Enhanced energy storage performance in bismuth layer-structured BaBi2Me2O9 (Me = Nb and Ta) relaxor ferroelectric ceramics

Bismuth layer-structured BaBi₂Nb₂O₉ (BBN) and BaBi₂Ta₂O₉ (BBT) relaxor ferroelectric ceramics were explored as potential energy storage materials. Remarkable energy storage performances were obtained in both BBN and BBT ceramics, featured by large recoverable energy storage density (~0.84 J/cm³ and ~0.68 J/cm³) and high energy storage efficiency (~90% and ~94%), respectively. Furthermore, both the two ceramics exhibit good thermal and frequency stabilities. Delightedly, both the BBN and BBT ceramics can complete the discharge process within 0.15 μs, resulting in ultrahigh current density of 195 A/cm² and 234 A/cm² and excellent power density of 10.74 MW/cm³ and 12.89 MW/cm³, respectively. The obtained results suggest that BaBi₂Nb₂O₉ and BaBi₂Ta₂O₉ ceramics could have a promising future in energy storage applications. This study also demonstrates that the bismuth layer-structured relaxor ferroelectric ceramic can be considered as a novel potential lead-free energy storage materials, in addition to the widely studied pervoskite-structured relaxor ferroelectric ceramics.     

Structural,ferroelectric, magnetic and magnetoelectric properties of (1-x) Ba0.85Ca0.15Zr0.1Ti0.9O3 -x La0.67Sr0.33MnO3 lead-free magnetoelectric composites

The influence of an additional La_0.67Sr_0.33MnO₃ (LSMO) magnetic phase on the structural, ferromagnetic, ferroelectric, and magnetoelectric properties of Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT) ferroelectric phase was studied for composites of (1-x)BCZT -xLSMO (x = 0, 25, 50, 75 and 100%). The ferroelectric BCZT sample showed a perovskite single phase formation with a tetragonal crystal structure of the P4mm space group, and the magnetic phase of LSMO presented a rhombohedral crystal structure of R3c space group as shown by XRD. The composite sample with 25% LSMO exhibited large ferroelectric and piezoelectric properties with remnant, saturation polarization, and coercive electric field P_r ~7.74 μC/cm², P_s ~11.69 μC/cm² and E_C ~12.22 kV/cm with a piezoelectric coefficient d₃₃ ~ 231 pC/N. The magnetic characterization for the composites showed that the sample containing 75% of LSMO revealed the highest remnant, saturation magnetization, and coercive field of M_r ~1.358 emu/g, M_s ~19.17 emu/g, and H_C ~33.19 Oe, respectively. Moreover, it revealed the largest magnetoelectric coupling coefficient α_ME ~2.51 mV/cm.Oe with high coupling quality at a lower applied magnetic field. The results highlight the value of these composites as lead-free room temperature magnetoelectric sensors and actuators.     

Synthesis and structural,optical, photocatalytic,and electrochemical properties of undoped and yttrium-doped tetragonal ZrO2 nanoparticles

Template-free undoped and yttrium-doped tetragonal ZrO₂ nanoparticles were successfully synthesized using a hydrothermal technique, and their structural, morphological, optical, and electrochemical properties were characterized. The photocatalytic activity for the dye degradation of the Rhodamine B (RhB) was also studied under UV light irradiation. The tetragonal crystal phase of the nanoparticles was confirmed by XRD analysis. The observed peak shift in XRD patterns confirmed the incorporation of dopant into host lattice. The Yttrium-doped ZrO₂ nanoparticles showed a higher specific surface area and smaller optical band gap (191.5?m²/g and 3.66?eV) than the pristine ZrO₂ nanoparticles (108.6?m²/g and 4.94?eV). The yttrium-doped ZrO₂ nanoparticles exhibited greater photocatalytic activity (~98%) than the pure ZrO₂ nanoparticles within 40?min, due to their high specific surface area and reduced photogenerated charge carrier recombination rate. The Nyquist plot of yttrium-doped sample exhibited lower charge transfer resistance than that of the undoped sample. The photocurrent of the doped sample (28.6?mA/cm²) was ~9 times higher than that of pristine ZrO₂ sample (3.2?mA/cm²). The doped sample showed stable and higher photocurrent density up to 520?s under light illumination.     

Oxetanyl-functionalized 9-aryl[3,3′]bicarbazolyl derivatives as building blocks for electro-active polymers

9-Aryl[3,3′]bicarbazolyl derivatives containing reactive functional groups were synthesized by the multi-step synthetic rout. The monomers were examined by various techniques including thermogravimetry, differential scanning calorimetry, UV and fluorescence spectrometry as well as electron photoemission and time of flight techniques. The electron photoemission spectra of the layers showed the ionisation potentials of 5.2–5.5 eV. Time-of-flight hole drift mobilities in amorphous layers of bisphenol Z polycarbonate containing 50 wt. % of the electroactive materials exceed 10⁻⁵ cm²/Vs at high electric fields.     

