Dielectric Loss Values Research Articles

Preparation and EMI shielding performance of epoxy/non-metallic conductive fillers nano-composites

Nonmetallic conductive materials such as inherently conducting polymers (ICPs) and carbon nanomaterials play an important role in the manufacturing of electrically conductive polymer nanocomposites for Electromagnetic Interference (EMI) shielding applications. In this study, the electrical, dielectric and EMI shielding properties of epoxy (E)/non-metallic conductive materials are investigated. Polyaniline (PANI) as an ICP, graphene and multi-walled carbon nanotubes (MWCNTs), as the most well-known carbon nanomaterials, have been selected in order to make conductive epoxy nanocomposites. The composites were prepared through solvent mixing method and characterized by the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and electrical conductivity measurements. Furthermore, dielectric properties of epoxy nano composites were measured by reflection/transmission method using a vector network analyzer (VNA) in the frequency range of 8.2–12.2 GHz. It was observed that both real and imaginary parts of permittivity increase with CNT and thermally reduced graphene oxide (TRGO) loadings. Highest dielectric loss values were observed for E/PANI (35 %) composites, while dielectric constant was highest for both E/PANI (35 %) and E/TRGO (3%) nanocomposites. Furthermore, the EMI Shielding Effectiveness (SE) was higher at high loadings of conductive fillers. The maximum reflection loss was observed for E/CNT (2.5 %) and E/PANI (15 %); in fact, E/PANI (15 %) exhibited a relatively broad effective bandwidth (i.e., reflection loss<-10 dB) of 3.6 GHz, while this parameter is 2.1 GHz for E/CNT (2.5 %).

Investigation on the effect of tungsten doping and sintering temperature on microwave dielectric properties of lithium magnesium silicate ceramics

Demand for dielectric ceramics has been increasing due to their broad range of applications in microwave communication domains. Lithium Magnesium Silicate (LMS) can be categorized as a dielectric ceramic which owns good dielectric properties suitable for substrates in microwave integrated circuits. Effect of tungsten doping on the structural and dielectric characteristics of LMS is examined in this work. Tungsten-doped LMS ceramic systems were synthesized through conventional solid-state method. Doping effect on crystal structure and microstructure of the samples was analyzed using X-ray diffractograms and field emission scanning electron micrographs. Impact of dopant concentration and sintering temperature on the microstructural densification was investigated. Parallel plate capacitor method using DUT in LCR meter was employed to measure the relative permittivity and dielectric loss values of tungsten-doped LMS ceramics. 10% tungsten-doped LMS (Li2Mg0.90W0.10SiO4) ceramic was sintered at 1100 C for 4 h and it exhibited a lowest dielectric loss value of 9.65 × 10−3 and relative permittivity of 7.22.

Broadband Colossal Dielectric Constant in the Superionic Halide RbAg4I5: Role of Intercluster Ag+ Diffusion

Materials with ultrahigh dielectric constants and a low value of dielectric loss are important for energy storage and electronic devices. Traditionally, high dielectric constant is found in ferroelectric complex oxides, but they exhibit high dielectric loss as well. Herein, a broadband colossal dielectric constant in a superionic halide, RbAg4I5, with a low dielectric loss is presented. The real part of the dielectric constant, ε′, increases by 102 orders of magnitude as RbAg4I5 goes through a superionic transition at 121 K. At room temperature, ε′ > 106 in the frequency range 10–1 to 104 Hz with a low dielectric loss, which ranges between 2.03 and 0.53. The maximum of ε′ reaches a colossal value of 6.4 × 108 at 0.1 Hz at 300 K. The molecular dynamics simulation reveals the presence of Ag+ clusters with a broad size distribution. The intercluster diffusion of Ag+ causes significant instantaneous charge separation and a consequent large fluctuation in the dipole moments. The fluctuating dipoles, in turn, result in the colossal dielectric constant in RbAg4I5.

