Facile route for synthesis of Er doped Cobalt Nanoferrites and Investigation on Structural, Magnetic and Humidity sensor properties

doi:10.21203/rs.3.rs-2189731/v1

Download PDF

Research Article

Facile route for synthesis of Er doped Cobalt Nanoferrites and Investigation on Structural, Magnetic and Humidity sensor properties

https://doi.org/10.21203/rs.3.rs-2189731/v1

This work is licensed under a CC BY 4.0 License

Journal Publication

published 22 Mar, 2023

Read the published version in Journal of Inorganic and Organometallic Polymers and Materials →

You are reading this latest preprint version

In this work, Er³⁺ doped Cobalt Nanoferrite particles CoEr_xFe_2−xO₄ (x = 0.0, 0.01, 0.03, 0.05) were synthesized using optimized citrate-gel auto-combustion method and analyzed for Humidity sensor applications. Preliminary X-ray diffraction and Raman spectroscopic studies and confirm the formation of single-phase spinel structure. Average crystallite sizes from Williamson-Hall method are in the range 28 nm to 32 nm, which are in close agreement with TEM data. Temperature dependent magnetization ZFC-FC curves shows above room temperature blocking temperature. Hysteresis loops obtained by vibrating sample magnetometry clearly enhances the magnetization of cobalt ferrite. Electrical resistance measurements in different relative humidity conditions (RH 10–95%) and frequencies were done using a High Frequency LCR Meter. Er doped Cobalt ferrite samples shows a decrease in electrical resistance and improved sensitivity compared to the pure ones. The variation of Resistance with respect to humidity conditions suggested that Er doped Cobalt ferrite nanoparticles are potentially suitable for resistive humidity sensor applications.

Cobalt ferrite

Er doping

ZFC-FC

Spinel ferrite

Humidity sensors

Over the last two decades, magnetic nanomaterials fascinated researchers due to their flexible and unique properties at ultra-low dimension scale. These magnetic nanomaterials are used in various types of technological applications such as data storage, sensors, biomedicine, automotive industry, refrigeration systems and AC–DC converters in high-frequency equipment’s due to their high magnetization, resistivity and permeability [1–2]. Among these magnetic materials, Cobalt ferrite nanoparticles are practically reliable spinel ferrites and serves in electronics, energy scavenging, biomedical applications owing to their compositional and mechanical stability, large magneto crystalline anisotropy, Curie temperature and high electrical resistivity [3–9]. In particular, these peculiar properties can be significantly tailored through method of preparation, heat treatment and control over the size and shape of the particles.

