CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Jiahui Ma,Ning Xu,Yuxin Luo,Qi Liu,Yongping Pu
Ceria is widely used in industrial fields due to its unique chemical properties. In this work, a series of CeO 2 particles with controllable morphology, size, and defect concentration were obtained by a simple molten salt method. The adjustment of temperature and molten salt concentration has a considerable effect on the morphology and particle size of the final CeO 2 particles while prolonging the holding time has little effect. Ion doping and reducing atmosphere calcination were used to regulate the defect concentration to improve the chemical activity of CeO 2 particles. SEM results show that the morphology of CeO 2 particles transforms from sphere to octahedron under the two treatments. The Rietveld refinement results and the XPS spectra indicate that increasing calcination temperature, reducing atmosphere calcination and ion doping are beneficial to improving the oxygen vacancies and Ce 3+ concentration of CeO 2 samples, which are the reason for enhancing the photocatalytic activity of the samples. Moreover, the oriented attachment, agglomeration and merging of crystals formed by the decomposition of cerium precursors are the key to the growth of CeO 2 particles. Aggregates with exposed low-energy planes merge directly to form particles of various morphologies to maintain their own low energy.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 42
·20760-20768
·
IF 9.931
Xiaoqin Sun,Fangfang Wu,Gang Liu,Xiaoxiang Xu
The perovskite oxynitride SrTaO2N is a promising compound for solar energy conversion because it has strong visible light absorption at wavelengths as long as 650 nm. However, its photocatalytic activity is generally very poor, primarily because of the high defect concentration induced during its synthetic procedures as well as photocatalytic self-decomposition events. In this work, we introduce Sr into the B site of SrTaO2N to form a complex perovskite oxynitride, Sr3(Sr1/3Ta2/3)3O9−xNy (i.e. Sr4Ta2O9−xNy). The new compound has a much lower defect concentration compared to SrTaO2N and much higher stability against photocatalytic self-decomposition. More importantly, Sr4Ta2O9−xNy demonstrates significantly improved photocatalytic activity for water oxidation and reduction reactions under visible light irradiation (λ ≥ 400 nm) than SrTaO2N, approaching an apparent quantum efficiency as high as 3.4% at 420 ± 20 nm.
研究领域:
材料科学
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能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
·
2021
·Vol. 40
·期 1
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IF 2.427
Hsain Hanan Alexandra,Lee Younghwan,Materano Monica,Mittmann Terence,Payne Alexis,Mikolajick Thomas,Schroeder Uwe,Parsons Gregory N.,Jones Jacob L.
Although 10 years have passed since the initial report of ferroelectricity in hafnia (HfO 2 ), researchers are still intensely fascinated by this material system and the promise it holds for future applications. A wide variety of deposition methods have been deployed to create ferroelectric HfO 2 thin films such as atomic layer deposition, chemical solution deposition, and physical vapor deposition methods such as sputtering and pulsed laser deposition. Process and design parameters such as deposition temperature, precursor choice, target source, vacuum level, reactive gases, substrate strain, and many others are often integral in stabilizing the polar orthorhombic phase and ferroelectricity. We examine processing parameters across four main different deposition methods and their effect on film microstructure, phase evolution, defect concentration, and resultant electrical properties. The goal of this review is to integrate the process knowledge collected over the past 10 years in the field of ferroelectric HfO 2 into a single comprehensive guide for the design of future HfO 2 -based ferroelectric materials and devices.
研究领域:
材料科学
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电子工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Mingming Peng,Deng You,Hui Shi,Penghui Shao,Wei Ren,Liming Yang,Xin Sheng,Jiachuang Shao,Xuan Ding,Lin Ding,Haozhi Wang,Kai Yu,Xubiao Luo
Metal-organic frameworks (MOFs) with ability to create rich defects in the structures for exposed binding sites are beneficial for wastewater treatment. However, the inter-relation between the defect concentration and heavy metal removal performance still deserves the exploration. Herein, UiO-66-X crystal materials are successfully synthesized in the presence of monocarboxylic acid of acetic, benzoic, and trifluoroacetic acid, and the effect of defect concentration on Sb(V) removal performance is systematically studied. XRD, TG, EPR and XPS characterizations reveal that the addition of modulators increases the content of defects in the UiO-66-X, which is beneficial to improve the sites utilization. As expected, the Sb(V) adsorption properties of UiO-66-AA, UiO-66-BA and UiO-66-TFA are boosted by 54.1%, 140.0% and 197.7% compared to that of pristine UiO-66. Density functional theory (DFT) calculations further confirm that UiO-66-TFA with the most defects exhibits lower adsorption energy and higher charge transfer, significantly improving the uptake performance of Sb(V). Additionally, the UiO-66-TFA successfully removes antimony in actual water from the Tianyi Lake and Ganjiang River with residual concentrations below 5 μg L −1 , meeting the drinking water standard. This work provides guidance for the rational selection of modulators for efficient heavy metal removal from wastewater.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2018
·
IF 5.018
Qiang Sun,Xiu Gong,Hao Li,Shuangshuang Liu,Xiaojuan Zhao,Yan Shen,Mingkui Wang
This work presents an easy and controllable method for introducing I 3 - ions into organic cation dripping solution via chemical reaction of I - + I 2 → I 3 - to effectively decrease the concentration of defects in organic-inorganic lead halide perovskite films. The perovskite solar cells based on additional I 3 - ions exhibited better photovoltaic performance , with a maximum power conversion efficiency of 18.7%, being about 15% higher than that of the control device. The elucidation of defects and its suppression by employing additional I 3 - ions provide an important direction for defects elimination and future enhancement of perovskite solar cells efficiency.
