Search

Abstract 0.025LiNbO 3 (LN) modified 0.94Bi 0.5 Na 0.5 TiO 3 -0.06BaTiO 3 (BNT-BT) ceramics with micrometer-size and nanometer-size grains have been prepared by conventional soild state sintering (CS) and spark plasma sintering (SPS) processes, respectively. Comparing with the CS sample, the SPS sample presents a smaller dielectric constant but a larger piezoelectric constant and a lower triggering electric field. At room temperature, the maximum strain of the SPS ceramic is up to 0.64% at 50 kV/cm electric field, the corresponding d * 33 reaches the maximum value of 1280 pm/V, which is much higher than that of the CS ceramic and also the ever reported lead-free polycrystalline ceramics. Morever, the strain hysteresis of the SPS ceramic is only 19.5%, while the ceramics prepared by CS process show a much larger strain hysteresis of 58.5%. Thus, the LN doped BNT-BT ceramics with nano grains can achieve maximum strain in designing high-precision devices and actuators with small hysteresis. Highlights • Nano-grain 0.975(0.94BNT-0.06BT)-0.025 LiNbO 3 ceramic was prepared by SPS. • A maximum strain of 0.64% at 50 kV/cm and a d 33 ∗ of 1280 pm/V were obtained. • Much lower strain hysteresis of only 19.5% was found in the nano-grain ceramic. • The improved piezoelectric performance is related to fine core-shell structures. [ABSTRACT FROM AUTHOR]

Exploring efficient multi-functional catalysts with is critical for oxidase-like catalysis and environmental pollutant degradation. In this paper, we report a RuCo alloy embedded in a nitrogen-doped carbon matrix (RuCo@NC) derived from a Co-based metal-organic framework (ZIF-67). RuCo@NC exhibits highly efficient oxidase activity for dopamine (DA) detection, excellent activity for 4-nitrophenol (4-NP) reduction to the higher valued 4-aminophenol (4-AP) with the addition of NaBH 4 solution, and remarkable activity for rhodamine B (RhB) degradation with the addition of the NaBH 4. Owing to the presence of the reactive oxygen species •OH, the oxidase-like activity of RuCo@NC is increased by 1.94 times that of bare Co@NC. RuCo@NC exhibits superior activity for the 4-NP reduction with a high turnover frequency (TOF) of 1.04×10−3 mmol mg−1 min−1. Moreover, when RuCo@NC is employed for RhB degradation with NaBH 4 , the efficiency of the system can reach 93.8 %. [Display omitted] • The RuCo@NC is designed and suceessful synthesized. • The RuCo@NC exhibits superior slectivity and sensitivity for dopamine (DA) detection. • The RuCo@NC shows excellent activity for the reduction of 4-nitrophenol (4-NP). • The RuCo@NC structures achieved superb activity for the degradation of rhodamine B. [ABSTRACT FROM AUTHOR]

The development and comparison of Latent Fingerprint Patterns (LFPs) constitute critical components of research in fingerprint detection and identification. However, the development of nanomaterials visualization and digital algorithms for LFPs analysis are mostly studied independently, resulting in inaccurate LFPs. This research synthesized a series of efficient red-emitting NaYF 4 :20 %Yb, 2 %Er, x %Mn (x = 0, 5, 10, 15, 20, 25, 30, 35, and 40) upconversion nanoparticles (UCNPs) for image development, which were combined with a digital algorithm for accurate LFP recognition. The eightfold increase in luminescence intensity of NaYF 4 :Yb, Er, 30 %Mn at 653 nm effectively avoids interference from biological tissue fluorescence. This improvement is credited to the efficient reverse energy transfer mechanism between Er3+ and Mn2+ ions, specifically the transition sequence 4S 3/2 (Er3+) → 4T 1 (Mn2+) → 4F 9/2 (Er3+). Furthermore, a MATLAB program was employed to process the fluorescent images of LFPs developed using the UCNPs nanophosphors, achieving a high matching score of 90.09 % for the optimized sample, significantly outperforming traditional benchmarks. These results demonstrate the superior effectiveness of the NaYF 4 :Yb, Er, 30 %Mn nanophosphor, combined with digital processing algorithms, for practical LFP recognition applications. • The NaYF 4 :20 %Yb, 2 %Er, 30 % Mn phosphor emits intense red light and the intensity of UCL is eightfold higher than in Mn2+-undoped samples. • NaYF 4 :20 %Yb, 2 %Er UCNPs doped with Mn2+ effectively reduce background fluorescence interference under NIR excitation, rendering the LFPs ridges visible with a contrast ratio of 92.31 %. • LFPs impressive matching score of up to 90.09 % represents a significant improvement over traditional benchmark. [ABSTRACT FROM AUTHOR]

