Research Article

Optimizing Structural and Mechanical Properties of Cobalt Ferrite with Magnesium Doping via Solid State Route

Ankita Patil¹, Pooja Sudi¹, Awinash Awati¹, Sushant Kakati², S N Mathad²*, A S Pujar³, Shishir Patil⁴, S V Angadi¹, C S Hiremath⁵, L D Horakeri¹, R B Pujar¹, Shweta G M⁶ and Sindhu S⁷

¹Department of Physics, P C Jabin Science College, India

²Department of Engineering Physics, K L E Institute of Technology, India

³Department of Physics, R L S Institute, India

⁴Department of Electrical and Electronics, KLE Technological University, India

⁵Department of Physics, S K Arts and H S Kotambari Science Institute, India

⁶K R Pete Krishna Government Engineering College, India

⁷Department of Applied Sciences and Humanities, Guru Nanak Dev Engineering College, India

Submitted: May 29, 2024; Published: June 26, 2024

*Corresponding author: S N Mathad, Department of Engineering Physics, K L E Institute of Technology, India

How to cite this article: Ankita Patil, Pooja Sudi, Awinash Awati, Sushant Kakati, S N Mathad, et al. Optimizing Structural and Mechanical Properties of Cobalt Ferrite with Magnesium Doping via Solid State Route. JOJ Material Sci. 2024; 8(5): 555749. DOI:10.19080/JOJMS.2024.08.555749

Abstract

Co_1-xMg_xFe₂O₄ (x=0.1, 0.2, 0.3 and 0.4) has been synthesized utilizing the solid-state method at 800°C for 10 hours. X-ray diffraction (XRD), FTIR, SEM, and EDAX are the characterization techniques that were utilized to study the produced powders. Single phase spinal yield is confirmed by the XRD patterns of the produced samples. Some aggregated spherical and polyhedral form morphology may be seen in the SEM picture results. Aside from that, it was discovered that the typical crystallite size varied between (55-68nm). Mg²⁺ ion substitution determines the structural and magnetic characteristics of Mg-Co ferrite nanoparticles.

Keywords: Ferrites; Ferrofluids; Catalysis; Energy

Introduction

Magnetic materials which have combined electrical and magnetic attributes are known as ferrites being a class of “Oxides” with remarkable magnetic properties have been under investigation for five decades [1]. Due to unique magnetic, electric, and dielectric properties extensively used in a wide range of applications from low to high permeability devices, including electronics, ferrofluids, high density information storage devices, and magnetic drug delivery microwave devices [2-4]. The general molecular formula of materials having spinel structure is AB₂O₄ in which A²⁺ and B³⁺ are the divalent and trivalent ions respectively [5]. CoFe₂O₄ shows a predominantly inverse structure with cobalt (Co²⁺) ions main lyon octahedral sites and iron (Fe³⁺) ions in a close manner equally located between octahedral and tetrahedral sites [6]. Spinel ferrites, being one of the most versatile systems, have found applications in a wide variety of fields that include data storage, catalysis, energy, environment, and in particular, biomedicine. Indeed, the use of magnetic nanoparticles for biomedical purposes has been proposed to a large extent in recent years [7]. Muthurani et al. reported the humidity sensing properties of Cu–Co– and mixed Cu–Co ferrites where CuFe₂O₄ showed better results than others at room temperature [8]. Among the ferrite family, CoFe₂O₄ nanoparticles (NPs) have received significant attention due to their inherent magnetic, electrical, and mechanical properties along with high chemical stability [9]. Cobalt ferrite NPs are a suitable candidate for various technological applications, such as biosensors, gas sensors [10], stress sensors [11], Magnetic recording media [12], magneto-optical devices, magnetic resonance imaging, catalysis [13], biomedical applications [14].

Recently, several scientists have reported on substitution of Co2+ ion with nonmagnetic ions (Zn²⁺, Mg²⁺, Al³⁺ and Y³⁺) [15-17]. For the Mg_xCo_{1- x}Fe₂O₄ ferrites, these reported results indicated that Mg²⁺ with burning preference of B sites can strongly change the dielectric or magnetic behaviours of CoFe₂O₄ for developing technologically modern applications in materials. Sharma et al. analyzed the dielectric properties of Co_xMg_1-xFe₂O₄ sample with single phase structure. Dielectric constant was found to be decreasing rapidly with the increasing frequency. The maximum of dielectric loss was acquired when the hopping frequency was consistent with external field [16,17]. Apart from the influence of substitution, various approaches also occupy a significant status in altering the properties of ferrites such as sol-gel method [18], polyacrylamide gel electrophoresis [19], hydrothermal method [20], co-precipitation method [21] etc. In particular, sol-gel method is an efficient technique which can be used to control microstructure, grain size and distribution of defects of samples [22-26].

