JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2020
·
IF 6.155
Hao Liu,Xuan Ge,Qiaodan Hu,Fan Yang,Jianguo Li
La- and Nb-doped BaTi 2 O 5 (BT 2 ) spherical glasses were prepared by a containerless aerodynamic levitation method and their glass-forming regions were established. It is found that La-doping on the Ba-site (network-modifier) and Nb-doping on the Ti-site (network-former) show distinct difference in the glass-forming region: less than 10 % La can replace Ba whereas 40 % Nb can incorporate into BT 2 glass. The distinction in glass-forming ability induced by La- and Nb-doping is discussed mainly from the structural arrangement of the glass. Raman spectroscopy analysis shows that La-doping elongates the short Ti–O bonds in the distorted [TiO 5 ] polyhedra and thus relaxes the network. Nb-doping introduces [NbO 6 ] polyhedra into BT 2 and there exists a critical doping level (20 %), below which incorporation of Nb into BT 2 relaxes the [TiO n ] polyhedra by shortening the long Ti–O bond and above which [NbO 6 ] starts to participate in the network skeleton construction resulting in a dramatic change in the glass structure, which is supported by the dramatic change in the exothermic peak on the DTA curves. This work triggers the speculation that the network-modifiers in BT 2 glass possess a very important role in the structure of network-former skeleton than those in glasses based on traditional network-former oxides such as SiO 2 , GeO 2 and B 2 O 3 , which may provide a useful strategy for modifying the properties of these novel glasses by chemical doping.
研究领域:
材料科学
·
玻璃科学
·
无机化学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2018
·
IF 5.091
W.Q. Wang,Z.J. Yao,X.L. Wang,X.H. Xia,C.D. Gu,J.P. Tu
Exploring high performance cathode materials is of great means for the development of bi-functional electrochromic energy storage devices. Herein, Nb-doped WO 3 mesoporous films as integrated high-quality cathode are successfully constructed via a facile sol-gel method. Chemical state and crystallinity of the WO 3 based films are significantly influenced by doping concentration. Compared with the pure WO 3 , the optimal Nb-doped film shows improved optical-electrochemical properties with high specific capacity (74.4 mAh g −1 at 2 A g −1 ), excellent high-rate capability, large optical contrast (61.7% at 633 nm), and ultra-fast switching speed (3.6 s and 2.1 s for coloring and bleaching process, respectively). These positive features suggest the potential application of Nb-doped WO 3 mesoporous cathode. Our research paves the way for the development of multifunctional photoelectrochemical energy devices.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
Journal of Superconductivity and Novel Magnetism
·
2023
·Vol. 36
·期 7
·1737-1750
·
IF 1.8
Shan Shuo,Li Jie,Li Pengwei,Wang Yonglun,Pi Siwen,Zhao Xuan
BaFe 12− x Nb x O 19 ( x = 0.00, 0.04, 0.08, 0.12, 0.16, and 0.20) with a nominal composition for M-type hexagonal barium ferrite was prepared using solid-state sintering methods. The microstructure and magnetic properties of hexaferrite were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FESEM), and vibrating-sample magnetometry (VSM). XRD results revealed that the crystal structure of barium ferrite remained intact after Nb doping, maintaining a single barium ferrite phase. FESEM confirmed the hexagonal crystal structure of the sample. Energy-dispersive X-ray spectroscopy showed increased Nb content and decreased Fe content without the formation of other elements. FTIR revealed bands at 598 and 445 cm −1 corresponding to tetrahedral and octahedral clusters, respectively. The VSM test showed that the saturation magnetization ( M s ), residual magnetization ( M r ), and coercivity ( H c ) initially increased and then decreased with increasing Nb doping, reaching maximum values of 92.297 emu/g, 44.256 emu/g, and 3367.53 Oe, respectively, at x = 0.08.
