Sol-gel Auto Combustion Research Articles

Rietveld refined structural and sintering temperature dependent electromagnetic properties of Al3+ substituted Ni–Co ferrites prepared through sol–gel auto combustion method for high-frequency and microwave devices

Rietveld refined structural and sintering temperature dependent electromagnetic properties of Al3+ substituted Ni–Co ferrites prepared through sol–gel auto combustion method for high-frequency and microwave devices

Effect of rare earth doping on the electromagnetic response of hard ferrites SrFe12O19 for potential application in high-frequency devices

This work explores the synthesis, characterization, and potential application of rare earth doping on hard ferrites, focusing on their unique electromagnetic properties for potential applications in radio frequency (RF) devices. This study investigates the influence of rare earth (Sm+3) doping on structural and dielectric properties of strontium ferrite. Samarium doped strontium ferrite with composition Sr1-xSmxFe12O19(x = 0.0,0.1,0.2,0.3) is prepared using the sol-gel auto combustion technique. The prepared samples' crystal structural and morphological properties were studied using an X-ray diffractometer (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and RAMAN spectroscopy. XRD patterns of rare earth substituted strontium ferrite confirmed the formation of a hexagonal phase together with an impurity phase of Fe2O3 for x = 0.3. FTIR analysis establishes metal and Oxygen (M-O) stretching vibrations in Sr1-xSmxFe12O19 due to various interstitial sites in its structure. The Raman result shows the presence of four Raman active modes in prepared powders. Meanwhile, the broadening of Raman peaks with Sm2+ doping is also observed. Electromagnetic properties were obtained in the frequency region 2–18 GHz. An increasing tendency is observed in the real part of permittivity and permeability of all doped samples in the frequency region 2–18 GHz. The reflection loss was observed for sample x = 0.2 with the maximum value of > -40 dB at 18 GHz, and the adequate absorption bandwidth is 10 GHz from 8 GHz to above 18 GHz. On the basis of these results, among all prepared samples, Sr0.8Sm0.2 Fe12O19 is found to be the most suitable candidate for microwave absorbers.

Effect of divalent ion of strontium substitution on the structural, optical, magnetic and blood compatibility studies in cobalt ferrite

This study investigates the effects of Sr2+ substitution on the structural, morphological, and magnetic properties of magnetic cobalt ferrite (CoFe2O4). Through sol–gel auto-combustion synthesis, Sr2+ was substituted into Co-spinel ferrites (Co1-xSrxFe2O4, where x = 0.0, 0.25, 0.5, 0.75, 1.0). SEM analysis revealed spherical grains with an average size of 54.4 nm. XRD analysis indicated systematic changes in crystallographic parameters and the formation of secondary phases with Sr-substitution. While the crystal size for CoFe2O4 was calculated as 262 nm, this value was determined as 18 nm for Co0.25Sr0.75Fe2O4. FT-IR results suggested increased force constants of octahedral and tetrahedral bonds with higher Sr content, with main vibration bands at 423.6 and 606 cm−1. M-H curves exhibited S-shaped behavior, indicating drastic magnetic property changes with Sr2+ substitution. Coercivity field (Hc), saturation magnetization (M S ), and remanent magnetization (M r ) values ranged from 1447.8–545.4 Oe, 58.8-14 emu g−1, and 36.8-7.6 emu g−1, respectively. Blood compatibility experiments highlighted Co0.75Sr0.25Fe2O4 nanoparticles with significantly low hemolysis rates compared to other concentrations.

Influence of bismuth and cobalt doping on structural, dielectric, and magnetic properties of M-type calcium hexagonal ferrites

