Dielectric and optical properties of Ni doped Na0.5Bi0.5TiO3

Polycrystalline Ni doped Na_.5Bi_0.5TiO₃ samples (Na_0.5Bi_0.5)Ti_1-xNi_xO_3, (x?=?0.5, 0.10, 0.15) have been prepared by solid state reaction. The appearance of the additional peak in X-ray diffraction pattern indicates the ordering of Ti⁴⁺ and Ni²⁺ ions. Polygonal grains are converted into flakes with an increase of Ni concentration. Replacement of Ti⁴⁺ by Ni²⁺ strongly modifies the relative contribution of two peaks in the Raman bands within 200–400?cm^?1. Oxygen vacancy is observed in X-ray photoelectron spectrum to maintain charge neutrality due to aliovalent doping. Broad diffuse phase transition centered at the dielectric constant maximum indicates relaxor behaviour. Comparison between impedance and electric modulus spectrum suggests non-Debye relaxation. The ac conductivity follows the power law with the frequency exponent lies 0.52???0.72. The generation of holes by divalent Ni dopant at tetravalent Ti sites enhances optical band gap.     

Magnetoelectric effect of Ni0.8Zn0.2Fe2O4/Sr0.5Ba0.5Nb2O6 composites

Novel magnetoelectric composites were prepared by incorporating the dispersed Ni_0.8Zn_0.2Fe₂O₄ ferromagnetic particles into Sr_0.5Ba_0.5Nb₂O₆ relaxor ferroelectric matrix. Dense composite ceramics were obtained with the co-presence of Sr_0.5Ba_0.5Nb₂O₆ and Ni_0.8Zn_0.2Fe₂O₄, and they could be electrically and magnetically poled to exhibit a significant magnetoelectric effect. A maximum magnetoelectric voltage coefficient of 26.6 mV/cm/Oe was observed from the composites with 70 mol% Sr_0.5Ba_0.5Nb₂O₆, which was much greater than that of magnetoelectric compounds and solid solutions. It is convenient to use the Pb-free (Sr,Ba)Nb₂O₆ relaxor as the matrix for ferromagnetic/ferroelectric composites in the future development of magnetoelectric materials.     

Processing and characterization of nano-magnetic Co0.5Ni0.5Fe2O4 system

Various techniques such as X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron micrographs (SEM), energy dispersive X-ray (EDX) and a vibrating sample magnetometer (VSM) were used to investigate the structural, morphological, and magnetic properties of spinel Co_0.5Ni_0.5Fe₂O₄ system. XRD and IR analyses enabled us to determine the functional group and structural parameters of Co_0.5Ni_0.5Fe₂O₄. EDX measurements showed the concentrations of O, Ni, Fe, and Co species involved in Co_0.5Ni_0.5Fe₂O₄ specimen from the uppermost surface to the bulk layers. The magnetization and coercivity of the as synthesized composite were 77 emu/g and 128 Oe, respectively.     

Study of (La,Sr)(Ti,Ni)O3-δ materials for symmetrical Solid Oxide Cell electrode - Part B: Conditions of Ni exsolution

The stability of La_2xSr_1-2xTi_1-xNi_xO_3-δ (LSTN) and La_7x/4Sr_1-7x/4Ti_1-xNi_xO_3-δ (25LSTN) materials in high temperature reducing conditions has been studied with a special focus on the Ni exsolution process for SOFC anode / SOEC cathode application. In a general way, LSTN and 25LSTN compounds are stable after treatments at 800 °C in air and wet reducing atmosphere. The low chemical expansion makes them compatible with a use in an electrochemical Solid Oxide Cell. Those materials are therefore useful for an application as symmetric oxide cell electrode or only hydrogen electrode. In situ Nickel exsolution is evidenced at 800 °C in Ar/H₂(2%) but is limited by a slow kinetics and a higher temperature pre-reduction is preferred before a use as SOFC anode (SOEC cathode). Depending on the treatment, in situ reduction or pre-reduction (T>1000 °C), the compounds are not in the same thermodynamic equilibrium state.     

