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1.
Zhen‐Hua Ge Yang Qiu Yue‐Xing Chen Xiaoyu Chong Jing Feng Zi‐Kui Liu Jiaqing He 《Advanced functional materials》2019,29(28)
SnSe has attracted much attention due to the excellent thermoelectric (TE) properties of both p‐ and n‐type single crystals. However, the TE performance of polycrystalline SnSe is still low, especially in n‐type materials, because SnSe is an intrinsic p‐type semiconductor. In this work, a three‐step doping process is employed on polycrystalline SnSe to make it n‐type and enhance its TE properties. It is found that the Sn0.97Re0.03Se0.93Cl0.02 sample achieves a peak ZT value of ≈1.5 at 798 K, which is the highest ZT reported, to date, in n‐type polycrystalline SnSe. This is attributed to the synergistic effects of a series of point defects: . In those defects, the compensates for the intrinsic Sn vacancies in SnSe, the acts as a donor, the acts as an acceptor, all of which contribute to optimizing the carrier concentration. Rhenium (Re) doping surprisingly plays dual‐roles, in that it both significantly enhances the electrical transport properties and largely reduces the thermal conductivity by introducing the point defects, . The method paves the way for obtaining high‐performance TE properties in SnSe crystals using multipoint‐defect synergy via a step‐by‐step multielement doping methodology. 相似文献
2.
Mohammed Sayyad Ying Qin Jan Kopaczek Adway Gupta Naim Patoary Shantanu Sinha Emmie Benard Austin Davis Kentaro Yumigeta Cheng-Lun Wu Han Li Shize Yang Ivan Sanchez Esqueda Arunima Singh Sefaattin Tongay 《Advanced functional materials》2023,33(42):2303526
2D Janus transition metal dichalcogenides (TMDs) have attracted attention due to their emergent properties arising from broken mirror symmetry and self-driven polarization fields. While it has been proposed that their vdW superlattices hold the key to achieving superior properties in piezoelectricity and photovoltaic, available synthesis has ultimately limited their realization. Here, the first packed vdW nanoscrolls made from Janus TMDs through a simple one-drop solution technique are reported. The results, including ab initio simulations, show that the Bohr radius difference between the top sulfur and the bottom selenium atoms within Janus (M = Mo, W) results in a permanent compressive surface strain that acts as a nanoscroll formation catalyst after small liquid interaction. Unlike classical 2D layers, the surface strain in Janus TMDs can be engineered from compressive to tensile by placing larger Bohr radius atoms on top (to yield inverted C scrolls. Detailed microscopy studies offer the first insights into their morphology and readily formed Moiré lattices. In contrast, spectroscopy and FETs studies establish their excitonic and device properties and highlight significant differences compared to 2D flat Janus TMDs. These results introduce the first polar Janus TMD nanoscrolls and introduce inherent strain-driven scrolling dynamics as a catalyst to create superlattices. 相似文献
3.
Binquan Wang Geng Huangfu Zhipeng Zheng Yiping Guo 《Advanced functional materials》2023,33(20):2214643
Large-strain (K,Na)NbO3 (KNN) based piezoceramics are attractive for next-generation actuators because of growing environmental concerns. However, inferior performance with poor temperature stability greatly hinders their industrialized procedure. Herein, a feasible strategy is proposed by introducing - defect dipoles and constructing grain orientation to enhance the strain performance and temperature stability of KNN-based piezoceramics. This textured ceramics with 90.3% texture degree exhibit a giant strain (1.35%) and a large converse piezoelectric coefficient d33* (2700 pm V−1), outperforming most lead-free piezoceramics and even some single crystals. Meanwhile, the strain deviation at high temperature of 100 °C–200 °C is obviously alleviated from 61% to 35% through texture engineering. From the perspective of practical applications, piezo-actuators are commonly utilized in the form of multilayer. In order to illustrate the applicability on multilayer actuators, a stack-type actuator consisted of 5 layers of 0.4 mm thick ceramics is fabricated. It can generate large field-induced displacement (11.6 µm), and the promising potential in precise positioning and optical modulation are further demonstrated. This work provides a textured KNN-based piezoceramic with temperature-stable giant strain properties, and facilitates the lead-free piezoceramic materials in actuator applications. 相似文献
4.