M-type hexagonal ferrites have been getting considerable attention owing to their promising application in electronic fields. Though, the growth of nanosized M-type hexagonal ferrites is still a big challenge. Herein the fabrication of M-type hexaferrite with nominal composition Ca1-xBixFe12-xCoxO19 (x=0.00, 0.05, 0.10, 0.15, 0.20) with high quality is reported by the sol-gel auto combustion route. The objective of the study is to improve the structural, spectral, dielectric, and magnetic characteristics of M-type hexagonal ferrite which was achieved through the variation of concentration of Cobalt and Bismuth. X-ray diffraction (XRD) patterns confirmed the single-phase M-type hexagonal structure. The crystallite size of all samples was found to be in the range of 42–49 nm. Other parameters such as lattice parameters a & c, unit cell volume, crystallite size, X-ray density, Bulk density, and porosity were also calculated. The doping contents were found to decrease the bulk and X-ray densities while increasing the porosity. Fourier-transform infrared (FTIR) spectra showed the formation of metal-oxygen stretching vibrations that confirmed the formation of hexagonal ferrites. The scanning electron microscopy (SEM) images revealed a regular platelet hexagonal structure and homogeneously distributed grains were examined. The dielectric constant was high at low frequency and then decreased with increasing frequency, while the dielectric loss was decreased appreciably with doping. The saturation magnetization ranged from 15.51 to 38.27 emu/g, coercivity increased from 207.93 to 1359.69 Oe, and the squareness ratio was found to be in the range of 0.19–0.78. The dielectric and magnetic properties of Ca1-xBixFe12-xCoxO19 (x=0.00, 0.05, 0.10, 0.15, 0.20) with the variation of Co and Bi revealed that these materials are good candidates for modern devices.

Synthesis of nickel-cobalt ferrite/graphene oxide nanocomposites

Current investigation is an attempt to study the structural, optical, magnetic and dielectric properties of Ni0.5Co0.5Fe2O4/graphene oxide (NCF/GO) nanocomposites. NCF/GO nanocomposites were synthesized through the ultrasonication technique. NCF nanoparticles (NPs) and GO (with varying weight percentages of GO) were synthesized through sol–gel auto-combustion and modified Hummer’s method, respectively. The effect of nickel–cobalt ferrite NPs incorporation on graphene oxide was studied using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM) and Impedance Analyzer. electrical and dielectric measurements. XRD and FTIR studies showed and confirmed the formation of both spinel for the NCF NPs and amorphous graphene oxide for NCF/GO nanocomposites. The crystallite size and lattice parameter for NCF NPs were found in the range of 21–47 nm and 8.33–8.36 Å, respectively. The optical band gap was found in the range of 1.73–1.83 eV with increasing GO concentration. VSM studies revealed that the saturation magnetization (Ms) value for NCF/GO nanocomposites is found to be decreased from 59 emu/g (for NCF) to 30 emu/g (for 60 wt% of GO) with increased GO weight percentage. There was a drastic variation observed in the value of coercivity (Hc) for NCF and NCF/GO nanocomposites. However, it remains almost constant within NCF/GO nanocomposites. Dielectric studies showed the exponentially decaying nature of dielectric constant and loss tangent with logarithmic frequency. Further, the dielectric constant is increased with increasing GO content. A maximum dielectric constant is observed for NCF/GO nanocomposites with 60 wt% of GO. The AC conductivity is found to be increasing with an increase in GO weight percentage and showed its sharply increasing nature at higher frequencies.

Advancements in multiferroic, dielectric, and impedance properties of copper–yttrium co-doped cobalt ferrite for hydroelectric cell applications

This paper explores yttrium and copper co-doped cobalt ferrite [Co1−x Cu x Fe1.85Y0.15O4] synthesized via the sol–gel auto-combustion route (0.0 ⩽ x ⩽ 0.08). Investigating the impact of co-dopants on CoFe2O4, the study reveals altered cation distribution affecting the structure, multiferroic, and electrical properties. X-ray diffraction studies show nanocrystalline co-doped cobalt ferrites with lattice expansion and smaller grains due to Cu–Y co-doping. Fourier transform infrared spectroscopy confirms inverse spinel family classification with tetrahedral lattice shrinkage. Field emission scanning electron microscopy indicates a grain size of approximately 0.12 μm. Ferroelectric analysis reveals a peak saturation polarization of 23.42 μC cm−2 for 8% copper doping, attributed to increased Fe3+ ions at tetrahedral sites. Saturation magnetization peaks at 54.4706 emu g−1 for 2% Cu2+ ion substitution [Co0.98Cu0.02Fe1.85Y0.15O4] and decreases to 37.09 emu g−1 for 4% Cu substitution due to irregular iron atom distribution at tetrahedral sites. Dielectric studies uncover Maxwell–Wagner polarization and high resistance in grain and grain boundaries using impedance spectroscopy. Fabricated hydroelectric cells exhibit improved ionic diffusion, suggesting their use in potential hydroelectric cell applications.