Abstract: Pb(Mg1/3Ta2/3)O3–Pb(Mn1/3Sb2/3)O3–Pb(Zr x Ti1−x )O3 quaternary piezoelectric ceramics with different compositions near the morphotropic phase boundary were synthesized using a conventional solid state reaction method. The phases, microstructures, ferroelectric, piezoelectric and dielectric properties of the system were investigated. A transition from rhombohedral to tetragonal phase was observed as the Zr/Ti ratio decreased. The P–E loops presented pinched shapes at low electric fields and the distortions disappeared at high electric fields. The dielectric study revealed a diffuse phase transition behavior in the ceramics. The optimal dielectric and piezoelectric properties ɛ r =817, d 33 =285pC/N, k p =0.55, T C =302°C, tan δ =0.4% and Q m =1600 of the ceramics were obtained at the composition of Zr/Ti=50/50. Vibration velocity at ΔT =20°C was found as high as 0.74m/s for this composition, which was almost 2.5 times as that of the commercial hard PZT ceramics. [ABSTRACT FROM AUTHOR]

The multiferroic (1−x)BiFeO 3 −xBi 0.5 K 0.5 TiO 3 (BFO–xBKT) ceramic was prepared to investigate the dependence of its structural and electrical properties on BKT component. The ceramic processes a rhombohedral phase at 0 ≤ x ≤ 0.3 and a tetragonal phase at 0.5 ≤ x ≤ 1.0 while it owns the coexistence of these two phases at x∼0.4, according to the XRD patterns and the corresponding simulation with the Reitveld method. Specifically, BFO–0.4BKT shows a saturated polarization of 65.8 μC/cm 2 and an enhanced piezoelectric d 33 of 61 pC/N at room temperature which are much larger than those of other ceramics at x = 0–0.7. The dependence of dielectric constant on temperature suggests a strong relaxor characteristic and a high Curie temperature of ∼462 °C. Furthermore, the poled BFO–0.4BKT ceramic shows radial dielectric resonances at 20–300 °C due to the piezoelectric effect. [ABSTRACT FROM AUTHOR]

For the first time, uniform octahedral-shaped Y 2 O 3 :Eu 3+ submicron single crystals with photoluminescence (PL) superior to the as-prepared aggregated spherical counterparts were prepared via a room-temperature solid-state metathesis reaction and subsequent calcination of the as-milled mixtures containing an in situ formed salt as by-product. Their formation mechanism is also discussed based on preferential growth and self-assembling of nanocrystals in the presence of the salt. In summary, the approach promises a great potential in the large scale preparation of octahedral Y 2 O 3 :Eu 3+ submicron phosphors due to its solvent-free, addictive-free, high-yielding and eco-friendly characteristics. [ABSTRACT FROM AUTHOR]

The application of supercapacitor is often restricted by unsatisfactory performance of negative electrodes and limited voltage window. Herein, the CuS/Fe 2 O 3 nano-heterojunction with O and S vacancies is constructed by calcination and selective sulfurization, and applied as negative electrode for asymmetric supercapacitor devices. Compared with bare Fe 2 O 3 and CuS, the heterojunction and defect endow the hybrid with improved conductivity, exposed full electrochemical active sites and enhanced charge transfer. Density functional theory (DFT) calculations suggest that the electronic interface reconstruction between CuS and Fe 2 O 3 optimizes the electronic structure and accelerates the electron transport. Therefore, the heterostructured CuS/Fe 2 O 3 exhibits superior supercapacitor negative performance with high capacitance (921 F g-1 at 1 A g-1) and good rate capability. After assembling an asymmetric solid-state supercapacitor (CuS/Fe 2 O 3 //MnO 2 ASC) in a PVA/KOH gel, the device shows a high energy density of 56.6 Wh kg-1 at the power density of 900 W kg-1. In addition, employing polyvinyl alcohol/sodium alginate (PVA/SA/KOH) gel as the electrolyte, a flexible solid-state supercapacitor (CuS/Fe 2 O 3 //MnO 2 SSC) provides 27.8 Wh kg-1 at 900 W kg-1. This work designs and fabricates defect-rich heterojunction between metal sulfide and oxide and provides insights into developing high-performance electrode materials for supercapacitors. [Display omitted] • CuS/Fe 2 O 3 was formed via simple calcination and selective sulfurization. • The composite exhibited an oxygen and sulfur vacancies-rich nano heterostructure. • The hybrid presented increased conductivity and electrochemical active sites. • Compared with CuS and Fe 2 O 3 , the composite showed enhanced specific capacitance. • Flexible solid-state supercapacitor showed excellent energy density. [ABSTRACT FROM AUTHOR]

Highlights: [•] Dielectric and impedance properties for different CLBO orientations were studied. [•] (001) face has the highest electromechanical coupling factor at 300-450°C. [•] (001) face has the highest dielectric constant, AC conductivity at high temperature. [•] The ions arrangement in CLBO leads to the anisotropy of electric properties. [ABSTRACT FROM AUTHOR]