Jialing Kang Senhe Huang Kaiyue Jiang Chenbao Lu Zhenying Chen Jinhui Zhu Chongqing Yang Artur Ciesielski Feng Qiu Xiaodong Zhuang 《Advanced functional materials》2020,30(27)
2D porous polymers with a planar architecture and high specific surface area have significant applications potential, such as for photocatalysis, electrochemical catalysis, gas storage and separation, and sensing. Such 2D porous polymers have generally been classified as 2D metal–organic frameworks, 2D covalent organic frameworks, graphitic carbon nitride, graphdiyne, and sandwich‐like porous polymer nanosheets. Among these, 2D porous polymers with sp2‐hybridized carbon ( ) bonding are an emerging field of interest. Compared with 2D porous polymers linked by B? O, C?N, or C?C bonds, ‐linked 2D porous polymers exhibit extended electron delocalization resulting in unique optical/electrical properties, as well as high chemical/photostability and tunable electrochemical performance. Furthermore, such 2D porous polymers are one of the best precursors for the fabrication of 2D porous carbon materials and carbon skeletons with atomically dispersed transition‐metal active sites. Herein, rational synthetic approaches for 2D porous polymers with bonding are summarized. Their current practical photoelectric applications, including for gas separation, luminescent sensing and imaging, electrodes for batteries and supercapacitors, and photocatalysis are also discussed. 相似文献
5.
Jiaqi Dai Jingsi Qiao Cong Wang Linwei Zhou Xu Wu Liwei Liu Xuan Song Fei Pang Zhihai Cheng Xianghua Kong Yeliang Wang Wei Ji 《Advanced functional materials》2023,33(38):2302989
Correlated 2D layers, like 1T-phases of TaS2, TaSe2, and NbSe2, exhibit rich tunability through varying interlayer couplings, which promotes the understanding of electron correlation in the 2D limit. However, the coupling mechanism is, so far, poorly understood and is tentatively ascribed to interactions among the orbitals of Ta or Nb atoms. Here, it is theoretically shown that the interlayer hybridization and localization strength of interfacial Se pz orbitals, rather than Nb orbitals, govern the variation of electron-correlated properties upon interlayer sliding or twisting in correlated magnetic 1T-NbSe2 bilayers. Each of the layers is in a star-of-David (SOD) charge-density-wave phase. Geometric and electronic structures and magnetic properties of 28 different stacking configurations are examined and analyzed using density-functional-theory calculations. It is found that the SOD contains a localized region, in which interlayer Se pz hybridization plays a paramount role in varying the energy levels of the two Hubbard bands. These variations lead to three electronic transitions among four insulating states, which demonstrate the effectiveness of interlayer interactions to modulate correlated magnetic properties in a prototypical correlated magnetic insulator. 相似文献
6.
Weijun Luo Akinola D. Oyedele Yiyi Gu Tianshu Li Xingzhi Wang Amanda V. Haglund David Mandrus Alexander A. Puretzky Kai Xiao Liangbo Liang Xi Ling 《Advanced functional materials》2020,30(35)
PdSe2, an emerging 2D material with a novel anisotropic puckered pentagonal structure, has attracted growing interest due to its layer‐dependent electronic bandgap, high carrier mobility, and good air stability. Herein, a detailed Raman spectroscopic study of few‐layer PdSe2 (two to five layers) under the in‐plane uniaxial tensile strain up to 3.33% is performed. Two of the prominent PdSe2 Raman peaks are influenced differently depending on the direction of strain application. The mode redshifts more than the mode when the strain is applied along the a‐axis of the crystal, while the mode redshifts more than the mode when the strain is applied along the b‐axis. Such an anisotropic phonon response to strain indicates directionally dependent mechanical and thermal properties of PdSe2 and also allows the identification of the crystal axes. The results are further supported using first‐principles density‐functional theory. Interestingly, the near‐zero Poisson’s ratios for few‐layer PdSe2 are found, suggesting that the uniaxial tensile strain can easily be applied to few‐layer PdSe2 without significantly altering their dimensions at the perpendicular directions, which is a major contributing factor to the observed distinct phonon behavior. The findings pave the way for further development of 2D PdSe2‐based flexible electronics. 相似文献
7.
8.
Peng Zeng Xi Zhou Jiao Peng Xuelin Huang Baobao Chang Gairong Chen Manfang Chen Liping Zheng Yong Pei Jincang Su Xianyou Wang 《Advanced functional materials》2023,33(4):2211818
The chemical binding between metal compounds and polysulfides provides a good solution to inhibit shuttle effect in Li-S batteries. However, the Sabatier principle predicts that overly strong adsorption will commonly hinder the conversion of polysulfides, so building the synergetic effect mechanism between “strong adsorption” and “fast conversion” for polysulfides is a significant strategy. To realize this goal, in this study, the defect-enriched Co9S8 hollow prisms (DHCPs) as both S host and catalyst material for Li-S batteries are designed. Based on in situ UV–vis spectroscopy results, it is found that DHCPs can profitably promote the generation of radicals during the discharge process. In the case of the relatively high conversion barrier of “liquid–liquid” reaction, the generated radicals are responsible for the fast conversion reaction via a unique reaction pathway. When the sulfur loading is 4.63 mg cm−2, the cell with DHCP/S cathode delivers a high areal capacity of 4.75 mAh cm−2 at 0.1 C and keeps a high capacity of 2.99 mAh cm−2 after 100 cycles at 0.5 C. This study provides a positive attempt to achieve “strong adsorption” and “fast conversion” of polysulfides simultaneously, which will convincingly boost the development and practical process of Li-S batteries. 相似文献
9.
