Journal of Electroceramics最新文献

Graphene-oxide (GO) based composites exhibit promising energy storage properties like adaptable porosity, chemical stability, excellent conductivity, and exceptional ability to charge storage processes. However, the inherent rigid structure of GO limits its use for modern flexible and disposable energy storage devices. This study presents the fabrication of Graphene oxide/tin sulfide-based flexible composites by employing natural fibers (as a binder) extracted from wasted bioresources (banana peels). GO and tin sulfide (SnS) nanoparticles are synthesized by a facile and fast microwave-assisted approach. Furthermore, SnS nanoparticles are deposited electrochemically on fabricated GO-based paper electrodes to enhance their electronic conductivity and energy storage characteristics. Highly flexible paper-based electrodes are characterized by different characterization techniques, i.e., scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and RAMAN spectroscopy to observe their morphology and chemical bonding. Electrochemical measurements, including Cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS), are performed to observe the kinetics and capacitive behavior of the electrodes. LC/GO/SnS 2400 s exhibit specific capacitance of 68.78 F/g at which is greater than GO/LC (30.97 F/g). Prepared tertiary composite (GO/LC/SnS) depicts excellent charge-discharge behavior. LC/GO/SnS 2400 s reveals power density of 84.6 W/kg at 4.57 Wh/kg and also show specific capacitance of 55.4 F/g. Superior electrochemical characteristics are indicated by the GO/LC/SnS (2400 s) electrode and lower Rs (0.89Ω) and Rct(1.7Ω) values as compared to the binary composite (GO/LC). These composites provide a deep insight into the construction of electrodes with high ionic/electronic conductivity for fast-charging energy storage devices.

Renewable energy is accelerating rapidly, driven by the urgent need to mitigate environmental depletion, which has intensified the demand to produce environment-friendly perovskite materials. Among the promising candidates, undoped bismuth sodium titanate-strontium titanate 0.74Bi_0.5Na_0.5TiO₃–0.26SrTiO₃ (BNST) ceramics and niobium-doped BNST (BNST–Nb) ceramics have emerged as innovative materials that were prepared using mixed oxide solid-state synthesis. The X-ray diffraction (XRD) confirmed the phase structure of BNST–Nb, while the dense microstructure with equiaxed grain size was confirmed by scanning electron microscopy (SEM). The electrochemical impedance spectroscopy (EIS) confirmed that electrical microstructure explained the grain and grain boundary contribution. Increasing temperature, with increased Nb content in BNST, predicts a dielectric constant (ε_r ̴ 3000), and curie temperature (T_c ̴ 250 ℃) for 0.5% Nb. It has an energy density (W) of 0.6 J/cm³ and an efficiency (η) of 93% was observed. Niobium-doped BNST ceramics have specific benefits over other materials, especially for high-temperature applications at 500 ℃. Unlike many typical ceramics, which deteriorate at high temperatures, BNST-Nb retains and even improves its dielectric characteristics. The investigation of charge conduction and polarization at high temperatures yields novel insights, making BNST–Nb a viable material for advanced thermal and electrical applications.

The magnetic characterization of the multiferroic composites has become much important for their applicability in improving devices efficiencies. In this report, we have attempted to study the magnetic properties of the multiferroic composites consisting of Mn/Nd doped CoFe₂O₄ and Yb doped PbZrTiO₃ by exploring a new technique called the First Order Reversal Curve (FORC) and also include morphological analysis of the composites and the parent phases. The morphological characterization with the Scanning Electron Microscope confirmed the average grain size decreased with an increase in the ferrite content. The FORC analysis of Mn/Nd doped Cobalt ferrite (CMnFO) and the composites grant the information about the switching field and the interaction field distribution, determining the various magnetic properties of the composites including the magnetic mixtures and the domain state of magnetisation. The FORC analysis also confirmed the nature of the interactions occurring in the system subjected to the shift of the FORC distribution along the interaction axis. The FORC studies determined the existence of the unique magnetic phase CMnFO in all the composites with no additional magnetic phase. The FORC study also describes the influence of the grain size on the FORC distribution of the samples and also the impact of the varying concentration of the ferrite phase on the intensity of the FORC distribution. Further, the Day plots obtained reveal that all the composites and CNdFO have pseudo-domain while the CMnFO phase has a single domain structure.

