Substituted Copper Ferrites Research Articles

Sol-gel Synthesis of Mn-substituted Copper Ferrite Nano Particles as Anode for Lithium Ion Batteries

Mn substituted copper ferrites (MnxCu1-xFe2O4, x = 0, 0.33, 0.67, 1.00) have been synthesized from metal nitrates and citric acid by sol-gel method (chemical process). This study aims to know the effects of Mn substitution on structural, magnetic, and electrochemical properties of copper ferrites. For characterizing the prepared ferrites, different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy were used. In addition, vibrating sample magnetometer (VSM) is used to investigate the magnetic properties such as saturation magnetization (Ms), residual magnetism (Mr) and coercive force (Hc). A single-phase spinal structure was confirmed by XRD and lattice parameter was increased from 8.36 Å to 8.52 Å with increasing Mn contents. Micrographs of SEM shows that nanoparticles are agglomerated and non-uniform in size. The FTIR analysis shows that theses absorption band about 1422 cm-1 to 1434 cm-1 was attributed octahedral B-site. For pure copper ferrite, band is shifted towards higher frequency by manganese content. The results from CV showed that the increasing in scan rate and specific capacitance decreases due to increase in the area loop which clearly means that the investigated samples are best for storage devices such as lithium ion batteries (LIBs).

Solar photoactive magnesium substituted copper ferrite photocatalysts for Rose Bengal treatment

In the present investigation, we have reported solar photo active, cost effective and magnetically recoverable magnesium substituted copper ferrites successfully prepared by simple co-precipitation method. The prepared materials were characterized for structural and microstructural analysis using PXRD, SEM, EDS, FT-IR and UV–Visible spectroscopy. It was observed that, when copper introduces into magnesium ferrite system light absorption shifted to visible region, this is due to formation of metastable energy levels just below the conduction band of magnesium ferrites. As a result an MgCuFe2O4 catalyst exhibits excellent efficiency under solar light irradiation. These catalysts are stable for longer period even after many runs and magnetically separable. Based on the analysis result these nanomaterials can be used as potential environmental and energy applications under natural sunlight irradiation.

Microstructural investigation of sonochemically synthesized Zn substituted CuFe2O4 nanoparticles for heterogeneous green catalytic click chemistry and dye degradation

Heterogeneous green catalysis by means of magnetically separable nanometal–oxide catalysts is an attractive field of present day research. The microstructural characterization, optical and magnetic properties of sonochemically synthesized Zn substituted CuFe2O4 (CZF) nanoparticles (NPs) are investigated and compared with the unsubstituted CuFe2O4. PXRD (powder X-ray diffraction) pattern and HRTEM (high-resolution transmisson electron microscopy) observation with FTIR (Fourier transform infrared) spectroscopy are applied to analyze the microstructural and optical properties of nanosized (∼14.7 nm) zinc substituted copper ferrite. Rietveld refinement of the PXRD pattern reveals the mixed spinel structure of zinc substituted copper ferrite NPs. Magnetic data confirms the presence of ferromagnetic/ferrimagnetic phase with some admixture of finer superparamagnetic (SPM) nanophases within the sample. The lack of saturation in the M-H loops is due to the presence of spin-canting as well as SPM NPs in the system. These coupled Zn substituted CuFe2O4 magnetic NPs are used as a heterogeneous catalyst for three-component Huisgen 1,3-dipolar CuAAC green catalytic click reactions in aqueous media and dye degradation. Its catalytic reactivity has been compared with CuFe2O4 NPs. By this synthesized magnetic catalytic CZF NPs, we have successfully coupled alkyl halides and boronic acids with terminal alkynes to obtain 1,4-disubstituted 1,2,3-triazoles in good to excellent yields within a short time. The Heterogeneity, reproducibility and reusability of the catalyst has been also tested successfully up to several cycles without significant decrease in the product yield. We have explored CZF NPs as magnetically separable heterogeneous green catalyst for multi-component click reaction. Our synthesized CZF NPs has been used as photocatalyst for the photo degradation of organic dyes under visible light irradiation. The results demonstrate that the unique features of the CZF NPs make it an excellent material for a click chemistry catalyst as well as a highly active photocatalyst under visible light irradiation.