Preparation of Fe–Si–Al intermetallic alloy and their composite coating for EM absorbing application in 6–18 GHz

An energy efficient and scalable process has been developed for the preparation of intermetallic Fe–Si–Al alloy particles. The preparation process involves initial homogenization & mechanical activation of elemental metal powders followed by vacuum annealing at elevated temperature ~ 650 °C. The physical properties of the as synthesized powders were investigated by means of X-ray Diffraction (XRD), Energy Dispersive Xray Flourence (EDXRF),Vibration Sample Magnetometer (VSM), Scanning Electron Microscope (SEM) and Particle Size Analyser. Composite coatings have been prepared by dispersing 30–60 wt% of Fe–Si–Al alloy in polyurethane (PU) resin. The effect of loading of Fe–Si–Al alloy on dielectric and electromagnetic (EM) properties of composites are studied in 6–18 GHz. A suitable formulation (50 wt% Fe–Si–Al) has been identified, wherein, proper combination of dielectric and magnetic loss of coating composite showed optimal microwave (MW) absorption in 6–18 GHz. The identified composite coating of thickness ~ 1.6 mm showed maximum Return Loss (RL) value ~ − 43 dB at 11.9 GHz and the loss values can exceed more than 10 dB within 6.5 to 16 GHz while varying thickness of coating from 1.2 to 2.2 mm. In the present study, microwave absorption properties of coatings are mainly credited to dielectric and magnetic loss values of the composites. The Fe-Si-Al filled resin composite with optimal loading of alloy particles can be a promising candidate for microwave absorbing coating applications.

Effect of Porous Structure on the Microwave Absorption Capacity of Soft Magnetic Connecting Network Ni/Al2O3/Ni Film.

Microwave radar absorbing materials have been the focus of the radar stealth research field. In this study, ceramic structured porous honeycomb-like Al2O3 film was prepared by anodic oxidation, and an Ni layer was deposited on the Al2O3 film via electrodeposition in a neutral environment to form a flower- and grain-like structure in a three-dimensional (3D) network Ni/Al2O3/Ni film. The films both have a through-hole internal structure, soft magnetic properties, and absorb microwaves. The dielectric loss values of two films were little changed, and the maximum microwave absorption values of flower- and grain-like Ni/Al2O3/Ni film were −45.3 and −31.05 dB with relatively wide effective bandwidths, respectively. The porous ceramic structure Al2O3 interlayer prevented the reunion of Ni and isolated the eddy current to improve the microwave absorption properties. The material presented in our paper has good microwave absorption performance with a thin thickness, which indicates the potential for lightweight and efficient microwave absorption applications.

Structural, dielectric and electrical properties of Gd-substituted lithium nano-ferrites prepared by the WOWS sol–gel method

To synthesize lithium ferrite with various Gd concentrations (Li0.5Fe2.5−xGdxO4), x = 0.00, 0.025, 0.05, 0.075, 0.1, solutes were dissolved in glycol, i.e. by using the without water and surfactant (WOWS) sol–gel method. X-ray diffraction (XRD) analysis confirmed that the material possessed an inverse spinel cubic structure and is single phase. Pellets of all samples were sintered at 700 °C and XRD confirmed that samples were crystalline, phase pure and had an inverse spinel cubic lattice. Scanning electron microscopy indicated that the grains were agglomerated and had a predominantly spherical shape. It is concluded that Gd acts as a grain refiner in lithium ferrite up to a Gd concentration of 0.05. AC conductivity and dielectric constant increased by increasing Gd concentration. The Maxwell–Wagner model and Johnsher’s power law were used to explain the dielectric properties. DC conductivity was measured from 100 to 600 °C. DC conductivity was explained by the hopping mechanism. It is concluded that DC resistivity and dielectric constant values are related reciprocally in the prepared sample. AC electrical properties were also measured at a constant frequency of 1 MHz in the temperature range from 400 to 600 °C. Gd-substituted lithium ferrite showed high AC conductivity, high DC resistivity and constant dielectric values, but low dielectric loss values as compared to pure lithium ferrite.

A comprehensive study on the impact of RGO/MWCNT hybrid filler reinforced polychloroprene rubber multifunctional nanocomposites

Flexible dielectric chloroprene rubber (CR) nanocomposites reinforced by one-dimensional carbon nanotube (CNT)/two dimensional reduced graphene oxide hybrids have been prepared using two-roll mill mixing technique. Non-covalent π-π interaction between multiwalled carbon nanotubes (MWCNTs) and reduced graphene oxide (RGO) nanosheets and the secondary interaction between fillers and chloroprene rubber matrix are responsible for generating the effective load transfer between RGO/MWCNTs and CR. The prepared RGO-MWCNT hybrid nanocomposites with high dielectric constant (≈650), low dielectric loss (≈0.42) and high energy storage efficiency (78.6%) values are practically good enough to use as a low cost polymeric dielectric layer in transistors. Furthermore, the prepared nanocomposites showed excellent electromagnetic effectiveness; a maximum shielding efficiency of 11.87 dB @ 3.5 GHz was achieved at 4 phr of MWCNT loading. This excellent electromechanical performance can be ascribed to the synergistic effect of RGO-MWCNT hybrid suggesting that this novel hybrid nanocomposite serves as an attractive candidate in modern electronics and electric power systems.