Xiwen Zhang Zhaobo Zhou Xing Yu Yilv Guo Yunfei Chen Jinlan Wang 《Advanced functional materials》2023,33(32):2301353
Ferroelectric (FE) control of magnetism at nanoscale, for instance, FE control of the polarity of spin-polarized current is crucial for technological advances in magnetoelectric and spintronic applications. However, this fascinating functionality has not been reported in nanoscale systems yet. Herein, a new class of FE/A-type antiferromagnetic heterobilayer/FE van der Waals (vdW) multiferroic structures is found, in which the FE control of polarity of spin-polarized current is found possible. Take Sc2CO2/CrSiTe3/CrGeTe3/Sc2CO2 heterostructure as a successful example. First-principles calculations reveal that its polarity of half-metallicity can be switched by flipping the FE polarization orientation. Meanwhile, device transport simulation shows that its up/down spin current transmission ratio is as large as 0.1 × 103 at Sc2CO2 configuration and is only 2.6 × 10−3 at Sc2CO2 configuration in the vdW multiferroic heterostructures. Essentially, it stems from the reversible FE switch of the internal electric field across the CrSiTe3/CrGeTe3 heterobilayer and the FE control of the interfacial effect between Sc2CO2 and Cr(Si/Ge)Te3 layers. This work opens a direction for constructing low-energy-dissipation, non-volatile, and high-sensitive spintronic devices such as spin field-effect transistors. 相似文献
10.
Wenshu Chen Jiajun Gu Yongping Du Fang Song Fanxing Bu Jinghan Li Yang Yuan Ruichun Luo Qinglei Liu Di Zhang 《Advanced functional materials》2020,30(25)
Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS2 nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active / heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich / sites, the fabricated 1T–MoS2 QS/Ni(OH)2 hybrid (quantum sized 1T–MoS2 sheets decorated with Ni(OH)2 via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm?2, respectively, and has a low Tafel slope of 30 mV dec?1 in 1 m KOH. So far, this is the best performance for MoS2‐based electrocatalysts and the 1T–MoS2 QS/Ni(OH)2 hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions. 相似文献
11.
Tian‐Long Zhao Alexei A. Bokov Jingen Wu Hongli Wang Chun‐Ming Wang Yang Yu Chun‐Lei Wang Kaiyang Zeng Zuo‐Guang Ye Shuxiang Dong 《Advanced functional materials》2019,29(12)
Here, novel ferroelectric ceramics of (0.95 ? x)BiScO3‐xPbTiO3‐0.05Pb(Sn1/3Nb2/3)O3 (BS‐xPT‐PSN) of complex perovskite structure are reported with compositions near the morphotropic phase boundary (MPB), and which exhibit a piezoelectric coefficient d33 = 555 pC N?1, a large‐signal coefficient ≈ 1200 pm V?1 at room temperature, and a high Curie temperature TC of 408 °C. More interestingly, this ternary system exhibits a giant and stable piezoelectric response at 200 °C with a large‐signal ≈ 2500 pm V?1, matching that of the costly relaxor‐based piezoelectric single crystals at room temperature. The mechanisms of such giant piezoelectricity and its characteristic temperature dependence are attributed to the spontaneous polarization rotation and extension under an electric field and the MPB‐related phase transition. The findings reveal that the BS‐xPT‐PSN ceramics constitute a new family of high‐performance piezoelectric materials suitable for electromechanical transducers that can be operated at high temperatures (at 200 °C, or higher). 相似文献
12.