In this work, NN-based lead-free ceramics [Na_{1 − 3x/2}Bi_3x/2) (Nb_1 − xSr_x) O₃] where x = 0.00, 0.04, 0.05, 0.06, 0.07, and 0.08 were synthesized via solid-state reaction route. XRD study confirmed the increase of the appearance of secondary phase with the increase of doping concentrations. FE-SEM study showed the decrease of average grain size with the increase of doping concentration. Dielectric study showed dielectric constant (ε_r) ⁓ 1051 with low dielectric loss (tanδ) < 0.6 near T_c in [(Na_0.91Bi_0.09) (Nb_0.94Sr_0.06) O₃] ceramics at 1 kHz frequency. Polarization vs. electric field ferroelectric study of [(Na_0.91Bi_0.09) (Nb_0.94Sr_0.06) O₃] ceramics demonstrated the highest total energy storage density (W_total) of ~ 1.74 J/cm³ with a high recoverable energy storage density (W_rec) of ~ 1.28 J/cm³, with an efficiency (η) ~ 74% at an electric field of 145 kV/cm among the synthesized ceramics.

Piezoelectric ceramics are widely used in aviation, aerospace, communications, weapons, electronics and other high-tech fields. This study focuses on high piezoelectric Pb(Nb_2/3Ni_1/3)O₃-Pb(Hf_1/2Ti_1/2)O₃ (PNN-PHT) binary ceramic as the research matrix. By doping Li₂CO₃, the Curie temperature is increased, and the effects of doping concentration on microstructure, phase structure, and electrical performances of the ceramics are discussed. The study found that all ceramics were rhombohedral -tetragonal mixed phases, and no impurity phases were generated. When x = 0.20, the samples have the best mass density ρ = 8.0291 g/cm³, the best piezoelectric constant d₃₃ = 702 pC/N, the largest signal piezoelectric constant d₃₃* = 943 pm/V, the largest strain value S = 0.56%, the highest electromechanical coupling coefficient k_p = 51.9%, excellent hardness H = 4.5221 GPa and fracture toughness K_IC = 1.06 MPa•m^0.5, and a higher Curie temperature T_C = 155 ^oC. At the same time, the x = 0.20 sample has excellent temperature stability in 20 ~ 150 ^oC, achieving a balance and compromise between piezoelectric properties and temperature stability.

High-temperature solid-phase method were used to prepare lead-free piezoelectric ceramics of 0.67BiFeO₃-0.3BaTi_1 − xHf_xO₃ and the effects of B-site Hf⁴⁺ doping on the microstructure, dielectric properties, and ferroelectric properties of the ceramics were investigated systematically. The results have shown that partial substitution of Hf⁴⁺ for Ti⁴⁺ did not cause significant changes in the phase structure, and the components remained in the multi-phase boundary region where tetragonal and rhombohedral structures coexisted, resulting from the same electricity price and small differences of Hf⁴⁺/Ti⁴⁺ ion radius. However, doping with Hf⁴⁺ can effectively increase the content of Fe³⁺ and reduce the leakage current of BFO-BT binary system. The Curie temperature of BFO-BT-0.05Hf ceramic is 387 ℃, which effectively maintaining the high Curie point of the BFO-BT binary system. The undoped BFO-BT exhibits a typical ferroelectric P-E hysteresis loop, with P_r=26.47µC/cm² and E_C=34.54 kV/cm. After appropriate modification with Hf⁴⁺, the ferroelectric properties of the BFO-BT system were significantly improved, with P_r of 33.34 µC/cm² and E_C of 31.90 kV/cm for BFO-BT-0.05Hf. The strain of BFO-BT-0.05Hf ceramic at room temperature is 0.19%. Meanwhile, the electric field induced-strain of the ceramic at 125 ℃ and 80 kV/cm is 0.43%, and the high-field piezoelectric coefficient (d₃₃^*) is 543 pm/V.