Optical, Magnetic, and Electrical Studies of Nanometric Bi1−xNdxFeO3 Perovskite

The effect of Nd-doped BiFeO3 perovskite (Bi1−xNdxFeO) with ratios (x = 0, 0.05, 0.1, and 0.15) was studied. All samples were prepared by flash combustion technique. X-ray diffraction (XRD) confirmed single-phase structure for all samples. The effect of Nd-doped BiFeO3 appears in the decrease of unit cell parameters. Microstructure was studied by transmission electron microscope (TEM). Physical property measurements (optical, electric, and magnetic) were reported. Maximum conductivity and magnetization were obtained at Nd content x = 0.15. For example, the saturation magnetization increased from 0.141 to 0.353 emu/g. Doped samples with Nd3+ show larger value of dielectric constant and dielectric loss than pure one. Nd doping enhanced clearly the properties of BFO and opens an era of applications.

Identification of frequency regimes for short and long range mobility of charge carriers in GO/MnFe2O4/PPy nanocomposites

The physico-chemical properties of polymer ceramic composites highly depend upon the nature of ceramic, polymer and their interface. Among other interesting features, they have potential for flexible electronics and energy storage devices. Especially, graphene based polymer ceramic composites are unique for their high dielectric characteristics. In this regard, we synthesized a three constituent novel nanocomposite with polymer matrix to check their potential for energy storage applications. Here in, the polypyrrole has been exquisitely decorated with graphene oxide and manganese ferrite nanoparticles with their different concentrations. The development of spherical grains and their transformation into rod like morphology with a significant change in their dimension is noticed. The weight percentage of all elements according to their stoichiometric formula and the finger prints of different constituents in the form of their functional groups are also identified before their dielectric and ferroelectric analyses. The highest value of dielectric constant (121449) has been noticed at 100 Hz frequency, which reduced to 1066 at 1 MHz. The dielectric loss was also quite high at lower frequency which decreased to 1.2 at same high value of frequency (1 MHz). The calculations for recoverable energy density and energy loss density are performed using PE hysteresis loops and the highest value of recoverable energy density is recorded as 4.7 × 10−8 mJ/cm3. Thus, high values of dielectric constant and low dielectric loss of these nanocomposites make them attractive dielectric material in electrical appliances for capacitive applications.

Synthesis, structural, dielectric and magnetic properties of Cd2+ based Mn nanosized ferrites

ABSTRACT Cadmium-substituted manganese ferrite nanoparticles with the general formula Mn1‒xCdxFe2O4(x = 0.0, 0.2, 0.4, 0.6, 0.8) were synthesised by the citrate‒gel auto combustion method. X-ray diffraction patterns revealed formation of a cubic phase spinel structure with space group. FT-IR confirms stretching vibration of tetrahedral and octahedral interstitial sites in the spinel lattice. Microstructural features observed by scanning electron microscopy (SEM) demonstrate that agglomerated particles were formed with an increase in average grain size according to Cd2+ content. Elemental composition features and particle size of samples were examined by energy dispersive spectroscopy (EDX) and Transmission electron microscopy (TEM). The magnetic properties characterised by the highly sensitive magnetometer system (SQUID VSM) at room temperature revealed ferromagnetism in all the samples. The values of dielectric permittivity and tangent loss () decreased exponentially at low frequencies and were in accordance with the Maxwell–Wagner model and Koop’s theory.