High energy density capacitors based on 0.88BaTiO3–0.12Bi(Mg0.5, Ti0.5)O3/PbZrO3 multilayered thin films

Multilayered thin films consisting of both 0.88BaTiO₃–0.12Bi(Mg_0.5,Ti_0.5)O₃ ferroelectric layers and PbZrO₃ antiferroelectric layers were prepared by sol–gel method, exhibiting high dielectric permittivity, large polarization, high recoverable energy storage density and high energy storage efficiency. A maximum polarization of 93 μC/cm², recoverable energy storage density of 24.7 J/cm³ and energy storage efficiency of ~60% have been achieved at an electric field of 1050 kV/cm. Furthermore, the energy storage performance of the multilayered thin films was improved by modified layer-by-layer annealing process, where larger polarization (115 μC/cm²), higher recoverable energy storage density (33 J/cm³) and higher energy storage efficiency (~70%) were obtained.     

Structural,electrical and magnetic properties of (110)-oriented BF-BZT-ST Films

Highly (110)-oriented BiFeO₃-Bi(Zn/Ti)O₃-SrTiO₃ thin films were prepared on conductive Nb doped SrTiO₃ substrates by pulsed laser deposition. The results demonstrate that the films show a pure perovskite phase with R3c symmetry. The films have a low dielectric loss, and a typical multiferroics character, possessing both of ferroelectric and ferromagnetic properties. The reduced dielectric loss is attributed to thermodynamic stabilization and charge compensation mechanisms in the BiFeO₃ system. The remnant polarization (P_r) and the remnant magnetization (M_r) are ~ 46.2?μC/cm² and ~ 4.6?emu/cm³ respectively.     

Investigation of the Structure and Electrical Properties of (KxNa0.96−xLi0.04)(Nb0.96−yTaySb0.04)O3 Piezoelectric Ceramics Modified with Manganese

The effect of high doping levels of manganese (Mn) on the structure and electrical properties of (K_xNa_1?x)NbO₃ (KNN) ceramics containing Li, Ta, and Sb has been investigated. The samples were measured using synchrotron X‐ray diffraction whereas Rietveld refinement with Fullprof was used to determine the structural information as a function of temperature. Temperature‐dependent dielectric measurement was used to compare the phase transition temperatures. The results show that Mn decreases the temperature range of phase coexistence between the orthorhombic and tetragonal phase from ~180°C to ~120°C. The Curie temperature remained unchanged with Mn addition while the dielectric constant and dielectric loss increased with Mn addition. High amounts of Mn led to a reduction in both piezoelectric and ferroelectric properties. The remnant polarization, remnant strain, and piezoelectric coefficient values decreased from 24 μC/cm², 0.000824, 338 ± 37 pm/V to 13 μC/cm², 0,00014 and 208 ± 27 pm/V, respectively for the undoped and 5 mol% Mn‐doped sample.     

Raman,infra-red and neutron studies of low frequency vibrations in some substituted polystyrenes

The Raman, i.r. and neutron spectra of polystyrene in amorphous and partly crystalline isotactic forms are reported, together with similar data for polystyrene derivatives, in the frequency region below 560 cm^?1. The band at about 60 cm^?1 in polystyrene is assigned to a phenyl group libration, and there is evidence of increased steric hindrance in the case of ortho substitutions to the phenyl group. The band at 20 cm^?1 is unaffected by substitutions and may arise from acoustic vibrations. Earlier assignments of certain i.r. and Raman bands in the range 140–560 cm^?1 are generally supported by the present measurements on polystyrene derivatives, but there is no indication of the C–X out of plane bending vibration, 10b, coupling with deformations of different backbone conformations. The absence of a band corresponding to backbone motion near 200 cm^?1 implies that wavevector selection rules are not relaxed in this region.     

