JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2019
·Vol. 30
·期 15
·14424-14429
·
IF 2.195
Kuang Lingtong,Dai Ying,Pei Xinmei,Chen Wen
BaNb x Ti 2–x O 5 (x = 0, 0.002, 0.004, 0.006, 0.008, 0.01) thin films were deposited on the Pt(111)/Ti/SiO 2 /Si substrates using the sol–gel method. The effect of Nb 5+ substitution on the electric properties of BaNb x Ti 2–x O 5 films was investigated. Diffuse phase transition was observed in all the thin films. The relationship between the dielectric constant and temperature of these films showed a wide platform and no frequency dependence. For the film with x = 0.006, an abnormally broadened dielectric platform was obtained in the temperature range of 200–400 °C, and its value fluctuated in the range of 350 ± 10. The research showed that Nb-doped and thermal stress contributed greatly to this abnormally broadened platform of ε(T) curve. The substituting Nb 5+ in BaTi 2 O 5 thin films caused small microscopic composition fluctuation, which enhanced the degree of diffusion phase transition of the films. And the thermal stress on the films caused inhomogeneous polarization of the surface and center of the films, resulting in a change in phase transition behavior. In addition, the BaNb x Ti 2–x O 5 thin films with high dielectric constant at high temperatures were successfully obtained, which were beneficial to the application of BaTi 2 O 5 films under high temperature conditions.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2015
·
IF 2.999
Y. Lu,S. Khan,C.L. Song,K.K. Wang,G.Z. Yuan,W. Li,G.R. Han,Y. Liu
The column-structured Nb-doped TiO 2 (TNO) films with various Nb concentrations in the range between 0 and 10 at.% have been prepared by a sol–gel method. The phase compositions, element concentrations, microstructures, and optical-electron properties have been characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, electron microscopy , and UV/Vis/Near-IR spectrophotometer. The experimental results show that all of the samples prepared in the present work exhibit column-structured morphology and Nb doping concentration has a non-monotonic effect upon the microstructure. The relatively low conductivity and high transmittance of the samples demonstrate that column-structured microstructures greatly improve the optical and electronic properties of TNO films. The favorable sample with 10 at.% Nb doping concentration exhibits a resistance of about 2.27 Ω cm and transmittance of approximately 68.78% with 85 nm thickness.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Man Yang,Xiaochen Zhao,Yujing Ren,Jia Wang,Nian Lei,Aiqin Wang,Tao Zhang
Selective hydrogenolysis of glycerol to 1,3-propanediol (1,3-PD) is an important yet challenging method for the transformation of biomass into value-added chemicals due to steric hindrance and unfavorable thermodynamics. In previous studies, chemoselective performances were found demanding and sensitive to H 2 pressure. In this regard, we manipulate the chemical/physical characteristics of the catalyst supports via doping Nb into WO x and prepared 1D needle-, 2D flake-, and 3D sphere-stack mesoporous structured Nb-WO x with increased surface acid sites. Moreover, Nb doping can successfully inhibit the over-reduction of active W species during glycerol hydrogenolysis and substantially broaden the optimal H 2 pressure from 1 to 5 MPa. When Nb doping is 2%, supported Pt catalysts showed promising performance for the selective hydrogenolysis of glycerol to 1,3-PD over an unprecedentedly wide H 2 pressure range, which will guarantee better catalyst stability in the long run, as well as expand their applications to other hydrogen-related reactions.
