JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2019
·Vol. 30
·期 15
·14424-14429
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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
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物理学
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DOI
高影响因子
Science China-Materials
·
2024
·Vol. 67
·期 7
·2142-2152
·
IF 6.8
Li Yaying,Yang Huijuan,Li Jili,Li Yefei,Ren Wei,Wen Jin,Xiao Qi,Xu Jingsan
Heterojunction photocatalysis has been widely studied as a means of efficiently converting solar energy to chemicals. However, the major challenge in developing high-performing heterojunction photocatalytic systems lies in achieving efficient transfer of electrons between the components. Herein, a novel S-scheme heterojunction photocatalyst was developed by combining BaTi 2 O5 nanorods with g-C 3 N 4 lamellae. The preferential deposition of Pt nanoparticles as cocatalyst via the one-step impregnation-reduction method on g-C 3 N 4 nanosheets with enhanced interfacial contact and strong electronic interaction has been proved essential for the photocatalytic performance. The developed Pti mp /20BaTi 2 O 5 /g-C 3 N 4 photocatalyst delivers the optimal hydrogen production rate of 2587 µmol g −1 h −1 with high stability after cycles. Photoelectrochemical analysis and theoretical calculation suggest that the formation of BaTi 2 O 5 /g-C 3 N 4 heterojunction results in the staggered band alignment and improved charge carrier dynamics. This work highlights the importance and feasibility of promoting photocatalysis by a new S-scheme heterojunction with viable cocatalysts.
研究领域:
材料科学
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光催化
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Wenzhong Zou,Guoyun Zhou,Yan Hong,Wei He,Shouxu Wang,Yuanming Chen,Chong Wang,Yao Tang,Yukai Sun,Chaoying Ma
In this work, the high-yield synthesis of BaTi 2 O 5 (BT2) nanorods with a growth direction at [020] was achieved in the medium of KCl salt through the molten-salt synthesis (MSS) with Ba(NO 3 ) 2 and anatase TiO 2 as reactants. By optimizing the involved reaction factors including particle sizes, thermal holding durations and crystalline forms of TiO 2 , ultra-pure BT2 nanorods with uniform size were obtained after 45 min of heating at 950 °C. Meanwhile, anatase and rutile TiO 2 were respectively mixed and calcined in KCl to study the formation and transformation process of BT2 nanorods in detail. It was found that anatase TiO 2 tends to merge together and convert into rutile TiO 2 . In particular, the formed rutile TiO 2 reacts with BaO and BaTiO 3 to spontaneously form BT2 nanorods without any presence of rod-like templates. Besides, BT2 takes priority over K 2 Ti 6 O 13 to generate the corresponding nanorods in the molten salt with high content of K + . In addition, the O 2 in air also promotes the formation of nanorods. According to the experimental results, a probable mechanism for the initial formation, subsequent growth and transformation of BT2 nanorods was thus proposed, which helps to facilitate the preparation of BT2-based one-dimensional nanomaterials.
研究领域:
材料科学
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无机化学
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产品关联
DOI
高影响因子
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
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玻璃科学
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无机化学
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DOI
高影响因子
ACS Applied Materials & Interfaces
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2022
·
IF 10.383
Xingang Liu,Yinghao Shang,Jingfeng Liu,Zhuzhu Shao,Chuhong Zhang
Piezoelectric energy harvesters (PEHs) with a three-dimensional (3D) structure are arousing increasing interest because of the ability to efficiently convert mechanical energy into electricity catering for self-powered systems. Among them, 3D PEHs composed of 1–3-type piezoelectric composites which exploit one-dimensional (1D) piezoceramic fillers rather than conventional powders are particularly attractive. However, an issue involving the orientation of the 1D fillers to utilize the piezoelectric effect renders the 3D structural design for high-efficiency energy conversion more challenging. Herein, for the first time, we introduce the fused deposition modeling (FDM) 3D printing to the flexible construction of poly(vinylidene fluoride) (PVDF)-based 3D PEHs by incorporating 1D BaTi2O5 (BT2) nanorods as piezoelectric fillers. The shearing force generated by FDM successfully realizes the in situ uniform orientation of BT2 nanorods in the PVDF (98% β crystals) matrix along the nozzle extrusion direction. Besides, by coupling 3D printing with the appealing piezoelectric anisotropy feature of BT2 nanorods, the 3D PEH is able to generate different piezoelectric responses to the same applied external force from X, Y, and Z directions. Furthermore, an optimized 3D conical array structure is constructed to amplify the effective deformation of the PEH to enhance its piezoelectric output. As expected, customized PEH can continuously power commercial electronic devices and monitor various human motions, indicating 3D printing as a multifunctional strategy to fabricate 3D PEHs with 1–3-type piezoelectric composite materials for self-powering microelectronic applications.
