Nonlinear Constants Research Articles

Ab initio calculations of second-, third-, and fourth-order partial and inner elastic constants of diamond.

By means of ab initio calculations, a unified framework is presented to investigate the effect of internal displacement on the linear and nonlinear elasticity of single diamond crystals. The calculated linear and nonlinear elastic constants, internal strain tensor and internal displacement in single diamond crystals are compatible with the available experimental data and other theoretical calculations. The complete set of second-, third- and fourth-order elastic constants and internal strain tensor not only offer a better insight into the nonlinear and anisotropic elasticity behaviors, but also shows us the basic internal mechanical response of diamond. This study provides a route to calculate the nonlinear internal and external elasticity response in a nonprimitive lattice.

Symmetries and symmetry-generated averages of elastic constants up to the sixth order of nonlinearity for all crystal classes, isotropy and transverse isotropy.

Algebraic expressions for averaging linear and nonlinear stiffness tensors from general anisotropy to different effective symmetries (11 Laue classes elastically representing all 32 crystal classes, and two non-crystalline symmetries: isotropic and cylindrical) have been derived by automatic symbolic computations of the arithmetic mean over the set of rotational transforms determining a given symmetry. This approach generalizes the Voigt average to nonlinear constants and desired approximate symmetries other than isotropic, which can be useful for a description of textured polycrystals and rocks preserving some symmetry aspects. Low-symmetry averages have been used to derive averages of higher symmetry to speed up computations. Relationships between the elastic constants of each symmetry have been deduced from their corresponding averages by resolving the rank-deficient system of linear equations. Isotropy has also been considered in terms of generalized Lamé constants. The results are published in the form of appendices in the supporting information for this article and have been deposited in the Mendeley database.

Genetic algorithm-based shape optimization of rubber mount for tractor-cabin mounting system

Tractors are widely used for agricultural activities worldwide by farmers. The cabin mount of a tractor supports the weight of the cabin and isolates vibrations from the chassis. In this study, the cabin mount-shape parameters were optimized considering its design characteristics to reduce vibration and noise inside the cabin. Additionally, vibration and noise tests were conducted to evaluate the improvement in isolation performance owing to the optimization. The nonlinear material constants of the Mooney–Rivlin hyperelastic model were obtained through tensile tests on rubber materials. A finite element model of the cabin mount was developed, and an analysis model was constructed to derive the vertical and lateral stiffness and displacement transmissibility through static and dynamic analyses using the ABAQUS program. The shape parameters influencing vertical and lateral stiffness were determined, and an objective function to minimize displacement transmissibility was defined for optimization. The vertical and lateral displacement transmission rates of the mount were successfully decreased through the optimization. The noise and vibration test results indicate that the cabin noise decreased by approximately 1–2 dB, while vibrations in the frequency range below 100 Hz were reduced by more than 3 dB in all directions. The proposed technique can help engineers and manufacturers improve driver comfort and mitigate the adverse effects of excessive noise and vibrations on their mental and physical health.

Surface-near domain engineering in multi-domain x-cut lithium niobate tantalate mixed crystals

Lithium niobate and lithium tantalate are among the most widespread materials for nonlinear, integrated photonics. Mixed crystals with arbitrary Nb–Ta ratios provide an additional degree of freedom to not only tune materials properties, such as the birefringence but also leverage the advantages of the singular compounds, for example, by combining the thermal stability of lithium tantalate with the larger nonlinear or piezoelectric constants of lithium niobate. Periodic poling allows to achieve phase-matching independent of waveguide geometry and is, therefore, one of the commonly used methods in integrated nonlinear optics. For mixed crystals, periodic poling has been challenging so far due to the lack of homogeneous, mono-domain crystals, which severely inhibit domain growth and nucleation. In this work, we investigate surface-near (<1μm depth) domain inversion on x-cut lithium niobate tantalate mixed crystals via electric field poling and lithographically structured electrodes. We find that naturally occurring head-to-head or tail-to-tail domain walls in the as-grown crystal inhibit domain inversion at a larger scale. However, periodic poling is possible if the gap size between the poling electrodes is of the same order of magnitude or smaller than the average size of naturally occurring domains. This work provides the basis for the nonlinear optical application of lithium niobate tantalate mixed crystals.

