key: cord-1035101-hhgewmda authors: Murugesan, C.; Ugendar, K.; Okrasa, L.; Shen, Jun; Chandrasekaran, G. title: Zinc substitution effect on the structural, spectroscopic and electrical properties of nanocrystalline MnFe(2)O(4) spinel ferrite date: 2020-09-01 journal: Ceram Int DOI: 10.1016/j.ceramint.2020.08.284 sha: 90e53b9ee1ec8fb5f25337f5c60fba99b5d27cc4 doc_id: 1035101 cord_uid: hhgewmda This paper reports the structural, morphological, spectroscopic, dielectric, ac conductivity, and impedance properties of nanocrystalline Mn(1-x)Zn(x)Fe(2)O(4). The nanocrystalline Mn–Zn ferrites were synthesized using a solvent-free combustion reaction method. The structural analysis using X-ray diffraction (XRD) pattern reveals the single-phase of all the samples and the Rietveld refined XRD patterns confirmed the cubic-spinel structure. The calculated crystallite size values increase from 8.5 nm to 19.6 nm with the Zn concentration. The surface morphological analysis using field emission scanning electron microscopy and the transmission electron microscopy confirms the nano size of the prepared ferrites. X-ray photoelectron spectroscopy was used to study the ionic state of the atoms present in the samples. Further, the high-resolution Mn 2p, Zn 2p, Fe 2p, and O 1s spectra of Mn(1-x)Zn(x)Fe(2)O(4) does not result in the appearance of new peaks with Zn content, indicating that the Zn substitution does not change the ionic state of Mn, Zn, Fe, and O present in nanocrystalline Mn(1-x)Zn(x)Fe(2)O(4). The investigated electrical properties show that the dielectric constant, tan δ and ac conductivity gradually decrease with increasing Zn substitution and the sample Mn(0.2)Zn(0.8)Fe(2)O(4) has the lowest value of conductivity at 303 K. The ac conductivity measured at different temperatures shows the semiconducting nature of the ferrites. The impedance spectra analysis shows that the contribution of grain boundary is higher compared with the grain to the resistance. The obtained results suggest that the Zn substituted manganese ferrite nanoparticles can act as a promising candidate for high-frequency electronic devices applications. Two types of interstitial sites exist such as tetrahedral site coordinates 4 surrounding O ions and the octahedral site coordinates 6 surrounding O ions [19] . The important properties of ferrites are determined by the distribution of cations within these interstitial sites. Depending on the occupancy of divalent cations and the Fe 3+ ions in interstitial sites, the spinel ferrites are generally categorized as normal, inverse, and mixed. Among these three types, mixed ferrites are considered significant materials because of their wide range of tunability in properties. In recent decades, several investigations have been done to explore and enhance the magnetic and electrical properties of end member ferrites by substituting different divalent and trivalent cations using various synthesis methods [16, [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] . Among the spinel ferrites, the Zn substituted ferrites are attracted special interest due to the strong tetrahedral site preference of Zn 2+ ion. Choodamani et al. [25] prepared the Zn substituted MgFe 2 O 4 . The evaluated crystallite sizes were in the range of 47-80 nm. The dielectric constant, tan δ, and electrical conductivity were the lowest for x=0.50 sample. The saturation magnetization of the ferrites increases up to x=0.5 with the Zn concentration. In our previous work, we investigated the nanocrystalline Cu 1-x Zn x Fe 2 O 4 mixed ferrites. The size of the crystallites was in the range of 9.6-31 nm. The magnetization of the samples increases up to x = 0.2 (44.16 emu/g). The prepared ferrites exhibit superparamagnetic behavior for x ≥ 0.4 concentration of Zn [35] . Andhare et al. [27] prepared the Co 1-x Zn x Fe 2 O 4 mixed ferrite nanoparticles. The crystallite size, lattice constant, and X-ray density were increases with zinc substitution. The energy band gap of prepared ferrites was increasing from 2.258 eV to 2.8306 eV. The