Sol-gel synthesized Ba-Nd-Cd-In nanohexaferrites for high frequency and microwave devices applications

Nanocrystalline cadmium and indium substituted barium M-type hexagonal ferrite-based nanomaterials were prepared via sol-gel auto-combustion technique for studying the electrical, dielectric and conductivity characteristics of prepared samples such as dc resistivity, dielectric constant (ε’), dielectric loss (tan δ) and ac conductivity (σac) with the usage of different characterizing techniques like keithley 2611 two probe system and impedance analyzer. The room temperature dc resistivity of synthesized samples increases for lower concentrations i.e. x = 0.1 of Cd2+/In3+ but for the higher concentrations i.e. x = 0.2, it starts decreasing consequently. The temperature dependent dc resistivity also showing a decreasing trend as a function of temperature which continuously indicating the semi-conducting behaviour of BaM hexagonal nanohexaferrites. The room temperature dielectric characteristics was investigated as a function of logarithmic frequency and it can be explained on the basis of Maxwell Wagner model and space chare polarization. From the dielectric measurements, the dielectric constant (ε’) was found to be increasing with the increasing logarithmic frequency working as good energy storage material. The dielectric loss (tan δ) was found to be decreasing for the undoped sample (x = 0.0) but for the undoped samples (x = 0.1–0.2), it starts increasing in a very minute manner. Therefore, such materials of high increasing dielectric constant with minute values of dielectric losses make it suitable for the high frequency, energy storage and microwave devices application.

Influence of spark plasma sintering temperature on the microstructures, dielectric and I–V properties of CaCu3Ti4O12 ceramics

CaCu3Ti4O12 (CCTO) ceramics were prepared by the sol–gel process and sintered by the spark plasma sintering (SPS) process at different temperatures. The SPS process temperature has an important effect on the microtopography of CCTO ceramics. The results of EDS and positron annihilation spectroscopy indicate that Cu2+ diffuses from the inside to the surface of grains during the sintering process at high temperature. The permittivity (εr) of CCTO ceramics at the corresponding frequencies increases with increasing SPS temperature. However, the frequency stability of εr over the frequency range 40–106 Hz wanes gradually. The CCTO ceramics sintered at 900°Cand 950 °C present very low dielectric loss values(about 0.02) near 10 kHz. The change in εr and tanδ for CCTO ceramics can be explained by the internal barrier layer capacitance (IBLC) model and AC (alternating current) impedance spectra. The results of I–V nonlinear characteristics for CCTO ceramics make clear that the potential barrier height has a positive effect on the value of nonlinear coefficient.

Silicone elastomers filled with rare earth oxides

Silicones which possess, amongst others, remarkable mechanical properties, thermal stability over a wide range of temperatures and processability, and rare earth oxides (REO), known for their unique optic, magnetic and catalytic properties can be coupled into multifunctional composite materials (S-REOs). In addition, the intrinsic hydrophobicity of REO and polysiloxanes makes them easily compatible without the need for surface treatments of the former. Thus, europium oxide (Eu2O3), gadolinium oxide (Gd2O3) and dysprosium oxide (Dy2O3) in amounts of 20 pph are incorporated as fillers into silicone matrices, followed by processing mixture as thin films and crosslinking at room temperature. The analysis of the obtained films reveals the changes induced by these fillers in the thermal, mechanical, dielectric and optical properties, as well as the hydrophobicity of the silicones. The luminescence properties of S-REO composites were investigated by fluorescence spectra and lifetime - resolved measurements with a multiemission peaks from blue to greenish register. The thermogravimetrical analysis indicates an increasing of thermal stability of the composites that contain REO, compared to pure silicone. As expected, the dielectric permittivity significantly increased due to nature of the fillers, while the dielectric loss values are relatively low for all samples, indicating a minimal conversion of electrical energy in the form of heat within bulk composites. The presence of rare earth oxides into the silicone matrix facilitates the motions of long-range charge carriers through the network resulting in higher values of conductivity of the composite films. The stress-strain measurements revealed the reinforcing effect of the rare earth metal oxides on a silicone matrix, leading to a significant increase of Young modulus. The known hydrophobicity of silicones is further enhanced by the presence of REO.