Influence of Ni2+ ions on structural, spectral and dielectric properties of Sr–Co spinel ferrites synthesized by sol-gel auto-combustion route

Nickel substituted Sr–Co nano spinel ferrites with composition Sr0.5-xNixCo0.5Fe2O4 (0.0, 0.1, 0.2, and 0.3) were prepared with the help of a sol-gel auto combustion route. The prepared materials were sintered at 800 for four and a half hours. Analysis of XRD confirmed that the material is composed of a cubic spinel structure with a single phase, and its space group is Fd-3m. Rietveld refinement of X-ray diffraction data was done for all prepared compositions using FULLPROF software. As the composition under study contains more nickel than lattice constant, crystalline size, X-ray density, and bulk density decrease. The dielectric properties were observed about frequency. The dielectric properties revealed that dielectric loss, dielectric constant, and ac conductivity decrease with increasing the Ni2+ content. The activation energy (ΔE) was calculated from the slope of Arrhenius plots. The ΔE found in the range of 0.580–0.096 eV. The analysis of XPS was carried out to examine the elemental state of annealed samples. The prepared material is suitable for employment in applications involving high frequencies because the Ni-doped Sr–Co ferrites with the greatest Ni2+ concentration have the lowest dielectric loss, dielectric constant, and tangent loss value.

Microstructural, morphological and magnetic behaviour of Al3+ replaced BaFe11.5Co0.5O19 hexaferrites synthesized via sol-gel auto combustion route

In this work, polycrystalline BaFe11.5-xAlxCo0.5O19 (0≤x≤2) hexaferrite samples were synthesised by means of the sol–gel technique. Thereafter, the magnetic and structural properties are thoroughly examined. Cell refinement and XRD examination verified a magnetoplumbite hexaferrite arrangement with a space group of P63/mmc for each sample. The parameters ‘a’ and ‘c’ in the lattice fall in value from 5.885 Å to 5.875 Å and from 23.117 Å to 23.049 Å, respectively. Both the average crystallite size and the unit cell volume exhibit a declining trend as the doping level increases. For M-type hexaferrites, the optimal range of c/a values is determined to be 3.923–3.928. X-ray density (dx) and bulk density (db) decline with rising doping contents until x=1.5 doping content, at which point they exhibit an increasing trend. The results showed that as the doping amount increased, the saturation and remanence magnetizations decreased. Coercivity and magnetocrystalline anisotropy are rising together. Both the anisotropy field (Ha) and the anisotropy parameter (B) exhibit a rising trend with doping content. Coercivity of 5.896 kOe, anisotropic applied field of 1.84 kOe, saturation magnetization of 42.68 emu g−1, remanence magnetization of 24.414 (emu/g), and magnetic moment per formula unit-(mB) of 11.19 μ B are the best magnetic properties obtained for the BaFe10Al1.5Co0.5O19 sample.

Universal Dielectric Response in Electronically Correlated Functional Oxides CaCu3Ti4O12, LaFeO3, YFe0.5Cr0.5O3 and their Nanocomposites: A Comparative Study

AbstractCaCu3Ti4O12 (CCTO), LaFeO3 (LFO) and YFe0.5Cr0.5O3 (YFCO) were synthesized via conventional sol–gel auto–combustion method using citric acid as gelling agent. The X‐ray diffraction analysis revealed the phase purity of the samples. The energy dispersive X‐ray (EDX) analysis confirms the stoichiometry of the pristine phases. The average particle size obtained from the field emission Scanning electron microscopy (FE−SEM) images revealed that CaCu3Ti4O12 exhibits a broad range of particle size starting from a couple of hundreds of nanometer to micrometer, whereas that for LaFeO3 and YFe0.5Cr0.5O3 are about 110 nm and 50 nm, respectively. We have fabricated the new composites: CCTO–LFO, CCTO–YFCO and LFO–YFCO. The grain sizes of the composite phases are consistent with the pristine phases as they are prepared by at lower sintering temperatures and duration. The dielectric properties of these ceramic composites were compared to those of the pristine phases. The temperature and frequency dependent dielectric measurements reveal a wide range of dielectric constant with moderate tan δ values. The temperature dependent dielectric constant of the investigated samples varies from 100 to 1500 at room temperature and the data have been analyzed using universal dielectric response (UDR) model.

