Impact of Ce-Cu metal ions on Structural, Magneto-Electrical properties of Co 2+ based nano ferrites and their application in Photo Catalytic activity

Cobalt based nanoferrites Co 1 − x Cu x Ce y Fe 2−y O 4 Where nano ferrites produced through citrate gel auto combustion technique and their structural and topographical studies were inspected through x-ray diffraction technique and �eld emission scanning electron microscope. The structural analysis con�rms the prepared nano ferrites having single-phase cubic spinel, along Fd3m space group. Crystalline size of the synthesized samples found 20–26 nm calculated by Debey Scherrer formula. Catalytic activity of the samples con�rmed by dye degradation studies of methylene blue and acid red dye degradation. Magnetic behavior of the materials measured by a vibrating sample magnetometer, saturation magnetization gradually decreases as increasing Cu and Ce content and found to be 26 to 18 emu/gm. Electrical properties were measured by LCR meter.


Introduction
Magnetic nanoferrites (NFs) have key interest to the researchers over the last 20 years due to their adaptable and different characteristics at nano dimension scale (Chung et al., 2009;Liu et al., 2009;Zhang et al., 2009).These type of ferrite materials have good magnetization, permeability, resistivity and low loss, which can be used extensively in the eld of data storage, capacitors, sensors, bio-medical, automobile, converters, and cooling system.This type of materials also exhibits different properties like thermal stability, mechanical stability, and composition stability (Almessiere et al., 2018; Tefera Kebede et al., 2022;Venkat Savunthari & Shanmugam, 2019a, 2019b).Among the various nano ferrite's cobalt based magnetic nano ferrite materials are key interest because used in versatile applications.The formula of spinel ferrites is AB 2 O 4 , where A is tetrahedral (A-site) and B is octahedral (B-site) (Almessiere et al., 2019;Goud et al., 2022a;Hussain et al., 2021;Kebede et al., 2022).The spinel unit cell is made up with16 trivalent and 8 divalent metal ions closely packed with FCC (face centered cubic) structure.The properties like structural, magnetic, electrical, optical, and catalytic activity in uenced by ratio of cation occupancy in A and B site.Nanomaterials differ greatly from bulk materials because of their large surface area and small crystalline size(S.I. Ahmad et al., 2019;Al-Bassami et al., 2023;Lee et al., 2012;Zakir et al., 2021).Nanomaterials differ completely from bulk materials in terms of optical, crystalline size, magnetic, electrical and photocatalytic properties (Ajroudi et al., 2014;Ashiq et al., 2012;Rana et al., 2015;Shyamaldas et al., 2020).Surface effects are connected to how the properties of nanomaterials differ from those of their corresponding bulk materials.Surface area, volume, particle interaction, particle size, and material composition can all have an impact.Spinel nanoferrites are technological application in various eld including catalytic activity, production of electrical, magnetic, microwave devices(R.Ahmad et al., 2016;P. et al., 2016;Zubair et al., 2017).
A number of techniques, including the solid-state technique (Varma et al., 2008), microemulsion technique (Ali et al., 2014a), coprecipitation technique (Javed et al., 2011), ball milling technique (Sinha et al., 2006) been much interest because of inexpensive, low temperature, obtain homogeneous mixture, and simple reaction setup (Kumar et al., 2019a).These days, there is a tremendous increase in environmental contamination, particularly in water pollution, as a result of global industrial pollution (Kumar Ambala et al., 2023b;Venkatesh, Ashok Goud, et al., 2023).Humans and aquatic animals are harmed by the vast amounts of pollutants released into waste water, particularly from paint, leather, textile industries.Microorganisms, organic dyes, detergents, and pesticides are the primary sources of environmental pollution.Pathogens, nitrates, uorides, and heavy metals are examples of e uent agents.In the soft tissues, these biological and chemical species bioaccumulate.The researchers nd it di cult to remove the organic pigments from waste water.Numerous techniques, including occulation, ultra ltration, reverse osmosis, activated charcoal, and photocatalytic dye degradation, have been developed to remove organic dyes (Attia et

Materials used
Nitrates of cobalt, copper, Cerium, ferric and citric acid were used as starting materials all the nitrates are pure AR grade with 99% purity and SD ne chemicals.