The main objective of our work is to synthesize the Co_{1- x}Mg_xFe₂O₄ (x=0.1, 0.2, 0.3 and 0.4) by solid state method. Systematic structural study has been performed from XRD, SEM and FITR characterizations. Our primary goal is to use the solidstate approach to synthesis Co_1-xMg_xFe₂O₄ (x = 0.1, 0.2, 0.3, and 0.4). This is precisely combining magnesium oxide (MgO), iron oxide (Fe₂O₄), and cobalt oxide (CoO) in the right proportions. After that, the mixture is heated at high temperatures (800°C) in order to cause solid-state reactions and form the required ferrite phase. To improve density and crystallinity, the material is sintered at even higher temperatures after being cooled and ground into pellets.

Materials and Methods

Experimental Technique

Cobalt oxide, magnesium oxide, and ferric oxide were mixed mechanically in an agate motor in acetone medium to create the ferrites with the general chemical formula Co_1-xMg_xFe₂O₄ where x=0.1, 0.2, 0.3 and 0.4 Following that, ferrite samples were presintered for 10 hours at 800oC. To understand the structural properties, we perform systematic studies using X-ray diffraction (XRD) for crystal structure analysis, scanning electron microscopy (SEM) for examining surface morphology, and Fourier transform infrared spectroscopy (FTIR) for identifying functional groups and bonding characteristics. These characterizations confirm the formation and quality of the synthesized Co_1-xMg_xFe₂O₄ ferrites (Figure 1).

Results and Discussion

XRD Analysis

The XRD patterns of Co-Mg ferrite Co_1-xMg_xFe₂O₄ (x=0.1, 0.2, 0.3 and 0.4) calcined powders at 800 ̊C are shown in Figure 2. The XRD pattern shows that all the reflection peaks corresponding to (220), (311), (400), (511) and (440) planes indexed, confirms cubic phase and peak position in XRD patterns are perfectly matched the standard pattern (JCPDS-CARD 00-001-1121, 98- 011-2788 with 98-011-0946). The diffraction maxima from Bragg’s law is prevailed by

The lattice constant lies in the fr2ange 8.3928 Å to 8.4150 Å. The resultant variation in lattice parameter does not appear to be a simple linear function. Radius of Mg²⁺ ions (0.72 Å) has a smaller ionic radius compared to that of Co²⁺ ions (0.745Å). The possible interpretation for the observed occurrence might possibly be due to the change in Mg²⁺ substitute rate in the tetrahedral and octahedral sites with increase in Mg2+ concentration. The lattice parameter was expected to decrease as the substituted magnesium content increases assuming that it follows Vegard’s law [27]. The changes in lattice constant is attributed to the difference in the ionic radii of Co²⁺ and Mg²⁺. The slight variation in lattice constant may be due to slight difference in the ionic radii of Co²⁺ (0.74 Ǻ) and Mg²⁺ (0.72 Ǻ) ions.

The crystallite size (D), Micro-Strain and Dislocation density of all the samples were calculated using as given below

The detailed information of sample like lattice parameter (a), crystallite size (D), Dislocation density and micro- strain are tabulated in Table 1.

The distance between magnetic ions (hopping length) in A site (Tetrahedral) and B site (Octahedral) were calculated by using the complying relations {(L_A and L_B)}[21].

where a is lattice constant.

SEM analysis

SEM images of the sintered magnesium substituted cobalt spinel ferrites shown in Figure 3 seen that the morphology of the particles were almost spherical in shape, but agglomerated to remarkable extent due to the interaction with shares to each particles. It is also observed that grains of uniform size are distributed throughout the surface which exhibits decreasing trend together with magnesium substitution in the range 1.15μm to 0.827μm. The virtually spherical particles are heavily agglomerated, as can be seen in the SEM pictures of the sintered magnesium-substituted cobalt spinel ferrites (Figure 3). The particles’ interactions with one another are probably what caused this agglomeration. In spite of this, the grains on the surface retain a consistent size distribution. The grain size notably reduces from 1.15μm to 0.827μm as the magnesium content rises. The reason for this reduction in grain size is that magnesium has a smaller ionic radius than cobalt, which causes a denser packing in the crystal lattice.

The decrements of grain size significantly with increasing magnesium concentration owing to ionic radius of magnesium are smaller than that of cobalt. After final sintering elemental analysis of ferrites carried from X-ray (EDX) spectrum in Figure 4 allowed for a quantitative analysis, with the corresponding results displayed in Table S1 the contents of O, Mg, Co, and Fe were wt %, respectively, authorizes the Mg-Co ferrites have been successfully gone into the ceramics with good distributions. Moreover, the absence of additional elemental peaks in the EDX spectra suggests the absence of contaminants. The atomic percentages of the constituent elements align with the anticipated composition, so confirming the effective development of the ferrite phase. The lack of additional peaks in the EDX spectra and XRD patterns verifies the synthesized ferrites’ purity, guaranteeing that they are devoid of contaminants and have the proper stoichiometry. In-depth examination of the material’s structure and composition confirms that magnesium has been successfully incorporated into the ferrite structure.

Inter-atomic distances (Bond lengths) and hopping length

The distance between magnetic ions called hopping length at tetrahedral (A) site and octahedral [B] site for all the samples was evaluated using the values of lattice constant by the following equations. The hopping lengths decrease as additions of magnesium content (x).