Enhanced magneto-dielectric characteristics of Ni–Cd ferrites/GNPs composites synthesized via sol-gel auto-combustion method

Graphene nanoplatelets (GNPs) and spinel ferrites (SFs) composites enhance their properties and enable multifunctional applications, ranging from electronics to environmental and biomedical fields. This study investigates the Ni0.4Cd0.6Fe2O4/x-GNPs (x = 0 %, 2.5 %, and 5 %) [NCF/0%GNPs, NCF/2.5%GNPs, and NCF/5%GNPs] composites prepared via sol-gel auto combustion (SGAC) synthesis and their enhanced magneto-dielectric characteristics. XRD analysis confirmed the formation of a single-phase spinel matrix of NCF/GNPs composites and observed that the crystallite size (D) was enhanced from 22.8 nm to 33.6 nm with the increasing concentration of GNPs. Moreover, the bandgap energy (Eg) was reduced with the incorporation of GNPs in the NCF sample. The dielectric constant and tangent loss were enhanced with the addition of GNPs in the NCF spinel lattice. The saturation magnetization and microwave operating frequency were reduced from 97.42 emu/g to 55.13 emu/g and 21.49 GHz–11.97 GHz, respectively, while the coercivity was observed to increase from 92.66 Oe to 263 Oe with the incorporation of GNPs in the NCF lattice. The study highlights the potential of NCF/GNPs composites for applications in electronics, energy storage, sensors, and biomedical devices.

Investigation of structural, electrical, and magnetic variations of Ni-Zn-Co ferrites by substituting rare earth Ho3+ for high-frequency applications

The investigation of structural, magnetic, and electrical properties of Ni0.6Zn0.3Co0.1HoxFe2−xO4 (NZCHF, 0 ≤ x ≤ 0.2) ferrites, synthesized through the sol–gel autocombustion method, has been undertaken. The refined x-ray diffraction (XRD) analysis was performed for XRD data analysis using Fullprof Suite software and it confirmed a single-phase cubic spinel structure, with the determination of crystallite size, refinement parameters and lattice constants. The bulk density of the samples consistently remained lower than the x-ray density, with densities increasing proportionally to the enhancement of Ho concentration. FTIR analysis corroborated the presence of metal-oxygen bonds within the ferrite possessing a spinel cubic structure. 57Fe Mossbauer spectroscopy showed that the hyperfine magnetic field of tetrahedral (A) and octahedral (B) sites decreased with the substitution of Ho3+ ions that preferentially occupy the B site. The impedance analyzer and vibrating sample magnetometer (VSM) were utilized to measure the real and imaginary parts of the complex permeability and magnetic properties of the samples, respectively. Complex impedance plots were scrutinized to discern the contributions of grain and grain boundary resistances, providing insights into the electrical behavior of the ferrite samples. Furthermore, the introduction of Ho concentration led to alterations in other key properties of the ferrites, including coercivity (H c ), retentivity (M r ), anisotropy constant (K), and magnetic moment (μ B ).The impact of the rare-earth content on the magnetic features of the prepared NiZnCo ferrite microspheres was investigated by analyzing magnetic-hysteresis (M-H) loops, which showed soft ferrimagnetism. Concurrently, the dielectric constant and dielectric loss tangent of the studied samples exhibited a decrease with the rise in Ho3+ concentration. The expected reduction in tan loss in the prepared samples is attributed to the increase in ac resistivity associated with the higher Ho3+ content.

Structural, physicochemical and electrical properties of Co2Y-type barium hexaferrites

Y-type hexaferrite ceramic materials of nominal composition Ba2Co2CrxYxFe12-2xO22 (x = 0.00, 0.03, 0.06, 0.09, and 0.12) were synthesized by sol-gel auto combustion route. Y-type hexaferrites are technologically important ceramic materials for fabricating modern electronic devices and microwave absorbers due to their unique electrical and dielectric properties and reflection loss behavior. XRD classifies the single-phase formations with space group R 3‾ m. The crystallite size of the synthesized samples was calculated in (34–41) nm range. The specific absorption band in FTIR spectra approves the (Fe–O) stretching vibrations at wavenumbers 446 and 478 cm−1. The substitution of iron by Cr3+ and Y3+ increases DC resistivity from 1.03 × 1011 to 1.17 × 1012 Ω cm by limiting the electrons jumping between ferrous and ferric ions. The activation energy and drift mobility were also calculated among the substituting content of Cr3+-Y3+. The dielectric response in 1 MHz–6 GHz frequency was determined and the effect of substitution has been observed. The Maxwell-Wagner (MW) bilayer model is used to study dispersion in dielectric parameters with reference to applied frequency. The maximum values of dielectric losses were obtained at 6 GHz in the range of 0.37–0.60. The coercivity values confirms the soft magnetic nature of synthesized samples. The microwave absorption (MW) properties of synthesized materials were improved upon Cr3+-Y3+ substitution. Minimum reflection loss RLmin = −66 dB (99.99% absorption of MW) at 1.46 GHz frequency and 1.96 mm thickness was obtained for x = 0.09 composition. All investigated samples are efficient materials for stealth technology, radar cross-reduction, EM interference shielding, and high-frequency applications.