Synthesis of samples
The chosen ferrite composition Co The synthesised materials' phase and crystallinity were assessed using the Shimadzu XRD 700 model.
The Zeiss brand model was used for morphological (SEM) studies and elemental (EDS) analysis.A Shimadzu FTIR 8400 spectro meter has been utilized for room temperature FTIR spectral analysis.VSM Lake Shore 8600 model was used to measure the magnetic properties at room temperature.Electrical properties are tested using LCR meters under various frequency and temperature conditions.
3 RESULTS AND DISCUSSIONS ).The various X-ray parameters named Avg.crystalline size, lattice parameter, volume of unit cell and x-ray density were calculated from X-rd.pattern.The average crystalline size of samples was calculated by using following Debye-Scherrer equation.
Where λ, β, and illustrates the wavelength, full width half maxima (FWHM) and angle respectively.The typical crystal size for these samples, which ranges from 22.54 to 28.92 nm.As the concentration of Cu and Ce dopant increases crystalline size was decreased.Pure cobalt ferrites crystalline sized found to be 28.92 nm, then decreased 0.1 concentration later gradually increased with Ce and Cu content.The difference in crystalline size may be due to Ce 3+ metal ions having a larger ionic radius (1.034A o ) than Fe + 3 (0.64A o ) (Balavijayalakshmi et al., 2013a(Balavijayalakshmi et al., , 2013b;;Deraz, 2010).The prepared Cu and Ce co doped cobalt nano ferrites' lattice parameter measure by using the formula below.
Where d illustrate the inter planar distance and h, k, l indicates the Millar indices.Figure 3 shows the differences in average crystal size and also lattice parameter of prepared the Cu-Ni-Co nano Materials.
The nano material lattice parameter was found to be 8.

FE-SEM and EDS analysis of Cu-Ce-Co Nano Ferrites
A high-resolution type of microscope that offers thorough material analyses is the FE-SEM.For the synthesized nano materials their surface grains and grain boundaries analyzed by the FE-SEM images.
An advanced method for guring out the topography, crystallography, and morphology of nanomaterials is FE-SEM.

FTIR Studies of Cu-Ce-Co Nano Ferrites
FTIR spectra extensively used to recognize the functional group of nano material.FTIR spectrum also used to investigate chemical composition and band vibrations of the materials.FTIR spectrum was used to identify the formation of spinel with cubic structure of the materials.FTIR spectrum also used to nd the distribution of cations at tetrahedral and octahedral sites.values found to be 10 −5 to 10 −4 Ω −1 cm −1 whereas high frequency region is 10 −5 to 10 −2 Ω −1 cm −1 .Materials conductivity varies with applied as a result of the charge carriers in the sample.The AC conductivity process depends on polarons.

Di electric Constant of Cu-Ce-Co nano ferrites
In Fig. 10 (a-h) shows the dielectric constant difference of Co 1 − x Cu x Ce y Fe 2−y O 4 Where nano ferrites as frequency applied.The dielectric constant of the ferrite materials decreases as frequency increases.In low frequency range real part of dielectric constant high, later gradually decreases as increasing frequency and nally saturated because of relaxation mechanism of the material varies.This phenomenon was explained by Koop's theory of mechanism.
Koop's theory mechanism states that the existence of high conducting grains and low conducting grain boundaries in fabricated nano materials reveals dielectric constant variation.These examples also show that the relationship between the dielectric constant and σAC is inverse.The movement of charge carriers more effects on dielectric constant of ferrite materials.It is also demonstrating the electron displacement occurs between the Fe 2+ and Fe 3+ ions in octahedral regions(Gupta et al., 2023).nano ferrites displayed in Fig. 12 (a-f).The relation among magnetization (µB) and applied magnetic eld (Oe) is provided by hysteresis loops (Tanveer et al., 2022).Saturation magnetization, coercivity, remanence magnetization, and squareness ratio of the materials were obtained by these hysteresis loops, which are presented in Table 4.While doping Cu and Ce concentration in the Co nano ferrites samples, saturation magnetization varied.Saturation magnetization of the pure cobalt ferrites found to be 43 emu/gm, then gradually decreases, but x = 0.1 sample found highest saturation (52.68 emu/gm).When the Ce 3+ ions are doped to host, which replace the Fe 3+ ions in the octahedral site (A-site), the magnetization of the Co Nano ferrite decreases along with the Ce concentration (Nagasree et al., 2023b;Vijayalaxmi et al., 2023b).Pure cobalt ferrites highest coercivity found to be 2399.89Oe, as substituted copper and cerium content coercivity found to be low.Similar type of results observed in remanence magnetization also.The properties depend on the size of metal ions, morphology, micro strain, and crystalline anisotropy of the material (Junaid et al., 2022).