研究领域:
材料科学
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能源技术
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Nano Energy
·
2022
·
IF 19.069
Bowen Jin,Yidong Ming,Zixin Wu,Jinguo Cao,Yuxue Liu,Yongqi Zhu,Shimin Wang,Zihui Liang,Congcong Wu
The photoactive lead halide perovskites with a highly crystalline structure and low trap state density were regarded as the prerequisites for achieving high photovoltaic performance . The perovskite thin films were typically synthesized by simple wet chemistry routes, where the fluctuations in the fabrication readily generate lattice defects and induce stacking faults during the crystal growth. The growth of highly crystalline and low-defect perovskite usually needs complicated synthetical manipulation and well-designed additive engineering. Here in this work, we reported a naturally available protein, silk fibroin (SF), whereby the highly ordered β-sheets component can adequately interact with perovskite intermediates and work as the crystal growth template and trap passivation agent , which induced facile self-assembly of the perovskite crystals with homeotropic alignment structure and low defect concentrations. As a result, the SF incorporated perovskite layer exhibited a much-improved conversion efficiency with charge carrier mobility 1000 times higher than that of pristine film, as well as showed robust stability under various harsh conditions.
研究领域:
材料科学
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生物材料
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Tengfei Yu,Xiang Ji,Zhijun Fu,Baorui Xia,Subin Jiang,Meizhen Gao
Ba 0.85- x (Bi 0.58 Na 0.42 ) x Ca 0.15 Ti 0.85 Zr 0.15 O 3 (BCTZ- x BN) was employed as the research focus to modulate grain size, lattice distortion, and defect concentration by adjusting the BN content, thereby regulating energy storage performance. The influence mechanisms of grain size, lattice distortion, and defect concentration on energy storage performance were investigated through experimental and numerical calculations. Experimental characterization (XRD diffraction, high-resolution transmission electron microscopy, and impedance testing) and theoretical analysis (V-F model, macroscopic and phenomenological models, and Landau Devonshire theory) revealed that the polar nanoregions (PNRs) induced by lattice distortion and charge defects improved energy storage efficiency. Finite element simulation and impedance analysis indicate that fine grain size and fewer charge defects contribute to improved breakdown strength. As a result, the W rec and η of the modified samples were significantly improved by 6 and 1.7 times, respectively. This work provides insights into the design of high-performance ceramic capacitors and establishes a theoretical framework for understanding the energy storage mechanism.
研究领域:
材料科学
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能源存储
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2021
·
IF 9.127
Xiao Liu,Yu Jing,Ruoshui Li,Deng Wang,Chunyan Wang,Zhongliang Yan,Weihai Sun,Jihuai Wu,Zhang Lan
Solution-prepared perovskite films are accompanied by high defect density . Defects gathered on the surface or grain boundaries of the perovskite accelerate the degradation of the perovskite and affect the photovoltaic performance and long-term stability of the device, which is one of the bottlenecks to curb the further development of perovskite solar cells (PSCs). In this work, a simple and effective surface passivation method is designed by choosing metal (IIB) diethyldithiocarbamate salts [M(DDTC) 2 , M = Pb 2+ , Cd 2+ and Zn 2+ ]. The DDTC has excellent complexing ability with metal ions and chelate bidentately with unpaired Pb 2+ ions on the surface of perovskite. IIB metal ions have a small ion radius and could easily diffuse into the perovskite to occupy Pb vacancies. The synergistic effect of anions and cations effectively reduces the defect concentration and non-radiative recombination in the CsPbIBr 2 all-inorganic perovskite, thereby obtaining carbon-based CsPbIBr 2 all-inorganic PSCs with high efficiency and high stability. Ultimately, champion efficiency of the Cd(DDTC) 2 and Zn(DDTC) 2 -treated CsPbIBr 2 PSCs yield 9.59% and 10.21%, respectively, obviously higher than that of the pristine one (8.74%).
研究领域:
材料科学
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能源科学
✓ 已验证
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2017
·
IF 4.798
Hongmei Chen,Xiaoqin Sun,Xiaoxiang Xu
Here we report two Ruddlesden-Popper type ferrite perovskites (SrO)(LaFeO 3 ) n (n = 1 and 2) which demonstrate p-type semiconductivity. Their crystal structure, optical absorption and other physicochemical properties have been systematically explored. Our results show that both ferrites crystallize in tetragonal symmetry with structural lamination along c axis. Efficient photocatalytic hydrogen production has been achieved for both samples under full range and visible light illumination. Better performance is noticed for LaSrFeO 4 with apparent quantum efficiency approaches 0.31% and 0.19% under full range and visible light illumination, respectively. The p-type semiconductivity is verified by their cathodic photocurrent as well as negative Mott-Schottky slop during Photoelectrochemical measurement. The relative lower activity for La 2 SrFe 2 O 7 compared to LaSrFeO 4 is likely due to its higher defect concentration which facilitates charge recombination. Both compounds exhibit anisotropic phenomenon for charge migrations according to theoretical calculations. Their p-type semiconductivity, strong visible light absorption, chemical inertness and high abundance of constituent elements signify promising applications in the field of solar energy conversion and optoelectronics.