The general formula to describe the structure of spinel ferrites is AB₂O₄, where A and B are tetrahedral (A-site) and octahedral (B-site) sublattices. The normal spinel unit cell composed of closely packed face-centered-cubic arrangement of 32 Oxygen ions with the combination of 16 trivalent and 8 divalent metal ions [10]. The ratio of cations occupancy in A and B sites plays vital role in deciding magnetic, electric and optical properties. In case of Cobalt ferrite, most of the trivalent iron ions (Fe³⁺) ions prefer to occupy A site and divalent cobalt and trivalent iron [Co²⁺Fe³⁺] ions occupy B site. Therefore, one of the major advantages in these ferrites is the wider probability to achieve desirable feature by simply modifying/altering the cation distribution among A and B sites. Sumanthi reported significant improvement in magnetic and dielectric properties of Cu and Bi co-doped Cobalt ferrite [11]. Further, the presence of Cu in Cobalt ferrite causes a reduction of 4-nitrophenol to 4-aminophenol is achieved in seconds. In case of Ni substitution Coercivity and saturation magnetization were reduced due to lowering of magneto crystallite anisotropy along with particle size [12–13]. Maintaining the stoichiometry and charge balance is another important factor to obtain optimum and reproducible Cobalt ferrite. Physico-Chemical properties of Zn substituted Cobalt-Nickel ferrite synthesized through chemical co-precipitation route by Rani [14] concluded that substitution of foreign cations in spinel ferrite substantially improves the physical properties without affecting the morphology of cobalt ferrite. In another report, substitution of Zn at the expense of Fe in Cobalt ferrite reduces the controls the average particle size (12-15nm), homogenous grain size and improves the magnetization for lower concentrations. These modifications are particularly ascribed to the method of preparation and cation modification due to Zn [15]. Apart from divalent and trivalent metal ions, small replacements of Fe ions by rare earths have been discovered to favorably influence the magnetic and electrical properties of cobalt ferrite. This is due to the fact that rare earth ions have large ionic radii, different stable oxidation state and the interaction between 3d (Fe) and 4f (rare earth ions) shells would dramatically improves electrical and magnetic properties. Substitution of Y³⁺, Yb³⁺ predominantly improves the magnetization of Ni- Cu-Co ferrite than that of Sm³⁺, La³⁺ was reported by Suo [16] Further, both Y³⁺, Yb³⁺ prefer to occupy octahedral B site causes migration of Fe³⁺ ions from B site to A site is the pertinent reason for the increase in magnetic nature, whereas due to the larger ionic radii Sm³⁺, La³⁺ may not enter in to B site and occupy A site. Selecting a suitable rare earth and optimizing its solubility is another important factor to achieve optimum results. Wang reported the solubility of Nd³⁺ ions in cobalt ferrite lattice is limited to 15mol%, beyond this Nd causes forms secondary phase [17]. Therefore, apart from introducing foreign elements in the spinel unit cells, substituting a lower portion of dopants with controlled method of preparation obviously improves the features of also plays a vital role in controlling structural, electrical and magnetic properties reported earlier by other investigators [18]. Among the reported synthesizing methods, sol-gel auto-combustion route attracts the researchers because of lucid and one step preparation, resulted in stoichiometric single-phase final compound, which do not require calcination. Moreover, the possibility in controlling the particle size, and low processing costs are the merits of this method.

Recently, Cobalt ferrites are employed to precisely measure the humidity as resistive type in real time applications like automated systems, food production, agriculture and industrial, and medical fields [19–24]. In order to make a better humidity sensor low hysteresis with high mechanical stability are required to improve sensing and recovery time. However, with in the knowledge of the authors the Er doped Cobalt ferrite for humidity sensor application scarce in the literature. In this work, we have reported a systematic study on structural, morphological, magnetic properties of Er³⁺ substitution in Cobalt ferrite synthesized through sol-gel auto-combustion route. Further, these samples were preliminarily analyzed for their electrical resistances in the humidity range of 10 RH% – 95 RH%.

The stoichiometric amounts of Cobalt Nitrate hexahydrate Co(NO₃)₂.6H₂O (Merck) Iron Nitrate Nonahydrate Fe(NO₃)₂.9H₂O (Merck), Erbium nitrate hexahydrate Er(NO₃)₃·6H₂O (SRL) are used without any further purification to synthesize CoEr_xFe_2−xO₄ (0.0 ≤ x ≤ 0.03) nano-ferrite particles. The individual metal nitrates were weighed and stirred continuously for one hour by mixed required amount of metal nitrates in minimum amount of deionized water and ethanol to obtain a clear solution. Further, Citric acid (C₆H₈O₇, Merck) was added to the above metal nitrate mixture in the ratio 1:1 to act as a chelating agent (molar ratio of metal nitrate mixture to citric acid) at 60^oC temperature and few drops of NH₄OH solution was added to maintain the pH at 7. Further, the solution was gradually converted in to a brown thick viscous gel and with time the gel was self-ignited and a grey-colored ash was obtained. The final residue was grounded to obtain fine powder and heated at 600^oC for 3hr in a high temperature furnace at ambient air conditions followed by natural cooling to room temperature. Structural and phase evaluation measurements were carried out using X’Pert Pro X-ray diffractometer (operating at a temperature of 25°C, at a voltage of 40 kV, and a current of 30 mA) with Cu-kα (λ = 1.54060 Å) radiation on 650^oC heat treated Nanopowders.

