Advances in Applied Ceramics
·
2016
·
IF 1.162
Z. B. Shen,X. H. Wang,D. S. Song,L. T. Li
Nb-doped 0.90BaTiO3-0.10(Bi0.5Na0.5)TiO3 temperature-insensitive ceramics with novel core-shell structure were sintered at low temperature by the conventional solid-state reaction method. The beneficial role of Nb in facilitating the formation of core-shell structure because of chemical inhomogeneity is verified, which is responsible for the weak temperature dependence of dielectric properties. Temperature dependence of permittivity measured at different frequencies shows high frequency dispersion at low temperature, while without relaxor characteristic at high temperature. The Vogel–Fulcher model was adopted to study the relaxor behaviour of Nb-doped 0.90BaTiO3-0.10(Bi0.5Na0.5)TiO3 ceramics at low temperature. The samples with an addition of 1.5 mol% Nb2O5 provide a temperature coefficient of capacitance meeting the requirements of the X9R characteristic, and result exhibits an optimum dielectric behaviour of εr ∼1900, tanδ ∼1.8% at room temperature, making the material a promising candidate for high temperature applications.
研究领域:
材料科学
·
电子材料
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2024
·
IF 5.2
Changlong Yin,Yihang Han,Lingtong Meng,Yongqiang Guo,Yu Yan,Dong Liu,Huiji Zhao,Yongming Chai,Chenguang Liu
Biolipids and oil hydrogenation are prominent alternatives to petroleum-based fuels. Currently, the catalysts used are limited to deoxidation activity, resulting in the reaction products with a high content of n-alkanes and waxes, necessitating secondary treatment to increase iso-alkane content. Herein, an unsupported Ni–Nb–O catalyst with trifunctional capabilities (i.e., hydrodeoxygenation, hydrocracking, and isomerization) was developed for the efficient conversion of methyl stearate and jatropha oil into small molecular alkanes. The metal ratio significantly affects the catalytic performance, in which Ni/Nb = 2:0.6 exhibited the highest isomerization activity. Moreover, 84% of the deoxidized products are C8–C17 hydrocarbons, with 53.4% being isomeric hydrocarbons. The catalyst also demonstrated excellent stability, maintaining 54% selectivity for C8–C17 iso-alkanes in jatropha oil feedstock during 240 h of operation.
研究领域:
催化化学
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能源化学
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生物燃料技术
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Biao Ran,Yun Wu,Kaiyang Zhang,Rui Yao,Jinping Li,Guang Liu
In the evolution of proton exchange membrane (PEM) electrolysis, the development of durable electrocatalysts for the acidic oxygen evolution reaction (OER) is crucial. This work introduces an electrocatalyst with a core–shell architecture, consisting of amorphous iridium oxide (IrO x ) supported on lanthanum (La) and niobium (Nb) co-doped titanium dioxide (denoted as La, Nb-TiO 2 @IrO x ). The resultant La, Nb-TiO 2 @IrO x , synthesized via a hydrothermal method, exhibits enhanced OER activity and remarkable durability in acidic media. The theoretical calculations provide insight into the enhanced performance of La, Nb-TiO 2 @IrO x , revealing a narrowed bandgap and improved conductivity due to co-doping. Additionally, there is an increase in charge transfer and binding energy at the heterointerface. As a result, electrochemical evaluations show a significant reduction in overpotential and enhancement in long-term stability, achieving an overpotential of 234 mV at 10 mA cm −2 and maintaining impressive stability for 150 h. These findings underscore the potential of La, Nb-TiO 2 as a robust platform for acidic OER electrocatalysts, offering valuable insights into the design of durable and efficient systems for energy conversion applications and advancing the development of next-generation technologies.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Ping Wang,Peixi Wang,Jie Wang,Shoutao Lv,Jiaqing Wang,Hui Zheng
With the rapid development of wireless charging technology, there is a growing demand for ferrite materials with high permeability, high saturation magnetic induction intensity, and low power loss. This study aims to enhance the electromagnetic performance of NiCuZn ferrite by co-doping Nb 5+ and Li + . The influence of the doping levels Nb 5+ and Li + on the morphology, crystal structure, and electromagnetic properties of NiCuZn ferrite were studied in detail. Structural analysis shows that the lattice constant decreases as the Nb 5+ -Li + doping concentration increases, and the NiCuZn ferrite exhibits a high density and homogeneous microscopic morphology at the optimum concentration of x = 0.004. Specifically, at a doping concentration of x = 0.004, the magnetic permeability at 1 MHz measured at 1112.1, the saturation magnetic induction intensity reached 458.98 mT, and the power loss was minimized to 521.85 kW/m 3 , demonstrating significant improvement in the transmission power of wireless charging applications.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2016
·Vol. 28
·期 5
·4204-4210
·
IF 1.798
Huang Xuechen,Zhang Wenqin,Xie Juan,Xu Qi,Zhang Lin,Hao Hua,Liu Hanxing,Cao Minghe
Nb 2 O 5 doped 0.8BaTiO 3 –0.2(Na 1/4 Bi 3/4 )(Mg 1/4 Ti 3/4 )O 3 (0.8BT–0.2NBMT) polycrystalline ceramics were prepared by solid state reaction method. 0.8BT–0.2NBMT samples were observed to possess two dielectric peaks, which were attributed to the formation of core–shell structure (Huang et al. in J Eur Ceram Soc 36:533–540, 2015 ). Longer sintering induced uniform distributions of the additives. The introduction of Nb 2 O 5 into 0.8BT–0.2NBMT could obviously bring about the improvement of the dielectric temperature stability, the degradation of the dielectric loss at room temperature and the decrease of the sintering temperature. The 0.8BT–0.2NBMT ceramics doped with 2.0 at% Nb 2 O 5 could satisfy the temperature range of the X9R (−55 to 200 °C, △C/C 25°C = ±15% or less) characteristics, with a moderate dielectric constant of 1130, low dielectric loss of 0.7%, low sintering temperature of 1050 °C and insulation resistivity of 5 × 10 12 Ω cm at room temperature, which might be promising for practical use in multilayer ceramic capacitors. The inhomogeneous distribution and the existence of the secondary phases were responsible for this excellent dielectric temperature characteristic. The complex impedance analysis was introduced to elaborate the conduction mechanism.