Trifunctional electrocatalysts based on feather-like NiCoP 3D architecture for hydrogen evolution,oxygen evolution,and urea oxidation reactions

Finding efficient and versatile catalysts that can both produce clean energy H₂ and treat wastewater is an important matter to solve energy shortages and wastewater pollution. Herein, a feather-like NiCoP supported on NF was synthesized via the two-step hydrothermal-phosphorization process. NiCoP/NF requires only overpotentials of 44 and 203 mV to reach 10 mA cm^?2 for HER and OER in 1 M KOH, respectively. Besides, NiCoP/NF requires only 1.13 V (vs RHE) to achieve 10 mA cm^?2 in 1 M KOH containing 0.33 M urea. DFT calculation shows that NiCoP exhibits enhanced DOS in the Fermi level attachment, which promotes charge transfer. Subsequently, the trifunctional NiCoP/NF, for overall water splitting, requires a lower potential of 1.48 V to gain 10 mA cm^?2 in 1 M KOH. For urea electrolysis, NiCoP/NF requires just 1.36 V to drive 10 mA cm^?2 in 1 M KOH with 0.33 M urea. This work provides extraordinary insights into electrolytic hydrogen production and wastewater treatment through simple preparative methods. The performance of the prepared catalyst is at a high level in non-noble metal.     

Synthesis of novel photochromic spiropyran dyes containing quaternary ammonium salt or cinnamoyl moiety and their properties as photoinitiators

Three novel spiropyran (SP) dyes containing quaternary ammonium salt or cinnamoyl moiety were synthesized and their photosensitive properties as photoinitiator were characterized by UV–vis spectroscopy. The intramolecular electron transfer of SP dyes containing quaternary ammonium salt was much faster and can initiate the photopolymerization under UV irradiation though the photochromic properties than those of SPs containing cinnamoyl group. A photoinitiation system containing SPs and the hexaarylbisimidazoles was studies, and the initiation properties were tested by monitoring the conversion rate of double‐bond at 810 and 1640 cm^?1 with ‐time infrared spectroscopy. It was found that the system containing our SP derivatives exhibited much higher initiating efficiency than ever reported SP dyes in the photopolymerization of 2‐phenoxyethylacrylate/N‐vinylcarbazole. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A Novel Multifunctional Upconversion Phosphor: Yb3+/Er3+ Codoped La2S3

Yb³⁺/Er³⁺ codoped La₂S₃ upconversion (UC) phosphors have been synthesized using high‐temperature solid‐state method. Under 971‐nm excitation, the maximum luminescence power can reach 0.64 mW at the excitation power density of 16 W/cm² and an absolute power yield of 0.36% was determined by an absolute method at the excitation power density of 3 W/cm², and the quantum yield of La₂S₃:Yb³⁺, Er³⁺ (green ~0.18%, red ~0.03%, integration ~0.21) was comparable to that of NaYF₄:Yb³⁺, Er³⁺ nanocrystals (integration ~0.005–0.30). Frequency upconverted emissions from two thermally coupled excited states of Er³⁺ were recorded in the temperature range 100–900 K. The maximum sensitivity of temperature sensing is 0.0075 K^?1. As the excitation power density increases, the temperature of host materials rapidly rises and the top temperature can reach to 600 K. Given the intense UC emission, high sensitivity, as well as good photothermal stability, La₂S₃:Yb³⁺/Er³⁺ phosphor can become a promising composite material for photothermal ablation of cancer cells possessing the functions of temperature sensing and in vivo imaging.     

酞菁氧钛/咔唑化合物的合成与其二阶非线性光学性能的研究

合成了具有潜在非线性光学性能的酞菁氧钛(简写为TiOPc)/咔唑化合物,用红外光谱、元素分析进行了表征,并通过实验得到了合成该化合物最佳工艺条件:n(TiOPc-SO2Cl)∶n(咔唑)=1∶1 5,反应温度150℃,反应时间为240min时,产率达到75 2%。采用溶剂化变色法估算了其二阶非线性光学性能。结果表明,其二阶非线性光学系数与基态偶极距的复合量βCTμg的值为33 9×10-30esu.D。     

High–Energy‐Storage Density Capacitors of Bi(Ni1/2Ti1/2)O3–PbTiO3 Thin Films with Good Temperature Stability

High–energy‐storage density capacitors with thin films of 0.5Bi(Ni_1/2Ti_1/2)O₃–0.5PbTiO₃ (BNT–PT) were fabricated by chemical solution deposition technique on Pt/Ti/SiO₂/Si substrates. The dense thin films with pure‐phase perovskite structure could be obtained by annealing at 750°C. High capacitance density (~1925 nF/cm² at 1 kHz) and extremely high‐energy density (~45.1 J/cm³) under an electric field of 2250 kV/cm were achieved at room temperature. The energy‐storage density and efficiency varied little in a wide temperature range from ?190°C to 250°C. The high–energy‐storage density and good temperature stability make BNT–PT films promising candidates for high power electric applications.     