The room temperature Raman spectroscopy measurements were carried by Horiba Scientific LabRam HR Raman spectrometer with excitation wavelength of 532 nm. Low temperature magnetic properties were investigated through a physical property measurement system (PPMS) with an applied magnetic field ± 2T. The transmission electron microscopy (TEM) (Talos F200X, Thermo Fisher Scientific) images of the samples were taken to measure the size of the particles. Room temperature electrical resistivity measurements in different humidity conditions (RH 10% - RH 95%).

3.1 Structural and magnetic properties

X-ray diffraction (XRD) patterns of CoFe_2–xEr_xO₄ nanoparticles (x = 0.0, 0.01, 0.03, 0.05) heat treated at 600^oC for 3h are shown in Fig. 1. The prominent diffraction peaks corresponding to the miller indices (220), (311), (222), (400), (422), (511) and (440) observed in the spectra for all the samples are identical to cubic spinel phase (JCPDS card No 20-1086) with space group Fd3̅m. A clear investigation of XRD spectra ruled out the formation of secondary phase, whereas several other researchers reported an insignificant amount of secondary phase in rare earth doped ferrites due to higher mol percentage of dopant concentration [25–27]. Therefore, the adopted method of preparation in the present work promisingly produced Er³⁺ doped Cobalt spinel ferrite and the lower heating temperature 600^oC is also sufficient to obtain pure single-phase ferrite. The lattice parameter of the samples was determined using the following relation.

a_exp = d_hkl$\sqrt{{h}^{2}+{k}^{2}+{l}^{2}}$ (1)

where d_hkl is the interplanar spacing of the crystal system. The lattice constant is found to 7increase from 8.3547 to 8.3723 Å with increasing Er³⁺ content shown in Table 1. This variation in lattice constant is a direct consequence of the difference in the ionic radii of Er³⁺ and Fe³⁺ ions 0.89Å and 0.645Å, respectively. In general, most of the rare-earth elements couldn’t enter in to the host lattice due to (i) their larger size (ii) preferential occupancy of sublattice and (iii) exceed solubility limit in the host lattice. In the present work, reasonable ionic radii, linear increase in lattice constant with no secondary phase formation confirms that Er³⁺ ions occupy the host lattice. It was an expected result, where octahedral and tetrahedral sublattice expands in such a way that they do not disturb the final structure of the spinel unit cell. This kind of variation or modification in the unit cell increases the distance between cations, bond lengths and bond angles, where they can significantly impact magnetic and electrical properties. Williamson-Hall method was used to estimate the average crystallite of Er doped Cobalt ferrite nanoparticles by considering FWHM of all the prominent peaks to separate the size and strain broadenings influence on crystallite size and listed in Table 1. It is clear that, average crystallite size increases with increasing Er³⁺ doping similar to other reports [28]. Figure 3 shows TEM image of pure and doped cobalt ferrite revels that particles distributed homogenously. The particle was estimated using Image J software and listed in Table 1, which are in good agreement with XRD results. Further, structural parameters like X-ray Density (ρ_x), Lattice Strain (ε) of the samples were calculated and listed in Table 1 using standard equations to understand the influence of Er³⁺ ions. In order to justify the magnetic properties and solubility of Er³⁺ ions in to the host lattice Theoretical cation distribution and lattice parameter were calculated using the following relation and listed Table 1.

Table 1

Composition (x), Experimental (a) and theoretical lattice parameters (a_th), Crystallite size (D_W−H), Density (ρ) and Strain (ε) of Er doped Cobalt ferrite nanoparticles heat treated at 650^oC for 3h.
Composition	Lattice Constant		Crystallite size	Density	Strain
(x)	a (Å)	a_th (Å)	D_W−H (nm)	X-ray	(ε) x10^− 3
0.00	8.3547	8.4089	28	5.24	1.276
0.01	8.3612	8.4124	34	5.26	0.865
0.03	8.3692	8.4189	32	5.3	0.977
0.05	8.3723	8.4255	35	5.33	0.816

$${a}_{th} = \frac{8}{3\sqrt{3}}\left[\left({r}_{A}+{R}_{0}\right)+\sqrt{3}\left({r}_{B}+{R}_{0}\right)\right]$$

Where ${R}_{0}$is the radius of oxygen ion (1.38A^o),${r}_{A}$ and${ r}_{B}$ are the ionic radii to tetrahedral (A-Site) and octahedral (B-Site) respectively. In general, Co²⁺ and partial Fe³⁺ions prefer to occupy B site and remaining Fe³⁺ occupy A site. However, due to substitution of different radii ions a marginal shift or migration occurs among A and B sites. In order to estimate the cation distribution experimental magnetic moments are also considered and the following distribution proposed and listed in Table 2. It is clear that a fraction Co²⁺ ions migrated from B site to A site, to accommodate Er³⁺ ions at B site. The good agreement between theoretical and experimental lattice constant suggests that Er³⁺ ions prefer to occupy octahedral (B) site.

