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Actuating performance for functionally graded piezoelectric materials with interdigitated electrodes
Materials Today Bio ( IF 0 ) Pub Date: 2023-01-07 , DOI:
10.1007/s10832-022-00299-2
In this article, the actuating performance for functionally graded piezoelectric materials (FGPM) using the \(d_{33}\) mode actuation is investigated. The material properties vary continuously across the thickness direction, according to a fraction volume power law distribution, so that top and bottom surfaces consist of pure PZTG and the mid surface is composed of pure aluminium. The percolation phenomenon is taken into account. The optimization of the interdigitated electrode (IDE) design for FGPM is performed using finite element analysis. Several design parameters (electrodes number, width and spacing) are considered to improve the produced displacement for a cantilever plate, and the use of multilayered IDE is intended. Results are discussed for several distributions of the components in the FGPM thickness. A comparison with the \(d_{31}\) mode actuation is presented.
Materials Today Bio ( IF 0 ) Pub Date: 2023-03-08 , DOI:
10.1007/s10832-023-00305-1
The preparation of CuCo2O4 material with a suitable phase structure and grain size can improve its lithium storage performance. In this paper, CuCo2O4 hexagonal nanocrystal were successfully obtained by molten salt modified urea combustion method. Compared with the traditional high temperature solid state methods such as combustion method, rheological phase method and precipitation method, this method maintains the advantage of simple operation, and the particle size of the sample is smaller. The effect of heat treatment temperature on the lithium storage performance of CuCo2O4 was also studied systematically in this paper. The result shows that 800 ℃ is the best heat treatment temperature for CuCo2O4, and the sample synthesized by the molten salt urea combustion method exhibited the best electrochemical properties with a specific capacity of 705 mA h g-1 after 100 cycles under a constant current of 200 mA g-1 in the voltage range of 0.01-3?V. Therefore, a new strategy of high temperature solid state preparation has been developed in this paper, and the CuCo2O4 synthesized by this method is a promising anode material for lithium ion battery application.
Materials Today Bio ( IF 0 ) Pub Date: 2022-06-25 , DOI:
10.1007/s10832-022-00288-5
The ferroelectric Ir/PZT/Pt and Au/PZT/Pt capacitor structures are studied by the electron beam induced current (EBIC) technique and the steady-state current–voltage dependencies. EBIC data reveal the change in the local field at the PZT/metal interfaces caused by migration of oxygen vacancies \({V}_{o}^{**}\) under an action of applied electric field. Ir/PZT and Pt/PZT interfaces block \({V}_{o}^{**}\) movement causing their accumulation near the cathode interface. An electrons injection from the metal cathode to the PZT leads to formation of induced p–n junction. The steady-state leakage current in this case is well described by modified equation for the p-n diode, which considers an action of the counter electric field caused by electrons injection. In the case of transparent for oxygen vacancies Au/PZT cathode oxygen vacancies leave the PZT bulk and current–voltage dependence demonstrates a region of negative differential conductivity at high electric fields. The proposed p–n junction formalism can be used for engineering of PZT-based devices.
Materials Today Bio ( IF 0 ) Pub Date: 2022-08-06 , DOI:
10.1007/s10832-022-00290-x
Polycrystalline samples of Bi4V2(1-x)Cu2xO11-3× were prepared by solid state reaction method. Thrust of the work is to stabilize high temperature conducting γ-phase at room temperature. XRD and DSC analysis indicates orthorhombic ‘α’ phase for x?≤?0.08 to tetragonal γ-phase transition for x?=?0.1, at room temperature. Variations of real and imaginary impedance as well as complex electrical modulus with frequency are reported. Experimental impedance spectroscopic data was theoretically fitted and equivalent circuits are proposed. Nyquist plots revealed contribution from grain as well as interface. Variations of impedance, dielectric permittivity and AC conductivity as a function of frequency at selected temperatures are reported. The AC conductivity was fitted with Jonscher’s power law and the power law exponent (η) was found to be?
Materials Today Bio ( IF 0 ) Pub Date: 2023-07-03 , DOI:
10.1007/s10832-023-00320-2
The substitution of Dy3+ ions in the M-type hexaferrite structure has been successfully synthesized by sol-gel combustion method according to the formula SrDyxFe12-xO19 (x = 0.0, 0.08, 0.16, 0.24, 0.32, and 0.40). The XRD analysis confirmed the formation of single-phase M-type hexagonal structures up to x = 0.24 compositions. The average crystallite size for the SrDyxFe12-xO19 samples ranges from 90.64 to 290.04 nm, whereas the value of the lattice parameters 'a' and 'c' vary from 5.8590 - 5.8879 ? and 22.9675 - 23.0761 ?, respectively. Scanning electron microscopy (SEM) was used for morphological analysis. Due to ceasing effect of polarization, the dielectric constant decreases in the higher frequencies. The SrDyxFe12-xO19 hexaferrites exhibit non-Debye type dielectric relaxation behavior confirmed by complex impedance spectroscopy (CIS) investigation. The SrDyxFe12-xO19 samples can be utilized as a promising material for various device applications due to a decrease in dielectric loss and an increase in dielectric constant with increasing Dy3+ ions concentration.