研究领域:
材料科学
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机械工程
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纳米技术
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能量收集
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产品关联
DOI
PubMed
高影响因子
Small Methods
·
2023
·Vol. 7
·期 9
·2300701
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IF 12.4
Zhuzhu Shao,Xuan Zhang,Jingfeng Liu,Xingang Liu,Chuhong Zhang
Flexible piezoelectric energy harvesters (PEHs) have gained substantial attention owing to their wearability, breathability, and sustainable self-powered supply. However, existing film PEHs cannot identify forces in different bending directions, limiting their applications in wearable electronics and artificial intelligence. This study constructs a fabric PEH for the first time by introducing piezoelectric anisotropic BaTi 2 O 5 nanorods (BT2-nr) into piezoelectric polyvinylidene fluoride (PVDF) nanofibers with a bi-oriented architecture, in which BT2-nr uniformly aligns in the PVDF nanofiber during electrospinning. The dual-orientation feature endows the flexible PEH with anisotropy, which can sensitively identify the forces at different bending directions (e.g., bent vertically, parallelly, or twisted by 45° along the fiber orientations). Simultaneously, the composite PVDF/BT2 PEH containing 15 wt.% BT2-nr delivers an optimal piezoelectric output of 31.2 V with a high sensitivity of 5.22 V N −1 . The developed anisotropic PEH can be used as a self-powered pressure sensor for multimodal intelligent biomonitoring of human movement. This study provides a feasible strategy for fabricating self-powered flexible PEHs with high electromechanical conversion efficiency and multifunctionality for wearable piezoelectric pressure sensors.
研究领域:
材料科学
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纳米技术
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智能设备
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Scientific Reports
·
2019
·Vol. 9
·期 1
·1-17
·
IF 4.011
Ge Xuan,Hu Qiaodan,Lu Wenquan,Cao Sheng,Yang Liang,Xu Mingqin,Xia Mingxu,Li Jianguo
The nucleation pathway plays an important role in vitrification, preparation of glass-ceramic composites and synthesis of metastable materials. In this paper, we studied the nucleation pathway of a novel ferroelectric BaTi 2 O 5 (BT2) during crystallization from undercooled liquid by aerodynamic levitation (ADL) containerless processing and structural analysis. An interesting polymorphic transition of BT2 regulated by the undercooling was observed during the crystallization process: the ferroelectric monoclinic phase ( γ -BT2) was fabricated at low undercoolings and the paraelectric orthorhombic metastable phase ( β -BT2) was obtained from hypercooled liquid. This polymorphic transition phenomenon corresponds to a non-classical nucleation pathway: metastable β -BT2 preferentially nucleates from undercooled melt and γ -BT2 is generated from β phase by solid-state phase transition. The two-step nucleation pathway stems from the structural heredity between the undercooled liquid and crystals. A stronger structural homology exists between the undercooled melt and β -BT2 than γ -BT2 based on diffraction data and atomic configurations analysis. This structural homology coupled with nucleation barrier calculation was used to elucidate the non-classical nucleation pathway of BT2 crystallization: the similarity of the structural unit (Ti-O polyhedra) between the undercooled liquid and the metastable β -BT2 reduces the nucleation barrier and contributes to the preferential precipitation of β -like clusters. This work reveals the formation route of BT2 from cooling melt, which not only benefits the synthesis and application of this novel functional material but also provides a guideline of the crystallization process of titanates from melt at atomic level.
研究领域:
材料科学
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晶体学
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凝聚态物理
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2021
·Vol. 104
·期 12
·6207-6226
·
IF 3.784
Xuan Ge,Jun Xu,Qiaodan Hu,Ren Qiu,Pingsheng Lai,Yanfeng Han,Fan Yang,Yongquan Zhou,Jingyu Qin,Pengfei Yu,Wenquan Lu,Jianguo Li
Although remarkable development of titanate-based glasses has been achieved, challenge remains to elucidate the correlation between structure and glass-forming properties in these systems due to their complex structure that is inconsistent with the classic Zachariasen's model. In this work, we aim to correlate the structural evolution of titanate melts to their glass-forming ability (GFA). The prototypical material barium dititanate (BaTi 2 O 5 , BT2) melts with different GFA were rendered by controlled melting atmospheres, and the corresponding structural changes were determined using in situ high-energy synchrotron X-ray diffraction combined with empirical potential structure refinement and ab initio molecular dynamics. The results show that BT2 melt in reducing atmosphere shows poor GFA but that in oxidizing atmosphere presents good GFA. Structural analysis demonstrates the mean coordination number of [TiO m ] polyhedra is analogous in the melt under two different atmospheres but an enhanced heterogeneous cations aggregation takes place in the melt under reducing atmosphere, which is closely related to oxygen-deficiencies. Furthermore, we reveal that the enhanced heterogeneous cations aggregation promotes crystallization (and therefore hinders glass formation) through disordering the distribution of [TiO m ] and [BaO n ] polyhedra, changing the connectivity between these polyhedra, creating more crystal-like Ti-Ti clusters, and decreasing topological disorder of BT2 melt. Our work provides a new viewpoint to understand the GFA of titanates melt from structural heterogeneity beyond the previous perspectives that only focus on [TiO m ] polyhedra.
研究领域:
材料科学
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无机化学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）