Table 2

Estimated cation distribution of Er doped Cobalt ferrite nanoparticles heat treated at 650^oC for 3h.
Composition
x	A site	B Site
0.00	Fe₁	Co₁Fe₁O₄
0.01	Co_0.05Fe_0.95	Co_0.95Er_0.01Fe_1.04O₄
0.03	Co_0.05Fe_0.95	Co_0.95Er_0.03Fe_1.02O₄
0.05	Co_0.05Fe_0.95	Co_0.95Er_0.05Fe₁O₄

Raman spectra of the pure and doped cobalt ferrite in the spectral range 200-800cm^-1 region are depicted in Fig. 3. Raman spectra is merely useful to understand the modifications/adjustments that occur in the lattice due to the incorporation of foreign ions by studying vibrational and rotational band spectrum of corresponding materials. According to group theory the following phonon modes the following set of phonon modes in the normal spinel structure at ambient temperature [29]

Γ = A_1g(R) + E_g(R) + T_1g + 3T_2g(R) + 2A_2u + 2E_u + 5T_1u(IR) + 2T_2u (3)

where R and IR are Raman and Infrared activity modes and g and u are representing symmetry and asymmetric modes, respectively. In the above Eq. (2), 5T₁u modes are infrared active, A_1g + E_g+T_1g+2T_2g are Raman active modes which are generally observed at in the range 150–750 cm^-1. For an instance, A_1g and E_g are associated with symmetric stretching and bending of anion and T_2g is due to asymmetric stretching of anion at A and B sites. Each mode is a result of changes in the motion/position of ‘O’ ions and both A and B sites [30,31]. In particular, vibrational mode above 600cm^-1 is a direct consequence of ‘O’ and tetrahedral (A-site) cations and below are in response to ‘O’ and octahedral (B-site) cations [32]. Therefore, any change in the position of ions would affect the shape and position of Raman bands. There are four major bands observed in Fig. 2 at ~ 323,~ 475, ~ 637 and ~ 692 cm-1 respectively. These bands are assigned to five Raman active modes of vibrations Eg, T2g, A1g(2) amd A1g(1), respectively which reconfirms the formation of spinel phase. The significant variation in the position and shape suggests the incorporation of Er³⁺ ions in to the host lattice.

In order to evaluate the influence of Er³⁺ on magnetic properties low temperature magnetic measurements were carried out on powder samples. Figure 3 shows FC-ZFC curves at 500Oe for Er doped Cobalt ferrite for the composition x = 0.00 and 0.02. It is clear that the both ZFC and FC curves distinctly separated and they will not meet at 300K. This suggest that blocking temperature is higher than the room temperature and the separation between FC-ZFC suggest the presence of large anisotropy at lower temperature region. Similar behavior in magnetization at lower temperature was reported in the literature [8,33]. Further, Fig. 3c shows room temperature hysteresis loops of Er doped Cobalt ferrite. The saturation magnetization slightly increases with increasing Er³⁺ concentration. As mentioned earlier in theoretical cation distribution, a fraction of Co²⁺ and Fe³⁺ are migrated between A and B sites, which further result in the observed increase in net magnetization as a function of Er doping concentration.