Materials Today Bio ( IF 0 ) Pub Date: 2022-06-04 , DOI:
10.1007/s10832-022-00283-w
NaNbO3-based antiferroelectric (AFE) ceramics have the prominent advantages of stable performance and low cost. However, its energy storage property is often remarkably limited by the hysteresis of the antiferroelectric to ferroelectric phase transformation. In this work, 0.88Na(Nb1?xTax)O3–0.12Bi0.2Sr0.7TiO3 (x?=?0–0.075) antiferroelectric ceramics were synthesized using a conventional mixed oxide route. Ta5+ were completely dissolved into the lattice of 0.88NaNbO3–0.12Bi0.2Sr0.7TiO3 to form a pure perovskite structure. With increased Ta content, the AFE orthogonal P phase was replaced by AFE orthogonal R phase progressively. Meanwhile, the dielectric constant curve showed relaxor-like properties. As a result, slender P–E curves with reduced hysteresis loss and decreased residual polarization were achieved. Interestingly, a large recoverable energy storage density (Wrec?~?2.16?J?cm?3) and high energy storage efficiency (η?~?80.7%) were obtained simultaneously under a low?driving electric field of 15?kV?mm?1 at doping ratio (x) of 0.075. In addition, the 0.88Na(Nb0.925Ta0.075)O3–0.12Bi0.2Sr0.7TiO3 sample exhibited excellent temperature stability, indicating an ideal candidate in future pulsed power capacitor.
Materials Today Bio ( IF 0 ) Pub Date: 2023-04-28 , DOI:
10.1007/s10832-023-00310-4
La0.6Sr0.4FeO3 ceramic was elaborated by solid-state route. Preliminary room-temperature structural analysis evidences the sample formation in the orthorhombic structure and its phase purity. Electrical properties of the studied ceramic have been investigated according to dielectric measurements in the frequency range 10–1 - 106 Hz and the temperature range 93 - 313 K. Electrical conductivity curves exhibit a step-like behavior, at low temperatures, attributed to grain boundaries and grain contributions which are well described by the two Jonscher equations. The grains conduction mechanism is consistent with the thermally activated hopping of small polaron (SPH). Whereas, this mechanism is no longer satisfied for grain boundaries conduction mechanism at lower temperatures. Indeed, this latter is governed by the variable range hopping (VRH) model. This electrical conductivity analysis is further confirmed by the complex impedance formalism according to the obtained activation energies. Analysis of Nyquist plots at low temperatures has evidenced the presence of two grain boundaries effects attributed to the heterogeneous structure of La0.6Sr0.4FeO3 grain boundary according to the morphological analysis. Such characteristic may be at the origin of the grain boundaries electrical conductivity mechanism change at low temperatures.
Materials Today Bio ( IF 0 ) Pub Date: 2023-03-16 , DOI:
10.1007/s10832-023-00306-0
In this work, it was aimed to synthesize and characterize rare earth metal-free cerium-based electrolytes that might be used in solid oxide fuel cells (SOFCs) by doping calcium, strontium, or magnesium to CeO2. For this purpose, CeO2, CaxCe(1-x)O(2?δ) (0.16 ≤ x ≤ 0.24), SrxCe(1-x)O(2?δ) (0.02 ≤ x ≤ 0.08) and MgxCe(1-x)O(2?δ) (0.07 ≤ x ≤ 0.13) were prepared by using citrate-nitrate combustion method. The solubility limits, microstructural and physical properties of the samples were characterized with XRD, SEM, TG-DTA and impedance analysis. It was found that all samples were in fluorite structure similar to the undoped ceria. The solubility limits of Ca2+, Sr2+ and Mg2+ were 21%, 6% and 12% (by mole) respectively based on XRD analysis results. The relative densities of sintered pellets at 1400 °C were more than 90%. Electrochemical impedance spectroscopy analysis, in which the ionic conductivities of the samples were measured, revealed that the Ca0.2Ce0.8O2-δ (CCO20) sample sintered at 1400 °C showed the highest ionic conductivity value of 4.47 x10-2 S.cm?1 at 800 °C. It was determined that the O2- ion conductivity decreased with the order of Ca2+ ≈ Sr2+ >> Mg2+. Conductivities increased with increasing dopant ratio, reached a maximum below the ratios of solubility limits, and then decreased. The obtained results showed that Ca or Sr doped electrolytes prepared by the citrate-nitrate method can show ionic conductivities close to the state-of-the-art Sm doped Ceria electrolytes. It has been determined that Mg doping is quite ineffective.
Materials Today Bio ( IF 0 ) Pub Date: 2021-11-11 , DOI:
10.1007/s10832-021-00273-4
Optical and photocatalytic applications of Al2O3 and TiO2 ceramics are limited, especially under visible light, due to their wide bandgap; so, this parameter plays an important and even decisive role in these applications. In the present study, Al2O3-TiO2 ball milled powders were sintered by spark plasma sintering (SPS) at 1573?K. The products were characterized using XRD, SEM, UV–Vis and electrochemical methods. The results indicated effective improvement in the light absorbing capability of the composites (up to 95%) under visible light and the decrease of the band gap down to 2.2?eV owing to the increase of oxygen vacancies, which was, in turn, due to the reduced atmosphere of the sintering process. In addition, formation of a new phase (Al2TiO5) during sintering greatly affected the absorption of Al2O3-TiO2 composites in the visible light region due to the increase in the fraction of the charge carrier separation centers. Photo-luminescence spectroscopy also showed that tialite formation could be effective in improving the charge separation efficiency.
Materials Today Bio ( IF 0 ) Pub Date: 2021-11-10 , DOI:
10.1007/s10832-021-00266-3
Piezoelectric nanogenerators (PENG) collect energy from the environment and biomechanical movements and convert this mechanical energy into electrical energy. They have become an attractive alternative to traditional rechargeable batteries for providing electrical power low energy portable devices. As PENGs became the center of attention in robots, wearable devices, medical equipment, and many other fields, the development of piezoelectric materials has become mandatory. This review reviews the basic information, structure, properties, and preparation methods of Barium Titanate, one of the most important PENGs, its development in recent years, and the progress towards high energy generation.
Supplementary Information
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