不同含锰化合物掺杂对BST-MgO陶瓷介电性能的影响

采用普通固相反应法制备了0.45Ba0.55Sr0.45TiO3-0.55MgO-Mn(NO3)2/MnCO3(简称BST-MgO)陶瓷,通过XRD和SEM研究了不同形态含锰化合物(固态MnCO3及液态Mn(NO3)2)掺杂对所制BST-MgO陶瓷致密化及微波介电性能的影响。结果表明,液态Mn(NO3)2掺杂可以增加锰离子进入BST晶格的几率,同时抑制镁离子进入BST晶格,提高BST-MgO陶瓷的致密度,降低介质损耗,获得较高的综合性能:10 kHz下r=116,tan=0.003 8,可调率(Tu)为19.64%,优值K=51.68;3 GHz时Q.f值达788 GHz。     

BSTO/Mg2SiO4/MgO复合材料的介电性能研究

采用传统的电子陶瓷制备工艺制备了BSTO／Mg2SiO4／MgO复合材料，并对样品的结构及其介电性能进行了表征与分析，讨论了Mg2SiO4／MgO掺杂对BSTO／Mg2SiO4／MgO复合材料结构和性能的影响．结果表明，与前其他掺杂改性的BSTO复合材料相比，BSTO／Mg2SiO4／MgO复合材料不仅可以在较低的温度烧结致密，而且在介电常数降低的同时，仍能保持较高的可调性，如BSTO／39wt％Mg2SiO4／17wt％MgO的介电常数εr为-80．21，在2kV／mm的直流偏置电场下，其可调性达到-12％，介电损耗为-0．003．     

Giant Magnetocaloric Effect in Magnets Down to the Monolayer Limit

2D magnets can potentially revolutionize information technology, but their potential application to cooling technology and magnetocaloric effect (MCE) in a material down to the monolayer limit remain unexplored. Herein, it is revealed through multiscale calculations the existence of giant MCE and its strain tunability in monolayer magnets such as CrX₃ (X = F, Cl, Br, I), CrAX (A = O, S, Se; X = F, Cl, Br, I), and Fe₃GeTe₂. The maximum adiabatic temperature change ($\Delta T_{\text{ad}}^{\max }$), maximum isothermal magnetic entropy change, and specific cooling power in monolayer CrF₃ are found as high as 11 K, 35 µJ m⁻² K⁻¹, and 3.5 nW cm⁻² under a magnetic field of 5 T, respectively. A 2% biaxial and 5% a-axis uniaxial compressive strain can remarkably increase $\Delta T_{\text{ad}}^{\max }$ of CrCl₃ and CrOF by 230% and 37% (up to 15.3 and 6.0 K), respectively. It is found that large net magnetic moment per unit area favors improved MCE. These findings advocate the giant-MCE monolayer magnets, opening new opportunities for magnetic cooling at nanoscale.     

3D Shape-Morphing Display Enabled by Electrothermally Responsive,Stiffness-Tunable Liquid Metal Platform with Stretchable Electroluminescent Device

3D displays are of great interest as next-generation displays by providing intensified realism of 3D visual information and haptic perception. However, challenges lie in implementing 3D displays due to the limitation of conventional display manufacturing technologies that restrict the dimensional scaling of their forms beyond the 2D layout. Furthermore, on account of the inherent static mechanical properties of constituent materials, the current display form factors can hardly achieve robust and complex 3D structures, thereby hindering their diversity in morphologies and applications. Herein, a versatile shape-morphing display is presented that can reconfigure its shape into various complex 3D structures through electrothermal operation and firmly maintain its morphed states without power consumption. To achieve this, a shape-morphing platform, which is composed of a low melting point alloy (LMPA)-graphene nanoplatelets (GNPs)-elastomer composite, is integrated with a stretchable electroluminescent (EL) device. The LMPA in the composite, the key material for variable stiffness, imparts shape memory property and forms conductive pathways with GNPs enabling rapid electrothermal actuation. The stretchable EL device provides reliable illumination in 3D shape implementations. Experimental studies and proof-of-concept demonstrations show the potential of the shape-morphing display, opening new opportunities for 3D art displays, transformative wearable electronics, and visio-tactile automotive interfaces.     

Robust Full-Spectral Color Tuning of Photonic Colloids

Creation of color through photonic morphologies manufactured by molecular self-assembly is a promising approach, but the complexity and lack of robustness of the fabrication processes have limited their technical exploitation. Here, it is shown that photonic spheres with full-color tuning across the entire visible spectrum can be readily and reliably achieved by the emulsification of solutions containing a block copolymer (BCP) and two swelling additives. Solvent diffusion out of the emulsion droplets gives rise to 20–150 µm-sized spheres with an onion-like lamellar morphology. Controlling the lamellar thickness by differential swelling with the two additives enables color tuning of the Bragg interference-based reflection band across the entire visible spectrum. By studying five different systems, a set of important principles for manufacturing photonic colloids is established. Two swelling additives are required, one of which must exhibit strong interactions with one of the BCP blocks. The additives should be chosen to enhance the dielectric contrast, and the formation kinetics of the spheres must be sufficiently slow to enable the emergence of the photonic morphology. The proposed approach is versatile and robust and allows the scalable production of photonic pigments with possible future applications in inks for cosmetics and arts, coatings, and displays.     

Emerging Versatile Two-Dimensional MoSi2N4 Family

The discovery of 2D layered MoSi₂N₄ and WSi₂N₄ without knowing their 3D parents by chemical vapor deposition in 2020 has stimulated extensive studies of 2D MA₂Z₄ system due to its structural complexity and diversity as well as versatile and intriguing properties. Here, a comprehensive overview on the state-of-the-art progress of this 2D MA₂Z₄ family is presented. Starting by describing the unique sandwich structural characteristics of the emerging monolayer MA₂Z₄, their versatile properties including mechanics, piezoelectricity, thermal transport, electronics, optics/optoelectronics, and magnetism is summarized and anatomized. The property tunability via strain engineering, surface functionalization and layered strategy is also elaborated. Theoretical and experimental attempts or advances in applying 2D MA₂Z₄ to transistors, photocatalysts, batteries and gas sensors are then reviewed to show its prospective applications over a vast territory. New opportunities are further discussed and prospects are suggested for this emerging 2D family. The overview is anticipated to guide the further understanding and exploration on 2D MA₂Z₄.     

CNTFET Based Fully Differential First Order All Pass Filter

A novel, carbon nanotube field effect transistor (CNTFET) based fully differential first order all pass filter (FDFAPF) circuit configuration is presented. The FDFAPF uses CNTFET based negative transconductors (NTs) and positive transconductors (PTs) in its realization. The proposed circuit topology employs two PTs, two NTs, two resistors and one capacitor. All the passive components of the realized topology are grounded. Active only fully differential first order all pass filter (AO-FDFAPF) topology is also derived from the proposed FDFAPF. The electronic tunability of the AO-FDFAPF is obtained by controlling the employed CNTFET based varactor. A tunabilty of pole frequency in the range of 10.5 to 26 GHz is obtained. Both the circuits are potential candidates for high frequency fully differential analog signal processing applications. As compared to prior state-of-the-art works, both the realized topologies have achieved highest pole frequency and lowest power dissipation. Moreover, they utilize compact circuit structures and suitable for low voltage applications. Moreover, both topologies work equally well in the deep submicron. The proposed filters are analyzed and verified through HPSPICE simulations by utilizing Stanford CNTFET model at 16 nm technology node. It is observed that the proposed circuit simulation outcomes verify the theory.