Facile synthesis of Al substituted Cu-ferrite infused reduced graphene oxide (rGO) nanohybrid for improving microwave absorption at gigahertz frequencies

This work mainly deals with the synthesis of Al substituted copper ferrite infused reduced graphene oxide (rGO) as a microwave absorbing material in a frequency ranging from 8.2 to 12.4 GHz (X-band). Firstly, Al substituted copper ferrite (CAF) infused rGO was synthesized using the solvothermal method. Then it mixed in the epoxy media to fabricate lightweight nanocomposites for their potential uses as competent electromagnetic wave absorbers. The structural analysis using XRD validates the successful substitution of Al into copper ferrite lattice. TEM results showed that copper-Al-ferrite's spherical morphology with size ~20–30 nm is well infused on rGO in the as-synthesized nanohybrid. BET analysis confirmed numerous pore formations in the nanohybrid that created during CAF over rGO. Furthermore, the effect of rGO-loaded/and unloaded nanohybrid on the microwave absorption properties was also studied. Notably, it is seen that the strategy to infuse CAF on rGO was found more effective in enhancing the absorption capacity of pure CAF. Remarkably, the CAF-rGO/epoxy nanocomposite exhibited excellent microwave absorption capacity as the reflection loss (RL) value of − 35.7 dB (99.973% absorption) is achieved with 3.55 GHz of broad − 10 dB (90% absorption) bandwidths under the low filler content of 20 wt% and small matching thickness of 2.2 mm. Besides, the possible microwave absorption mechanisms in the nanohybrid composite are also disclosed. Therefore, our results could be helpful to manufacture the rGO based dielectric-magnetic hybrid nanocomposites for the highly efficient and lightweight microwave absorber exclusively for X band application, i.e., in the high gigahertz range.

Visible Light Enhanced Photocatalytic Activity of Sr Substituted Copper Ferrites [Cu1-Xsrxfe2o4 (0 ≤ X ≤ 1.0)] on Textile Dye Degradation from Wastewater

Visible Light Enhanced Photocatalytic Activity of Sr Substituted Copper Ferrites [Cu1-Xsrxfe2o4 (0 ≤ X ≤ 1.0)] on Textile Dye Degradation from Wastewater

Development of cost effective, solar light active Cu1-xCaxFe2O4 nanocomposite catalysts for water treatment

Novel, efficient and magnetically recyclable calcium substituted copper ferrite photocatalysts were synthesized via a facile green approach. As prepared Cu1-xCaxFe2O4 composites were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electronic microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and UV–Vis spectrophotometer. The result shows that there is an enhancement in electron transfer and charge separation efficiency of calcium substituted copper ferrites leading to a significant improvement in photocatalytic efficiency. As prepared samples shows high visible light absorption which favors catalytic activity and also shows good magnetic separation for reuse. UV–Vis spectrophotometer was used for the destruction of model organic pollutant. Under natural sun light irradiation the as prepared samples exhibit superior photocatalytic activity toward malachite green (MG). The model organic pollutant inactivation mechanism was investigated in a scavenger study, and •O2, H2O2, and h+ were identified as the major reactive species for organic pollutant inactivation. The calcium substituted copper ferrite exhibit excellent stability and reusability. The experimental results indicate that calcium substituted copper ferrites have great potential in large scale photocatalytic disinfection operations.

Structural, spectral, dielectric and magnetic properties of indium substituted copper spinel ferrites synthesized via sol gel technique

Indium (In) substituted copper ferrites with nominal composition CuInxFe2-xO4 (where 0.00 ≤ x ≤ 0.32) were prepared via sol gel route. Influence of In3+ on thermal, structural, spectral, magnetic and dielectric properties are elucidated. The complete decomposition and stable phase formation was assessed from thermal gravimetric analysis (TGA) and differential thermal gravimetric analysis (DTA). The structure of copper ferrite is single phase estimated from X-ray diffraction (XRD) analysis. Lattice constant (a) and crystallite size first increased then decreased with the inclusion of In3+ ions. Cell volume, X-ray density and bulk density are improved due to substitution of indium ions. Magnetic studies are carried out by vibrating sample magnetometer (VSM). The various magnetic parameters i.e saturation magnetization (Ms), coercivity (Hc) and retentivity (MR) are elucidated. The value of Ms and Hc are reduced with the substitution of In3+ ions. The squareness ratio, anisotropy constant and Bohr's magneton were also decreased as the inclusion of indium concentration. The value of dielectric constant (ε′), dielectric loss (ε") and tan loss were reduced as frequency increased. The surface morphology was studied by SEM (scanning electron microscopy). The small value of dielectric parameters and coercivity of synthesized ferrites suggested that indium substituted copper ferrites might be useful in switching and high frequency applications.