hysteresis curve of ferrites shows that the prepared ZnFe 2 O 4 was magnetically softer than is an attractive ferrite with important applications in catalysis [36, 37] , gas sensor [38] , MRI contrast agents [39] , hyperthermia [40] , transformer core [41, 42] , deflection yokes [43] , and microwave device [44, 45] because of the high value of magnetization and resistivity. The bulk MnFe 2 O 4 is crystallized in cubic symmetry with Fd3 m space group, in which 80 % of Mn ions occupy the A sites, and 20% occupy the B sites [46] . Over the past few decades, researchers focused on the synthesis of various nano ferrites to explore the novel properties. The synthesis method and synthesis parameters have an important impact on the size of the particles which subsequently results into the change in properties for the same ferrite [32, 47, 48] . Since different synthesis methods yield different magnetic and electrical properties, in this work a simple and low-cost solvent-free synthesis method is used to synthesize nanosized Zn substituted MnFe 2 O 4 with the chemical formula of Mn 1−x Zn x Fe 2 O 4 . The advantage of this synthesis route is that it does not involve any solvent to dissolve the precursor. Since the metal nitrates used during the synthesis are hygroscopic in nature, they tend to form a homogeneous mixture so that the solvent evaporation time can be minimized. The total synthesis process completed within an hour. In our previous investigation the structural and magnetic properties of the same compounds were reported [28] . In this work, the structural, morphological, spectroscopic, dielectric, ac conductivity, and impedance properties of the Mn-Zn ferrites were systematically studied and the obtained results are discussed in detail in the following sections. Then the nitrate and citric acid mixture were heat-treated at 75 o C until it forms a dry gel. Since the metal nitrates are hygroscopic in nature, the mixed metal nitrates form gel during mixing. The obtained dried gel was heated continuously until self-combusted. The resultant ferrite powder was heat-treated for 1 h at 300 ºC and then used for further characterization [28, 49] . The X-ray diffraction (XRD) pattern of the ferrites was recorded using a powder X-ray diffractometer (Ultima IV, RIGAKU) by employing Cu-Kα 1 (Wavelength-1.5406 Å) radiation. Rietveld refinement was carried out using the GSAS program and its EXPGUI user interface. The surface morphology image of the ferrites was examined using Carl Zeiss SUPRA 55 field emission scanning electron microscope (FE-SEM). Particle morphology was obtained using transmission electron microscopy (TEM) observations using a JEOL JEM-2100F microscope that operates at 200 kV. The spectra of oxidation states at the surface were recorded using a Thermo Fisher ESCALAB 250xi photoelectron spectroscopy (XPS). The pass energy for a wide survey and narrow spectra is 100 eV and 30 eV, respectively. The AC electrical properties were measured using a broadband dielectric spectrometer (BDS) Alpha Analyser Concept80, Novocontrol. J o u r n a l P r e -p r o o f The Rietveld refined powder XRD patterns of spinel Mn 1-x Zn x Fe 2 O 4 ferrites are shown in Fig.1 . The broadening of diffraction peaks shows that the prepared ferrite samples are smaller sized [28] . No additional reflection peaks correspond to any secondary phase was observed in nanocrystalline Mn 1-x Zn x Fe 2 O 4 . The values of crystallite sizes are calculated using Scherrer's formula [49] and given in Table 1 . of the crystallites increases slowly up to x=0.8 and suddenly reaches to 19.6 nm for x=1.0. This finding indicates that the Mn and Zn ratio has a major influence on the crystallites size [50] . The lattice constant values of nanocrystalline Mn 1-x Zn x Fe 2 O 4 are determined using the relation given in [49] and are given in Table 1 occupancy in different sites also was refined and given in Table 2 which indicates the change in cation distribution with Zn concentration. J o u r n a l P r e -p r o o f The The TEM images for selected samples