ACS Applied Materials & Interfaces
·
2023
·
IF 9.5
Jianguang Xu,Zhiyong Liu,Qiang Wang,Junsheng Li,Yuxiang Huang,Mengnan Wang,Linyu Cao,Wei Yao,Haijiang Wu,Chi Chen
MXenes show promising potential in supercapacitors due to their unique two-dimensional (2D) structure and abundant surface functional groups. However, most studies about MXenes have focused on tailoring surface structures by alternating synthesis methods or post-etch treatments, and little is known about the inherent relationship between surface groups and M elements. Herein, we propose a simple and novel strategy to adjust the surface structure of few-layered MXene flakes by adding a small amount of Nb element. Because of the strong affinity between Nb and O elements, the as-received V1.8Nb0.2CTx and Ti2.7Nb0.3C2Tx MXenes have much fewer −F functional groups and a higher O content than V2CTx and Ti3C2Tx MXenes, respectively. Thus, both V1.8Nb0.2CTx and Ti2.7Nb0.3C2Tx MXenes show enhanced pseudocapacitance performance. Especially, V1.8Nb0.2CTx delivers an ultrahigh volumetric capacitance of 1698 F/cm3 at a scan rate of 2 mV/s. Moreover, benefiting from the high activity of MAX precursors obtained through a fast self-propagating high-temperature synthesis, the etching time to produce V-based MXenes is much shorter than that in previous reports. Therefore, the results presented here are applicable to the surface engineering and rational design of 2D MXene materials and develop them into promising, cost-effective electrode materials for supercapacitors or other energy-storage equipment.
研究领域:
材料科学
·
能源存储技术
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DOI
PubMed
高影响因子
Frontiers of Physics
·
2022
·Vol. 18
·期 1
·1-10
·
IF 5.142
Xu Meng,Guo Lei,Chen Lei,Zhang Ying,Li Shuang-Shuang,Zhao Weiyao,Wang Xiaolin,Dong Shuai,Zheng Ren-Kui
Weak antilocalization (WAL) effect is commonly observed in low-dimensional systems, three-dimensional (3D) topological insulators and semimetals. Here, we report the growth of high-quality Ta 0.7 Nb 0.3 Sb 2 single crystals via the chemical vapor transport (CVT). Clear sign of the WAL effect is observed below 50 K, probably due to the strong spin—orbital coupling in 3D bulk. In addition, it is worth noting that a relatively large MR of 120% appears under 1 T magnetic field at T = 2 K. Hall measurements and two-band model fitting results reveal high carrier mobility (>1000 cm 2 · V −1 ·s− 1 in 2–300 K region), and off-compensation electron/hole ratio of ∼8:1. Due to the angular dependence of the WAL effect and the fermiology of the Ta 0.7 Nb 0.3 Sb 2 crystals, interesting magnetic-field-induced changes of the symmetry of the anisotropic magnetoresistance (MR) from two-fold (≤ 0.6 T) to four-fold (0.8–1.5 T) and finally to two-fold (≥ 2 T) are observed. This phenomenon is attributed to the mechanism shift from the low-field WAL dominated MR to WAL and fermiology co-dominated MR and finally to high-field fermiology dominated MR. All these signs indicate that Ta 0.7 Nb 0.3 Sb 2 may be a topological semimetal candidate, and these magnetotransport properties may attract more theoretical and experimental exploration of the (Ta,Nb)Sb 2 family.
研究领域:
凝聚态物理
·
材料科学
·
量子输运
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拓扑物态
·
半导体物理
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Dan Zhong,Zhiyong Liu,Qifang Ruan,Kun Guo,Bing Xie,Pu Mao,Haijun Sun
High dielectric loss and temperature-dependent dielectric constant are the main obstacles limiting the application of giant dielectric materials in microelectronic devices. Here, (Nb 0.5 Bi 0.5 ) x Ti 1- x O 2 (NBTO- x ) ceramics modified by defect cluster synergistic interfacial effects were designed to improve the dielectric properties, and the mechanism of the giant dielectric behavior was thoroughly investigated. The defect clusters formed by co-doping of Bi 3+ and Nb 5+ ions confined the free electrons to a limited range of jumps, leading to a significant increase in the dielectric constant and a decrease in the dielectric loss of the NBTO- x ceramics. Defect clusters aggregated near grain boundaries accumulated free electrons and carriers, which formed an interfacial effect with insulating grain boundaries, further reducing the dielectric loss. Thus, a high dielectric constant of 10 5 and a low loss of 0.04 at 1 kHz with a temperature stability of Δ ε′ / ε′ 25 °C ≤ ±15% (-55 °C to 105 °C) was obtained in the NBTO-0.5% ceramic. This study offers a new approach to the design of high-performing giant dielectrics with excellent potential for application in microelectronic devices.