Yajun Zhang Xu He Jingtong Zhang Jie Wang Philippe Ghosez 《Advanced functional materials》2023,33(44):2304187
The discovery of superconductivity in hole-doped infinite-layer nickelates has fueled intense research to identify the critical factor responsible for high-Tc superconductivity. Magnetism and superconductivity are closely entangled, and elucidating the magnetic interactions in hole-doped nickelates is critical for understanding the pairing mechanism. Here, these calculations based on the generalized Bloch theorem (GBT) and magnetic force theorem (MFT) consistently reveal that hole doping stabilizes an incommensurate (IC) spin state and increases the IC wave vector continuously, in a way strikingly similar to hole-doped cuprates. Going further, a nonlinear Heisenberg model including first-neighbor and third-neighbor in-plane magnetic interactions is developed. The analytical solutions successfully reproduce GBT and MFT results and reveal that the competition between the two magnetic interactions is the decisive factor for the IC magnetic transition. Eventually, by analyzing the doping-controlled spin splitting of band and orbital-contributed exchange interactions, direct links between hole doping, magnetization, exchange constants, and magnetic order are established. This discovery of the IC spin state, new understanding of its electronic origin, and establishment of direct connection with the paring electrons radically change the current understanding of the magnetic properties in hole-doped NdNiO2 and open new perspectives for the superconducting mechanism in nickelates superconductors. 相似文献
13.
A first‐principles‐based effective Hamiltonian is developed and employed to investigate finite‐temperature structural properties of a prototype of perovskite halides, that is CsPbI3. Such simulations, when using first‐principles‐extracted coefficients, successfully reproduce the existence of an orthorhombic Pnma state and its iodine octahedral tilting angles around room temperature. However, they also yield a direct transformation from Pnma to cubic upon heating, unlike measurements that reported the occurrence of an intermediate long‐range‐tilted tetragonal P4/mbm phase in‐between the orthorhombic and cubic phases. Such disagreement, which may cast some doubts about the extent to which first‐principle methods can be trusted to mimic hybrid perovskites, can be resolved by “only” changing one short‐range tilting parameter in the whole set of effective Hamiltonian coefficients. In such a case, some reasonable values of this specific parameter result in the predictions that i) the intermediate P4/mbm state originates from fluctuations over many different tilted states; and ii) the cubic phase is highly locally distorted and develops strong transverse antiphase correlation between first‐nearest neighbor iodine octahedral tiltings, before undergoing a phase transition to P4/mbm under cooling. 相似文献
14.
Samuele Cornia Valeria Demontis Valentina Zannier Lucia Sorba Alberto Ghirri Francesco Rossella Marco Affronte 《Advanced functional materials》2023,33(19):2212517
At the cutting-edge of microwave detection technology, novel approaches which exploit the interaction between microwaves and quantum devices are rising. In this study, microwaves are efficiently detected exploiting the unique transport features of InAs/InP nanowire double quantum dot-based devices, suitably configured to allow the precise and calibration-free measurement of the local field. Prototypical nanoscale detectors are operated both at zero and finite source-drain bias, addressing and rationalizing the microwave impact on the charge stability diagram. The detector performance is addressed by measuring its responsivity, quantum efficiency and noise equivalent power that, upon impedance matching optimization, are estimated to reach values up to ≈2000 A W−1, 0.04 and ≈, respectively. The interaction mechanism between the microwave field and the quantum confined energy levels of the double quantum dots is unveiled and it is shown that these semiconductor nanostructures allow the direct assessment of the local intensity of the microwave field without the need for any calibration tool. Thus, the reported nanoscale devices based on III-V nanowire heterostructures represent a novel class of calibration-free and highly sensitive probes of microwave radiation, with nanometer-scale spatial resolution, that may foster the development of novel high-performance microwave circuitries. 相似文献
15.
Rajagopal Kangeyan Madurakavi Karthikeyan 《International Journal of Communication Systems》2023,36(11):e5509
A novel fractal-shaped wideband multiple-input multiple-output (MIMO) antenna is proposed for brain and skin implantable applications. This antenna works in the 2.4–2.48 GHz band of industrial, scientific, and medical (ISM) standards. The fractal-shaped wideband MIMO antenna is miniature in size with a footprint of . Rogers RT/Duroid 6010 high-dielectric substrate material is used to fabricate the optimized design in order to validate the implantable MIMO antenna structure. The same high-permittivity substrate material has been used as a superstrate. Experiments were carried out in brain and skin-mimicking gel at 2.45 GHz in the ISM band. The proposed antenna has a peak gain of −21.3 dBi at 2.45 GHz. High isolation (>20 dB) between two MIMO ports is attained. The proposed antenna achieves a fractional bandwidth of 36.76% and an impedance bandwidth of 1.02 GHz. According to IEEE safety regulations for 1- and 10-g tissues, the computed maximum specific absorption rate (SAR) is safe bound. 相似文献
16.