Evaluation of Cu-substituted La1.5Sr0.5NiO4+δ as air electrode for CO2 electrolysis in solid oxide electrolysis cells

Ruddlesden-Popper oxide, Cu-substituted La_1.5Sr_0.5NiO_4+δ series materials (La_1.5Sr_0.5Ni_1-xCu_xO_4+δ; denoted as LSNCu_x; x = 0, 0.1, 0.25, 0.5) are investigated as air electrodes in solid oxide electrolysis cells (SOECs) for electrolysis of CO₂. Room temperature crystal structure, electrical conductivity and oxygen exchange capacity, as well as electrochemical performance of LSNCu_x are comprehensively investigated. Among the series of samples, LSNCu_0.25 half-cell exhibits the lowest polarization resistance value of 0.179 Ω cm² at 800 °C, which decreases by approximately 86.07% compared with that of LSN. In addition, the fuel electrode-supported single cell with LSNCu_0.25 air electrode presents a high current density of 1.2 A cm^?2 at 1.5 V under 30% CO–70% CO₂ condition at 800 °C, which is 207% of LSN (0.58 A cm^?2) under the same condition. Results show that the impressive catalytic activity for oxygen evolution reaction (OER) is ascribed to the improved electronic conductivity and oxygen exchange capacity. With Cu substitution for Ni-site, the contraction of Ni–O bond in NiO₆ octahedron and increased concentration of charge carries owing to the oxidation of Ni²⁺ to Ni³⁺ are beneficial to the electron conduction. The formation of more interstitial oxygen as ionic compensation also favors the oxygen ion diffusion/exchange and greatly accelerates the charge transfer process. Furthermore, no degradation is observed for the single cell durability test at 750 °C for 50 h, which demonstrates the highly stable performance of LSNCu_0.25 air electrode for electrolysis of CO₂.     

Structural,dielectric and luminescent properties of novel Li1.0Nb0.6Ti0.5O3: Tb3+ ceramics

Novel Li_1.0Nb_0.6Ti_0.5O₃: Tb³⁺ ceramics with favorable luminescent and dielectric properties were prepared by solid-state reaction (SSR) method. The X-ray diffraction (XRD) results indicated that the Tb³⁺ ions were effectively dissolved into the “M-phase” matrix synthesized at 1000–1100°C. The ceramic with a dense microstructure could be obtained at 1050°C. The Li_1.0Nb_0.6Ti_0.5O₃: Tb³⁺ ceramics emitted green light at 550 nm and relatively strong red light at 660 nm under the excitation of 440 nm, which were located in the orange-red light region shown in the chromaticity diagram. The color coordinates were (0.5574, 0.4417) for the Li_1.0Nb_0.6Ti_0.5O₃: 2wt% Tb³⁺ ceramic sintered at 1050°C. The quantum efficiency of Li_1.0Nb_0.6Ti_0.5O₃: 2wt%Tb³⁺ ceramic was 19%, which was much higher than that of 9.6% for commercial red Y₂O₃: Eu³⁺ phosphors. Furthermore, for Li_1.0Nb_0.6Ti_0.5O₃: 2wt%Tb³⁺ ceramic synthesized at 1050°C, the ideal dielectric properties with ε_r of 66.263 and Q*f of 5582 GHz were obtained, which might be used as a potentially multifunctional ceramic applied in the fields of LED packaging to improve the lack of red light for blue LEDs combined with yellow phosphors.     

Facile synthesis of Ni0.5Mn0.5Co2O4 nanoflowers as high-performance electrode material for supercapacitors

The rational synthesis of mixed transition metal oxides (MTMOs) with three-dimensional hierarchical porous structure has been proved to be an effective strategy for improving electrochemical performances of binary metal oxides. Herein, the hierarchically Ni_1-xMn_xCo₂O₄ nanoflowers are synthesized by a facile hydrothermal method combined with subsequent heat-treatment. It is found that Ni/Mn atom ratio has a significant influence on the microstructures and electrochemical properties of Ni_1-xMn_xCo₂O₄. The Ni_0.5Mn_0.5Co₂O₄ sample with a Ni/Mn atom ratio of 1 exhibits the highest specific capacity of 366 F/g at a current density of 1 A/g as compared to the other Ni_1-xMn_xCo₂O₄ samples. In addition, Ni_0.5Mn_0.5Co₂O₄ displays high rate capability and cycling performance. The excellent electrochemical performances of Ni_0.5Mn_0.5Co₂O₄ could be ascribed to the large surface area and high mesoporosity, leading to the increased accessible surface for ion access and the rapid electrochemical reactions. The as-synthesized Ni_0.5Mn_0.5Co₂O₄ nanoflowers could be used as a potential electrode materials for Supercapacitors. Furthermore, this study provides a facile method to synthesize other MTMOs with three-dimensional hierarchical nanostructure. An asymmetric supercapacitor is assembled with Ni_0.5Mn_0.5Co₂O₄ as the positive electrode and activated carbon as the negative electrode. The supercapacitor shows an energy density of 20.2 Wh/kg at a power density of 700 W/kg. Cycling stability is achieved with 82% retention after 5000 charge-discharge cycles.     

