Papers by Keyword: BaTiO₃

Abstract: We report double scaling electrical transport in (Fe₃O₄)_1-x/(BaTiO₃)ₓ nanoparticle-composite sinters (NPCSs), where charge conduction arises from the coexistence of variable range hopping and percolation. Understanding the interplay between these mechanisms is essential for designing composite materials in which microstructural connectivity and carrier localization can be tuned for targeted electronic properties. The NPCSs were synthesized via low-temperature hydrogen reduction and sintering of α-Fe₂O₃ and BaTiO₃ nanoparticles (average diameter ~100 nm) at 500 °C for 3 h in an Ar (90%)/H₂(10%) atmosphere, yielding x values from 0.0 to 0.7. X-ray diffraction and scanning electron microscopy confirmed phase purity, the coexistence of Fe₃O₄ and BaTiO₃, and systematic grain-size evolution with BaTiO₃ content. Electrical resistivity increased with x and followed 3D Mott’s variable range hopping behavior, with ln ρ vs. T ⁻¹ᐟ⁴ (ρ: electrical resistivity; T: temperature) remaining linear and slopes increasing with x, consistent with shorter hopping lengths and enhanced carrier localization. Percolation analysis in the 150–300 K range yielded a conductivity critical exponent of ~3, significantly higher than the ~2 predicted for simple 3D percolation, indicating that geometric connectivity alone cannot explain the transport. These results provide compelling evidence that charge conduction in these composites is governed by a double scaling mechanism, in which variable range hopping and percolation coexist and jointly control electronic transport through the combined influence of microstructure and composition.

Abstract: The oil and gas sector faces challenges in optimizing oil recovery from reservoirs due to trapped oil due to interfacial tension and surface forces. Characterizing anisotropic dielectric properties is crucial. The petroleum business is quickly changing, and a massive advancement in the application of nanotechnology in this field is envisaged. Because magnetic nanoparticles (MNP) are solid, tiny, and adsorb at the oil-water interface, they might be helpful. The interaction of MNP with electromagnetic waves appears to be capable of altering interfacial tension, which will boost oil recovery. The interaction of an oscillating B-field of electromagnetic waves with magnetic domains causes energy dissipation due to a shift in magnetic anisotropy from the easy axis of magnetization. The use of anisotropy energy in mobilizing oil in a porous media has recently been investigated. BaTiO₃ nanoparticles (NPs) were synthesized for this purpose, and their influence on oil mobility under electromagnetic waves (EM) was studied. The anisotropy energy was computed and determined to be 7.34kJ/mol. Under EM, the easy axis magnetization of BaTiO₃ nanoparticles oscillates and changes direction continually, facilitating oil mobilization in the porous media. The EM findings for reducing interfacial tension (IFT) between oil and water ranged from 4.5mN/m to 0.89mN/m. Under EM, it was discovered that BaTiO₃ nanoparticles might lower IFT by roughly 60%. The IFT must be small enough to allow oil flow during mobilization. The simulation findings demonstrate that the adsorption energy of n-hexane on the surface of hematite has a 47.9% lower energy value than water. With a 115.4% percentage difference, the stress autocorrelation function of n-hexane with hematite is greater than that of water.

Abstract: The 5 mol% Fe-doped BaTiO₃ ceramic has been synthesized by using solid-state method. The sample was characterized by X-ray diffraction (XRD) and Impedance spectroscopy. It is interesting to note that the sample can developed a phase transformation between 1000 °C to 1350 °C. The XRD results showed that sample exhibited cubic structure when heated at 1000 °C and developed oxygen non-stoichiometry when it was heated at 1350 °C for 8 hours. It was confirmed by the ceramic color changes. The dielectric properties of the sample is relatively low which is due to the oxygen non-stoichiometry effect and gives the dielectric constant, ε_r value around 150 at 30 °C with frequency 1 kHz. The capacitance value of this sample lies within 10^-8 to 10^-10 which represents that the electrical properties of the sample has shown bulk and grain boundary response. There are pores that can be observed from the SEM images indicates the porosity of the sample which is in a good agreement with the low dielectric constant value. Moreover, the grains are composed of rectangular orientations, hexagonal shapes and inhomogeneous microstructures that might represent the coexistence of tetragonal and hexagonal phase of the sample.

Abstract: The BaTi_0.88Zr_0.12O₃ ceramic has been synthesized by using a conventional solid-state reaction method and sintered at 1450 °C in air for 3 hours. The structural and dielectric properties of the sample were investigated. It was found that the sample exhibited tetragonal structure with space group P4mm. The maximum dielectric constant, ε_r value was obtained at T_c (70 °C) about 2800 measured at 1 kHz. The dielectric peak was broad which might be due to the pinching effect. However, maximum ε_r value was quite low may be attributed by the T_c and other phase transition point might be not fully coalescence. Another phase transition temperature was vaguely observed around 30 °C to 40 °C. The dielectric properties of the sample were dominated by the grain effect with capacitance values lie within range of 10^-10 to 10^-9. The SEM images shows that the average grain size of the sample was quite small about 2.9087 μm. It might be due to the contribution of Zr⁴⁺ with lower grain growth rate.