3.2 Humidity response

Metal oxide-based materials are widely explored for humidity sensor applications due to their high mechanical and chemical stability coupled with high sensitivity low cost, and operable at different ambient conditions. Preliminary analysis of Room temperature resistance at different relative humidity ranges 0–100% were measured for Er³⁺ doped Cobalt ferrite disc shaped pellets (thickness 3mm and diameter 10mm) and shown in Fig. 4. These disc shaped pellets were coated with air dried silver paste on both sides for electroding and annealed at 250^oC for 5 min to achieve good ohmic contacts. Finally, these pellets were placed between electrodes and enclosed in a box and measured the resistance at room temperature for different relative humidities. It was observed that Resistance decreases for all the samples in similar way with increasing relative humidity. It is well established fact that method of processing and conditions, heat treatment, density, porosity, crystallite size, grain size, stoichiometry, valence state of the constituent ions present A and B sites are the influential parameters in determining sensing capabilities of the material. In general, hopping of charge carriers between ferrous and ferric ions is the fundamental conduction mechanism in spinel ferrites. A close investigation of Fig. 4 infers that, resistance decreases with increasing humidity concentration in a non-linear trend. Further, Er³⁺ doped samples show higher resistance than the pristine cobalt (x = 0.00), which was due to decreasing the concentration of Fe³⁺ ions at octahedral B site [19]. In the present work all the Er³⁺ doped Cobalt ferrite samples show a good response in resistivity with increasing humidity. Further, Resistance increases with increasing Er concentration and decreases with Relative Humidity. This is due to the increase of conductivity for higher humidity concentration. The sensing response, time as a function of frequency and temperature are in progress and will be reported shortly. Considering their low cost, magnetic response and environmental stability, these materials are potentially suitable for sensor industry.

Pure and Erbium doped cobalt ferrite nanoparticles were synthesized using facile auto-combustion route. XRD and Raman spectroscopy analysis of the CoFe₂O₄ samples revealed the formation of spinel phase and incorporation of Er ions in to host lattice without distorting the structure and phase. Average crystallite size, particle size increases with increasing Er concentration and are in agreement with TEM measurements. Low temperature magnetic measurements (ZFC-FC) evident large anisotropy and above room temperature blocking temperature. The electrical resistance of the pure and doped samples decreases with increasing Relative Humidity suggest that Er doped Cobalt ferrite samples are suitable for resistive type humidity sensors.

Acknowledgement: Author A. Venkateswara Rao, would like to thank the management of KLEF, Department of Science and Technology (DST), Govt. of India, for the award of the DST-FIST level-I (SR/FST/PS-I/2018/35) scheme to Department of Physics.

Conflict of Interest

The authors do not have conflict of Interest.