Di electric Loss of Cu-Ce-Co Nano Ferrites
In addition to interactions in between doped metal ions the material's A and B site, the magnetic saturation variation of the material is also affected by changes in its magnetic nature.A-A, B-B, and A-B contacts are three different types of interactions that have been seen in samples in previous reports.In A-B interaction magnetic ions spin alignment direction is one way in tetrahedral site and in octahedral site ions spin alignment is opposite direction, the total net magnetization stated below.

M = M B -M A
Where MA and MB indicate the magnetization of A and B site receptively.
3.5 Photocatalytic Properties of Cu-Ce-Co Nano Ferrites

Photocatalytic Activity of Methylene Blue
The photodegradation of methylene blue was used to test the photocatalytic activity of Co 1 − x Cu x Ce y Fe 2−y O 4 Where nano ferrites and the results are shown in Fig. 13 (a-d).In order to investigate the photocatalytic activity of the synthesized nanoparticles performed under visible light irradiation on MB was selected as the primary pollutant.A peak in methylene blue absorption was observed by UV-visible spectroscopy at max = 665 nm (Assi et al., 2017).The photodegradation of MB was observed by examining the normalization shift in the absorption spectra as a function of irradiation duration in the presence of nanoparticles (Chahar et al., 2023).As irradiation time increases color intensity of samples decreases.The decrease in absorption spectra may be caused by the MB x = 0.0to0.5with0.1variation x = 0.0, 0.1, 0.3&0.5 chromophores degrading.The degrading activity of the nanomaterial was calculated using the equation below.
. Where C 0 represents the dye concentration initial and C represents the dye concentration after t time.
Table 3 shows the degradation e ciency of methylene blue of Co

Photocatalytic activity of acid red dye
The e ciency of Cu-Ce-Co ferrite nanoparticles' catalytic degradation activity revealed by acid red coloring agent under visible light.The acid red is organic azo dye which is widely used as a coloring agent in textile industries.contaminant in dye waste e uents, was used to evaluate the e cacy of photocatalysts (Venkatesh, Kumar, et al., 2023b).Using acid red usual optical absorption maxima at 530 nm, the photocatalytic degradation process was observed.Figure 14 (a-d) displays the visible absorption spectra of the acid red dye degradation by Cu and Ce doped Co nanoparticles, which were recorded throughout a 90-minute exposure to visible light.It was clear that the acid red dye's absorbance intensity decreased signi cantly with increasing exposure time, which is consistent with the dye's photocatalysis (Goud et al., 2022b;Kumar Ambala et al., 2023a).Table 4. displays the acid red dye degradation e ciency values over time for Co 1 − x Cu x Ce y Fe 2−y O 4 Where nano ferrites.X=0.1 (Co 0.9 Cu 0.1 Ce 0.1 Fe 1.9 O 4 ) was the sample with the highest degradation e ciency.Photo light is an important factor in enhancing dye degradation activity.This method also used to purify the waste water and biological pollutants.

Mechanism of Photocatalytic Degradation
Cu-Ce-Co nano ferrites are exposed to visible light radiation, which results in conduction band electrons and in valency band hole are formed.Superoxide radical anions O 2− can be formed via the interaction of conduction band electrons with oxygen, as illustrated in Fig. 15.Another byproduct of the superoxide radical anion is the hydroxyl radical.Additionally, a proton and a superoxide radical anion combine to form the hydroperoxyl radical ( ).The positive hole can oxidize hydroxyl radicals from hydroxide ions or water molecules that have been adsorbed on the nanoferrite particles surface (Gaikwad et al., 2019).Usually, the resultant radical could react with organic dye to form a variety of intermediates, which when mixed with nitrate ions, mineralize to yield carbon dioxide, water, and inorganic nitrogen.By moving electrons from its excited energy level to the conduction band, curcumin increases reactive oxygen species (O2) and decreases electron hole recombination ( 2022b).The dye is kept from deteriorating too quickly by the presence of viologen, a conduction band electron scavenger, emphasizing the crucial role these electrons play in the process.