Nonlinear, elastic, piezoelectric, electrostrictive, and dielectric constants of lithium tantalate

Three third-order dielectric constants, 8 electrostrictive constants, 13 third-order piezoelectric constants, and 14 third-order elastic constants for lithium tantalate (LiTaO3) single crystals, which are mainly used in surface acoustic wave (SAW) devices, were determined as part of basic research to realize SAW devices with a low degree of nonlinearity. The third-order dielectric constants were determined by measuring the change in capacitance along selected directions when an alternating electric field was applied to the crystal. The electrostrictive constants were determined by measuring the change in capacitance when static stress was applied. Some of the piezoelectric constants were determined directly from the change in sound velocity due to the application of an alternating electric field, whereas others were obtained from the measured dielectric constants, electrostrictive constants, and the change in sound velocity due to an alternating electric field. In addition, the elastic constants (compliance) were determined using the three aforementioned determined nonlinear constants and the measured small-amplitude ultrasonic velocity change as a function of applied static stress. The measurements performed in the present study are more advanced than those reported for LiNbO3 single crystals in 1987 due to the adoption of the d-form nonlinear piezoelectric equation (instead of the e-form) and a higher degree of precision using dynamic measurement methods. The use of the d-form of the nonlinear piezoelectric equation allows many nonlinear constants to be determined independently from other nonlinear constants, eliminating measurement errors associated with these other constants. The d-form nonlinear constants obtained in the present study were converted to e-form constants to make them applicable to the analysis of nonlinear phenomena in piezoelectric devices.

Improving the optical properties of magnesium spinel chromites through Ni and Cu substitutions for optoelectronic applications.

In this study, we investigated the optoelectronic performance of magnesium spinel chromites with nickel (Ni) and copper (Cu) substitutions. Using the sol-gel method, we synthesized two spinel chromites: Mg0.6Ni0.4Cr2O4 (MNCO) and Mg0.6Cu0.4Cr2O4 (MCCO). We extensively characterized these samples to analyze their thermal, structural, elastic, and optical properties. Structural analysis reveals good agreement between the calculated and refined structural parameters, which supports the proposed cation distributions for the samples. By calculating stiffness constants from force constants, we derived elastic moduli such as bulk modulus, longitudinal modulus, and rigidity modulus. MCCO exhibited lower values for these moduli, as well as the Debye temperature, compared to MNCO. Both samples displayed a brittle mechanical nature according to the Pugh ratio, while the Poisson ratio remained constant at 0.25, indicating isotropic elasticity. UV-vis-NIR spectroscopy revealed that MNCO has higher band-gap (E g) and Urbach (E u) energies than MCCO. Further analysis of refractive index, penetration depth, extinction coefficients, nonlinear optical parameters, optical conductivity, and optical dielectric constants highlighted the promising optoelectronic applications of the synthesized materials. Our study found that the band-gap energy values of the as-synthesized samples were smaller than reported values for MgCr2O4 spinel chromites, indicating that Ni and Cu substitutions offer an opportunity to extend the sunlight absorption range of magnesium chromites.

Conversion of preferred crystalline orientation by annealing and its impacts on the structural, electronic, and optical properties of pulsed laser-deposited CdO thin films

The impact of annealing on the preferred crystalline orientation as well as the structural, electronic, and optical properties of pulsed laser-deposited 150 ± 3 nm thick cadmium oxide (CdO) films was studied. X-ray diffraction analysis revealed that the annealed CdO films have smaller crystallite sizes, as their molecules at the grain boundaries possessed enough kinetic energy to rearrange their preferred crystalline orientation between (111) and (200). The atomic force microscopy and field emission scanning electron microscopy analyses revealed an enhancement in the active surface area with optimized grain boundaries by annealing which facilitates gas adsorption/desorption. DC electrical conductivity depends on the annealing process and reveals two different conduction mechanisms. The direct optical energy gap was decreased from 3.41 eV to 2.76 eV by annealing at 473 K which is greater than the theoretical value, i.e. 2.2 eV, for bulk CdO. The findings agree with the Burstein-Moss effect as a result of the increased carrier concentration following the generation of numerous oxygen vacancy sites and Cd interstitials. However, mutual charge carrier-impurity interaction and charge carrier Columb interaction contributed to narrowing the band gap by increasing the annealing temperature. The enhanced values of Urbach energy, optical packing density, dispersion parameters, optical conductivity, dissipation factor, oscillator strength, and lattice dielectric constant supported the effectiveness of the annealing process on tailoring optoelectronic responses in the infrared region for the CdO thin films for use in optoelectronic devices. Moreover, the calculated linear optical susceptibility, and nonlinear constants (i.e. third-order optical susceptibility and nonlinear refractive index) were the highest for CdO films annealed at 473 K. The improved value of the figure of merit, solar material protection factor, and solar skin protection factor for the CdO films, annealed at 473 K supports its use in several photovoltaic applications, including solar cells.