Effect of Bi3+ ions on the humidity sensitive properties of copper ferrite nanoparticles

The response of humidity sensitivity factor of bismuth substituted copper ferrite nanoparticles is prepared by solution combustion route by using metal nitrates. From this preparation technique, bismuth substituted copper ferrites were confirmed to demonstrate the cubic spinel structure by X-ray diffraction measurement and FTIR spectral absorption bands observed at ν1 = 560 cm−1 to 580 cm−1 and ν2 = 404 cm−1 to 407 cm−1 for tetrahedral and octahedral sites in cubic spinel structure of ferrites. The prepared nanoparticles of ferrites are extremely resistive in the range of mega-ohm (MΩ) at room temperature and their humidity sensitivity is also very high. The electrical resistance is decreased for different concentration of bismuth in copper ferrites, noticeably with increasing the relative humidity. The relative humidity of BixCuFe2-xO4 nanoparticles in the range from 10% RH to 90% RH at room temperature is generated. With the substitution of bismuth, the sensitivity factor is decreased at low relative humidity. The maximum humidity sensitivity factor Sf = 925.64 was achieved for Bi0.1CuFe1.9O4 nanoparticles.

Fabrication of lithium substituted copper ferrite (Li-CuFe 2 O 4 ) thin film as an efficient gas sensor at room temperature

A Li-CuFe2O4 thin film has a well-defined nanocrystalline structure with a crystallite size of ∼17 nm. The TEM and SEM images of the Li-CuFe2O4 thin film show a polyhedron shape of nanoparticles with uneven sizes, resulting in a significant change in its gas sensing characteristics such as sensitivity and sensor response. An optical analysis shows that the Li-CuFe2O4 thin film has a semiconducting nature, and the band gap of the thin film is determined to be 1.15 eV. The gas sensor analysis demonstrates repeatability of the sensing behavior of the Li-CuFe2O4 thin film and this ensures a reliable and efficient gas sensor at room temperature.

Structural and Electrical Properties of Cobalt Substituted Copper Ferrites Synthesized by Sol–Gel Autocombustion Method

Structural and Electrical Properties of Cobalt Substituted Copper Ferrites Synthesized by Sol–Gel Autocombustion Method

Influence of sintering temperature on structural, dielectric and magnetic properties of Li substituted CuFe2O4 nanoparticles

Lithium substituted copper ferrite (LixCu(1−x)Fe2O4) nanoparticles have been successfully synthesized by chemical co-precipitation method. XRD analysis confirms the formation of Li substituted Cu ferrite with crystallite size in the range of 17–41nm. The SEM and TEM microstructure of nanoparticle is well characterized and fine nature improves while increasing of Li concentration and also FTIR analysis exhibit the usual behaviour of ferrite materials. The dielectric properties of the material are increased with increase of concentration. The hysteresis loop is increased which is evident from the increase of saturation magnetization which implies that soft magnetic material has altered into hard magnetic material

Structural, Optical and EXAFS Studies of Nickel Substituted Copper Ferrites Nano-Particle by Sol-Gel Auto Combustion Method

The Cu-Ni ferrites with general formula Cu1-xNixFe2O4 (where x=0.0, 0.1, 0.2, 0.3) were prepared by sol gel method. The Extended X-ray absorption fine structure (EXAFS), X- ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) measurements were carried out. EXAFS spectra have been recorded at the k edge of Iron using the dispersive EXAFS (DEXAFS) beam line at 2.5 GeV at Indus -2 synchrotron radiation source RRCAT, Indore, India. The EXAFS data have been analyzed using the computer software Athena. These have been used to determine the bond lengths in these ferrites with the help of three different methods, namely, Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The phase uncorrected bond lengths have also been obtained from Fourier transformation method and the results obtained have been compared with the results obtained from LSS method, which also gives phase uncorrected bond lengths. XRD shows the structure is the tetragonal, and FTIR was used to determine the nature of the vibrational modes present in the system.

Synthesis, electrical and dielectric characterization of cerium doped nano copper ferrites

The nanosized CuFe2−xCexO4 (x=0.0, 0.2, 0.4, 0.6, 0.8) ferrites doped with cerium are synthesized by chemical co-precipitation method. The synthesized materials are characterized by XRD, FTIR, TGA and SEM. XRD analysis of cerium substituted copper ferrites confirms the cubic spinel structure. The average crystallite size calculated by using Scherrer's formula ranges from 37 to 53nm. The values of cell constant and cell volume vary with the dopant concentration. These variations can be explained in terms of their ionic radii. The DC electrical resistivity, measured by two point probe method, increases with increase in dopant concentration while it decreases with rise in temperature exhibiting semiconductor behaviour. Energy of activation of these ferrites is calculated by using Arrhenius type resistivity plots. Dielectric measurements of the synthesized compounds show exponential decrease in dielectric constant and dielectric loss factor with increase in frequency. This indicates the normal dielectric behaviour of ferrites.