In this work, Ruddlesden popper phase (RPP) family member with formula La₂XO₄ has been explored by using theoretical quantum computational method CASTEP code to analyze its electronic, optical, and mechanical properties. Moreover, density functional perturbation theory has been employed to calculate the thermodynamic properties of the compounds. Results revel that these compounds have zero-point energy ranging from 0.8648 to 1.0875 eV which is important for solar applications since it affects electron-phonon coupling, bandgap, and material stability. Heat capacity clearly rises with temperature, approaching to Dulong–Petit limit at approximately 600 K. Electronic structure analysis revels that the compounds are semiconductor in nature with direct bandgaps for La₂ZnO₄ (1.62 eV) and La₂CaO₄ (2.09 eV) while La₂MgO₄ (3.40 eV) and La₂BeO₄ (3.56 eV) demonstrate indirect bandgaps. Optical features of the compounds are also analyzed including dielectric function, optical conductivity, absorption coefficient, extinction coefficient, reflectivity, refractive index, and loss function for photovoltaic applications. Notably, high values of absorption coefficient (10⁵ cm^− 1₎, dielectric function (10), optical conductivity (8 fs^− 1), refractive index ranging from 3 to 4 lie in the visible and near UV range. Additionally, elastic properties confirm the ductile nature of these materials, supporting their suitability for flexible photovoltaic and optoelectronic applications.

In this work, bismuth doped barium titanate was synthesized by the sol– gel method. The samples were prepared using the chemical formula, Ba_1 − xBi_xTiO₃ in which compositions corresponding to x = 0.05 and 0.15 i.e., Ba_0.95Bi_0.05TiO₃ (BBT5) and Ba_0.85Bi_0.15TiO₃ (BBT15), showed a relaxor - type behavior. The temperature and frequency dependent dielectric measurements, were made which clearly showed that the peak corresponding to the dielectric maxima shifted towards higher temperature as frequency is increased in both the cases. The calculated values of the index of relaxation and the broadening parameter from the linear fit of the experimental data which was plotted according to the modified Curie– Weiss law also supported this behavior. At 500 kHz, the index of relaxation was calculated as 1.61 and 1.43 for BBT5 and BBT15 respectively and the broadening parameter as 121.5 K and 96.9 K for BBT5 and BBT15 respectively. It was also concluded that lower concentration of bismuth (x = 0.05) showed a better performance as compared to that of the higher one.

In this work, Density Functional Theory (DFT) has been employed to examine the structural, electronic, magnetic and optical characteristics of alkaline earth metals doped (Be, Mg and Ca) doped (Hf_1-xA_xO₂) alloys using the FP-LAPW (full-potential augmented plane wave plus local orbital) method and GGA and TB-mBJ exchange correlation methods. All studied compounds are structurally stable due to negative (formation energy) values. The computed results, including the band gap and lattice characteristics, correspond well with the existing experimental results. According to the band structure and density of states calculation, Hf_1-xA_xO₂ has wider band gaps for spin up configuration and reduced energy gaps of 4.71 3.41, 3.35 and 3.02 eV has been found for pure c-HfO₂, Hf_1-xMg_xO_2, Hf_1-xCa_xO₂ and Hf_1-xBe_xO₂ respectively. The PDOS results demonstrate that the formation of conduction and valance bands is due to Hf-6s orbitals and Mg/Ca/Be-s states. Additionally, we have investigated the optical characteristics that correspond to the real and imaginary portion of the dielectric function in the region of 0–12 eV, such as absorption coefficient, optical conductivity, refractive index, reflectivity and energy loss function. Moreover, Hf_1-xCa_xO₂ has a wide range of absorption in the UV-visible region, which indicates that this material is suitable for opto-electronic and solar cell applications. The refractive index suggests that Hf_1-xCa_xO₂ could be a potential candidate for applications to high-density optical data storage devices.

In this investigation, we report the synthesis of barium iron tantalate (BaFe_0.5Ta_0.5O₃; BFT) utilizing the molten salt method. The process yielded pure-phase perovskite powders at the relatively low calcination temperature of 700 °C. Subsequent fabrication of BFT ceramics from these calcined powders revealed notable properties. X-ray diffraction (XRD) analysis confirmed the cubic symmetry of the ceramics. All samples exhibited pronounced frequency-dependent dielectric behavior, with those sintered at 1,250 °C demonstrating particularly remarkable properties. Specifically, these ceramics achieved exceptionally high dielectric constants (ε_r ~ 5.30 × 10⁵ at 1 kHz and 230 °C). Impedance spectroscopic analysis revealed that the dielectric behavior of the ceramics can be attributed to the Maxwell–Wagner polarization mechanism, as the ceramics demonstrated heterogeneous conduction.