Investigation of the structural and optical characteristics of La2FeCrO6 double perovskite for optoelectronic applications

La2FeCrO6 nanoparticles were prepared using sol-gel method and their linear and non-linear optical properties were investigated. Optical transmittance and absorption were measured for wavelengths between 200 and 1000 nm using UV–visible analysis at room temperature. The results demonstrated the potential use of La2FeCrO6 in optoelectronics applications due to its interesting optical properties. Transmittance and absorption, as well as absorption coefficients, band gap (Eg), Urbach energy (Eu), refractive coefficients, optical conductivity, and dielectric function were examined. According to the analysis, the band gap energy was determined to be 3.501 eV using the Tauc method, while the Urbach energy value was 0.324 eV. Non-linear sensitivities of the first and third order were also calculated, along with linear and non-linear refractive constants. The results lead to the conclusion that La2FeCrO6 represents a promising material for applications in the field of optical electronics, taking into consideration its optical properties, whether linear or non-linear.

Optical and Dielectric Characteristics of Poly (Methyl Methacrylate)/Polyethylene Oxide/Carbon Nanoparticle Composites Loaded with Nano NiFe2O4

The current study proposes a simple, low-cost, and functional method of doping a pure matrix of poly (methyl methacrylate)/polyethylene oxide/carbon nanoparticles (PMMA/PEO/CNPs) with nano nickel ferrite (NiFe2O4) as a filler. To create NiFe2O4 nanoparticles, a straightforward chemical growth, sol-gel auto-combustion system was used. Next, environmentally friendly and cost-effective, undoped and blended polymers doped with NiFe2O4 using a solution-casting method were synthesized. Rietveld refinement analysis was used to investigate the structure and microstructure of the NiFe2O4. Transmittance electron microscopy was used to confirm the nano nature of the filler. X-ray diffraction was used to verify the crystallite nature of the undoped and doped PMMA/PEO/CNPs blends with NiFe2O4. The linear optical characteristics of the proposed blends were obtained using a diffuse reflectance spectrophotometer. The measured optical parameters included transmittance, absorbance, reflectance, direct and indirect optical bandgaps, absorption coefficient, linear refractive index, extinction coefficient, dielectric constant, energy loss functions, in addition to optical and electrical conductivities. Also, nonlinear optical constants for the synthesized blends, such as the linear and third nonlinear susceptibilities, nonlinear refraction coefficient and nonlinear absorption coefficient, were calculated. The direct and indirect optical band gap energies of the PMMA/PEO/CNPs blends were 4.97 and 4.8 eV, respectively. As the NiFe2O4 doping level increased in the blend to 2.5 wt%, the optical band gap energy values decreased to 4.54 and 4.64 eV, respectively. The fluorescence spectra of the undoped and doped PMMA/PEO/CNPs blended polymers with nano NiFe2O4 were also explored. The effect of NiFe2O4 doping amount on the energy density, electric dielectric constant, ac conductivity and electric moduli of the host blend was also studied. In conclusion, the considered NiFe2O4-doped PMMA/PEO/CNPs blends have an effective and promising role in optoelectronic applications.