Microstructure,mechanical properties and thermal conductivity of (Ti0.5Nb0.5)C–SiC composites

A series of (Ti_0.5Nb_0.5)C-x wt.% SiC (x = 0, 5, 10, 20) composites were prepared by spark plasma sintering. Dense microstructures with well‐dispersed SiC particles were obtained for all composites. With the increment of SiC content, the Vickers hardness, Young's modulus and fracture toughness increase monotonically. An optimized flexural strength of 706 MPa was achieved in (Ti_0.5Nb_0.5)C-5 wt.%SiC composite. (Ti_0.5Nb_0.5)C-20 wt%SiC composite exhibits the highest fracture toughness of 6.8 MPa m^1/2. The crack deflections and the suppression of grain growth were the main strengthening and toughening mechanisms. Besides, (Ti_0.5Nb_0.5)C-20 wt%SiC composite exhibit the highest thermal conductivity of 45 W/m·K at 800 °C.     

Correlation between the structure and modified microwave dielectric characteristics of Zr4+ substituted Ni0.4Zn0.6Ti(1-x)ZrxNb2O8 ceramics

Microwave ceramics are an important classes of materials that are used in microwave communication systems, especially in the area of 5G wireless communication and the internet of things. In this work, to improve the Q×f values and enhance the temperature stability of Ni_0.4Zn_0.6TiNb₂O₈ ceramics, the influence of the substitution of Zr⁴⁺ ions at the Ti site in Ni_0.4Zn_0.6Ti_(1-x)Zr_xNb₂O₈ ceramics was investigated. The Q×f value increases from 32114 GHz to 45733 GHz and the τ_f value changes from 38.1 ppm/°C to 3 ppm/°C with a slight Zr⁴⁺ ion substitution (x = 0.1). Meanwhile, the sample with the Zr⁴⁺ ion substitution (x = 0.3) that was sintered at 1120 °C shows a very high Q×f value of 92078 GHz. Furthermore, the XRD results reveal that the phase and structure of the Ni_0.4Zn_0.6Ti_(1-x)Zr_xNb₂O₈ ceramics change with the different Zr⁴⁺ ion contents. The substitution of the Zr⁴⁺ ion can promote the sintering process for the Ni_0.4Zn_0.6Ti_(1-x)Zr_xNb₂O₈ ceramics and restrain the Ni_0.5Ti_0.5NbO₄ phase formation. The results obtained from Ni_0.4Zn_0.6Ti_(1-x)Zr_xNb₂O₈ ceramics can offer useful information for the study and application of high-frequency microwaves.     

Enhanced photodielectric effect in (0.88–x)Bi0.5Na0.5TiO3–0.12BaTiO3 –xBa(Ti0.5Ni0.5)O3–δ (BNBTNO) ceramics

In this work, solid solutions of (0.88–x)Bi_0.5Na_0.5TiO₃–0.12BaTiO₃– xBa(Ti_0.5Ni_0.5)O_3–δ were designed and prepared. These compositions exhibit ferroelectricity at room temperature, with the tetragonal symmetry. The c/a values are varied from ～1.0067 (x?=?0.1) to ～1.0208 (x?=?0.04). A transition from the high–temperature relaxor state to the low–temperature ferroelectric state is demonstrated by the temperature dependence of dielectric data and Raman spectrum. The direct bandgap decreases from 3.40?eV for x?=?0 to 3.16?eV for x?=?0.1. The Ba(Ti_0.5Ni_0.5)O_3–δ addition leads an additional optical absorption peak in the visible range. The obvious photodielectric effect was discovered. In particular, the relative permittivity of the x?=?0.1 composition rises from ～756 to ～807 under light illumination.     