研究领域:
催化化学
·
生物质转化
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2023
·Vol. 13
·期 2
·252
·
IF 5.3
Qi Yuan,Wencai Hu,Tao Wang,Sen Wang,Gaobin Liu,Xueyan Han,Feixiang Guo,Yongheng Fan
In this paper, Nb-doped BaTiO3nanoparticles (BaNb0.47Ti0.53O3) were prepared using an electrochemical method in an alkaline solution, with titanium-niobium alloy as the electrode. The results indicated that under relatively mild conditions (normal temperature and pressure, V < 60 V, I < 5 A), cubic perovskite phase Nb-doped BaTiO3nanoparticles with high crystallinity and uniform distribution can be synthesized. With this increase in alkalinity, the crystallinity of the sample increases, the crystal grain size decreases, and the particles become more equally dispersed. Furthermore, in our study, the average grain size of the nanoparticles was 5–20 nm, and the particles with good crystallinity were obtained at a concentration of 3 mol/L of NaOH. This provides a new idea and method for introducing foreign ions under high alkalinity conditions.Keywords:Nb-BaTiO3;electrochemical synthesis;microstructure;nanoparticles
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
·
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-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
·
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
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
OPTICAL MATERIALS
·
2022
·
IF 3.754
Bo Zhang,Jie Luo,Zhi Chen,Yuanshun Xiang,Lu Tang,Hongyi Jiang,Yuanyuan Tian,Shengli Liu
The development of high-quality cathode material is of important value to the research of bifunctional electrochromic energy storage device. Therefore, Nb-doped TiO 2 mesoporous film as the high-performance cathode was prepared via a facile sol-gel technology successfully. The Nb doping content has great effects on the crystallinity and chemical state of TiO 2 films. Compared to the pure TiO 2 film, the optimum Nb-doped TiO 2 film exhibits the excellent optical-electrochemical performance including highest large-rate capability, largest specific capacity (62.4 mAh/g), short switching time (3.4 s/4.5 s) and large transmittance modulation (50.7%). These data indicate that Nb-doped TiO 2 mesoporous films possess the important application prospect.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
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
ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Xiaodong Ren,Dong Yang,Zhou Yang,Jiangshan Feng,Xuejie Zhu,Jinzhi Niu,Yucheng Liu,Wangen Zhao,Shengzhong Frank Liu
Electron transport layer (ETL), facilitating charge carrier separation and electron extraction, is a key component in planar perovskite solar cells (PSCs). We developed an effective ETL using low-temperature solution-processed Nb-doped SnO2 (Nb:SnO2). Compared to the pristine SnO2, the power conversion efficiency of PSCs based on Nb:SnO2 ETL is raised to 17.57% from 15.13%. The splendid performance is attributed to the excellent optical and electronic properties of the Nb:SnO2 material, such as smooth surface, high electron mobility, appropriate electrical conductivity, therefore making a better growth platform for a high quality perovskite absorber layer. Experimental analyses reveal that the Nb:SnO2 ETL significantly enhances the electron extraction and effectively suppresses charge recombination, leading to improved solar cell performance.
研究领域:
材料科学
·
能源技术
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
·
2019
·
IF 2.752
Jingfeng Wang,Fei Jiao,Di Zhang,Meixia Chang,Lingbo Cai,Yunlong Li,Cao Wang,Shugang Tan,Qiang Jing,Bo Liu,Dong Qian
The relationship between the doping position of Nb in Bi 2 Se 3 and its superconductivity is investigated by XPS, magnetic measurement and transport measurement. It is found that for Nb x Bi 2 Se 3 , the main impurity phase comes from BiNbSe 3 . Superconducting volume fraction of Nb doped Bi 2 Se 3 increases with the ratio of Nb inserted in the van der Waals layers. The van der Waals-layer-position doped Nb may lead to superconductivity in Bi 2 Se 3 . This work may stimulate further investigation on topological superconductivity mechanism of Nb x Bi 2 Se 3 .
研究领域:
凝聚态物理
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yan Xue,Wenye Deng,Yi Liu,Jinyang Li,Ni Ai,Pengjun Zhao,Aimin Chang,Huimin Zhang,Yongxin Xie
A series of LaAl 1- x Nb x O 3 (0 ≤ x ≤ 0.100) samples were synthesized via the solid phase method. Characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) confirmed the formation of a solid solution in LaAl 1- x Nb x O 3 (0 ≤ x ≤ 0.100) materials without the emergence of additional phases following Nb doping. Transmission electron microscopy (TEM) revealed distinct lattice fringes with a d value of 0.274 nm, corresponding to the (110) plane of LaAlO 3 (PDF #82–0478). The introduction of Nb dopant caused distortions in the cell parameters of LaAlO 3 due to ionic radius size effects, changes in Nb valence, fluctuations in oxygen vacancy concentration and Coulomb forces. Specifically, the lattice exhibited a shrinkage for 0 ≤ x ≤ 0.025, expansion for 0.025 < x ≤ 0.075, and subsequent shrinkage for 0.075 < x ≤ 0.100. Resistance measurements indicated that LaAl 1- x Nb x O 3 (0 ≤ x ≤ 0.100) materials exhibited favorable negative temperature coefficient (NTC) characteristics in the temperature range of 600 °C–1400 °C. Hall measurements revealed that the materials functioned as P-type semiconductors with hole carriers, and Nb doping enhanced carrier concentration. Aging tests demonstrated that the aging drift rate of LaAl 0.9 Nb 0.1 O 3 could be as low as 0.906% after aging it at 1000 °C for 500 h, a crucial parameter for practical applications of LaAl 1- x Nb x O 3 (0 ≤ x ≤ 0.100) materials in high-temperature NTC applications.
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
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