Effect of Sn nanoparticles on the optical properties of PEDOT:PSS thin films

Introduction: In this study, we focus on enhancing the optical properties of PEDOT:PSS thin films by incorporating pure Sn nanoparticles (NPs) synthesized using the ultrasonic ablation technique. The objective is to investigate the impact of Sn concentration on the optical characteristics of the films, with a specific emphasis on applications in organic solar cells.Methods: We systematically varied the concentrations of Sn in PEDOT:PSS thin films and characterized their optical properties. The index of refraction (n) and extinction coefficient (k) were precisely determined by analyzing the transmission and reflection spectra of the films. Additionally, Sellmeier’s dispersal model was employed to elucidate the obtained results of n, and dispersive factors were calculated and interpreted.Results: The incorporation of Sn nanoparticles led to improvements in the energy bandgap (Eg) values of PEDOT:PSS films. Notably, as the concentration of Sn increased, the n values decreased, indicating enhanced suitability for organic solar cell applications. The study also unveiled a decrease in the dielectric constant of PEDOT:PSS/Sn films with increasing Sn content, resulting in improved transmittance velocity and enhanced efficacy of microelectronic devices. This, in turn, promotes the development of large-frequency and large-velocity stretchy circuit boards.Discussion: The comprehensive assessment of optical and dielectric parameters, including complex dielectric constant, complex optical conductance, and nonlinear optical constants, provides valuable insights into the potential applications of PEDOT:PSS/Sn films. The larger nonlinear optical constants observed in the present films suggest their suitability for diverse applications such as all-optical switching, limiting, phase modulation, and frequency conversion. Overall, our findings highlight the promising potential of Sn-incorporated PEDOT:PSS thin films in advancing the field of optoelectronics and microelectronics.

Exact periodic solution of the undamped Helmholtz oscillator subject to a constant force and arbitrary initial conditions

The Helmholtz oscillator is a nonlinear mixed‐parity oscillator that models the asymmetric vibrations of many engineering and scientific systems. This paper investigated a general and completely integrable form of the Helmholtz oscillator and derived its exact periodic solution from the first integral of the governing differential equation. The considered Helmholtz oscillator has general linear and nonlinear stiffness constants, is subject to a constant force, and has arbitrary initial conditions. Its exact time period was derived in terms of the complete elliptic integral of the first kind, while the exact displacement was derived in terms of the Jacobi elliptic sine function. The validity of the exact solutions was verified for various combinations of the system parameters and initial conditions by comparing with numerical solutions. The exact solutions and numerical solutions were found to match perfectly. Furthermore, the exact solution was applied to analyze the vibration response of real‐world systems that could be modeled as Helmholtz oscillators. The present exact solutions provide benchmark solutions that could be used to determine the accuracy of new and existing approximate solutions for the Helmholtz oscillator.

Predictive functional control for separation processes by liquid-liquid extraction

A separation process by liquid-liquid extraction is a well-known and widespread industrial technology implemented to quantitatively recover valuable chemical elements. In the nuclear industry, such processes have been used for decades to recover uranium and plutonium from spent fuel. The process is non-linear and time constants vary over a wide range. Former studies on a simplified model showed linear controllers such as PID were not adapted to regulate these separation processes. The objective of this study is to propose process monitoring by using available physical models within the PAREX code and to validate the feasibility to monitor a separation process by using directly the PAREX code as a black box. The Predictive Functional Control (PFC) command law manages to monitor non-linear separation processes by liquid-liquid extraction, when using an existing physical model implemented in the PAREX code. An online alignment of the model on process values is necessary to keep the model sufficiently representative to predict the future behaviour of the process. As a reference benchmark, the PID control loop is also simulated with the physical model. The PFC and PID regulations are compared to evaluate the gain of using physical models implemented in the PAREX code. A simulation tool has been developed to implement the PID and Predictive Functional Control (PFC) controllers for separation processes by liquid-liquid extraction. The PFC command law manages to monitor non-linear separation processes, when using a physical model connected to the PAREX code. Even if the PID controller may be locally more efficient, the great strength of the PFC controller is to enable good performances on wider operating conditions, with an easier parametrization. The PFC algorithm is a mean to deal with the process characteristic features, like non-linearity and time constant change. The PFC controller appears to be a good candidate for experimental tests. A mid-term objective is to include the state estimator tool in the control loop to consolidate the controlled variable measurements. These developments may be regarded as an add-on module in a digital factory concept. Results shown in this article are only from simulation. For the sake of data confidentiality, studies with the PAREX code cannot be published and numerical parameters of the process are normalized. These simulations will be validated during further experimental tests.