Suo, N., Sun, A., Yu, L. et al. Effect of different rare earth (RE = Y³⁺, Sm³+, La³⁺, and Yb³⁺) ions doped on the magnetic properties of Ni–Cu–Co ferrite nanomagnetic materials. J Mater Sci: Mater Electron 32, 246 (2021)
Rani, B.J., Mageswari, R., Ravi, G. et al. Physico-chemical properties of pure and zinc incorporated cobalt nickel mixed ferrite (Zn_xCo_0.005−xNi_0.005Fe₂O₄, where x = 0, 0.002, 0.004 M) nanoparticles. J Mater Sci: Mater Electron 28, 16450 (2017).
Alisa Govender, Ezra J. Olivier, Emanuela Carleschi, Eric Prestat, Sarah J. Haigh, Hendrik van Rensburg, Bryan P. Doyle, Werner Barnard, Roy P. Forbes, Johannes H. Neethling, Eric van Steen, Morphological and compositional changes of MFe₂O₄@Co₃O₄ (M = Ni, Zn) core-shell nanoparticles after mild reduction, Materials Characterization, 155, 109806 (2019)
Thomas Dippong, Erika-Andrea Levei, Christian L. Lengauer, Andrada Daniel, Dana Toloman, Oana Cadar, Investigation of thermal, structural, morphological and photocatalytic properties of Cu_xCo_1-xFe₂O₄ (0 ≤ x ≤ 1) nanoparticles embedded in SiO2 matrix, Materials Characterization,163 110268 (2020).
Alisa Govender, Werner Barnard, Ezra J. Olivier, Roy P. Forbes, Eric van Steen, Johannes H. Neethling, Synthesis and characterization of NiFe₂O₄@Co₃O₄ core-shell nanoparticles, Materials Characterization, 121, 93 (2016).
Min Fu, Qingze Jiao, Yun Zhao, In situ fabrication and characterization of cobalt ferrite nanorods/graphene composites, Materials Characterization, 86 303 (2013)
Rohit Ranga, Ashok Kumar, Parveen Kumari, Permender Singh, Vasundhara Madaan, Krishan Kumar,Ferrite application as an electrochemical sensor: A review, Materials Characterization, 178, 111269 (2021)
Thomas Dippong, Iosif Grigore Deac, Oana Cadar, Erika Andrea Levei, Ioan Petean, Impact of Cu²⁺ substitution by Co²⁺ on the structural and magnetic properties of CuFe₂O₄ synthesized by sol-gel route, Materials Characterization, 163, 110248 (2020)
Thomas Dippong, Erika Andrea Levei, Firuta Goga, Oana Cadar, Influence of Mn2+ substitution with Co2+ on structural, morphological and coloristic properties of MnFe2O4/SiO2 nanocomposites, Materials Characterization, 172, 110835 (2021)
Sivaram Prasad, M., Vara Prasad, B.B.V.S., Ramesh, K.V. et al. Structural, Magnetic and DC Electrical Resistivity Studies of Ni–Zn–Cr Ferrites Prepared by the Citrate-Gel Auto-Combustion Method. J Inorg. Organomet. Polym. 31, 1163 (2021).
Sumathi, S., Lakshmipriya, V. Structural, magnetic, electrical and catalytic activity of copper and bismuth co-substituted cobalt ferrite nanoparticles. J Mater Sci: Mater Electron 28, 2795 (2017).
Chavan, S.G., Mane, S.M., Kulkarni, S.B. et al. Micro-wave sintered nickel doped cobalt ferrite nanoparticles prepared by hydrothermal method. J Mater Sci: Mater Electron 27, 7105 (2016)
K. Maaz, S. Karim, A. Mashiatullah, J. Liu, M.D. Hou, Y.M. Sun, J.L. Duan, H.J. Yao, D. Mo, Y.F. Chen, Structural analysis of nickel doped cobalt ferrite nanoparticles prepared by coprecipitation route, Physica B: Condensed Matter 404, 3947 (2009)
Rani, B.J., Mageswari, R., Ravi, G. et al. Physico-chemical properties of pure and zinc incorporated cobalt nickel mixed ferrite (Zn_xCo_0.005−xNi_0.005Fe₂O₄, where x = 0, 0.002, 0.004 M) nanoparticles. J Mater Sci: Mater Electron 28, 16450 (2017).
Gonsalves, L.R., Gawas, S.G., Meena, S.S. et al. Size variation and magnetic dilution effects on the structure and magnetic properties of cobalt zinc ferrite. J Mater Sci: Mater, Electron 33, 20144 (2022).
Suo, N., Sun, A., Yu, L. et al. Effect of different rare earth (RE = Y³⁺, Sm³⁺, La³⁺, and Yb³⁺) ions doped on the magnetic properties of Ni–Cu–Co ferrite nanomagnetic materials. J Mater Sci: Mater Electron 32, 246 (2021).
Wang, Y. Structural, magnetic, and electrical properties of Nd-substituted cobalt ferrite. J Mater Sci: Mater Electron33, 11017 (2022)