Structural, electrical and magnetic properties of cadmium substituted copper ferrite by sol–gel method

Cu1−xCdxFe2O4 (x=0.0, 0.25, 0.50, 0.75, 1.0) ferrite nanoparticles were synthesized by sol–gel auto-combustion method. The thermal decomposition process was investigated by Differential Thermal Analysis (DTA) and Thermo Gravimetric Analysis (TGA) technique. The phase composition of the copper cadmium ferrite samples were characterized by powder X-ray diffraction analyses (XRD). All the samples reveal formation of cubic spinel symmetry. The surface morphology of Cu1−xCdxFe2O4 ferrite powder was investigated by scanning electron microscope (SEM), while elemental compositions of sample were studied by energy dispersive X-ray analysis (EDAX). The DC conductivity studies of the samples reveal their semiconducting nature. Vibrating sample magnetometer (VSM) studies showed that, all the samples are ferrimagnetic in nature at room temperature.

Thermoelectric Power Studies Cu-Cd Ferrites

Thermoelectric Power Studies of Cadmium Substituted Copper Ferrites of various compositions were investigated from room temperature to well beyond the curie temperature by differential method. The Seebeck coefficient is negative for all compositions showing that these ferrites behave as n-type semi conductors. Plots of Seebeck coefficient verses tem- perature shows maximum at Curie temperature. On the basis of these results an explanation for the conduction mechanism in Cu-Cd mixed ferrites is suggested.

PHYSICO-CHEMICAL, STRUCTURAL AND ELECTRICAL STUDIES OF Cu–Zn FERRITES SYNTHESIZED BY NOVEL CHEMICAL ROUTE

The physico-chemical, structural and electrical properties of zinc substituted copper ferrites having the general formula Cu 1-x Zn x Fe 2 O 4(x=0.0 to x=0.8) have been studied as a function of zinc ion concentration. The sample was prepared by co-precipitation method from corresponding metal sulphates. X-ray diffraction patterns were used to confirm the structure of synthesized samples. The calculated and theoretical values of average lattice constant, tetrahedral bond, tetrahedral edge and unshared octahedral edge were found to increase, while the shared octahedral edge and octahedral bond decrease as the Zn ion concentration increases. The dielectric constant (ε′) and dielectric loss tangent ( tan δ) were measured at a constant frequency 1 kHz as a function of temperature. The dielectric constant and loss tangent were found to increase with rise in temperature. The conduction mechanism in these ferrites is discussed on the basis of electron exchange between Fe 2+ and Fe 3+ ions. The temperature dependent dc resistivity was carried out in the temperature range 300 to 800 K. The plots of log ρ versus 103/ T are linear showing two regions, corresponding to ferrimagnetic and paramagnetic regions.

Negative magnetization, magnetic anisotropy and magnetic ordering studies on Al 3+-substituted copper ferrite

Detailed magnetic properties of Al 3+-modified CuFe 2O 4 spinel ferrite system: CuAl x Fe 2− x O 4; x = 0.0, 0.2, 0.4 and 0.6, have been studied by means of X-ray powder diffraction, field cooled (FC) and zero field cooled magnetization (ZFC) ( H = 10 mTesla, T = 4–325 K), magnetic hysteresis ( H ma x = 2 Tesla, T = 10 and 300 K) and low field (40 A/m) ac susceptibility ( T = 300–750 K) measurements. The system exhibits canted spin structure. It has been shown that the observed features of the FC–ZFC magnetization and ac susceptibility curves arise due to the low magneto crystalline anisotropy, not due to the cluster spin-glass-like magnetic ordering. The interesting features like low temperature cusp in the ZFC magnetization for all the compositions and negative magnetization for x = 0.6 composition have been observed. An attempt has been made to explain the negative magnetization within the framework of available models.

Thermoelectric power studies of Cu–Co ferrites

Thermoelectric power studies of cobalt substituted copper ferrites of various compositions were investigated from room temperature to well beyond the Curie temperature by the differential method. The Seebeck coefficient is negative for all the compositions showing that these ferrites behave as n-type semiconductors. Plot of Seebeck coefficient versus temperature show a maximum at Curie temperature. On the bases of these results an explanation for the conduction mechanism in Cu–Co mixed ferrites is suggested.

Electrical Conductivity of Chromium Substituted Copper Ferrites.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Temperature and composition dependence of thermoelectric power studies of copper-substituted lithium ferrites

Thermoelectric power studies of lithium substituted copper ferrites, having the chemical formula (Li 0.5Fe 0.5) 1− x Cu x Fe 2O 4, where x=0.2, 0.4, 0.5, 0.6 and 0.8, have been investigated as a function of temperature and composition by the differential method. On the basis of the sign of the Seebeck coefficient ( S), the ferrites under investigation have been classified as n-type semiconductors. Plots of S versus T are shown with a transition near Curie temperature. Based of these results, an explanation for the conduction mechanism in Li–Cu ferrites is suggested.