Effect of synthesis on structural, vibrational, and electrical properties of Ba1−xCaxCe0.8Nd0.2O3−δ (BCCN, 0 ≤ x ≤ 0.01) synthesized by sol–gel auto combustion method

Effect of synthesis on structural, vibrational, and electrical properties of Ba1−xCaxCe0.8Nd0.2O3−δ (BCCN, 0 ≤ x ≤ 0.01) synthesized by sol–gel auto combustion method

Structural and magnetic properties of GdFeO3 nanomaterial prepared through one-step sol-gel auto combustion technique

Structural and magnetic properties of GdFeO3 nanomaterial prepared through one-step sol-gel auto combustion technique

Influence of Zirconium substitution on electrical properties of Nickel-Zinc Ferrites

The Zirconium substituted Nickel Zinc Ferrite nano particles with chemical composition of Ni(0.5-x)Zn(0.5-x)ZrxFe2O4, where the value of x varies from 0 to 0.2, have been synthesized by the sol-gel auto combustion method, using high purity nitrates and fuelling agent citric acid. The structural property was studies from X-ray diffraction spectra. The crystallite size decreases with increase in Zirconium substitution. The electrical property of the same was investigated by studying the dielectric constant, and AC conductivity. There are fluctuations in these properties with variation in Zirconium substitution in Ni-Zn Ferrite.

Effect of lanthanum substitution and annealing temperature on the structural and morphological properties of M-type calcium hexaferrite

To investigate the influence of annealing temperature and lanthanum substitution on the structural properties of M-type calcium hexaferrite, we prepared unsubstituted and lanthanum-substituted Ca1-xLaxFe12O19 (x = 0.3, 0.4 and 0.5) powders by mean of sol–gel auto-combustion procedure, annealed between 800 °C and 1350 °C during 5 h in a rate of 180 °C per hour. XRD analysis showed that the M-type phase does not appear in the unsubstituted samples even with annealing at 1200 °C. The XRD patterns of the substituted samples contained peaks of the M-type phase with the presence of α-Fe2O3 as a secondary phase, the intensity of α-Fe2O3 decreased with increasing annealing temperature between 1200 °C and 1350 °C, and also as a function of lanthanum substitution concentration, which shows that the best lanthanum substitution concentration was x = 0.5. Lattice parameters of synthesized Ca0.5La0.5Fe12O19 align with literature results of various M-type hexaferrite. SEM micrographs of the Ca0.5La0.5Fe12O19 annealed at 1350 °C revealed that the mean and median crystallite size values were calculated to be 4.37 μm and 4.32 μm respectively.

Performance boosting of Sb2Se3 photodetectors by a sol–gel auto-combustion ZnO overlayer

Antimony selenide (Sb2Se3) is a promising material for low-cost, high-performance optoelectronic devices. In this study, a sol–gel auto-combustion ZnO overlayer was introduced into the Sb2Se3 photodetector (PD) for the first time. The sol–gel auto-combustion method is simple, efficient and low-cost, and when the solution ratio of the ZnO overlayer (Zn(CH3COO)2·2H2O: Zn(NO3)2·6H2O) is optimized to 6:4, the constructed heterojunction improves the electron transport efficiency and shows the best performance. The results showed that the ameliorated PD exhibits higher on/off ratio (6054), responsivity (R) (23.5 mA W−1) and detectivity (D*) (2.1 × 1011 Jones) than the original device, which are improved by 22 times, 6 times and 10 times @ 660 nm, respectively. This work can enlighten the synthesis and application of low temperature ZnO thin film that can be applied for high performance Sb2Se3 PDs and other optoelectronic devices with heat-labile materials.