Thermoreactive compaction of an alumina — Polymethylsiloxane composition

Conclusions An investigation was carried out of the thermoreactive compaction of a composition of alumina with polymethylsiloxane, the technological parameters being varied. Before a heat treatment the open porosity of specimens containing 20% PMS is 0.8%, the bending strength 260 kgf/cm², and the cold-crushing strength 1070 kgf/cm².Firing at 1700°C gave a high-alumina composition ceramic with an open porosity of 2%, a bending strength of 1000 kgf/cm², a cold-crushing strength up to 5000 kgf/cm², and a thermal-shock resistance of 14–20 reversals from 1300°C into water (in tests with specimens).Translated from Ogneupory, No. 5, pp. 47–50, May, 1978.     

Novel bismuth ferrite‐based lead‐free ceramics with high energy and power density

In this work, a new lead‐free relaxor ferroelectric 0.60BiFeO₃‐0.34BaTiO₃‐0.06Sr(Al_0.5Nb_0.5)O₃ (BBFTO‐SAN) ceramic was prepared via the conventional solid‐state reaction method. High recoverable energy density (1.75 J/cm³) and efficiency (81%) were achieved, which is superior to some other lead‐free ceramics. Good thermal stability in a wide temperature range (30‐120°C) was also investigated in this system. Moreover, we first studied the charge‐discharge performance of bulk BFO‐based energy storage ceramics and obtained an ultra‐high power density p_D (~57 MW/cm³) as well as a large current density value of ~1353 A/cm². Consequently, all the results indicate that this ceramic is a promising lead‐free candidate for energy storage materials.     

Super-insulating,ultralight and high-strength mullite-based nanofiber composite aerogels

Ceramic nanofiber aerogel is one of the most attractive insulation materials in recent years. However, its practical application ability is limited at high temperature due to high radiation heat transfer. Herein, we constructed a novel closed-cell/nanowire structured mullite-based nanofiber composite aerogel via electrospinning technology and solvothermal synthesis method. Hollow TiO₂ spheres were used as pore-making material and infrared opacifier to reduce fiber solid heat conduction and high temperature radiation heat transfer simultaneously. In addition, TiO₂ nanowires grown in-situ on the fiber surface further decrease the radiation heat transfer of aerogel and improve the mechanical properties. The unique structure endows the aerogel with high mechanical robustness (0.32–0.35 MPa, 10% strain), low density (39.2–47.5 mg/cm³) and ultralow thermal conductivity (~0.017 W m^?1 K^?1 at 25 ℃ and ~0.056 W m^?1 K^?1 at 1000 ℃). This work offers a novel strategy for the development of ceramic nanofiber aerogel at high temperature.     

Synthesis and adsorption properties for metal ions of crosslinked chitosan acetate crown ethers

Two novel chitosan derivatives—crosslinked chitosan dibenzo‐16‐c‐5 acetate crown ether (CCTS‐1) and crosslinked chitosan 3,5‐di‐tert‐butyl dibenzo‐14‐c‐4 diacetate crown ether (CCTS‐2)—were synthesized by the reaction of crosslinked chitosan with dibenzo‐16‐c‐5 chloracetate crown ether and 3,5‐di‐tert‐butyl dibenzo‐14‐c‐4 dichloracetate crown ether with the intent of forming polymers that could be used in hazardous waste remediation as toxic metal‐binding agents in aqueous environments. Their structures were confirmed with elemental analysis, infrared spectral analysis, and X‐ray diffraction analysis. In the infrared spectra of CCTS‐1 and CCTS‐2, the characteristic peaks of aromatic backbone vibration appeared at 1595 cm⁻¹ and 1500 cm⁻¹; the intensity of the N H and O H stretching vibration in the region of 3150–3200 cm⁻¹ decreased greatly. The X‐ray diffraction analysis showed that the peak at 2θ = 20° decreased greatly in CCTS‐1 and CCTS‐2. The adsorption and selectivity properties of CCTS‐1 and CCTS‐2 for Pb²⁺, Cu²⁺, Cr³⁺, and Ni²⁺ were studied. Experimental results showed that the two crosslinked chitosan derivatives had not only good adsorption capacities for Pb²⁺, Cu²⁺, but also high selectivity for Pb²⁺, Cu²⁺ in the coexistence of Ni²⁺. For aqueous systems containing Pb²⁺, Ni²⁺, or Cu²⁺, Ni²⁺, CCTS‐1 only adsorbed Pb²⁺ or Cu²⁺. For aqueous systems containing Pb²⁺, Cr²⁺ and Ni²⁺, CCTS‐2 had high adsorption and selectivity properties for Pb²⁺. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2069–2074, 1999     

