Journal of Materials Science: Materials in Electronics最新文献

In this work, Ba_1-xLa_xZrO₃ (x = 0, 0.04, 0.08, 0.12, 0.16) samples were prepared using a solid-state reaction method. The analysis of XRD patterns ensured the cubic structures with space group Pm3m and lattice parameters by Rietveld refinement. The density functional theory (DFT) has been employed to study the electronic band structure and density of states. The field emission scanning electron microscope (FESEM) is used to investigate the surface morphology of studied samples and calculate the average grain size in the 0.2 to 0.8 µm range. Fourier transform infrared (FTIR) spectroscopy observes the existence of functional bonding in all samples. The dielectric and impedance measurements have been carried out using electrochemical impedance spectroscopy (EIS) in the high-frequency region. The electronic and optical of pure BaZrO₃ and Ba_1-xLa_xZrO₃ (x = 0.12) are computed by density functional theory (DFT) calculations. The BaZrO₃ has an indirect band gap of 3.52 eV, whereas Ba_1-xLa_xZrO₃ (x = 0.12) reveals a direct band gap of 3.36 eV. The band gap transitions from an indirect to a direct band gap with La-doping. The optical characteristics, such as dielectric constants, absorption coefficient, reflection, refractive index, optical conductivity, and optical loss, are investigated, and Ba_1-xLa_xZrO₃ (x = 0.12) responds optically well to the ultraviolet range. This analysis suggests that Ba_1-xLa_xZrO₃ is a suitable candidate for UV-based photovoltaics and photodetectors.

An effective growth method utilizing a slow evaporation process at room temperature has been implemented to produce the centrosymmetric semi-organic crystal of succinic acid magnesium sulphate (SAMS). The single crystal X-ray diffraction analysis indicates that the SAMS crystal exhibits a monoclinic crystal structure, with cell dimensions of a = 5.18 Å, b = 8.88 Å, c = 5.60 Å. The powder x-ray diffraction analysis indicates that the grown crystals possesses excellent crystallinity. The findings indicated a negligible level of absorption within the UV–Visible spectrum, with a lower cutoff wavelength identified at 245 nm. Furthermore, the optical band gap energy was determined to be E_g = 5.06 eV and optical transmittance spectrum demonstrated. An examination was conducted to determine the vibrational frequencies of the crystal through FT-IR spectral studies. The dielectric investigations of the crystal sample in its original state reveal a diminished dielectric constant and loss when subjected to higher frequencies. The fluorescence spectral study has been conducted to analyse the luminescence behaviour of SAMS. The analysis conducted via (SEM) provides valuable information regarding the quality of the sample and the distribution of grains on its surface. Additionally, the chemical composition of the SAMS crystal was assessed through energy-dispersive X-ray analysis. The crystal's bulk resistance and dc conductivity were determined using a Nyquist plot. The mechanical stability of the crystal was assessed using Vickers microhardness tests. The laser damage threshold (LDT) for the SAMS crystal was measured with an Nd: YAG laser functioning at a wavelength of 1064 nm. The Z-scan method, which employs an Nd: YAG laser, has been utilized to investigate third order nonlinear (SAMS). This technique demonstrates its potential for future applications in fields such as optoelectronics and optical limiting application.

In this study, the impact of co-doping Y and Gd on the structure and electrical properties of BaCe_0.6Zr_0.2Y_0.2-xGd_xO_3-δ (x = 0, 0.05, 0.10, and 0.15; denoted as BCZY, BCZYG5, BCZYG10, and BCZYG15) perovskite proton conductors were systematically studied. The BCZYGx materials were synthesised via a solid-state reaction. The XRD results demonstrate that the Gd elements have been successfully incorporated into the lattice of the material phase, resulting in the formation of a single perovskite phase. The SEM and EDS results demonstrate that the doping of Gd can facilitate grain growth and enhance the material’s density. The electrical properties of BCZYGx materials are investigated by relaxation time distribution (DRT) and equivalent circuit scheme (ECS) based on the defect equilibrium model. The results demonstrate that the BCZYG5 exhibits the highest conductivity and proton transport number at 600 °C, which were 9.47 × 10^–3 S·cm⁻¹ and 0.88, respectively. The experimental results indicate that the co-doping strategy can effectively enhance the conductivity and proton transport number of the BCZYG5 proton conductor material. This paper presents a novel approach to optimising the performance of perovskite proton conductors, offering valuable insights for the development of high-performance protonic ceramic fuel cells.