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Ning Zhang,Ying Tang,Huaicheng Xiang,Liang Fang
Two cubic garnet ceramics, Ca 3 B 2 ZnGa 2 O 12 ( B = Nb, Sb), were synthesized via the solid-state approach, where Zn 2+ and Ga 3+ jointly occupied the tetrahedra ( C -site), and Nb 5+ (or Sb 5+ ) fully occupied the octahedra ( B -site). Ca 3 Nb 2 ZnGa 2 O 12 ceramic sintered at 1390 °C possessed a relatively larger ε r , τ f , and Q × f value of 16.57, −44.0 ppm/°C, and 39,200 GHz compared to ε r = 9.04, Q × f = 25,300 GHz, and τ f = −61.2 ppm/°C for Ca 3 Sb 2 ZnGa 2 O 12 fired at 1270 °C. Bond valence, ionic polarizability, packing fraction, Raman spectroscopy , and the P–V-L chemical bond theory were used to investigate the intrinsic factors affecting microwave dielectric properties . Compared with the measured permittivity ε r , the theoretical permittivity ε r (C-M) of Ca 3 Nb 2 ZnGa 2 O 12 is underestimated, and Ca 3 Sb 2 ZnGa 2 O 12 shows the opposite trend, which is mainly related to the under- and over-bonding in the structure. The packing fraction of Ca 3 Nb 2 ZnGa 2 O 12 is slightly lower than that of Ca 3 Sb 2 ZnGa 2 O 12 , but it does not lead to the low Q × f value of Ca 3 Nb 2 ZnGa 2 O 12 . The variation in Q × f was related to relative density, weak short-range order (SRO), and lattice energy. The minus sign and magnitude of τ f for both ceramics were determined by their large positive τ αm values.
研究领域:
材料科学
·
化学
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DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2016
·
IF 8.328
Jing Guo,Shanhui Zhu,Youliang Cen,Zhangfeng Qin,Jianguo Wang,Weibin Fan
A series of ordered mesoporous Nb x W (8 − x) oxides with tunable Nb/W ratio were successfully synthesized by evaporation-induced self-assembly method. The mesoporous structure, morphologies, surface chemical state, and acidic properties of these catalysts were fully characterized by low-temperature sorption of N 2 , small-angle and wide-angle XRD, TEM, Raman, XPS, and Py-IR. It was shown that the Nb x W (8 − x) oxides created large amounts of Lewis as well as Brønsted acid sites, which promoted the isomerization of glucose to fructose followed its dehydration to 5-hydroxymethylfurfural (HMF). Mannose was also formed via the epimerization of glucose. Of them, the mesoporous Nb 4 W 4 exhibited the best catalytic activity with a comparatively low E a about 90.2 kJ/mol and good stability in aqueous medium. The kinetic behavior revealed that Lewis acid sites facilitated to glucose-to-fructose isomerization while Brønsted acid sites promoted the dehydration of fructose to form HMF.
研究领域:
催化化学
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生物质转化
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绿色化学
·
多相催化
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材料化学
·
碳水化合物化学
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DOI
高影响因子
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2015
·Vol. 15
·期 1
·549-555
·
IF 1.556
Huo Jiansheng,Wang Qianming
A group of LnM
v
O4 (M = Nb, Ta):RE3+ (RE = Eu3+, Tb3+) phosphors have been synthesized by pretreatments with a special reactor (supersonic microwave co-assistance (SMC) machine). Powder characteristics were studied by X-ray
Diffraction, photoluminescence, fluorescence microscope and scanning electronic microscope. Results showed the samples can exhibit green or red emissions upon the ultra-violet excitations. The influence of SMC method on the physical properties has been investigated in detail.