Vehicle Crashworthiness Performance Prediction Through Fusion of Multiple Data Sources

Abstract This study aims to improve the prediction accuracy of the computer-aided engineering (CAE) model for crashworthiness performance evaluation at speeds beyond those defined by current regulations and public domain testing protocols. One way of achieving this is by integrating data from a few physical crash tests with the CAE data using machine learning models. In this study, two scenarios are investigated: (1) improving CAE model prediction accuracy using test data of a vehicle type that is the same as that of the CAE model; (2) improving CAE model prediction accuracy using test data from two different types of vehicles (e.g., two different sizes of SUVs). In the first scenario, a novel approach is proposed in the displacement domain (deceleration versus displacement) to enable data fusion to help recover the unmodeled physics in the CAE model. A nonlinear spring-mass model is used to simulate rigid-barrier vehicle frontal impact. A Gaussian process regression (GPR) model is then applied in conjunction with a Gaussian mixture model to capture the model bias of the nonlinear spring constant under a dynamic analysis scheme. In the second scenario, we propose a time-domain method (deceleration versus time) based on temporal convolutional network (TCN) and transfer learning. An initial TCN model is first trained by fusing CAE data with physical test data of the first vehicle type based on data augmentation. This data-augmented TCN model is then fine-tuned through transfer learning using CAE and test data of the second vehicle type. It leverages the domain-invariant representations of the two types of vehicles to enhance the CAE model prediction accuracy of the second vehicle type. Case studies are used to validate the proposed approaches and to demonstrate their efficacy in improving the prediction accuracy of the CAE models.

Synthesis and Characterization of PANI/ZnFe2O4 nRs with Different Doping Concentrations for Potential Applications in Various Fields

The wide-ranging potential of polyaniline (PANI) composites in energy storage, electrochemical, sensing, and electromagnetic shielding applications emphasizes researchers to improve its properties. Here, the doping of ZnFe2O4 nRs by 1, 3, and 5 wt. % within polyaniline has been done. Then, we characterize the doped material using techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR) to verify the successful incorporation of polyaniline onto the nRs. TGA showed that doping of PANI with ZnFe2O4 nRs enhanced the interfacial interactions between the two components. This provided a more stable matrix structure and enhanced the thermal stability of the composite. The transmission of light has been increased by about 18% due to the increase in crystallinity accompanied by ZnFe2O4 doping. As the ZnFe2O4 nRs doping rose, our PANI samples’ optical band gap values slightly decreased by about 10%. In addition, it has been found that the optical characteristics such as refractive index, extension coefficient, surface, and volume energy loss function essentially showed ZnFe2O4 doping dependency. The nonlinear constants of the doped samples have increased due to the new charge carriers and altered the electronic and optical properties of the composite material. Our obtained results show that PANI@ ZnFe2O4 nRs have potential applications such as optical sensors, electrochemical, optoelectronics, and photocatalysis.

Improvement of electrical performance of ZnO linear resistors by Y2O3 doping

ZnO-TiO2−MgO-Al2O3 linear resistors with various Y2O3 dopant concentrations were fabricated using the conventional solid-state reaction method. The comprehensive investigation of the impact of Y2O3 addition on the microstructure and electrical characteristics of the resistors was carried out. The results indicated that the Y2O3 phase hindered the growth of zinc oxide particles. Additionally, the incorporation of yttrium oxide increased the linearity of the resistors and affected the height of the grain boundary barrier (φb). Subsequently, a Y2O3-doped ZnO linear resistor with a nonlinearity constant (α) of 1.09 and a resistance-temperature constant (αT) of -2.51 × 10−3/ °C was effectively produced. The comprehensive evaluation of the microstructure and relevant electrical characteristics enables the efficient production of linear resistors with excellent electrical properties.

Nonlinear radiation effects on water-based nanofluid containing CNTs subject to heat source/ sink past a wedge

In this paper, a two-dimensional and incompressible laminar flow comprised of water-based carbon nanotubes over convectively heated moving wedge under the magnetic field and nonlinear radiation and heat production/ absorption is investigated. The base nanofluid (water) contains single wall carbon nanotubes (SWCNTs) and multiple walls carbon nanotubes (MWCNTs). In order to convert the dimensional nonlinear partial differential equations in nondimensional nonlinear ordinary differential form, an adequate set of similarity variables had been used. These set of equations and boundary conditions are evaluated by the implementation of RKF-45 (Runge–Kutta–Fehlberg fourth-fifth) order scheme. The influence of several physical parameters on particular nanoparticle’s volume friction, temperature and velocity ratio parameter, heat source/ sink parameter, nonlinear radiative constraint, exponent constant, magnetic factor, Eckert and Biot numbers is studied. An opposite behavior of volume fraction and velocity ratio parameters on velocity and energy profiles is achieved.

