Mechanistic study of the effect of Ca–Sn co-doping on the microwave dielectric properties and magnetic properties of YIG

To investigate the crystal structure, electrical properties, and magnetic properties of Ca–Sn co-doped Y_3-xCa_xFe_5-xSn_xO₁₂ (x = 0.00–0.25 in steps of 0.05), solid-state reaction experiments, first principles calculations, and complex crystal bonding theoretical calculations were performed. The relative permittivity (ε_r) is strongly correlated with the average bond ionicity when Ca²⁺ is added. Furthermore, appropriate Sn⁴⁺ substitution significantly lowers the dielectric loss (tanδ_ε) associated with the lattice energy. The right amount of Ca–Sn co-doping can change the saturation magnetization (4πM_S) and improve the microscopic morphology of YIG, lowering the ferromagnetic resonance linewidth (ΔH) of YIG. The optimized microwave dielectric and magnetic properties are as follows: ε_r = 14.7, tanδ_ε = 4.15 × 10^?4, 4πM_S = 1680 G, and ΔH = 53 Oe for Y_2.8Ca_0.2Fe_4.8Sn_0.2O₁₂ sintered for 6 h at 1425 °C. Based on this material, a simple 3D model of a strip-line circulator with an insertion loss of less than 0.3 dB at each port and isolation greater than 20 dB in the 10–12 GHz range was developed, indicating the potential of the material for microwave high-frequency components such as circulators.     

Novel Authentic and Ultrafast Organic Photorecorders Enhanced by AIE-Active Polymer Electrets via Interlayer Charge Recombination

Organic photonic memory, featuring a variety of glamorously light-driven characteristics, is rapidly growing into an indispensable building block for next-generation optical communication systems. However, the ambiguity of their operating mechanism associated with the limitation of photoadaptive materials as an electronics promoter results in the slow development of photonic transistor-based devices. In this study, the conjugated polymers composed of donor–acceptor motifs with typical aggregation-induced emission (AIE) behaviors are designed and successfully discover high-performance photoprogrammable memory. Moreover, the mechanism of photoboosted recording behavior, attributed to the recombination of the formed interlayer excitons right after simultaneous excitation without applying vertical and parallel electric-field at the interface in-between active semiconductor and AIE polymers, is cautiously corroborated by steady-state PL and pulse PL measurements. The AIE-polymer memory devices perform ultrafast photoresponse time of 0.1 ms, an outstanding current switch ratio up to 10⁶, and retention stability over 40 000 s without significant dissipation. Furthermore, photoresponsive AIE-polymer electrets not only modulate the memory performance through the emission wavelength but easily switch storage behavior of nonvolatile memory from flash to WORM by adjusting the torsion-angle through the motif of the donor and acceptor moieties. These findings open an avenue for designing conjugated polymer electret for ultrafast optical storage devices.     

Crystallographically textured Ba0.8La0.2Fe11.8-xCu0.2O19-δ hexaferrites with narrow FMR linewidth

M-type hexaferrites which exhibit strong uniaxial anisotropy field, are promising for the applications in self-biased microwave and millimeter wave (MMW) devices. Here we demonstrate crystallographically textured hexaferrites with narrow ferromagnetic resonance (FMR) linewidth synthesized by the conventional ceramic method. Meanwhile, the relationship between iron-deficiency content and microstructure, crystallographic, and magnetic properties are researched. These hexaferrites have strong remanence ratio of above 0.9 along c-axis. By fitting of Lorentzian function to absorption derivative, we probe detailedly into the zero-field FMR linewidth of Ba_0.8La_0.2Fe_11.8-xCu_0.2O_19-δ hexaferrites. When x equals 1.0, it indicates the narrowest FMR linewidth of 324Oe, as compared with previous reports for crystallographically textured hexaferrites.     

Enhanced Thermoelectric Performance of n-Type Organic Semiconductor via Electric Field Modulated Photo-Thermoelectric Effect

Modulating photophysical processes is a fundamental way for tuning performance of many organic devices. However, it has not been explored as an effective strategy to manipulate the thermoelectric (TE) conversion of organic semiconductors (OSCs) owing to their critical requirement to carrier concentration (>10¹⁸ cm⁻³) and the fact of low exciton separation efficiency in single element OSCs. Here, an electric field modulated photo-thermoelectric (P-TE) effect in an n-type OSC is demonstrated to realize a significant improvement of TE performance. The electrical and spectroscopy characterizations reveal that the electric field gating generates combined modulation of exciton separation, charge screening, and carrier recombination, which produces a more than ten times improvement of photoinduced carrier concentration. These coupled processes contribute to the unconventional Seebeck coefficient (S)-electrical conductivity (σ) trade-off relationship of the photoexcited films, therefore leading to a more than 500% enhancement in the power factor for n-type OTE semiconductors. This work opens a unique way toward state-of-the-art organic P-TE materials for energy harvesting applications.     

铁的中子反应数据的计算

该工作利用现有的实验数据对天然铁~NFe(包括~(54)Fe,~(56)Fe和~(57)Fe)在中子入射能量为0.1-20 MeV范围内的中子反应数据进行了计算。采用的理论模型是光学模型、带宽度涨落修正的Hauser-Feshbach理论(WHF)以及包括预平衡发射的蒸发模型(YPH)。无论是天然元素还是同位素,理论计算结果和实验数据符合尚好。     

~(238)U,~(235)U和~(93)Nb的次级中子能谱和双微分截面计算

一、引言自1966年Griffin提出激子模型以来,经过人们多年的工作,激子模型在计算次级中子能谱方面取得了一定的成功,用于角分布计算也有所进展。但迄今预平衡计算和平衡(蒸发)计算不能统一,计算结果不能定量地符合实验。其一个主要的原因是激子态     

测量激光线宽的一种新装置

介绍了一种新的仅用一台激光器测定激光线宽或频率稳定的测量方法，用稳定的无源腔透过曲线腰处斜率将激光的频率扰动转为电压扰动。用所研制的测量装置对自制的边疆波染料激光频率的线宽和频率稳定性进行了测量。     

大功率微波铁氧体材料

简要介绍了大功率微波铁气体材料的设计原理及反采取的技术措施。人出了Ｄｙ：ＹＧｄＩＧ的主要实验结果以及实型材料的性能和使用情况。     

Charge‐Transfer Exciton Manipulation Based on Hydrogen Bond for Efficient White Thermally Activated Delayed Fluorescence

Despite the success of thermally activated delayed fluorescence (TADF) emitters in monochromatic organic light‐emitting diodes (OLED), only few efficient full‐TADF white OLEDs (WOLED) are reported because of the challenge in rational exciton allocation between blue and other color emitters. Herein, it is demonstrated that the appropriate exciton delocalization in blue TADF matrixes can simultaneously support the sufficient blue emission and the energy loss–free charge and exciton transfer to yellow TADF emitters. Through introducing steric hindrance–modulated intermolecular hydrogen bond networks, a fluorinated carbazole‐phosphine oxide hybrid realizes the balance of exciton localization and delocalization, giving rise to state‐of‐the‐art external quantum efficiency beyond 20% from its simple trilayer full‐TADF WOLEDs, accompanied by excellent spectral stability. The correlation between the efficiencies of the blue TADF matrixes and their intermolecular interactions reveals that the exciton delocalization is crucial for the exciton allocation optimization in multicomponent emission systems.