The distance between magnetic ions (hopping length) in A site (Tetrahedral) and B site (Octahedral) were calculated by using the following relations [21].

where a is lattice constant.

Using the experimental values of lattice constant ‘a’ and oxygen positional parameter ‘u’ other structural parameters like inter-atomic distances like tetrahedral bond length (dAx), Octahedral bond length (dBx), Shared tetragonal edge (dAEx), Shared octahedral edge(dBxE) and Unshared octahedral edge(dBxEu) has been calculated [28].

The variation of edge lengths & bond lengths as magnesium content found increasing systematically shown in Figure 5. This is attributed to the changes in lattice constant with the substitution of magnesium content (x).

In conclusion, there is a consistent fluctuation in bond lengths and interatomic distances when cobalt ferrites are substituted for magnesium. The primary causes of this are the variations in the lattice constant and the structural modifications that are naturally present in the crystal lattice. To precisely customize the physical properties of cobalt ferrites for particular applications, a detailed understanding of how magnesium impacts the overall structure of the minerals is provided by the accurate calculation of these lengths and distances.

FTIR studies

The infrared spectra of cobalt ferrite samples, including those with magnesium substitution, show two main absorption bands in the 400 cm⁻¹ to 1000 cm⁻¹ region, according to FTIR investigations. These bands are roughly 436.93 cm⁻¹ and 617.24 cm⁻¹ for pure cobalt ferrite, respectively, and show the formation of the spinel ferrite structure. These absorption bands indicate, respectively, the octahedral (ν1) and tetrahedral (ν2) positions of the inherent lattice vibrations of oxygen-metal ions. The reason for the variation in frequency between these bands is the longer bond lengths in the tetrahedral locations. Every ferrite sample used in this study has absorption bands that fall within the predicted range. Tetrahedral complexes are associated with the band around 600 cm⁻¹, whereas octahedral complexes are linked to the band about 400 cm⁻¹. The metal-oxygen stretching modes are revealed by FTIR spectra, which show shifts towards lower frequencies with increasing zinc content. This suggests that zinc has replaced cobalt inside the spinel structure. The difference in frequency between the characteristic vibrations ν1 and ν2 may be attributed to the long bond length of oxygen - metal ions in the tetrahedral sites.

The FTIR absorption spectra are shown in Figure 6. The bands near 600 cm-1 are attributed to tetrahedral complexes and near 400 cm-1 are attributed to octahedral complexes [28]. According to Wadron [1], the unit cell in cubic spinel structure is formed by tetrahedral and octahedral sites. Hence ν1 band is assigned to stretching vibrations of tetrahedral metal- oxygen bonds and the band ν2 is assigned to stretching vibrations of octahedral metaloxygen bonds. FT-IR can be also useful to give some information on the inorganic phase, the Me–O (Me =Co, Fe, Zn) stretching modes of spinel ferrites falling in the fingerprint range. The metal– oxygen stretching mode of the octahedral and tetrahedral sites moves towards lower values with increasing zinc content, from 582cm−1 for CoFe2O4 to 569cm−1 for Zn0.53Co0.47Fe2.0O4. Taking into account the values reported in the literature for cobalt (575 cm−1) and zinc (555 cm−1) ferrites, 63 this trend can be interpreted in the light of a gradual substitution of cobalt ions by zinc ones within the spinel structure. Therefore, in general, the vibration and bond stretching at the frequency bands of 400 cm−1 constitutes the metal-oxygen (Fe-Co-O) groups whereas at the frequency bands of 600 cm−1 belongs to still the Fe-Co-(Mg)-O groups. There might occurs a band peak variation in frequency and intensity among the samples studied due to differing bond strength and bond length [29].

Conclusion

The main objective of the research was to create Co1-xMgxFe2O4 ferrites by a solid-state technique employing metal oxides of analytical reagent (AR) grade. All of the synthetic samples formed a cubic spinel structure, as validated by structural investigation using X-ray diffraction (XRD). The samples predicted particle sizes, according to Debye Scherrer’s formula, fell between 55.14 to 68.43nm. The fact that the lattice constant dropped as the quantity of Mg2+ ions replaced Co2+ ions was one important discovery. The reason for this drop is that the crystal lattice contracts because Mg²⁺ ions have a smaller ionic radius than Co²⁺ ions. The infrared spectra showed characteristic absorption bands at about 600cm⁻¹ and 400cm⁻¹, which were found by spectroscopic analysis using Fourier Transform Infrared Spectroscopy (FTIR). These bands, which identify certain vibrational modes inside the crystal lattice and are typical of spinel ferrites, attest to the structural integrity of the material. Grain diameters ranged from 1.15μm to 0.827μm on average, according to morphological characterization performed using Scanning Electron Microscopy (SEM). This microscopic analysis shed light on the size distribution and shape of the particles, revealing information about the physical morphology of the material. All in all, the results of the study add to a thorough comprehension of the synthesis and characterization of Co-Mg ferrites. For applications in electronics, telecommunications, magnetic devices, and other fields, they offer useful information for streamlining synthesis procedures and customizing material properties.

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