Effect of Ru/CGO versus Ni/CGO Co‐Infiltration on the Performance and Stability of STN‐Based SOFCs

Electrolyte supported cells (ESC), with Sc₂O₃‐stabilized ZrO₂ (ScSZ) electrolytes, Gd‐doped ceria (CGO) or M/CGO (M = Ni, Ru) infiltrated Sr_0.94Ti_0.9Nb_0.1O₃ (STN94) anodes and LSM/YSZ cathodes, were evaluated for their initial performance and long‐term stability. Power density for the Ru/CGO infiltrated cell reached ∼0.7 W cm^–2 at 850 °C, 4% H₂O/H₂, whereas the Ni/CGO infiltrated cell reached ∼0.3 W cm^–2, with the current morphologies and loadings. Operation at 0.125 A cm^–2, 850 °C, feeding 50% H₂O/H₂ to the anode and air to the cathode, for a period >300 h, showed superior stability for the Ru/CGO infiltrated cell, with ∼0.04 mV h^–1 degradation rate, when compared to the Ni/CGO infiltrated cell (∼0.5 mV h^–1). For the Ni/CGO case, the observed degradation has been tentatively linked to initial changes in the electrochemical active area and long‐term detrimental interactions between components.     

Influence of Ti and Fe doping on the structural and electrochemical performance of LiCo0.6Ni0.4O2 cathode materials for Li-ion batteries

The combination of lithium cobalt oxide (LCO) and lithium nickel oxide (LNO) property for Li-ion batteries (LIB) brings a very promising cathode material, LiCo_1?xNi_xO₂ with a high specific reversible capacity and good cycling behaviour. Nonetheless, high toxic Co content and an instability of Li⁺/Ni²⁺ interaction in LiCo_1?xNi_xO₂ crystal structure paved the way for some modification for the development of this potential material. In this research, the self-propagating combustion method is used to reduce 40% Co content of LCO by replacing it with 40% Ni content resulting in cathode material with the stoichiometry of LiCo_0.6Ni_0.4O₂ (LCN). To improve the stability of the LiCo_0.6Ni_0.4O₂ structure, 5% of Ti and Fe was substituted at the Co site of the LCN material. The effect of these different cation substitutions (Ti⁴⁺ and Fe³⁺) on the structural and electrochemical performance of layered LiCo_0.6Ni_0.4O₂ cathode materials was investigated. Rietveld refinement revealed that Fe doped material has the longest atomic distance Li–O in the structure that allow better Li⁺ diffusion during intercalation/deintercalation to give an excellent electrochemical performance (138 mAhg^?1). After 50th cycle, it is found that the discharge cycling for Ti and Fe substituted materials were improved by more than 5% compared to pristine material. Both Ti and Fe doped materials were also having less than 13% of capacity fading indicates that the substitution of some Co with Ti and Fe are stable and can retain their electrochemical properties.     

Doping behaviors of NiO and Nb2O5 in BaTiO3 and dielectric properties of BaTiO3-based X7R ceramics

Doping behaviors of NiO and Nb₂O₅ in BaTiO₃ in two doping ways and dielectric properties of BaTiO₃-based X7R ceramics were investigated. When doped in composite form, the additions rendered higher solubility than that doped separately due to the identical valence between the complex (Ni_1/3²⁺Nb_2/3⁵⁺)⁴⁺ and Ti⁴⁺. NiO–Nb₂O₅ composite oxide was more effective in broadening dielectric constant peaks which was responsible for the temperature-stability of BaTiO₃ ceramics. A reduction in grain size was observed in the specimens with 0.5–0.8 mol% NiO–Nb₂O₅ composite oxide, whereas the abnormal growth of individual grains took place in the 1.0 mol% NiO–Nb₂O₅ composite oxide-doped specimen. When the specimen of BaTiO₃ doped with 0.8 mol% NiO–Nb₂O₅ composite oxide was sintered at 1300 °C for 1.5 h in air, good dielectric properties were obtained and the requirement of (EIA) X7R specification with a dielectric constant of 4706 and dielectric loss lower than 1.5% were satisfied.     

Effect of MnO2 on the microstructure and electrical properties of 0.83Pb(Zr0.5Ti0.5)O3-0.11Pb(Zn1/3Nb2/3)O3-0.06Pb(Ni1/3Nb2/3)O3 piezoelectric ceramics

A sample of 0.83Pb(Zr_0.5Ti_0.5)O₃-0.11Pb(Zn_1/3Nb_2/3)O₃-0.06Pb(Ni_1/3Nb_2/3)O₃ (PZNNT) to which MnO₂ was added, with a high mechanical quality factor (Q_m) and a good transduction coefficient (d₃₃×g₃₃), were systematically investigated. Based on the SEM analysis there existed two kinds of “secondary phases”, Rich Ti and Rich Zn phases, which arose due to the B-site substation of PZNNT-based ceramics by manganese ions. One phase was due to the Mn³⁺ replacing the Ti⁴⁺ to create oxygen vacancies and induce the hardening effect. Another phase was due to the Mn²⁺ replacing the Zn-site to stabilize the perovskite phase. When the addition of MnO₂ reached the solubility limit of 1.5 mol% in the PZNNT-based ceramics, the sample showed optimal electrical properties (Q_m=357, d₃₃×g₃₃=9859 × 10⁻¹⁵ m²/N, k_p=0.56), which suggested its potential application for piezoelectric energy harvesting in larger field excitation environments.     