Dielectric spectroscopy of in-vitro human blood of diabetic and non-diabetic patients through low level laser therapy

The research work investigates the dielectric properties (dielectric constant, dielectric loss and conductivity) of both diabetic and non-diabetic patients’ blood in order to enhance of low level laser therapy (LLLT). Knowing the dielectric properties of blood, profile dose threshold exposure duration can improve LLLT for diabetic mellitus disease. This was achieved, using impedance analyser 4294A, frequency range 40 kHz - 30 MHz. Measurements were taken before and after blood irradiated with a portable diode-pumped solid state laser of wavelength 532 nm at power of 60 mW in standard cuvettes. Control diabetic patient’s bloods were high in dielectric parameter compared with the control non-diabetic patient’s blood. After exposure for 5 and 10 minute’s duration, the value of dielectric loss for the blood exposed for 5 minutes duration appreciated significantly. This is attributed to the energy acquired by haemoglobin and oxygen activation that increased cell membrane resistance, protecting the K+ions efflux and thus prevent perilous balance of Ca+2 ions. Laser power of 60 mW for 5 minutes exposure proved effective in LLL diabetic mellitus therapy.

Synthesis and characterization of GO doped bio-resource based composites for NLO and multifaceted applications

The objective of the present work is to synthesize three different types of cardanol based benzoxazines such as cardanol-{1,4-bis(4-aminophenoxy)ethane}benzoxazine (CBAE2Bz), cardanol-{1,4-bis(4-aminophenoxy)butane} benzoxazine (CBAE4Bz) and cardanol-{1,4-bis(4-aminophenoxy)octane}benzoxazine (CBAE8Bz) by varying aliphatic ether link chain length through solventless method. The benzoxazines obtained with varying chain length were converted in to three different types of composites using paraphenylenediamine (PPDA) functionalized gaphene oxide (f-GO) as nano-reinforcement with varying weight percentage and were characterized by different analytical techniques. The molecular structure of the monomers was confirmed from Fourier transform infrared (FTIR) spectroscopy, 1HNMR, 13C NMR and MALDI mass. Data obtained from thermal studies infer that the prepared composites possess good thermal stability and enhanced values of Tg with respect to weight percent of functionalized graphene oxide content. However, the values of thermal stability, Tg, dielectric constant and dielectric loss were marginally decreased with respect to increase in length of the spacer aliphatic chain. The SEM and TEM studies confirm the homogeneous dispersion and single layer thickness of graphene sheet, respectively. The feasibility of usage of f-GO/PCAE2Bz composite in both gram positive bacteria (Bacillus subtilis, Staphylococcus aureus) and gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli) environments were checked and the results obtained were discussed. Further, third-order NLO properties of open and closed aperture Z–scan results conclude that GO doped bio-resource based composites exhibit saturable absorption and self-defocusing type optical non-linearity. The third-order NLO susceptibility (χ3) of GO doped bio-resource based composites are increased with respect to quantity of reinforcement of GO to bio-based polymer. The maximum value of 1.03X 10−4 esu was observed and this nonlinearity is thermal in nature. Thus, the prepared composites may find wide range of applications in diverse surrounding conditions.

Effect of film thickness on dielectric properties and energy storage performance of Ba0.95Ca0.05Zr0.3Ti0.7O3 thick films prepared by tape casting

Free-standing Ba0.95Ca0.05Zr0.3Ti0.7O3 thick films with varying thicknesses (90–200 μm) were prepared by tape casting technology. The thick films exhibited dense microstructure with fine and uniform grains (~ 1 μm). The dielectric properties, dielectric breakdown strength, and energy storage performance of the thick films were examined. The dielectric properties of the thick films were essentially unaffected by changing film thickness. The thick films with varying thicknesses showed similar dielectric constant and loss values, ferroelectric phase transition behavior, and dielectric nonlinearity. In contrast, the dielectric breakdown strength and energy storage performance were substantially dependent on film thickness. The dielectric breakdown strength and recoverable energy storage density were increased with reducing film thickness, while the energy storage efficiency at an identical applied electric field was enhanced. The film with a thickness of 90 μm achieved the optimal energy storage performance among the specimens investigated, exhibiting a recoverable energy storage density of 1.1 J/cm3 and an energy storage efficiency of 81.7% at an electric field of 260 kV/cm. The thickness dependence of the dielectric breakdown strength and energy storage performance was explained with respect to presence of oxygen vacancies in the lattice.