研究领域:
材料科学
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电子工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2015
·
IF 6.723
Xiaosong Guo,Yulu Chen,Ming Su,Dong Li,Guicun Li,Chengdong Li,Yu Tian,Chuncheng Hao,Qingquan Lei
Titanium dioxide and Nb-doped titanium dioxide microspheres with the same size were fabricated by a simple sol–gel method, and the formation mechanism of Nb-doped titanium dioxide microspheres was proposed. Titanium dioxide and Nb-doped titanium dioxide microspheres were adopted as dispersed materials for electrorheological (ER) fluids to investigate the influence of the charge increase introduced by Nb doping on the ER activity. The results showed that Nb doping could effectively enhance the ER performance. Combining with the analysis of dielectric spectroscopy, it was found that the interface polarization of Nb-doped TiO2 ER fluid was larger than that of TiO2 ER fluid, which might be caused by more surface charges in Nb-TiO2 microspheres due to Nb5+ doping and resulting in enhancement of electric field force and strengthening of fibrous structure. In addition, by comparing and analyzing the permittivity curves of Nb-TiO2/LDPE solid composite and Nb-TiO2/silicone-oil fluid composite, it could be concluded that the enhancement of permittivity at low frequency resulted from the increase of the order degree of dispersed particles in ER fluid rather than from the quasi-dc (QDC) behavior. Moreover, the absolute value of slope of permittivity curves (K) at 0.01 Hz could be utilized as the standard for judging the ability to maintain the chainlike structure. The relationships between polarizability of dispersed particles, dielectric spectrum, parameter K, and ER properties were discussed in detail.
研究领域:
材料科学
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物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
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2023
·
IF 3.8
Shuo Shan,Jie Li,Xuan Zhao,Siwen Pi
M-type barium ferrite with the formula Ba 1− x Sm x Fe 12− y Nb y O 19 ( x = 0.00–0.10, y = 0.00–0.20), which was co-doped with Sm 3+ and Nb 5+ ions, was synthesized experimentally by a modified solid-phase reaction method. The crystal structure of samples was determined by X-ray diffraction, which confirmed that they were of high purity. The X-ray diffraction data were fitted with a full-spectrum correction using GSAS software. By Fourier transform infrared spectroscopy, the samples were observed to exhibit bands due to tetrahedral and octahedral sites at 598 cm −1 and 445 cm −1 , respectively. The samples were examined by field emission scanning electron microscopy, which showed that they partly comprised hexagonal structures but mostly consisted of irregular structures with rounded edges. Characterization of the elemental contents of the samples by energy-dispersive spectroscopy revealed an increase in the contents of Sm and Nb and a decrease in the contents of Ba and Fe. The magnetic properties of the samples were examined using a vibrating sample magnetometer. The results showed that the saturation magnetization and residual magnetization of the samples decreased slightly with an increase in the contents of the dopants. The coercivity reached its maximum value, namely, 3367.53 Oe, when x = 0.04 and y = 0.08.
研究领域:
材料科学
·
磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2021
·Vol. 56
·期 22
·12732-12739
·
IF 4.22
Li Yuping,Huo Haojie,Huang Hai,Guo Kai,Yang Xinxin,Xing Juanjuan,Luo Jun,Rao Guang-Hui,Zhao Jing-Tai
Layered oxygen-containing compound Bi 2 O 2 Se is a promising n-type thermoelectric material, favored by its considerably high Seebeck coefficient and low thermal conductivity. Significant preferred orientation along plane (110), identified in the hot-pressed sample, results in obvious anisotropy in the electrical and thermal transport properties. Nb substitution Bi in the insulating layer [Bi 2 O 2 ] 2+ can effectively increase the electron concentration (from 10 16 to 10 18 cm −3 ) by two orders of magnitude, while maintaining high mobility. Therefore, a larger power factor of 2.19 μW cm −1 K −2 has been obtained for Bi 1.94 Nb 0.06 O 2 Se at 823 K, which enlarges by three times in comparison with pristine Bi 2 O 2 Se (0.673 μW cm −1 K −2 ). Combined with the inherently low thermal conductivity, the ZT values of Bi 1.94 Nb 0.06 O 2 Se reach 0.195 at 823 K, corresponding to 325% enhancement. This study shows that the substitution of Nb for Bi is a promising way to optimize the thermoelectric properties of Bi 2 O 2 Se-based thermoelectric materials.