研究领域:
材料科学
·
磁学
✓ 已验证
DOI
高影响因子
ACS Applied Energy Materials
·
2020
·
IF 4.473
Lei Zhang,Tao Yuan,Luke Soule,Hao Sun,Yuepeng Pang,Junhe Yang,Shiyou Zheng
Sodium-ion batteries (SIBs) are promising candidates for inexpensive and sustainable energy storage devices for the widespread utilization of intermittent renewable energy because of the natural abundance of sodium raw materials. However, since the ionic radius of Na+ is inherently larger than that of Li+, Na-based intercalation materials often suffer from poor stability and slow reaction kinetics. Regarding SIB cathodes, layered transition metals oxides (NaxTMO2) show promising theoretical capacities but low stability. In this work, a series of O3-NaFe0.55Mn0.45–xNbxO2 (x = 0, 0.01, 0.02, and 0.03) compounds are synthesized and show superior stability and rate-capability compared with the pure oxide. For instance, the best-performing sample, NaFe0.55Mn0.44Nb0.01O2, has a specific capacity of 127 mAh g–1 and 80% capacity retention over 100 cycles at 0.1 C. Ex situ X-ray diffraction (XRD) result shows that the Nb incorporation could suppress TMO2 slip and reduce the energy barrier of the O3–P3 phases’ transition. When coupled with a hard carbon (HC) anode in a full cell, the battery exhibits significant weight and volume energy and power densities. It is believed that Nb-doping enlarges lattice spacing of the oxide and partially reduces Mn4+ to Mn3+, increasing the ionic conductivity of the cathodic materials.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Lei Jiang,Lei Sun,Dong Yang,Jian Zhang,Ya-Juan Li,Kun Zou,Wei-Qiao Deng
TiO2 nanocrystals with different reactive facets have attracted extensive interest since they were first synthesized. The anatase TiO2 nanocrystals with (001) or (100) dominate facets were considered to be excellent electrode materials to enhance the cell performance of dye-sensitized solar cells. However, which reactive facet presents the best surface for benefiting photovoltaic effect is still unknown. We report a systematic study of various anatase TiO2 surfaces interacting with N719 dye by means of density functional theory calculations in combination with microscopic techniques. The (001) surface interacting with N719 would have the lowest work function, leading to the best photovoltaic performances. To further increase the efficiency, Nb dopant was incorporated into the anatase TiO2 nanocrystals. Based on the theoretical prediction, we proposed and demonstrated novel Nb-doped (001)-dominated anatase TiO2 nanosheets as photoelectrode in a dye-sensitized solar cell to further enhance the open-circuit voltage. And a power conversion efficiency of 10% was achieved, which was 22% higher than that of the undoped device (P25 as an electrode).
研究领域:
材料科学
·
能源科学
·
理论计算化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Small
·
2023
·Vol. 19
·期 20
·2207569
·
IF 13.3
Yakun Tian,Ming Wen,Aijian Huang,Qingsheng Wu,Zhiguo Wang,Quanjing Zhu,Tao Zhou,Yongqing Fu
High stability and efficiency of electrocatalysts are crucial for hydrogen evolution reaction (HER) toward water splitting in an alkaline media. Herein, a novel nano-Pt/Nb-doped Co(OH) 2 (Pt/Nb Co(OH) 2 ) nanosheet is designed and synthesized using water-bath treatment and solvothermal reduction approaches. With nano-Pt uniformly anchored onto Nb Co(OH) 2 nanosheet, the synthesized Pt/Nb Co(OH) 2 shows outstanding electrocatalytic performances for alkaline HER, achieving a high stability for at least 33 h, a high mass activity of 0.65 mA µg −1 Pt, and a good catalytic activity with a low overpotential of 112 mV at 10 mA cm −2 . Both experimental and theoretical results prove that Nb-doping significantly optimizes the hydrogen adsorption free energy to accelerate the Heyrovsky step for HER, and boosts the adsorption of H 2 O, which further enhances the water activation. This study provides a new design methodology for the Nb-doped electrocatalysts in an alkaline HER field by facile and green way.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Peiyu Hou,Maosheng Gong,Yuhang Tian,Feng Li
Elevating the nickel (Ni) content within layered cathodes constitutes a straightforward and effective approach to enhance the energy density of lithium-ion batteries (LIBs). However, the phase transition from H2 to H3 introduces substantial alterations in lattice volume, leading to structural degradation and diminished electrochemical performance . This study employs density functional theory (DFT) calculations to determine that the formation energy for Nb 5+ occupied at Li 3 b sites is lower compared to that of Ni 3 a and Co 3 a sites, yet higher than that of Mn 3 a sites. This suggests a preference for Nb 5+ doping within the Li layer of Mn-free cathodes. Motivated by these DFT results, we show the viability of high-valence Nb 5+ as a stable pillar in the compositionally optimized binary oxide LiNi 0.9 Co 0.1 O 2 . The inclusion of this Nb 5+ pillar in the Li layer of Ni/Co-based oxide significantly enhances the reversibility of the H2–H3 redox couple and mitigates microcrack formation in polycrystalline cathodes. As a result, the Nb-doped Ni/Co-based cathode exhibits an extended cycling lifespan, elevated rate capability, and increased thermal stability compared to the undoped. This investigation achieves precise control over doping sites by optimizing the chemical composition of Ni-rich cathodes and provides novel insights into advancing their electrochemical performance for high-energy LIBs.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 47
·24232-24244
·
IF 9.931
Fengqi Lu,Qiang Chen,Shipeng Geng,Mathieu Allix,Hui Wu,Qingzhen Huang,Xiaojun Kuang
The soft-chemistry synthetic routes of anatase phases for energy conversion and storage usually employ expensive and air-sensitive amorphous alkoxides, which hardly access the electrochemically active cationic vacancy defects in the cationic donor-substituted anatase compositions. Here we demonstrate an innovative way of using layered K3Ti5NbO14 as a cost-effectively crystalline precursor to synthesize cation-deficient Nb-doped TiO2 (NTO, formulated as Ti0.8Nb0.16□0.04O2) anatase by a one-pot hydrothermal route. When used as an anode in lithium ion batteries, the NTO electrode displayed initial discharge and charge capacities of 618 and 384.6 mA h g−1 at a current density of 0.2C respectively, with a remarkable discharge capacity of ∼246.8 mA h g−1 retained after 100 cycles, representing the highest value among those reported for Nb-doped TiO2 anatases at low current density. A discharge capacity of 137.1 mA h g−1 was obtained even at a high current density of 2C. A full cell, fabricated using the NTO electrode as the anode and a commercial LiCoO2 cathode, is shown to deliver a discharge capacity of 220.2 mA h g−1 after 57 cycles, which exceeds those of most previously reported full cells based on the TiO2 anode and makes this NTO material a promising anode candidate for LIBs. These results present a practical synthetic strategy for tuning cationic vacancies through aliovalent cationic substitution to improve the electrochemical performance of actual LIBs and possibly to develop further relevant devices.