Nano MgCuAl2O5: Synthesis by Sol-Gel Auto-Combustion Process, Characterization and Reusable Heterogeneous Catalyst for the Hantzsch 1,4-Dihydropyridine Reaction

For the first time, MgCuAl2O5 heterogeneous nanocatalysts were prepared by sol-gel auto-combustion method, which displayed great yield and suitable activity for the preparation of 1,4-DHP derivatives with high efficiency in green solvent ethanol/water (1:1) at 80 °C under one pot condition. The synthesis materials were separated in short reaction times with excellent yield (80–95) %. Moreover, the synthesized nanocatalyst was easily retrieved and continuously reused for six reactions without a noticeable significant loss of proficiency. The solid catalyst was confirmed by XRD, BET, FTIR, FESEM and EDX, and the substituted 1,4-dihydropyridines were characterized by melting point, 1H and 13C NMR.

Antibacterial and sunlight-driven photocatalytic activity of graphene oxide conjugated CeO2 nanoparticles

This work focuses on the structural, morphological, optical, photocatalytic, antibacterial properties of pure CeO2 nanoparticles (NPs) and graphene oxide (GO) based CeO2 nanocomposites (GO-1/CeO2, GO-5/CeO2, GO-10/CeO2, GO-15/CeO2), synthesized using the sol–gel auto-combustion and subsequent sonication method, respectively. The single-phase cubic structure of CeO2 NPs was confirmed by Rietveld refined XRD, HRTEM, FTIR and Raman spectroscopy. The average crystallite size was calculated using Debye Scherrer formula and found to increase from 20 to 25 nm for CeO2 to GO-15/CeO2 samples, respectively. The related functional groups were observed from Fourier transform infrared (FTIR) spectroscopy, consistent with the outcomes of Raman spectroscopy. The optical band gap of each sample was calculated by using a Tauc plot, which was observed to decrease from 2.8 to 1.68 eV. The valence state of Ce (Ce3+ and Ce4+) was verified using X-ray photoelectron spectroscopy (XPS) for CeO2 and GO-10/CeO2. The poisonous methylene blue (MB) dye was used to evaluate the photocatalytic activity of each sample in direct sunlight. The GO-15/CeO2 nanocomposite showed the highest photocatalytic activity with rate constant (0.01633 min–1), and it degraded the MB dye molecules by 100% within 120 min. The high photocatalytic activity of this material for degrading MB dye establishes it as an outstanding candidate for wastewater treatment. Further, these nanocomposites also demonstrated excellent antimicrobial activity against Pseudomonas aeruginosa PAO1.

GO optimization strategies for improved capacity retention in transition metal oxides based ternary nanocomposites for high-performance supercapacitors

This work presents the optimization of GO in transition metal oxide based ternary nanocomposites (NiO/ZnO@(GO)x)for electrode materials in supercapacitor applications. The nanocomposites were synthesized using a straightforward sol-gel auto combustion route followed by sonication. It was observed from XRD analysis that crystallite sizes of NiO/ZnO@(GO)x nanocomposites vary between 49 and 24 nm. According to morphological study, the TEM images depict a hybrid nanoarchitecture with NiO/ZnO nanoparticles dispersed on graphene sheets. The maximum specific capacitance of 1833.9Fg−1 was obtained for NZG3 (NiO/ZnO with 6% GO).Furthermore, largest capacity retention of 98.7% was achieved for NZG3 after 6000 continuous cycles. NZ demonstrated 96% capacitance retention, for NZG1 it was 97.2% and capacity retention for NZG3, it was 98.7%. Therefore,optimized concentration of GO in NiO/ZnOnancomposite to achieve maximum specific capacitance and cyclic stability was found to be forNZG3 nanocomposite. The Rs values attained were found to be 6.7 Ω, 5.8 Ω, 5.4 Ω, 4.4 Ω and 4.9 Ω for NZ, NZG1, NZG2, NZG3 and NZG4 respectively whereas Rctvalues for NZ and NZG electrodes i.e. NZG1, NZG2, NZG3 and NZG4 10.0 Ω, 9.4 Ω,8.5 Ω,7.8 Ω and 8.1 Ω respectively, demonstrating that GO plays an important role in enhancing conductivity.