In this work, an analysis on the physicochemical properties of materials based on NiTe-Ni₂Te₃ synthesized through a mechanosynthesis process by using a planetary ball mill, at ambient conditions, was carried out. Pure nickel and tellurium powders with a mass ratio of 1:1 were used as precursors. The milling speed was kept constant at 500 rpm, and the effective milling time was varied, 2, 4, 6, 8 and 10 h. The structural, morphological, optical and electrical properties of NiTe-Ni₂Te₃ materials were studied. The crystallographic properties by X-ray powder diffraction (DRX) were analyzed, and it was determined that the materials present a mix of two different compounds; a hexagonal phase of NiTe and a monoclinic phase of Ni₂Te. From scanning electron microscopy (SEM) the presence of agglomerates of particles with irregular morphologies and others in disc form were evidenced. From reflectance measurements the bandgap energies, E_g, were estimated, and it was found an E_g increase with milling time. From the infrared spectroscopy analysis (FTIR), the characteristic vibrational frequencies, 425 and 672 cm⁻¹, of the NiTe-Ni₂Te₃ system were observed. The electrical properties were measured by Hall effect, using the Van Der Pauw contacts confiration, confirming the n-type conductivity in all the samples, and obtaining that sample synthesized with 8 h of milling presented the best electrical properties, resistivity of 0.77 Ωcm, electron concentration of 2.0 × 10¹⁷ cm⁻³ and mobility 53.08 cm²V⁻¹s⁻¹. The Seebeck coefficient and power factor were estimated to evaluate the thermoelectric properties of the samples. The sample synthesized with 4 h of milling presented the highest Seebeck coefficient and power factor, − 74.56 µVK⁻¹ and 4.27 µWcm⁻¹ K⁻², respectively. The obtained results showed promising properties of synthesized NiTe-Ni₂Te₃ powders and its possible application as thermoelectrical materials.

The rare-earth cobalt-based perovskite oxides LnCoO₃ are promising electronic functional materials. The different synthesis conditions and microstructures led to obviously different results in previous investigations. In this study, LnCoO₃ (Ln=La, Pr, Tb) with different Ln f-electron configurations [La³⁺ (4f ⁰), Pr³⁺ (4f ³), and Tb³⁺ (4f ⁹)] were investigated through careful synthesis controlling. The bond valence analysis, Mulliken population charge analysis and XPS analysis confirm that the Ln and Co ions in LnCoO₃ are all in + 3 oxide state (i.e. La³⁺, Pr³⁺, Tb³⁺, and Co³⁺). The different A-site cations have no significant effect on the [CoO₆] octahedra size in LnCoO₃ and average Co–O bond lengths are all ~ 1.93 Å. The band structure of LnCoO₃ shows similar coupling distribution between Co-3d and O-2p bands, which originates from the similarity of the [CoO₆] octahedra. This band structure leads to similar OER and ORR catalytic activities of LnCoO₃. The OER overpotential of LnCoO₃ is 463–506 mV, which is ~ 100 mV lower than that of commercial Pt/C catalysts, and the ORR half-wave potential is 0.63–0.67 V. The conductivity (σ) of LnCoO₃ is 0.11 S cm⁻¹ for LaCoO₃, 0.04 S cm⁻¹ for PrCoO₃ and 3.91 × 10^–4 S cm⁻¹ for TbCoO₃ at room temperature. This study reveals the [CoO₆] octahedra in LnCoO₃ perovskite is the key factor to their band structure and electrocatalytic behavior, providing an important knowledge for the research and development of these materials.