研究领域:
材料科学
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热电学
·
固体物理学
✓ 已验证
DOI
高影响因子
MATERIALS RESEARCH BULLETIN
·
2021
·
IF 4.641
Hao Li,Jiawei Wang,Ziwei You,Yuxi Yu,Pai Li,Liwei Xiong,Yunbin He
VO 2 thin films are widely studied materials for uncooled infrared detection because of their high temperature coefficient of resistance. In this research, Nb-doped VO 2 films were synthesized with the expectation that Nb doping would reduce the metal-insulator-transition temperature via electron doping and strain effects caused by the relatively large ionic radius of Nb, thus improving the resistance temperature coefficient of the doped films. The doped films displayed superior thermal sensing abilities compared with pure VO 2 films. As the amount of Nb doping increased, the thermal hysteresis and resistivity of the doped films decreased, while the transition temperature range widened. When the Nb-doping content reached 10%, the temperature coefficient of resistance reached -3.2%/K, while the metal-insulator transition temperature dropped to 52.2 °C. The high performance of the doped films proved that the strategy of Nb doping in VO 2 was promising for thermal-sensing applications.
研究领域:
材料科学
·
电气工程
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2022
·
IF 4.598
Bo Zhang,Jie Luo,Zhi Chen,Lintong Wu,Jianqin Li,Yuanyuan Tian,Shengli Liu
Nb-doped WO 3 films were prepared on FTO substrates by a facile sol–gel dip coating method. The influence of Nb doping on the microstructure and electrochromic characteristics of the films have been explored. The results indicate that the pure WO 3 film can achieve a synchronizing modulation of visible and near-infrared light bands by suppling voltage. However, the Nb-doped WO 3 films exhibit an ability of independent and selective transmittance modulation in both bands. Moreover, the Nb-doped WO 3 films undergo two electrochromic processes at different voltages, which are local surface plasmon resonance (LSPR) electrochromic process and electrochemical redox electrochromic process, respectively. These two electrochromic processes exhibit a unique photoelectric conversion behavior, that is, the reversible “bleached and warm” - “bleached and cool” - “colored and cool” modes. Additionally, with the increase of Nb doping content, the LSPR electrochromic effect becomes stronger. The high LSPR enhances the electrochemical redox electrochromic performance of the Nb-doped WO 3 films, enabling them to exhibit better electrochromic performance in the visible and near-infrared bands.
研究领域:
材料科学
·
电致变色材料
·
纳米技术
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2024
·
IF 20.2
Hongchun Sun,Cui Dong,Chao Feng,Hui Wang,Zhenping Qu
Co 3 O 4 catalysts possess high activity in selective catalytic oxidation of NH 3 (NH 3 -SCO), but the low N 2 selectivity hinders their potential application. To enhance N 2 selectivity, the chemical bonded Nb-O-Co catalyst by the deposition of Nb species onto Co 3 O 4 (Nb/Co 3 O 4 -0.03) is constructed. It shows 100 % NH 3 conversion and 82 % N 2 selectivity at 180°C, and the N 2 selectivity is 2.2-fold higher than that of Co 3 O 4 (38 %). The failure of enhancement in N 2 selectivity for physically mixed Co 3 O 4 and NbO x (NbO x |Co 3 O 4 -0.03) further indicates the crucial role of chemical bonded Nb-O-Co in enhancing N 2 selectivity. In situ diffuse reflectance infrared Fourier transform spectra and NH 3 temperature-programmed desorption results show the formation of new NH 3 adsorption sites. Importantly, intermediates NO - stabled on Nb/Co 3 O 4 -0.03 tends to react with -NH 2 to produce N 2 through internal selective catalytic reduction (iSCR). This work offers insights into enhancing the N 2 selectivity in NH 3 -SCO and advances understanding of iSCR mechanism.
研究领域:
化学工程
·
环境科学
✓ 已验证
DOI
高影响因子
NANO
·
2015
·
IF 1.09
He Li,Junli Lu,Yu Wang,Fenyun Yi,Xindong Guo
An ultrasensitive electrochemical immunosensor based on Nb-doped titanium dioxide was developed for detection of carcinoembryonic antigen (CEA). The electrochemical signal enhancement was due to the synergistic effect by NbT and nanogold. The influence factors (pH, temperature and incubation time) were investigated in detail. Under optimal conditions, the immunosensor was able to detect the concentration of CEA in the range of 0.5 ng ⋅ mL -1 to 150 ng ⋅ mL -1 , with a lower detection limit of 8.95 pg ⋅ mL -1 . The proposed immunosensor showed high sensitivity, excellent selectivity and good stability.
研究领域:
生物医学工程
·
肿瘤学
✓ 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）