研究领域:
材料科学
·
电化学
·
能源存储与转换
✓ 已验证
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2022
·Vol. 51
·期 12
·6885-6893
·
IF 2.047
Song Angang,Cao Guoqin,Zhu Di,Zhao Baofeng,Fu Zhenya,Cao Shuaiqi,Wang Qingjie,Hu Junhua
Nb-doped TiO 2 (NTO) thin films were sputtered on glass substrate followed by a simple annealing process in air. The photoelectric cooperative optimization was discussed based on the structural, optical and electrical characteristics. The influence of oxygen flow during deposition on materials chemistry and performance was analyzed. Hall measurement showed a strong dependence of transparent conductivity on the oxygen flow. Oxygen vacancies are related to the phase transitions from the rutile to anatase TiO 2 during annealing. The chemical states of Nb, Ti and O before and after annealing were discussed. The achievement of optimized transparent conductivity was resultant from the fine-tuning of the doped chemistry and special interplay of dopants and host lattice. Graphical
研究领域:
材料科学
·
薄膜技术
·
固体物理
·
光电材料
·
无机非金属材料
✓ 已验证
DOI
高影响因子
JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2023
·Vol. 37
·期 6
·1180-1184
·
IF 1.6
Song Xuyan,He Yunlu,Peng Sanwen,Wang Bo,Dong Ping,Tang Haolin,Yu Jun
We reported sol-gel-derived Nb-doped SnO 2 which is an effective catalyst carrier for deposition of IrO 2 , and the electrocatalytic activity of the synthesized catalysts for OER was investigated. It is found that the doping of Nb can refine the SnO 2 crystal grains and improve the electrical conductivity of SnO 2 . When the doping amount of Nb is 7%, the electrical conductivity of Nb-SnO 2 reaches a maximum value of 3.54 S/cm. With the increase in the loading amount of IrO 2 , the electrocatalytic activity towards OER of the thus-synthesized catalysts is improved, reaching a comparable OER activity with pristine IrO 2 with the loading content of about 44wt%.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
Crystals
·
2024
·Vol. 14
·期 5
·419
·
IF 2.4
Yifei Wang,Xiaoyang Chen
The demands of low-Curie-temperature (~−10 °C) positive temperature coefficient (PTC) thermistors are increasing in advanced precision integrated circuits and other industries. In this paper, the Nb-doped Ba0.55Sr0.45TiO3(BST)-based PTC resistivity materials are reported. The effects of the sintering process, especially the cooling rate on the PTC properties of the material, are investigated. The results indicate that the Ba0.55Sr0.45Ti0.9985Nb0.0015O3composition of the prepared PTC ceramics demonstrates promising PTC characteristics. These include a Curie temperature as low as −13 °C, a high temperature coefficient of 0.296 at −3.4 °C, a large enough resistivity change of 3.1 over a narrow phase transition temperature range of approximately 38 °C, and moderate resistivity below the Curie temperature. Such properties suggest that the Ba0.55Sr0.45Ti0.9985Nb0.0015O3ceramics are likely suitable for use in thermal management systems designed for low-temperature control.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Yu Zeng,Chenhan Xiong,Jingxuan Li,Zhiyong Huang,Guoping Du,Zhaoyang Fan,Nan Chen
Ceramic/polymer composites have great potential to achieve the concomitant enhancement of both dielectric constant and breakdown field while maintaining other superior properties of the polymer matrix , ideal for elastomer sensors, actuators, capacitive energy storage, and many other applications. However, material incompatibility between the ceramic filler and the polymer matrix often leads to void formation , particle aggregation and phase separation, with significantly degraded performance. Herein, through surface modification, co-doped TiO 2 particles were uniformly dispersed and bridged onto the silicone rubber matrix via a silane coupling agent for fabricating composites via mechanical mixing and hot-pressing. The synthesized composites exhibit enhanced dielectric constant, increased from 2.78 to 5.06 when 50 wt% co-doped TiO 2 particles are incorporated. Their dielectric loss is less than 0.001 in a broad frequency range. Theoretical modelling and experimental results reveal that the morphology and dispersion state of co-doped TiO 2 particles were crucial to the dielectric properties of the silicone rubber-based composites. Besides, the composites are thermally stable up to 400 °C. Significantly increased tensile strength (612 kPa) and elongation at break (330%) were obtained for the composite incorporated with 30 wt% co-doped TiO 2 particles, accompanied by a moderate increased elastic module (540 kPa). Such composites have the potential for different applications.
研究领域:
材料科学
·
电气工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）