Europium-activated bismuth yttrium tungstate (BYW: Eu³⁺) phosphors were synthesized by four various synthesis techniques such as solid-state reaction (SSR), sol–gel combustion (SGC), co-precipitation (CP), and hydrothermal (HT) methods. Relative investigations such as thermal, structural, morphological, and luminescence characterizations have been carried out to optimize the synthesis process of BYW:Eu³⁺phosphor. The TGA–DSC curves signify the endothermic/exothermic peaks and corresponding weight loss during heating. X-ray diffraction analysis and Rietveld refinement have been used to identify the phase and crystal structure of the undoped and doped BiYWO₆ sample. The field emission scanning electron microscope with energy-dispersive X-ray was carried out to examine the morphological and compositional behavior of the synthesized BYW: Eu³⁺phosphor. The luminescent spectral profiles indicate the strong absorption in the blue region (λ_ex = 465 nm) and intense emission in the red region (λ_em = 613 nm) ascribed to the ⁵D₀ → ⁷F₂ transition. The compared photoluminescence (PL) results signify that the phosphor synthesized by the CP method at calcination temperature 900 °C exhibits the strongest emission than the phosphor synthesized via other methods (SGC, SSR, and HT) and is especially two times higher than the phosphor synthesized by the SSR method. Further, the PL intensity enhanced with increasing activator concentration of Eu³⁺ ions up to 20 mol%. The calculated CIE chromaticity coordinates (0.654, 0.345) of 20.0 mol% Eu³⁺-doped BYW sample were situated in the red region, which is comparable with the commercially available red-emitting phosphors Y₂O₃:Eu³⁺ (0.645, 0.347) and Y₂O₂S:Eu³⁺ (0.647, 0.343). The average PL decay time of the synthesized phosphor was in the microseconds range. The obtained results suggest that the BiYWO₆ activated with Eu³⁺ ions phosphor synthesized by the CP method has distinctive PL characteristics with good morphology, which can be employed as an intense red-emitting component in photonics devices.

Because of the plentiful supply of sodium, sodium ion batteries (SIBs) as one of the most promising technologies for affordable rechargeable batteries. Here, we outline an easy method for creating a NaFePO₄@C hybrid composite cathode for SIBs. GCD, CV, and EIS tests have been conducted to study the samples’ electrochemical and kinematic properties. It is confirmed that modest carbon doping can enhance the electrocatalytic activity of NaFePO₄ (NFP). The resulting NFP@C nanocomposite as cathode material for SIBs displays good rate capability and lofty capacity (158.5 mAhg⁻¹) retention after 50 cycles at 0.1C. The NaFePO₄ and the carbon covering, which make it easier for the Na + ion and electron to access the material quickly during the process of charging and discharging, respectively, are responsible for the good electrochemical performances. This work highlights the value of investigating novel structures and offers a technique for the creation of NaFePO₄@C-based cathodes.

The spin coating is cost-effective, straightforward, and highly suitable for the large-scale production of solar cells. In this study, we report the fabrication of SnO₂/ZnO composite films for dye-sensitized solar cells (DSCs) using a simplified and cost-effective spin-coating technique on fluorine-doped tin oxide glass substrates. This study introduces a new way of preparing a multi-layered composite thin film using a suspension containing colloidal SnO₂ nanoparticles and ZnO nanoparticles followed by sonication and aging of TiO₂-free high-efficiency DSCs. Our approach provides a facile way of obtaining a uniform film of tunable thickness with high reproducibility by adjusting the total number of coating cycles. The spin-coating process achieved a nano-sized SnO₂-covered ZnO layer, contributing to enhanced conversion efficiency in DSCs. A specific number of seven coating cycles was identified as optimal for achieving the aspirational performance. Under standard AM 1.5 irradiation with an intensity of 100 mW/ cm², the fabricated SnO₂/ZnO composite films revealed an overall energy conversion efficiency of 6.5% with a thickness of 2.06 µm which is impressive for a TiO₂-free DSC. This achievement indicates the potential of the developed fabrication process for cost-effective and scalable production of efficient DSCs with SnO₂/ZnO composite.

Dielectric capacitors, possessing ultrafast charge–discharge speed and high-power density, have captured increasing attention and extensive research due to their potential applications in pulse power techniques. However, the limited energy density and efficiency hinder their applications in capacitive energy storage. Here, superparaelectric state, which exhibits a high polarization and a nearly nonhysteretic response to an external electric field, was designed by constructing (1-x)(0.3Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃-0.7SrTiO₃)-xBiMg_0.5Ti_0.5O₃ ternary system to establish a superior comprehensive energy storage system, considering the recoverable energy storage density (W_rec) and efficiency (η), working temperature range and fatigue resistance. A high efficiency of 94.2%, a large W_rec of 4.43 J/cm³ , and thus a superior overall energy storage performance U_F of 76.4 were realized in the ceramic with x = 0.3 at 460 kV/cm due to its suitable superparaelectric temperature range (24–126 °C) and the concomitant dynamic disordered polymorphic polar nanoregions. Benefiting from these features, remarkable long-term working and temperature stabilities, high power density of about 143.5 MW/cm³ and fast discharging speed (t_0.9 = 58 ns) were also obtained. This work provided an effective strategy in improving the comprehensive energy storage performance of dielectric capacitors especially for realizing high efficiency.