Mg0.5Ni0.5Fe2O4 nanoparticles as heating agents for hyperthermia treatment

In the present work, Mg_0.5Ni_0.5Fe₂O₄ nanopowders were prepared by a sol-gel combustion method. The magnetic properties, heat generation ability in an AC magnetic field and cytotoxicity of the mixed ferrite nanopowders were investigated. The results showed that the powders have crystalline spinel structure with a particle size in the range of 20-90 nm. Maximum saturation magnetization (Ms) of 51 emu/g was obtained for the Mg_0.5Ni_0.5Fe₂O₄ nanoparticles calcined at 900°C. The results showed that, the coercivity (Hc) of the Mg_0.5Ni_0.5Fe₂O₄ initially increases up to 700°C and then decreases with increasing temperature, whereas the Ms of the samples continuously increases. The Mg_0.5Ni_0.5Fe₂O₄ sample exhibited a temperature increase up to 45°C during 10 minutes in the exposure of magnetic field of 200 Oe. By increasing the viscosity of ferrofluid, the heat generation ability of nanoparticles reduced up to 9% at magnetic field of 200 Oe. Cell compatibility of the ferrite powders was studied by MTT assay using MG63 cell line proliferation. MTT results showed that calcination temperature of the Mg_0.5Ni_0.5Fe₂O₄ nanoparticles significantly affects the cell compatibility.     

Enhanced piezoelectric performance in Na0.5Bi4.5Ti4O15-based bismuth-layered ceramics by Nb/Mn doping modification

In this work, Na_0.5Bi_4.5Ti_3.94–xMn_0.06Nb_xO_15+y bismuth-layered ferroelectric ceramics were prepared by a solid-state reaction method. The effect of Nb⁵⁺ content on crystal morphology, electrical properties, and piezoelectric performance were systematically investigated. The results show that the introduction of Nb⁵⁺ into Na_0.5Bi_4.5Ti_3.94–xMn_0.06Nb_xO_15+y ceramics to replace Ti⁴⁺ increases the ratio of b/a lattice parameter, leading to the TiO₆ octahedral distortion and the structural transformation tendency from the orthorhombic to tetragonal phase, which facilitates dipole movements of Na_0.5Bi_4.5Ti_3.94–xMn_0.06Nb_xO_15+y ceramics. Therefore, the ferroelectric properties of Na_0.5Bi_4.5Ti_3.94–xMn_0.06Nb_xO_15+y ceramics are improved, and an enhanced piezoelectric coefficient of 30 pC/N combining great temperature stability with d₃₃ value higher than 25 pC/N in the temperature range of 25°C–450°C has been realized in Na_0.5Bi_4.5Ti_3.94–xMn_0.06Nb_xO_15+y ceramics with x = 0.08 mol. Our work provides a good model for designing lead-free ultrahigh Curie temperature piezoelectric devices that can be practically applied in extremely harsh environments.     

Synthesis and characterization of calcium double perovskites for the potential application of semiconducting CO2 sensors

A conventional solid-state sintering method was used to prepare double perovskite structured compounds BCN (Ba₂Ca_0.67Nb_1.33O₆), BCNCo (Ba₂Ca_0.67Nb_1.33-xCo_xO_6-δ) and BCNCoFe (Ba₂Ca_0.67Nb_0.67Co_0.66-yFe_yO_6-δ), which exhibit significant chemical stability in nitrogen, air, and 2 % CO₂ (balanced by nitrogen). SEM images show that the Co dopant causes a dense microstructure for BCNCo compounds. In contrast, the introduction of Fe tends to produce a porous and web-like microstructure for the BCNCoFe series. Ba₂Ca_0.67Nb_0.67Co_0.66O_6-δ has a reasonable response (recovery) time at 750 °C and it seems suitable for CO₂ detection at elevated temperatures. Among the BCNCoFe compounds, Ba₂Ca_0.67Nb_0.67Co_0.33Fe_0.33O_6-δ has the largest capacitance as the CO₂ concentration changes from 0 to 2000 ppm, and it exhibits satisfactory sensitivity and repeatability in the temperature range of 450–700 °C with an extra voltage of 0.1 V. To further consider the Ba₂Ca_0.67Nb_0.67Co_0.33Fe_0.33O_6-δ compound for CO₂ sensing, a sol-gel method was utilized. The sol-gel-prepared Ba₂Ca_0.67Nb_0.67Co_0.33Fe_0.33O_6-δ senses CO₂ well, and its concentration changes from 0 to 2000 ppm (or from 0 to 300 ppm) in the temperature range of 400–600 °C. The different CO₂ sensing properties of all prepared double perovskite compounds can be interpreted by the different surface areas that play critical roles in the chemical adsorption of related gaseous species.     

