Advancements in multiferroic, dielectric, and impedance properties of copper-yttrium co-doped cobalt ferrite for hydroelectric cell applications.

This paper explores yttrium and copper co-doped cobalt ferrite [Co1-xCuxFe1.85Y0.15O4] synthesized via the sol-gel auto-combustion route (0.0 ⩽x⩽ 0.08). Investigating the impact of co-dopants on CoFe2O4, the study reveals altered cation distribution affecting the structure, multiferroic, and electrical properties. X-ray diffraction studies show nanocrystalline co-doped cobalt ferrites with lattice expansion and smaller grains due to Cu-Y co-doping. Fourier transform infrared spectroscopy confirms inverse spinel family classification with tetrahedral lattice shrinkage. Field emission scanning electron microscopy indicates a grain size of approximately 0.12µm. Ferroelectric analysis reveals a peak saturation polarization of 23.42µC cm-2for 8% copper doping, attributed to increased Fe3+ions at tetrahedral sites. Saturation magnetization peaks at 54.4706 emu g-1for 2% Cu2+ion substitution [Co0.98Cu0.02Fe1.85Y0.15O4] and decreases to 37.09 emu g-1for 4% Cu substitution due to irregular iron atom distribution at tetrahedral sites. Dielectric studies uncover Maxwell-Wagner polarization and high resistance in grain and grain boundaries using impedance spectroscopy. Fabricated hydroelectric cells exhibit improved ionic diffusion, suggesting their use in potential hydroelectric cell applications.

Enhanced degradation of Congo-red dye by Cr3+ doped α-Fe2O3 nano-particles under sunlight and industrial wastewater treatment.

Considering the increasing amount of water pollution, nanocomposite advances for the effective elimination of hazardous pollutants are still needed. α-Fe2O3, Cr0·5Fe1·5O3 and CrFeO3 nanoparticles were synthesized via an eco-friendly material synthesis i. e hydrothermal route without using any precipitating agent and were studied to remove congo-red dye using photocatalytic properties. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FESEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) characterizations have been performed to know about the material structure and properties of synthesized samples. High efficiency (95.2%) of degradation was achieved under sunlight using a very low amount of CrFeO3 catalyst (0.2 g/L) at a 6-pH level of dye and was confirmed using UV spectroscopy, TOC (84%), LC-HRMS. Also, the potential to degrade the CR dye was concluded from the high rate of BOD5/COD. The results showed a significant enhancement in the degradation of α-Fe2O3 from 52.3% to 95.2% in a short duration of 15 min by introducing chromium as a dopant. The doping of chromium influenced the major factors responsible for the photocatalytic activity such as the increase in range of absorbance, increased e--h+ pair separation, improvement in the charge transfer process and active site formation which significantly enhanced the process of degradation. We found that the Cr-doped α-Fe2O3 nanomaterial could effectively remove dyes, such as congo-red, from industrial water-waste.

Unveiling the impact of Ni2+/Y3+ co-substitution on the structural, dielectric, and impedance properties of multiferroic spinel ferrite for hydroelectric cell application.

Substitution with rare earth (RE3+) and transition (X = Cu, Ni, Mn, Zn, etc.) metals can distort the spinel ferrite structure and create defects, which can be exploited in multifarious applications. In this study, yttrium and nickel co-substituted cobalt ferrites [Co1-xNixFe1.85Y0.15O4], (0.0 ≤ x ≤ 0.15) were synthesized by a modified sol-gel reaction route. The X-ray diffraction (XRD) patterns confirmed the single phase and highly crystalline nature of the prepared samples. Field emission scanning electron microscopy with energy dispersive X-ray (FESEM-EDX) spectroscopy confirmed the morphology of the prepared samples sintered at 800 °C and showed the grain sizes of the particles decreased with the addition of nickel ions. The simultaneous co-existence of saturation magnetization and ferroelectricity at room temperature confirmed the multiferroic nature of the co-substituted cobalt ferrites. The dielectric and impedance studies confirmed the Maxwell-Wagner polarization phenomenon and the enhanced values with Y-Ni co-substitution. The maximum saturation ferroelectric polarization was attained around 6.142 µC cm-2 for yttrium-substituted cobalt ferrite and then decreased with the increase in the substitution % of nickel. The maximum value of saturation magnetization (Ms = 99.50 emu g-1) was obtained with the highest substitution % of nickel of x = 0.15 in yttrium-substituted cobalt ferrite (YCFO) nanoferrites, which was also confirmed from the vibrating sample magnitude (VSM) studies at room temperature. The improvements in the structural, morphological, electrical, and multiferroic properties in the co-substituted cobalt ferrites were found to correlated to the substitution of the bigger cationic Y3+ ions compared to the Fe3+ ions, while the small substitution of Ni2+ ions lead to changes in the lattice parameters, porosity, and conduction behavior. These significant enhancements in co-substituted cobalt ferrites can be exploited for hydroelectric cell applications.

Structural and electrical properties of Gd3+ ion substituted CoGdxFe(2-x)O4 nano-ferrites.

Nano particles of CoGdxFe(2-x)O4, with x = 0.0, 0.1, 0.3, 0.5 have been prepared by chemical co-precipitation method. The as synthesized particles are annealed at 300 degrees C for two hours to improve crystallinity. The X-ray diffraction patterns reveal the single cobalt ferrite phase formation and the average crystallite size decreases to 7 nm in the Gd3+ ion doped sample (with x = 0.5) compared to 27 nm in case of un-doped cobalt ferrite sample. The electrical properties for the different compositions of Gd3+ ion substituted cobalt ferrite material were studied in the frequency range 100 Hz to 10 MHz at room temperature using WK impedance analyzer. It is found that the electrical conductivity of the samples increases with increasing Gd3+ ion concentration. The results of our investigations reveal a strong dependence of material properties on Gd3+ ion doping.

Electrical characteristics of PbSe nanoparticle/Si heterojunctions.

I-V characteristics of PbSe nanoparticle/single crystal Si heterojunctions prepared by chemical bath deposition method show a rectifying behavior. With decrease in average PbSe grain size between 72 nm and 9 nm currents decrease for forward and reverse bias. C-V characteristics indicate that the junctions transform into that of a metal insulator semiconductor (MIS) as the PbSe nanoparticle size decreases from 72 nm to 9 nm. This insulator like behavior of the small PbSe nanoparticle films is attributed to the highly resistive grain boundaries. Cole-Cole plots demonstrate that on decrease of grain size, the grain boundary contribution increases and grain contribution to the overall impedance decreases. Frequency dependence of capacitance proves space charge polarization in larger grains, which recedes with decrease in average grain size proving insulator like behavior of small PbSe nanoparticles.