Catalytic dehydrogenation of ethylene diamine bisborane in ethylene diamine media

This study focuses on the catalytic dehydrogenation of ethylene diamine bisborane (EDAB). To this end, Pd–Ni–Zr–B–O catalyst was prepared in two steps using the co-precipitation method with NaBH4 and the impregnation method. The catalyst was characterized with XRD, SEM-EDX, and multi-point BET analysis. The effect of temperature (90 ºC-120 °C) on the dehydrogenation reaction of EDAB in an ethylene diamine medium was investigated. The hydrogen production yield significantly increased as the temperature increased and the reaction time reduced as well. The highest yield of an equivalent mole of hydrogen reached 5.96 mol hydrogen/mole EDAB at 120 °C. The reusability test of the catalyst was also carried out and the average hydrogen gas release (HGR) was found as 66.64 mL min−1.g−1. Kinetic analysis was examined. The activation energy was found as 74.5 kJ/mol using non-linear model rate constants.

Mechanosynthesis of semiconductor nanocrystalline Cu2ZnSnSe4 for solar cells

Cu2ZnSnSe4 is a promising material that can be used to make low-cost, high-efficiency thin-film solar cells. The present study, we established a simple and efficient approach for producing a single-phase Cu2ZnSnSe4 bulk material from fundamental precursors (Cu, Zn, Sn and Se) using dry ball milling. After every two hours of the dry milling process, X-Ray Diffraction (XRD) and Raman Spectroscopy investigations were carried out to investigate the movement towards single phase Cu2ZnSnSe4 and the concurrent secondary phase depletion. The development of Cu2ZnSnSe4 materials that crystallize in a Kesterite system is shown by the prominent diffraction peaks. The crystalline size of the materials is 10–20 nm and dislocation density is 3.02–3.22 ×1015 lines/m2. UV–Vis spectroscopy was used to investigate the optical properties of the materials. Using transmittance and reflectance data, the linear and nonlinear optical constants of Cu2ZnSnSe4 films were calculated and the bandgap value is 1.6 eV. Hence from these results we can conclude that the above synthesized powder can be used for the development of thin films via thermal or electron beam evaporations on desired substrate and also we can use for various energy harvesting applications as a photoabsorber.

A first-principles method to calculate fourth-order elastic constants of solid materials

A first-principles method is presented to calculate elastic constants up to the fourth order of crystals with the cubic and hexagonal symmetries. The method relies on the numerical differentiation of the second Piola-Kirchhoff stress tensor and a density functional theory approach to calculate the Cauchy stress tensor for a list of deformed configurations of a reference state. The number of strained configurations required to calculate the independent elastic constants of the second, third, and fourth order is 24 and 37 for crystals with the cubic and hexagonal symmetries, respectively. Here, we present conceptual aspects of our method, we provide technical details of its implementation and use, we assess its accuracy, and we discuss several applications. In particular, this method is applied to five crystalline materials with the cubic symmetry (diamond, silicon, aluminum, silver, and gold) and two metals with the hexagonal close packing structure (beryllium and magnesium). Our results are compared to available experimental data and previous computational studies. Calculated linear and nonlinear elastic constants are also used in the context of nonlinear elasticity theory to predict values of volume and bulk modulus over an interval of pressures. These predictions are compared to results obtained from density functional theory calculations to assess the reliability of our method.

Multi-Scale Modeling of Dielectric Polarization in Polymer/Ferroelectric Composites

Ferroelectric materials are attractive fillers for polymer composites due to their high and non-linear dielectric constants. In this study, the dielectric response of the epoxy/BaTiO3 composite is obtained by a Sawyer–Tower measurement. In addition, we propose a multiscale computational approach that allows simulation of the polarization behavior of polymer/ferroelectric composites on the timescale above 100 ms, which is several orders of magnitude longer than previous studies. The model is free of ad hoc parameters and therefore can simulate the polarization characteristics from first-principles. Both in experiments and simulations, non-linear hysteresis behavior was observed in the epoxy/BaTiO3 composite even when the electric field across the BaTiO3 is more than an order of magnitude lower than the coercive field. The computational results suggested that this originates from the domain wall motion in BaTiO3. Some practical implications drawn from the computational results are discussed.