Conclusions
Ce-doped Mg nanoferrites have been successfully synthesized by citrate gel auto combustion technique.
The crystalline size was found to be 15 to 25 nm.Changes in crystal size and lattice constant indicate that Vegard's Law is being followed.SEM images show an agglomerated structure, and the samples are in the nano meter range.The presence of Ce, Mg, Fe, and O elements in the EDS spectrum indicates the absence of impurities.FTIR results for all prepared compounds demonstrated two absorption bands near 600 and 400 cm-1, indicating tetrahedral and octahedral structures.Optical band gap energy, found to be 2.56-3.51eV, exhibits semiconductor behaviour.The saturation magnetization, remanent magnetism, and coercivity variation observed with applied eld.Highest coercivity was found to be for MgCe0.1Fe1.9O4,which indicates the possess of the hard magnetic materials.According to dielectric results, as frequency is raised, both dielectric loss and dielectric constant decrease.At lower frequency dielectric constant decreases rapidly, although at high frequencies it was saturated.There are two regions of AC conductivity; in the low frequency region, it is low, but in the high frequency sector, it is high, and it rises with frequency.All synthesised nano-ferrites' assessed results suggested that they should be used for high frequency and microwave absorption applications.The synthesized samples (catalyst) were assessed using on Photocatalytic dye degradation.The prepared samples methylene blue and acid red degradation investigations indicates that the synthesised compounds could be useful in photocatalytic applications.The maximum organic azo dye degradation e ciency found for X = 0.5 mole concentration.A strong foundation for employing and exploring these materials for the ltration of water contaminated with various pollutants is provided by the degradation of methylene blue and acid red using prepared samples.

Declarations Acknowledgement
The authors are very much thankful to Head, Department of chemistry, O.U.Hyderabad for provided necessary facilities to carry out the research work.

Funding
No funding was received for this work Research Data Policy and Data Availability Data will be made available upon reasonable request

Con ict of interest
The authors declare that they have no known competing nancial interests or personal relationships that could have appeared to in uence the work reported in this paper.
, hydrothermal technique(Etemadi & Plieger, 2020), citrate-gel auto combustion route(Ravi Kumar et al., 2022a), sol gel technique (Mund & Ahuja, 2017)has been developed for the synthesis of nanomaterials especially nano ferrites.In these techniques citrate gel auto combustion technique has x = 0.0to0.5with0.1 the number of molecules per unit cell, M illustrate the molecular weight, N illustrates the Avogadro number, and a indicates the lattice parameter.X-ray density and volume of unit cell values of Co 1 − x Cu x Ce y Fe 2−y O 4 Where nano ferrites show in Fig. 4, with increased Cu and Ce content, X-ray density rises.For x= 0.5 content (Co 0.5 Cu 0.5 Ce 0.5 Fe 1.5 O 4 ) highest x-ray density was found 6.984 gm/cm 3 .As doping the Cu and Ce concentration on host well densi ed samples were observed.It is based on the lattice parameter, method of synthesis, sintering temperature, and molecular weight of the samples.All of the structural parameters were noted in Table .1.

Figure 5 ( 3 X
a-f) displays the FE-SEM images of Cu-Ce-Co ferrites.Every sample consists of an aggregated structure with unevenly spaced grains and grain borders.The formed agglomerated structure of the samples indicates the distribution of particles was not uniform(Singhal et al., 2006).Energy dispersive x-ray spectroscopy is an analytical method used to ascertain the chemical composition of samples and their elemental analysis.The EDS spectra graphs of Co 1 − x Cu x Ce y Fe 2−y O 4 are shown in Fig.6(a-l), x = 0.0 to 0.5 with variation of 0.1 in this case.These spectral graphs show that V olumeof unitcellV = a .0to0.5with0.1 all other elements are absent and only the elements Co, Cu, Ce, Fe, and O is present.These visualizations additionally display the atomic and elemental percentages of the samples based on stoichiometric ratios(Balavijayalakshmi et al., 2013b).