of The frequency dependant dielectric constant (ε′) of nanocrystalline Mn 1-x Zn x Fe 2 O 4 is shown in Fig. 14 Frequency-dependent dielectric loss tangent (tan δ) of nanocrystalline Mn 1-x Zn x Fe 2 O 4 is shown in Fig. 15 . Initially, tan δ decreases with frequency, and a relaxation peak emerges at particular frequencies. When the charge carrier's hopping frequency between Fe 2+ ↔Fe 3+ and Mn 3+ ↔Mn 2+ is larger than that of the applied field, the charge carriers able to follow the electric field, due to that more absorption occurs at lower frequencies, thereby incurring more loss. However, at higher frequencies, the hopping frequency of the charge carriers cannot follow the external field. Thus, less absorption occurs, and hence less loss is obtained. In addition to that, the dielectric loss also occurs from the dipole relaxation, which dissipates energy [55] . Relaxation peaks in tan δ arise when the charge carrier's hopping frequency is same as the frequency of the applied field. The substitution of Zn decreases tan δ, and the The frequency-dependent real part of ac electrical conductivity (σ′) of Mn 1-x Zn x Fe 2 O 4 mixed ferrites is shown in Fig.16 . At lower frequencies, conductivity increases slowly whereas rapidly increases at higher frequencies. At lower frequencies, the resistive natured grain boundaries are more active, and hence low conductivity value is observed. The high conductive nature of grains become highly active at higher frequencies, thereby increasing the hopping of charge carrier between the ions, and conductivity is also increased at high frequencies [56, 57] . The Cole-Cole plots of Mn 1-x Zn x Fe 2 O 4 ferrites are shown in Fig.19 . The plot shows two overlapped depressed semicircles that characterize the grain boundary and grain contribution of the samples [59] . The Cole-Cole plots were modeled using (R g CPE g ) (R gb CPE gb ) equivalent circuit model and the values are obtained by fitting Cole-Cole plots for the proposed circuit at 303 K and presented in Table 3 . R gb values are higher than those of R g values, whereas the CPE g values are higher than those of CPE gb values. This analysis shows that the contribution of grain boundary is higher compared with the grain to the resistance. using the Arrhenius relation for the grain and grain boundary resistance, and given in Table 3 . Among all samples, the x = 0.8 composition has the highest value of activation energy because of its high resistance. J o u r n a l P r e -p r o o f The Cellulose nanomaterials review: structure, properties and nanocomposites A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment Use of iron oxide nanomaterials in wastewater treatment: a review Surface spin disorder in NiFe 2 O 4 nanoparticles Size and shape dependent second order nonlinear optical properties of nanomaterials and their application in biological and chemical sensing Fe 2 O 4 (M= Ni, Cu, Mn, Mg) Carbon-Based Field-Effect Transistors for Nanoelectronics One-dimensional nanostructures of π-conjugated molecular systems: assembly, properties, and applications from photovoltaics, sensors, and nanophotonics to nanoelectronics Nanomagnetism and spintronics: fabrication, materials, characterization and applications Mixed spinel structure in nanocrystalline NiFe 2 O 4 Magnetic properties of nanostructured ferrimagnetic zinc ferrite Dielectric relaxation behaviour of nanostructured Mn-Zn ferrite Hyperthermic evaluation of oleic acid coated nano-spinel magnesium ferrite: enhancement via hydrophobic-to-hydrophilic surface transformation Hydrophobic to hydrophilic surface transformation of nano-scale zinc ferrite via oleic acid coating: magnetic hyperthermia study towards biomedical applications Multifunctional nano-magnetic particles assisted viral RNA-extraction protocol for potential detection of COVID-19 Magneto-structural and photocatalytic behavior of mixed Ni-Zn nano-spinel ferrites: visible light-enabled active photodegradation of rhodamine B Spinel zinc ferrite nanoparticles: an active nanocatalyst for microwave irradiated