A facile microwave-assisted synthesis of novel ZnMn2O4 nanoparticles and their structural, morphological, optical, surface area, and dielectric studies

Spinel ZnMn2O4 nanoparticles (ZMONPs) were successfully synthesized using a microwave-assisted chemical route. X-ray diffraction (XRD) revealed the growth of ZMONPs along the (211) plane with a tetragonal structure. The crystallite size was ~ 14 nm, estimated using the XRD data. Vibrational analysis confirmed the tetragonal structure of ZMONPs. Scanning electron microscopy images showed nanometer-sized particles, which was in agreement with the XRD results. EDX investigation of the samples demonstrated the good stoichiometric ratio of Zn, Mn, and O (1:2:4). The surface area and pore radius were also investigated in detail through Brunauer–Emmett–Teller analysis and were found to be 10.385 m2/g and 16.24 A, respectively. The direct band gap for the ZMONPs was estimated using Tauc’s relation and was found to be 2.07 eV, which is larger than that of bulk ZMO (1.91 eV). Dielectric constant and loss values decreased with increasing frequency, while conductivity increased with increasing frequency. The dielectric constant was found to be in the range of 17–25 considering the entire testing range. The dielectric constant value was larger than expected, which could be the result of quantum confinement.

Frequency and voltage dependence of electrical conductivity, complex electric modulus, and dielectric properties of Al/Alq3/p-Si structure

In order to enhance the capacitance of the Al/p-Si metal-semiconductor structure, the Alq3 thin film was coated between these two layers using the spin coating technique as the interlayer. The electrical conductivity, real and imaginary parts of electric modulus, dielectric loss and dielectric constant parameters were examined at the room temperature by the help of admittance measurements in the 100 kHz to 1 MHz frequency range. The effect of frequency on the dielectric constant and dielectric loss values is negligible at the negative voltage values, up to about 0.8 V, and these values rapidly ascended after 0.8 V. The function of electrical modulus complex has been examined from the point of permittivity and impedance in order to clutch the contribution of the particle border on the relaxation mechanism of the materials. It is established that the examined dielectric parameters strongly correlated with the voltage and frequency. As a result, the changes in the dielectric parameters and electrical modulus due to the varying frequency were described as the results of relaxation process, polarization and surface conditions. Furthermore, it could be stated that the Alq3 material used in the interfacial layer is a useful material which could be used in addition to the conventional materials.

A perspective approach towards appreciable size and cost-effective solar cell fabrication by synthesizing ZnO nanoparticles from Azadirachta indica leaves extract using domestic microwave oven

A simple domestic microwave oven-assisted solvothermal method has been used successfully to synthesize spherical nanoparticles of zinc oxide (ZnO NPs) for solar cell fabrication using Azadirachta indica (Neem) leaves extract as both capping and reducing agent. The hexagonal structure of ZnO nanoparticles was confirmed by X-ray powder diffraction analysis. The Fourier-transform infrared spectrum confirms the presence of Zn–O stretching vibrations. High-resolution transmission electron microscopy images have exhibited the spherical morphology of ZnO nanoparticles which has clearly illustrated the average particle size around 4.2 nm. The selected area electron diffraction pattern contains well uniform rings confirming standard orientation. The maximum absorption wavelength for the synthesized ZnO nanoparticles was found to be more than 352 nm. The electrical measurement demonstrated that the values of dielectric constant and dielectric loss gradually decrease with increase in frequency which is described by the basis Maxwell–Wagner model. The ac conductivity of ZnO nanoparticles was also carried out. The solar cell fabrication of ZnO nanoparticles and photovoltaic devices were displayed. It was further confirmed that smaller size of ZnO nanoparticles was synthesized which had shown better cell efficiency.

Magnetoelectric interactions in bismuth sodium-potassium titanate-nickel cobalt ferrite lead-free composite ceramics

Bismuth sodium-potassium titanate (BNKT) and nickel-cobalt ferrite (NCF) ceramic composite materials (xBNKT-(100-x)NCF), with different ferrite proportions, were studied. Piezoelectric and ferrite powders were separately synthesized by the solid-state method. Structural analyses were carried out by X-ray diffraction and Raman spectra studies of the composites whereas microstructural studies were performed by Scanning Electron Microscopy and the element distribution was studied by Energy Dispersive X-Ray Spectroscopy. Dielectric permittivity and loss values were sensitive to temperature and composition variations. Magnetic and magnetoelectric properties of the xBNKT-(100-x)NCF composites have been investigated. Ions diffusion and chemical reaction between BNKT and ferrite phases cause microstructural and structural variations that are responsible for moving away from the saturation magnetization from those calculated. Moreover, microstructural evolution controls the magnetoelectric properties of these lead-free composites.