Figure 7
shows the FTIR spectrum of Co 1 − x Cu x Ce y Fe 2−y O 4 Where nano ferrites.FTIR spectrum shows the two major absorption bands 1 and 2 at under 1000 cm −1 wavenumber range called tetrahedral and octahedral voids.In this one sharp band appeared at 550-600 cm − 1 indicates the stretching vibrations of metal oxygen band at tetrahedral called 1 site.Other band appeared at 350 to 400 cm − 1 corresponds M-O bond stretching frequency of 400 cm − 1 of octahedral sub lattices called 2 site (Deraz, 2010; Kumar et al., 2020; Trinadh et al., 2023; Vijaya Bharathi et al., 2023).The formation of bands also con rms the prepared samples are cubic spinel structure.3.1.5Raman spectra of Cu-Ce-Co Nano Ferrites Structural and Vibrational studies of nano materials mostly depend on Raman Spectroscopy.The fabricated Co based nano materials having Cubic spinal structure by the consisting of Ab 2 O 4 Fd 3 M space group and contains 8-unit formula in each unit cell.The current unit cell consisting of total 56 atoms which indicates 14 atoms per Bravais cell.The lattice vibrations of AB 2 O 4 can be expressed in terms of 5T u1 + A 1g + E g +3T 2g for Fd 3 m space group which can be predicted from group theory.In these vibration 5Tu1 are IR spectrum active modes and remaining like A1g + Eg + 3T2g attributes the Raman active modes of vibrations, was used to explain the optical phonon distribution.In the ferrite system, 600 cm-1 above mode of vibrations indicates the tetrahedral oxygen atom vibrations, while 600 cm − 1 below modes of vibrations indicates the octahedral oxygen atom vibrations(More et al., 2023; Sarker et al., 2022).Room-temperature Raman spectra of Cu-Ce-Co nano ferrites were examined using Raman spectroscopy and measured from 100 to 1600 cm − 1 .The Raman spectrum of Co 1 − x Cu x Ce y Fe 2−y O 4 Where nano materials depicted in Fig. 8(a-f).All the Raman spectrum were well tted with Gaussian tting.According to these spectral graphs, pure Co nano ferrite exhibits substantial peaks at wavenumbers of 183, 281, 453, 588, and 663 cm −1 , with broad band at 663 cm − 1 [20].The broad band at 663 cm-1 peak attributes the A 1g vibration mode and 281 cm − 1 attributes the E g vibrations.T 2g vibrations modes corresponds to the Raman band at 183, 453, and 588 cm − 1 .

Figure 11 (
Figure 11 (a-h) shows the dielectric loss variation of Co 1 − x Cu x Ce y Fe 2−y O 4 Wherenano spinal ferrites along with applied frequency.The value of dielectric loss for the present samples declines by enhancing frequency.All of the measured samples were shown low dielectric loss.At lower frequency and temperature high loss observed and high frequency it was saturated.The variation in the sample's dielectric loss demonstrates that the mechanism proposed by Koop's theory.The Cu-Ce-Co nano ferrite samples exhibit low dielectric loss at lower frequencies, proving the dielectric nature of the nano ferrites.As a result of ions becoming mobile at higher temperatures and frequencies and shorter Parhizkar et al., 2019; Ravi Kumar et al.,

Figure 13 ( 14 (
Figure 13 al., 2017; Mansour et al., 2021; Venkatesh, Kumar, et al., 2023a).In the present study investigated about the Co 1 − x Cu x Ce y Fe 2−y O 4 Where nano ferrites produced through citrate gel auto combustion technique and their structural, photo catalytic activity, magnetic and dielectric studies.
342 to 8.358 A o .x = 0.3 content Co 0.7 Cu 0.3 Ce 0.3 Fe 1.7 O 4 highest lattice parameter 8.358 A o was found.As doping Cu and Ce content on host lattice parameter variation was observed due to ionic radii variation.Following equation was used to calculate volume of unit cell of samples.
51e Unit cell Volume varied from 580.51to 583.85A o .lowest unit cell found (580.51A o ) for Co 0.8 Cu 0.2 Ce 0.2 Fe 1.8 O 4 sample.The x-ray density of the samples was calculated by given formula.
AC Conductivity of Cu-Ce-Co Nano Ferrites For Nano materials, especially ferrites, AC conductivity is a key study.The ndings of the current experiment demonstrate that AC conductivity changes by applied frequency and also temperature change.Low temperature and low frequency zones have poor conductivity values.Conductivity increases with temperature and frequency, highest conductivity found at higher temperatures and frequencies.Several theories, including the co-related hoping barrier model and quantum mechanical At low frequency region the AC conductivity values are low, later by enhancing frequency the AC conductivity values slowly raised and reaches maximum values at maximum frequency(Habib et al., 2022; Parajuli et al., 2022; Sankaranarayanan et al., 2023).In the low frequency region, conductivity 3.3 Electrical Properties of Cu-Ce-Co Nano Ferrites 1 − x Cu x Ce y Fe 2−y O 4 Where nano ferrites.The dye that degradation the fastest is X=0.1 (Co 0.9 Cu 0.1 Ce 0.1 Fe 1.9 O 4 ) composition.Material degradation activity was in uenced by sample surface area and band gap energy(Chahar et al., 2021).

Table 3
Degradation e ciency of methylene blue of Co 1 − x Cu x Ce y Fe 2−y O 4 Where

Table 4
Degradation e ciency of acid red of Co 1 − x Cu x Ce y Fe 2−y O 4 Where Co 0.7 Cu 0.3 Ce 0.3 Fe 1.7 O 4