A. Sutka, K. Arlis, A. Gross, Sensors Actuators B. 222, 95 (2016). R. Srivastava, B.C. Yadav, M. Singh, T.P. Yadav, J. Inorg. Organomet. Polym. Mater. 26, 1404 (2016).
Farhad Falsafi, Babak Hashemi, Ali Mirzaei, Enza Fazio, Fortunato Neri, Nicola Donato, Salvatore Gianluca Leonardi, Giovanni Neri, Sm-doped cobalt ferrite nanoparticles: A novel sensing material for conductometric hydrogen leak sensor, Ceramics International 43, 1029 (2017)
Pradeep Chavan Chemisorption and Physisorption of Water Vapors on the Surface of Lithium-Substituted Cobalt Ferrite Nanoparticles ACS Omega 6 (3) 1953-1959 (2021)
A. Gadkari, T. Shinde, P. Vasambekar Ferrite gas sensors EEE Sens. J., 11,849 (2011).
S. Singh, A. Singh, R.R. Yadav, P. Tandon, Growth of zinc ferrite aligned nanorods for ‎ liquefied petroleum gas sensing Mater. Lett., 131, 31 (2014).
Rana, Anu; Thakur, O. P.; Kumar, Vinod; Pant, R. P.; Singh, Bhikham Sensor Letters, 12, 1378 (2014),
Jiss Paul, Jacob Philip Design optimization and stability enhancement of modified inter-digital capacitive humidity transducer with cobalt ferrite nanoparticles as dielectric Transactions of the Institute of Measurement and Control, 42, 917 (2019)
Prathapani, S.; Vinitha, M.; Jayaraman, T. V.; Das, D. Effect of Er doping on the structural and magnetic properties of cobalt-ferrite. J. Appl. Phys. 115, 17A502 (2014)
Zubair, A.; Ahmad, Z.; Mahmood, A.; Cheong, W.-C.; Ali, I.; Khan, M. A.; Chughtai, A. H.; Ashiq, M. N. Structural, morphological and magnetic properties of Eu-doped CoFe2O4 nano-ferrites. Results Phys. 7, 3203 (2017)
Bharathi, K. K.; Markandeyulu, G.; Ramana, C. V. Structural, Magnetic, Electrical, and Magnetoelectric Properties of Sm- and Ho-Substituted Nickel Ferrites. J. Phys. Chem. C, 115, 554 (2011)
Z.W. Wang, D. Schiferi, Y.S. Zhao, H.St.C. o’Neilr, High pressure Raman spectroscopy of spinel-type ferrite ZnFe₂O₄ J. Phys. Chem. Solids 64, 2517 (2003).
Minhajul Islam, M. Khalilur Rahman Khan, Alok Kumar, M. Mozibur Rahman, Md. Abdullah-Al-Mamun, Rimi Rashid, Md. Mahbubul Haque, and Md. Samiul Islam Sarker, Sol-Gel Route for the Synthesis of CoFe_2-xEr_xO₄ Nanocrystalline Ferrites and the Investigation of Structural and Magnetic Properties for Magnetic Device Applications” ACS Omega 7, 20731 (2022).
R. Gupta, A.K. Sood, P. Metcalf, J.M. Honig, Raman study of stoichiometric and Zn-doped Fe₃O₄ Phys. Rev. B 65, 104430 (2002).
L.V. Gasparov, D.B. Tanner, D.B. Romero, H. Berger, G. Margaritondo, Phys. Rev.B 62, 7939 (2000).
Ansari, M.M.N., Khan, S. & Ahmad, N. Influence of Dy³⁺ and Cu substitution on the structural, electrical and dielectric properties of CoFe₂O₄ nanoferrites. J Mater Sci: Mater Electron 30, 17630 (2019).
Kumar, L., Kumar, P., Srivastava, S.K. et al. Low Temperature and High Magnetic Field Dependence and Magnetic Properties of Nanocrystalline Cobalt Ferrite. J Supercond Nov Magn 27, 1677 (2014)

No competing interests reported.

Download PDF

Journal Publication

published 22 Mar, 2023

Read the published version in Journal of Inorganic and Organometallic Polymers and Materials →

Editorial decision: Major revision
11 Jan, 2023
Reviews received at journal
16 Dec, 2022
Reviewers agreed at journal
06 Dec, 2022
Reviewers invited by journal
21 Oct, 2022
Editor assigned by journal
21 Oct, 2022
Submission checks completed at journal
21 Oct, 2022
First submitted to journal
21 Oct, 2022

You are reading this latest preprint version

Facile route for synthesis of Er doped Cobalt Nanoferrites and Investigation on Structural, Magnetic and Humidity sensor properties

Status:

Journal Publication

Version 1

Abstract

Figures

1. Introduction

2. Experimental details

3. Results and discussions

3.1 Structural and magnetic properties

3.2 Humidity response

Conclusions

Declarations

References

Additional Declarations

Status:

Journal Publication

Version 1