Dichang Guan Weigang Wang Bo Chen Jiahui Wu Guorong Hu Zhongdong Peng Yanbing Cao Lei Wen Ke Du 《Advanced functional materials》2023,33(30):2215113
A high-concentration electrolyte is favored in dual-ion batteries (DIBs) due to the lower onset potential for anion intercalation, higher specific discharge capacity, and better oxidation stability. Inspired by the correlation between the high-concentration electrolytes and localized high-concentration electrolytes, it is suspected that it is not the salt concentration but the solution structure of the electrolyte that determines the intercalation behavior of anion into graphite cathode. To prove the viewpoint, a series of electrolytes are prepared by controlling the salt concentration or solution structure and the intercalation behavior of within the graphite cathode is investigated in Li||graphite and graphite||graphite cells. It is found that anions exhibit similar onset potentials and specific discharge capacities in the electrolytes with different salt concentrations but similar solution structures. This study provides a new perspective on designing promising electrolytes for DIBs, which can accelerate the further exploitation of high-performance DIBs. 相似文献
17.
Highly efficient piezoelectric nanogenerator operation is demonstrated based on dynamic bending of graphene‐like ZnO nanosheets. Energy is harvested by an external resistor by virtue of a strong time‐varying piezoelectric polarization component perpendicular to the graphene‐like ZnO plane. It is shown analytically and verified numerically using molecular dynamics simulations that the m2 point group of flat graphene‐like ZnO is reduced to monoclinic m symmetry for bent graphene‐like ZnO. The latter symmetry allows for a nonzero and large piezoelectric polarization component perpendicular to the plane of the 2D structure. The numerical results confirm that flexoelectric effects are negligible subject to graphene‐like ZnO bending operation. 相似文献
18.
Yazeed Qasaymeh 《International Journal of Communication Systems》2023,36(10):e5491
In this communication, the author presents an eight-element sequentially rotated (SR) circularly polarized (CP) dielectric resonator antenna (DRA) for operation in the IEEE 802.11a standard. A novel resonating element composed of a crescent slot (CS) used to excite a rectangular dielectric resonator (RDR) is proposed that has two orthogonal modes and as required for CP radiation. An SR series–parallel geometry is used to prototype the array feed network to allocate the array elements to symmetrical positions. The phase progression of each element was 45° along the array, and the signal magnitude was distributed evenly based on the binomial theory to enhance the antenna performance. The prototyped SR array had a size of mm3 and was measured and characterized in order to authenticate the design. The resonance bandwidth (S11 ˂ −10 dB) was found to be 14.28% with a 3 dB axial ratio (AR) of 17.7% for right-hand CP. The gain varied from 15.71 to 16.26 dBi within the operating band. The size, gain, and impedance bandwidth of the proposed array make it a potential candidate for devices operating in the IEEE 802.11a band. 相似文献
19.
Kalyan Mondal Biplab Bag Partha Pratim Sarkar 《International Journal of Communication Systems》2024,37(5):e5688
A small size, dual-band and dual-sense monopole antenna is proposed to improve the axial ratio bandwidth (ARBW). The proposed antenna is considered on a low-cost lossy FR4 substrate with parasitic strips (PSs) and partial ground plane of half guided wavelength dimensions. The dimension of the antenna in terms of wavelength is , where is the wavelength at the lowest resonant frequency. The circularly polarized (CP) mode is created for strong orthogonal electric fields and . The obtained phase difference (PD) between two electric fields and is varied from to under ARBW. The achieved ARBW is 3.68–3.8 GHz, 4.84–12.58 GHz, and impedance bandwidth (IBW) is 3.51–3.82 GHz and 4.28–15 GHz. The applications of the proposed antenna are International Telecommunication Union (ITU) for 5G, C-band IEEE 802.11a wireless local area network (WLAN) at 5 GHz (5.15–5.825 GHz) and X-band wireless systems. 相似文献
20.
Wanbing Ge Richard Beanland Marin Alexe Ana M. Sanchez 《Advanced functional materials》2023,33(37):2301171
Previous studies of single crystal BiFeO3 have found a dense domain structure with alternating sawtooth and flat domain walls (DWs). The nature of these domains and their 3D structure has remained elusive to date. Herein, several sections taken at different orientations are used to examine the structure in detail, concentrating here on the sawtooth DWs using diffraction contrast transmission electron microscopy, electron diffraction, and aberration-corrected scanning transmission electron microscopy (STEM). All DWs are found to be 180° type; the flat walls have head-to-head polarity while the sawtooth DWs are tail-to-tail with peaks elongated along the polar [111] axis, formed by neutral () DW facets and slightly charged facets with orientations close to () and (). The neutral DW facets are Ising type and very abrupt, while the charged DW facets have mixed Néel/Bloch/Ising character with a chiral nature and a width of about 2 nm. 相似文献