Electrochemical characteristics of LiNi0.5Co0.5O2 synthesized at 800 °C from the different combinations of carbonates,oxides, and hydroxides

LiNi_0.5Co_0.5O₂ cathode materials were synthesized by a solid-state reaction method at 800 °C using Li₂CO₃, LiOH·H₂O; NiO, NiCO₃; CoCO₃, or Co₃O₄ as the sources of Li, Ni, and Co, respectively. The electrochemical properties of the synthesized samples were then investigated. The structure of the synthesized LiNi_0.5Co_0.5O₂ was analyzed, and the microstructures of the samples were observed. The curves of voltage vs. x in Li_xNi_0.5Co_0.5O₂ for first charge–discharge and intercalated and deintercalated Li quantity Δx were studied. Destruction of unstable 3b sites and phase transitions were discussed from the first and second charge–discharge curves of voltage vs. x in Li_xNi_0.5Co_0.5O₂. The LiNi_0.5Co_0.5O₂ sample synthesized from Li₂CO₃, NiCO₃ and Co₃O₄ has the largest first discharge capacity (142 mAh/g). The LiNi_0.5Co_0.5O₂ sample synthesized from Li₂CO₃, NiO and Co₃O₄ has a relatively large first discharge capacity (141 mAh/g) and the smallest capacity deterioration rate (4.6 mAh/g/cycle).     

Investigations of Structural and Magnetic Properties of Nanostructured Ni0.5+xZn0.5‐xFe2O4 Magnetic Feeders for CSEM Application

Marine CSEM is a new technique for detection of deep target hydrocarbons. Aluminum EM antenna was developed, and nanostructured NiZn magnetic feeders were used to increase the field strength from EM antenna for deep hydrocarbons. The doping of Ni²⁺ was aimed at the optimization of initial permeability and magnetic losses. Ni_0.5+xZn_0.5‐xFe₂O₄ (x = 0.3) samples sintered at 950°C presented highest initial permeability (106.23) and low magnetic loss (0.0002) as compared to other samples. Due to better magnetic properties, Ni_0.5+xZn_0.5‐xFe₂O₄ (x = 0.3) samples were used as magnetic feeders for EM antenna. Magnitude of EM waves from the antenna increased up to 186%.     

Graphene anchored Ce doped spinel ferrites for practical and technological applications

Graphene plays a remarkable role as a supporting material for the fabrication of a variety of nanocomposites. This work presents the fabrication of graphene-based Ce doped Ni–Co (Ni_0.5Co_0.5Ce_0.2Fe_1.8O₄/G) ferrite nanocomposites. Ni_0.5Co_0.5Fe₂O₄ and Ni_0.5Co_0.5Ce_0.2Fe_1.8O₄ were prepared using sol gel method. However, Ce doped Ni–Co spinel nanoferrite was chemically anchored on the surface of graphene. Different characterizations techniques were adopted to investigate the variations in the properties of ferrite composite due to the incorporation of graphene. Thermal analysis revealed 18% heat weight loss of Ce doped Ni–Co ferrite sample during treatment up to 1000 °C respectively. X-ray diffraction analysis depicted the presence of spinel phase structure of all synthesized nanocomposites. Fourier transform infrared analysis revealed two absorption bands of tetrahedral and octahedral sites of the spinel phase and presence of graphene contents in the Ni_0.8Ce_0.2CoFeO₄/G composite. FESEM images revealed an increased agglomeration due to the presence of graphene in the Ce doped Ni–Co ferrite composites. Graphene based Ce doped Ni–Co ferrite nanocomposite showed highest conductivity (4.52 mS/cm) than other ferrite composites. Magnetic characteristics showed an improvement in the Ni–Co ferrite sample by the substitutions of Ce³⁺ ions and graphene contents. The improvement in the properties of these nanocomposites makes them potential material for many applications such as fabrication of electrodes, energy storage and nanoelectronics devices.