solvent free synthesis of chalcones Cation distribution, magnetic and hyperfine interaction studies of Ni-Zn spinel ferrites: role of Jahn Teller ion (Cu 2+ ) substitution Structural and magnetic properties of calcium doped nickel ferrite nanoparticles by co-precipitation method Crystal field deformation by Ce 3+ doping in spinel Mn-Cr ferrite Ferrimagnetic Ni 2+ doped Mg-Zn spinel ferrite nanoparticles for high density information storage Cobalt substituted nickel ferrites via Pechini's sol-gel citrate route: X-band electromagnetic characterization Effect of rare earth doping on the vibrational spectra of spinel Mn-Cr ferrite Structural, electrical, and magnetic properties of Zn substituted magnesium ferrite Study of the optical properties of Zn doped Mn spinel ferrite nanocrystals shows multiple emission peaks in the visible range-a promising soft ferrite nanomaterial for deep blue LED Effect of Zn doping on structural, magnetic and optical properties of cobalt ferrite nanoparticles synthesized via. Coprecipitation method Structural and Magnetic Properties of Mn 1−x Zn x Fe 2 O 4 Ferrite Nanoparticles Effect of Zn substitution on the structural and magnetic properties of nanocrystalline NiFe 2 O 4 ferrites Crystal field distortion of La 3+ iondoped Mn-Cr ferrite Influence of trivalent Cr ion substitution on the physicochemical, optical, electrical, and dielectric properties of sprayed NiFe 2 O 4 spinel-magnetic thin films Structural, thermal, spectral, optical and surface analysis of rare earth metal ion (Gd 3+ ) doped mixed Zn-Mg nano-spinel ferrites Influential diamagnetic magnesium (Mg 2+ ) ion substitution in nano-spinel zinc ferrite (ZnFe 2 O 4 ): thermal, structural, spectral, optical and physisorption analysis Effect of Cd 2+ doping on structural, morphological, optical, magnetic and wettability properties of nickel ferrite thin films Influence of Zn concentration on the structural and magnetic properties of nanocrystalline Cu 1−x Zn x Fe 2 O 4 mixed ferrites synthesized using novel combustion method Fabrication of magnetic mesoporous manganese ferrite nanocomposites as efficient catalyst for degradation of dye pollutants High photocatalytic activity of magnetically separable manganese ferrite-graphene heteroarchitectures Nanostructured cobalt manganese ferrite thin films for gas sensor application Long-circulating PEGylated manganese ferrite nanoparticles for MRI-based molecular imaging towards cancer treatment Development of screen-printed polymer thick film planner transformer using Mn-Zn ferrite as core material The past, present, and future of ferrites 2: Development of New Ferrite Material for Deflection Yoke Core Microwave ferrites, part 2: passive components and electrical tuning Microwave ferrites Modern ferrite technology Structural, dielectric and magnetic properties of cobalt ferrite prepared using auto combustion and ceramic route Preparation and characterization of nanometric Mn ferrite via different methods Co or Cu) spinel ferrites Temperature sensitive ferrofluid composed of Mn 1−x Zn x Fe 2 O 4 nanoparticles prepared by a modified hydrothermal process Attestation in selfpropagating combustion approach of spinel AFe 2 O 4 (A= Co, Mg and Mn) complexes bearing mixed oxidation states: Magnetostructural properties Composition, Electronic and Magnetic Investigation of the Encapsulated ZnFe 2 O 4 Nanoparticles in Multiwall Carbon Nanotubes Containing Ni Residuals Electronic conduction of magnetite (Fe 3 O 4 ) and its transition point at low temperatures Dielectric Properties of Fine Particles of Fe 3 O 4 and Some Ferrites Electric and magnetic properties of Bi substituted cobalt ferrite nanoparticles: Evolution of grain effect Electricity and Magnetism On the dispersion of resistivity and dielectric constant of some semiconductors at audiofrequencies Dielectric properties of triethylene glycol-stabilized Mn 1−x Zn x Fe 2 O 4 nanoparticles Electric and magnetic properties of Bi substituted cobalt ferrite nanoparticles: Evolution of grain effect Plan of China (Grant No.2016YFB0300502).