Effects of 445 nm, 520 nm,and 638 nm Laser Irradiation on the Dermal Cells

Background: The invention of non-ionizing emission devices revolutionized science, medicine, industry, and the military. Currently, different laser systems are commonly used, generating the potential threat of excessive radiation exposure, which can lead to adverse health effects. Skin is the organ most exposed to laser irradiation; therefore, this study aims to evaluate the effects of 445 nm, 520 nm, and 638 nm non-ionizing irradiation on keratinocytes and fibroblasts. Methods: Keratinocytes and fibroblasts were exposed to a different fluency of 445 nm, 520 nm, and 638 nm laser irradiation. In addition, viability, type of cell death, cell cycle distribution, and proliferation rates were investigated. Results: The 445 nm irradiation was cytotoxic to BJ-5ta (≥58.7 J/cm²) but not to Ker-CT cells. Exposure influenced the cell cycle distribution of Ker-CT (≥61.2 J/cm²) and BJ-5ta (≥27.6 J/cm²) cells, as well as the Bj-5ta proliferation rate (≥50.5 J/cm²). The 520 nm irradiation was cytotoxic to BJ-5ta (≥468.4 J/cm²) and Ker-CT (≥385.7 J/cm²) cells. Cell cycle distribution (≥27.6 J/cm²) of Ker-CT cells was also affected. The 638 nm irradiation was cytotoxic to BJ-5ta and Ker-CT cells (≥151.5 J/cm²). The proliferation rate and cell cycle distribution of BJ-5ta (≥192.9 J/cm²) and Ker-CT (13.8 and 41.3 J/cm²) cells were also affected. Conclusions: At high fluences, 455 nm, 520 nm, and 638 nm irradiation, representing blue, green, and red light spectra, are hazardous to keratinocytes and fibroblasts. However, laser irradiation may benefit the cells at low fluences by modulating the cell cycle and proliferation rate.     

Composite material based on shale phenols for radioactive waste immobilization

A composite material with a cohesion strength of 2.94 MPa, an adhesion of 2.6 MPa to steel 3, and a specific elongation of 75% was prepared based on shale phenols. It was used for radioactive waste immobilization. The leachability of cesium from immobilized blocks was 1 × 10⁻¹⁰ cm²/s, which is several orders of magnitude lower than the leachability of 1 × 10⁻⁶ cm²/s from Portland cement. The leachability of cesium from immobilized spent ion exchanger containing cesium was 1 × 10⁻¹¹ cm²/s.     

Study of the synthesis of chitosan derivatives containing benzo‐21‐crown‐7 and their adsorption properties for metal ions

Three new chitosan crown ethers, N‐Schiff base‐type chitosan crown ethers (I, III), and N‐secondary amino type chitosan crown ether (II) were prepared. N‐Schiff base‐type chitosan crown ethers (I, III) were synthesized by the reaction of 4′‐formylbenzo‐21‐crown‐7 with chitosan or crosslinked chitosan. N‐Secondary amino type chitosan‐crown ether (II) was prepared through the reaction of N‐Schiff base type chitosan crown ether (I) with sodium brohydride. Their structures were characterized by elemental analysis, infrared spectra analysis, X‐ray diffraction analysis, and solid‐state ¹³C NMR analysis. In the infrared spectra, characteristic peaks of C?N stretch vibration appeared at 1636 cm^?1 for I and 1652 cm^?1 for II; characteristic peaks of N? H stretch vibration appeared at 1570 cm^?1 in II. The X‐ray diffraction analysis showed that the peaks at 2θ = 10° and 28° disappeared in chitosan derivatives I and III, respectively; the peak at 2θ = 10° disappeared and the peak at 2θ = 28° decreased in chitosan‐crown ether II; and the peak at 2θ = 20° decreased in all chitosan derivatives. In the solid‐state ¹³C NMR, characteristic aromatic carbon appeared at 129 ppm in all chitosan derivatives, and the characteristic peaks of carbon in C?N groups appeared at 151 ppm in chitosan crown ethers I and III. The adsorption and selectivity properties of I, II, and III for Pd²⁺, Au³⁺, Pt⁴⁺, Ag⁺, Cu²⁺, and Hg²⁺ were studied. Experimental results showed these adsorbents not only had good adsorption capacities for noble metal ions Pd²⁺, Au³⁺, Pt⁴⁺, and Ag⁺, but also high selectivity for the adsorption of Pd²⁺ with the coexistence of Cu²⁺ and Hg²⁺. Chitosan‐crown ether II only adsorbs Hg²⁺ and does not adsorbs Cu²⁺ in an aqueous system containing Pd²⁺, Cu²⁺, and Hg²⁺. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1886–1891, 2002