributed to lattice distortion and modified superexchange interactions. Optical properties investigated via UV–Visible spectroscopy reveal a direct band gap, which increases systematically with Pr concentration, highlighting effective band gap tuning—one of the key novel outcomes of this study. Dielectric and ferroelectric measurements indicate that Pr3+ ion substitution suppresses electrical leakage by stabilizing the lattice and hindering charge carrier mobility, thereby enhancing remnant polarization and coercive polarization. Overall, the improved structural stability, enhanced magnetic performance, tunable optical band gap, and favorable dielectric characteristics establish Pr-doped BaFe12O19 nanomaterials as promising multifunctional candidates for advanced optical, magnetic, electronic, and potential biomedical applications.

Diabetic retinopathy (DR) is one of the biggest causes of vision loss in the world, however, retinal image analysis can help prevent permanent vision loss by allowing DR to be detected early. Automated analysis of retinal blood vessels plays a critical role in diabetic retinopathy screening, and this paper presents a DR analysis with a focus on the U-Net frameworks and its use to segment blood vessels from wide field retinal images. Our model uses a unique and modified U-Net model that has both batch normalization (BN) and dropout regularization (DR) to address over and out of sample variability. It is hosted on a back end and dual front end offer DRIVE support. The proposed model achieved a sensitivity of 83.92 % and an AUC of 0.983, demonstrating strong discrimination between vessel and background pixels. We do find blood vessel segmentation is still optimal in thin blood vessels. We find our model is both computationally efficient and clinically trustworthy which makes our segmentation of retinal vessels optimal in automated screening for diabetic retinopathy (DR) programs.

La3+-substituted cobalt ferrite nanoparticles, CoLaxFe2₋xO4 (0.00 ≤ x ≤ 0.20), were synthesized using a green sol–gel auto-combustion route with lemon juice as a natural chelating and combustion precursor. X-ray diffraction confirmed the formation of a cubic spinel structure and successful La3+ incorporation, accompanied by lattice expansion and a reduction in crystallite size with increasing La content. FESEM analysis revealed a progressive reduction in particle agglomeration and improved morphological uniformity. FTIR spectra confirmed the characteristic metal–oxygen vibrations associated with tetrahedral and octahedral sites of the spinel framework. Optical analysis showed a gradual increase in the optical band gap with La substitution, indicating tunable electronic characteristics, while photoluminescence measurements revealed enhanced optical emission at the optimum La concentration. Elastic-property analysis demonstrated modified lattice stability and phonon dynamics following La incorporation. Magnetic measurements showed a systematic decrease in saturation magnetization with increasing La content, accompanied by an increase in coercivity, which was attributed to cation redistribution, lattice distortion, and enhanced magnetocrystalline anisotropy. Electrochemical measurements in a three-electrode configuration using 1 M KOH electrolyte demonstrated pronounced pseudocapacitive behavior with reversible Faradaic reactions and good electrochemical reversibility. Galvanostatic charge–discharge profiles exhibited near-symmetric characteristics and low internal resistance, with CoLa₀.2Fe1.8O4 delivering the highest specific capacitance and longest discharge time among the investigated compositions. The enhanced electrochemical response was associated with improved charge-transfer characteristics, increased oxygen-vacancy concentration, and facilitated ion-diffusion pathways induced by La substitution. Overall, the systematic La-induced modifications in structural, optical, elastic, luminescent, magnetic, and electrochemical properties demonstrate effective multifunctional property engineering of cobalt ferrite nanostructures, with CoLa₀.2Fe1.8O4 identified as the optimum composition for potential application in high-performance supercapacitor electrodes and other advanced energy-storage and electronic devices.

Praseodymium-substituted CoPrxFe2-xO4 nanoferrites (x = 0.0-0.3) were synthesized at 850 degrees C using a sol-gel method. XRD confirmed the cubic crystal structure and revealed notable changes in crystallite size (34 to 47 nm), lattice constant, and micro-strain as Pr3+ content increased, indicating lattice distortion. FESEM analysis showed that grain size declined (from 266 to 118 nm) with increased Pr3+ substitution at Fe3+ lattice sites. The FESEM images also displayed prominent grain boundaries and a porous structure. HRTEM results indicated that particle size decreased from 50 to 46 nm with higher Pr3+ concentrations. FTIR spectroscopy confirmed the formation of spinel ferrite via the identification of metal oxide bonds. Room-temperature photoluminescence spectra (from 419 to 595 nm) revealed crystallographic defects, near-band emissions, and oxygen deficiencies. With increased Pr3+, saturation magnetization, coercivity, and magnetic anisotropy also changed notably. Saturation magnetization, squareness ratio, and magnetocrystalline anisotropy constant increased as x rose from 0 to 0.2. The substituted ferrites showed enhanced coercivity (1047 to 1322 Oe) compared to pristine cobalt ferrite (1016 Oe). The dielectric constant increased systematically with added Pr3+, while dielectric loss declined substantially, indicating suitability for high-frequency device applications. Improved magnetic parameters and crystallographic defects with porosity may make these materials useful in permanent magnets and hydroelectric cells.

Hydroelectric cells (HECs) are new, eco-friendly, portable energy devices that generate clean energy by splitting H2O at room temperature without requiring external electrolytes. Using a sol-gel technique, nanocrystalline Mg1-xCoxFe2O4 (x = 0.1 and 0.3) was synthesized and used as the active component in the fabrication of an HEC. XRD verified a cubic spinel structure with a crystallite size ranging from 28 to 34 nm for the synthesized ferrites. FTIR spectroscopy revealed significant surface hydration required for water splitting. It also revealed strong absorption wavenumbers between 428 and 564 cm(-1), which correlated with metal-oxide bonds, and prominent water-related bands between 1632 cm(-1) and 3468 cm(-1). A theoretical porosity ranging from 39 to 56 % was determined from XRD data. The FESEM investigation also revealed a porous microstructure with an average grain size of 81 nm for the x = 0.3 ferrite sample. Agglomerated nanoparticles of the x = 0.3 ferrite, with an average particle size of 56 nm, were observed by HRTEM. BET analysis confirmed the mesoporosity in the prepared ferrite materials. Room-temperature photoluminescence investigations verified the existence of oxygen vacancies and crystallographic defects, which promote the chemidissociation of H2O into H3O+ and OH-. By promoting spontaneous water splitting through an electrolytic chain reaction, the ferrite surface produces a voltage across Zn/Ag electrodes. Compared to x = 0.3, the x = 0.1-based HEC demonstrated a higher short-circuit current and power output due to higher porosity and crystal defects. The Mg0.9Co0.1Fe2O4-fabricated HEC demonstrated an open-circuit voltage of 0.938 V, a short-circuit current of 10 mA, and a power output of 9.38 mW. This highlights the possible use of porous and oxygen-deficient Mg1-xCoxFe2O4 (x = 0.1 and 0.3) based HEC as a green energy producer.