研究领域:
材料科学
·
发光材料
·
纳米技术
·
固态化学
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DOI
高影响因子
Materials Chemistry Frontiers
·
2023
·Vol. 7
·期 17
·3754-3761
·
IF 7
Xue Han,Zhaolong Liu,Zhongnan Guo,Xiaojing Feng,Yan Gao,Shifeng Jin,Wenxia Yuan
Chemical intercalation has great potential to realize exotic electrical properties in van der Waals materials. Here we report the Ge intercalation in layered Nb dichalcogenides NbX2 (X = Se and S), which can induce ultrahigh conductivity and novel transport properties. Using the chemical vapor transport method, single crystals of two intercalated materials, namely, Ge0.33NbS2 and Ge0.26NbSe2, were grown. Despite the similar structures with an edge-sharing NbX6 triangular prism, the intercalated Ge shows different configurations in these two compounds, which is ordered in sulfide but disordered in selenide. The measurement of transport properties demonstrated that both Ge0.33NbS2 and Ge0.26NbSe2 are metallic and interestingly the conductivity of Ge0.33NbS2 at 300 K reaches 6.83 × 104 S cm−1, which is higher than those of other metallic transition metal dichalcogenides and even comparable to that of the electrode material Pt. Ge0.33NbS2 also shows high carrier mobility (83.40 cm2 V−1 s−1 at 300 K) and unsaturated linear magnetoresistance, while negative magnetoresistance was observed in Ge0.26NbSe2 below 10 K. The first-principles calculations indicated that the ultrahigh conductivity in Ge0.33NbS2 is ascribed to the non-trivial topological bands near the Fermi surface. Our work highlights the effective regulation of transport properties of van der Waals materials via modulating the band structures by chemical intercalation.
研究领域:
凝聚态物理
·
材料科学
·
纳米电子学
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DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2022
·Vol. 106
·期 2
·1089-1101
·
IF 4.186
Kui Liu,Huaiwu Zhang,Cheng Liu,Liang Shi,Xueying Wang,Jie Li,Yulong Liao,Dainan Zhang
The relationship among the sintering behavior, crystal structure, chemical bonding properties, and dielectric properties of wolframite-type ZnZr(Nb 1− x Ta x ) 2 O 8 (0.0 ≤ x ≤ 1.0) ceramics was investigated with the progressive replacement of Nb 5+ by Ta 5+ . The optimum sintering temperature increases from 1225 to 1375°C with increasing Ta 5+ content. The ε r value falls from 27.34 to 22.34 due to a gradual decrease in bond ionicity and a shift in the Raman vibration modes toward higher wave numbers. The Q × f increases from 63 604 GHz (@6.71 GHz) to 115 631 GHz (@7.89 GHz), which is since the increase in the total lattice of chemical bonds. Moreover, the reduction in grain boundary area and the gradual lowering of the full width at half maximum of the Raman vibration modes contribute to the reduction in dielectric losses. First-principles calculations illustrate that the growth in bandgap and electron cloud density in the internal space of the [Zn/ZrO 6 ] octahedron leads to a reduction in dielectric loss. Furthermore, the reduced degree of oxygen octahedral distortion causes a change in τ f from −46.56 to −37.40 ppm/°C.
研究领域:
材料科学
·
无机化学
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DOI
高影响因子
MATERIALS RESEARCH BULLETIN
·
2026
·
IF 5.8
Lei Wang,Zhengyu Yang,Yajun Xu,Yilin Wu,Jinsheng Li,Xiaoguo Bi,Xiqiu Wang,Xudong Sun,Weiping Lu
First systematic study of dielectric anisotropy in Nb:SrTiO 3 single crystals across seven orientations. • [311] shows the highest permittivity (2.35 ×10 5 ) but poor stability; [100] shows the lowest loss (<0.056) and excellent stability. • [310] orientation best balance defect concentration, electron binding, and dynamic response for orientation engineering. High-quality Nb-doped SrTiO 3 single crystals were successfully grown via the Verneuil method, and their dielectric properties were systematically investigated with respect to crystallographic orientation. The [311] orientation achieves the highest permittivity of 2.35 × 10 5 , accompanied by high Ti 3 ⁺ and oxygen vacancy concentrations, but exhibits poor frequency and temperature stability. In contrast, the [100] orientation shows the lowest permittivity of 6.0 × 10 4 , the lowest dielectric loss (<0.056), and excellent stability, attributed to its low defect concentrations and strong electron binding capability. Remarkably, the [310] orientation achieves an optimal balance, delivering a permittivity of 1.63 × 10 5 , a capacitance temperature variation of less than 8.5% from room temperature to 300 °C, and a high-frequency loss below 0.085, exhibiting outstanding thermal stability in the tested temperature range for capacitor applications. These findings provide direct guidance for designing textured polycrystalline ceramics and demonstrate that orientation engineering is a viable strategy for developing high-performance colossal dielectric materials. Download: Download high-res image (160KB) Download: Download full-size image
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DOI
高影响因子
Journal of Materials Chemistry C
·
2019
·Vol. 8
·期 3
·1143-1150
·
IF 6.641
Zhizhen Wang,Zhen Song,Lixin Ning,Quanlin Liu
Warm-color persistent luminescent materials are strongly desired for signage markings and medical imaging in comparison with green or blue counterparts. Herein we report a novel yellow long-persistent phosphor, Nb-doped Sr3SiO5:Eu2+, with a peak wavelength of ∼580 nm and persistence time of more than 14 hours at the 0.32 mcd m−2 threshold value after UV radiation. A combination of thermoluminescence (TL), thermoluminescence excitation (TLE), electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) calculations reveals that the persistent luminescence enhancement is attributed to a significant Nb-induced increase of oxygen vacancies that act as electron trapping centers with appropriate trap depths. Groups of time-dependent color-change images are realized with this material, which has potential applications as anti-counterfeit and indicator marks. This investigation also expands the application of transition metal (TM) ions to the field of persistent luminescence and would motivate further exploration of TM substitutions to design and improve silicate or aluminosilicate persistent phosphors with superior performance.