研究领域:
材料科学
·
能源转换技术
·
光电化学
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2022
·Vol. 12
·期 6
·1002
·
IF 5.719
Sushu Wan,Yajie Zhu,Daocheng Hong,Yuxi Tian
One of the unique characteristics of semiconductors is the strong dependence of their properties on crystal defects and doping. However, due to the species diversity and low density, it is very difficult to control the type and concentration of the defects. In perovskite materials, crystal defects are randomly formed during the fast crystallization process, causing large heterogeneity of the samples. Here, in this work, we report a controllable method to introduce surface defects on CH3NH3PbI3perovskite materials via the interaction with 1,4-benzoquinone (BQ) molecules on the gas and solid interface. After the adsorption of BQ molecules on the perovskite surface, surface defects can be generated by photoinduced chemical reactions. The concentration of the defects can thus be controlled by precisely regulating the laser irradiation time. The concentration of the defects can be characterized by a gradually decreased PL intensity and lifetime and was found to influence the atmospheric response and the subsequent acetone-induced degradation of the materials. These results demonstrate that crystal defects in perovskite materials can be controllably introduced, which provides a possible way to fully understand the correlation between the nature and chemical structure of these defects.Keywords:lead halide perovskite;polycrystalline thin films;defect modification;defect concentration;optical microscopy
研究领域:
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanomaterials
·
2021
·Vol. 11
·期 8
·2063
·
IF 5.076
Zihao Zhao,Xiang Zhao,Mu Zhang,Xudong Sun
Surface-enhanced Raman scattering (SERS) for semiconductor nanomaterial systems is limited due to weak Raman signal intensity and unclear charge-transfer (CT) processes for chemical enhancement. Here, rare-earth element neodymium-doped titanium dioxide (Nd-TiO2) nanoparticles (NPs) were synthesized by the sol–gel method. The characterizations show that the doping of Nd ions causes TiO2NPs to show an increase in the concentration of defects and change in the energy level structure. The CT process between Nd-TiO2NPs substrate and probe molecule 4-Mercaptopyridine (4-Mpy) was innovatively analyzed using the relative energy level location relationship of the Dorenbos model. The SERS signal intensity exhibits an exponential enhancement with increasing Nd doping concentration and reaches its optimum at 2%, which is attributed to two factors: (1) The increase in the defect concentration is beneficial to the CT process between the TiO2and the probe molecule; (2) the introduction of 4felectron orbital energy levels of rare-earth ions created unique CT process between Nd3+and 4-Mpy. Moreover, the Nd-TiO2NPs substrate shows excellent SERS performance in Raman signal reproducibility (RSD = 5.31%), the limit of detection (LOD = 10−6M), and enhancement factor (EF = 3.79 × 104). Our work not only improves the SERS performance of semiconductor substrates but also provides a novel approach to the development of selective detection of probe molecules.
研究领域:
材料科学
·
光谱学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Weijia Guo,Yiming Yang,Zhiyu Ma,Yutian Lu,Zhenxing Yue
Microwave dielectric ceramics with high relative permittivity ( ε r ) are commonly used for the miniaturation of microwave devices. The dielectric loss mechanism of microwave dielectric ceramics , as well as the property modification, has been a concerned topic among scholars. Herein, the lattice structure, defects, and broadband dielectric response of Zr 4+ and Hf 4+ substituted Ba 4 Sm 9.33 Ti 18 O 54 (BST) ceramics are systematically examined. The negative temperature coefficient of resonant frequency ( τ f ) of BST ceramics can be tuned to near zero via ion substitution, owing to the Sm 2 Ti 2 O 7 second phase with a large positive τ f . Optimal microwave dielectric properties of ε r = 81.3, Q × f = 10,800 GHz, and τ f = −4.6 ppm/°C are achieved. The lattice vibration behavior and defect concentration are analyzed by Raman spectra and thermally stimulated depolarization currents (TSDC), respectively. The increasing volume of the unit cell and TiO 6 octahedra, which is because of the large-radius substitution ions, leads to an increase in lattice vibration damping factor and the generation of more oxygen vacancies ( V O ∙ ∙ ). Therefore, the dielectric losses in the microwave and terahertz (THz) bands increase after substitution. Meanwhile, the low-frequency dielectric losses at high temperatures also increase due to the weak restraint of carriers by the lattice. The broadband loss mechanism of Zr 4+ and Hf 4+ substituted BST ceramics related to lattice vibration and defects might be referenced for developing low-loss dielectric ceramics.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
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