Abstract: The dielectric properties and crystal structure of Ba_0.85Sr_0.15TiO₃ and Ba_0.85Sr_0.15Ti_0.92Zr_0.08O₃ ceramics were studied. The samples were synthesized by using solid-state method. The results show that the samples were single phase. The Ba_0.85Sr_0.15TiO₃ exhibited tetragonal structure (space group P4mm), while with addition of 8 mol% Zr into Ba_0.85Sr_0.15TiO₃ it shows that the sample exhibited orthorhombic structure (space group Amm2). The dielectric constant value increased from 1094 for pure, up to 4211 for Ba_0.85Sr_0.15Ti_0.92Zr_0.08O₃ ceramic at T_c measured at 1 kHz. The T_c decreased from 80 °C down to 60 °C as 8 mol% Zr ions doped into Ba_0.85Sr_0.15TiO₃ composition. The Ba_0.85Sr_0.15Ti_0.92Zr_0.08O₃ ceramic exhibited lower dielectric loss, tan δ about 0.006 compared to Ba_0.85Sr_0.15TiO₃ ceramic (tan δ = 0.009) when measured at 110 °C with frequency 1 kHz. The slope at low frequency region in capacitance vs frequency plot for both samples attributed by the grain boundary effect, whereas the high frequency plateau associated with the bulk response. The impedance spectroscopy analysis results show that both samples are dominated by the bulk response when an incomplete semicircle arc was observed in Zʺ vs Zʹ plot.

Abstract: The BaTi_0.905Sn_0.095O₃ ceramic has been synthesized by using a solid-state method and sintered at 1450 °C in air for 3 hours. The doping effect of 9.5 mol% Sn into BaTiO₃ ceramic towards its crystal structure, dielectric properties and microstructure were investigated. The X-ray diffraction (XRD) analysis shows that the sample exhibited tetragonal structure with space group p4mm. The dielectric constant, ε_r measurement revealed that the sample reached the maximum ε_r value about 4393 when measured at T_c around 45 °C with frequency 1 kHz. The dielectric loss value was considerably low about below than 0.3 for the temperature range from 30 °C to 150 °C measured at 1 kHz. The capacitance value range lies between 10^-9 and 10^-10 indicates the bulk effect has dominated the electrical properties of the sample. It shows a good correlation with the microstructure results where the grains were well developed and homogenously distributed.

Abstract: In this work, PVDF/BaTiO₃ nanocomposites consisting of polyvinylidene fluoride (PVDF) as matrix and BaTiO₃ (BT) as fillers were prepared by ball milling and hot-pressing process. It is known that nanofillers content and frequency affect the effective dielectric permittivity of the nanocomposites materials. Therefore, a developed model based on deep neural network (DNN) was used to study the effect of the input parameters on the dielectric permittivity of the nanocomposites. The volume fraction (vol%) of BT and frequency of alternating current (AC) were selected as the input parameters and the effective dielectric permittivity as the output response. The results show that the developed DNN model was able to predict the effective dielectric permittivity of PVDF/BT nanocomposites with a correlation coefficient (R) of 0.997. Thus, our study confirmed the accuracy and efficiency of the developed DNN model for predicting the relative dielectric permittivity of PVDF/BT nanocomposites.

Abstract: Barium titanate (BaTiO₃) is a perovskite based oxides with many potential application in electronic devices. From experimental report BaTiO₃ has wide energy band gap of about 3.4 eV which by doped with Ca and Zr at A- and B- sites respectively can enhance their piezoelectric properties. Using first principles method within the density functional theory (DFT) as implement in Quantum Espresso (QE) with the plane wave pseudo potential function, the influence of the Ca and Zr doping in BaTiO₃ are studied via electronic properties: band structure, total density of states (TDOS) and partial density of states (PDOS). The energy band gap calculated was underestimation which is similar to other DFT work. Two direct band gap where observed in Ba_0.875Ca_0.125Ti_0.875Zr_0.125O₃ sample at Γ- Γ (2.31 eV) and X- X (2.35 eV) symmetry point.

Abstract: It is expected that BiFeO₃-based materials will have both ferroelectricity and ferromagnetism. (1-y)BiFe_(1-x)Mn_xO₃-yBaTiO₃ system was prepared using solid state reaction method. The goal of this study is to uncover the impacts of Mn doping and BaTiO₃ content on the crystal structure, magnetism and ferroelectric properties. By forming a solid solution with BaTiO₃, stable perovskite BiFeO₃ was achieved. The rhombohedrally distorted (1-y)BiFe_(1-x)Mn_xO₃-yBaTiO₃ showed weak ferromagnetism due to the composition of BaTiO₃ and the doping of Mn ion. 0.8BiFe_0.9Mn_0.1O₃-0.2BaTiO₃ and 0.7BiFe_0.9Mn_0.1O₃-0.3BaTiO₃ ceramics exhibited typical P-E hysteresis loops.

Abstract: In this work, BaTiO₃ nanoparticles were synthesized through hydrothermal method. The powder obtained from the hydrothermal process (as-synthesized powder) was calcined at 1000 °C. The phase formation and morphology of the as-synthesized and calcined powders were studied using X-ray diffraction (XRD), thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyzer, and transmission electron microscope (TEM). The XRD data showed that the as-synthesized powder is partially amorphous. Upon calcining the powder at 1000 °C, highly crystalline BaTiO₃ with tetragonal structure was obtained. As shown by TGA and DSC analysis, the precursor powder was completely transformed into BaTiO₃ at 1000 °C. The presence of BaCO₃ as an impurity phase in the powder is due to the lack of Ba²⁺ / Ti^3+/4+. Transmission electron microscope images showed that the particle size of the as-synthesized powder increased after calcination due to crystal growth. In addition, nanocubes with the average size of around 11.66 nm were obtained as a result of the calcination compared to the ellipsoid like particles of the as-synthesized powder.