研究领域:
材料科学
·
光学
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DOI
高影响因子
ELECTROCHIMICA ACTA
·
2025
·
IF 5.6
Zhihong Xiao,Xiangze Kong,Yujia Wang,Yunyao Chen,Kai Liu,Qingyin Zhang,Guifang Zhang,Zhiqiang Shi
Sodium-ion batteries (SIBs) are considered as one of the most competitive candidates for energy storage systems . While O3-type NaNi 0.5 Mn 0.5 O 2 cathode materials offer high theoretical capacity and operating voltage, their practical application is hindered by irreversible phase transitions during Na + extraction/insertion that degrade structural stability and reaction kinetics. This study synthesizes Nb-doped O3-Na[Ni 0.5 Mn 0.5 ] 1- x Nb x O 2 ( x = 0,0.01,0.02,0.03) through ball milling assisted coprecipitation . Nb doping enhances lattice stability through two mechanisms: on one hand promoting optimization of coprecipitated particle crystallization , and on the other hand effectively suppressing manganese activity through the formation of mixed cation-oxygen bonds. Na[Ni 0.5 Mn 0.5 ] 0.99 Nb 0.01 O 2 exhibits 108.7 mAh g –1 capacity at 0.5C with 77.4 % retention after 200 cycles, demonstrating enhanced cycling stability compared to the undoped material. When paired with hard carbon in full cell, the system achieves >190 Wh kg –1 energy density . Theoretical calculations also elucidate the mechanism by which Nb doping affects the hybridization of Ni-O bonds, stabilizes the structure of the material, and exhibits enhancement in electrochemical properties . This study provides an effective strategy for suppressing the phase transition and advancing the study of the doping mechanism in sodium-ion batteries.
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DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Xiangyu Xin,Yu Xiao,Wanyu Li,Rui Yao,Xiaoying Zhang,Shengting Li,Yufei Song,Jinping Li,Guang Liu
Magnesium hydride (MgH 2 ) is regarded as one of the most promising solid-state hydrogen storage materials. However, its practical application remains limited by thermodynamic stability, slow kinetics, and the gradual coarsening of particles during cycling. To address these limitations, we synthesized a stoichiometrically adjustable Mg-Nb nanocomposite using a liquid-phase in-situ growth strategy. Optimization revealed that the Mg-Nb (10:1) composite exhibits excellent hydrogen storage performance, releasing hydrogen at 239.5 °C with a capacity of 6.17 wt%. At 300°C, the composite released 5.72 wt% H₂ within 15 min, while hydrogen absorption commences at room temperature. Notably, after 100 cycles of hydrogenation/dehydrogenation, the capacity retention was maintained at 99.98 %, underscoring its exceptional cycling stability. The measured dehydrogenation activation energy was reduced to 85.38 kJ/mol, approximately 47.5 % lower than that of pure MgH 2 (162.54 kJ/mol). Mechanistic studies reveal that Nb 5 + is preferentially reduced and acts as a nucleation as well as growth site for Mg, allowing Mg to interact and distribute evenly with Nb. This structure not only provides abundant active sites and hydrogen diffusion pathways but also effectively suppresses the agglomeration and growth of Mg/MgH 2 matrix during hydrogenation/dehydrogenation. Furthermore, NbH 2 phases are formed during the hydrogenation/dehydrogenation process, significantly promoting the adsorption and dissociation of hydrogen atoms, thereby optimizing the hydrogen storage performance of the material.
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DOI
高影响因子
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