MATERIALS TECHNOLOGY
·
2020
·
IF 1.738
Binggong Yan,Shaoning Lin,Lei Kang,Xuan Song,Zhao Tian,Kaiyong Jiang
Laser annealing is used for preparation of LiMn2O4. The electrochemical characterisation shows that the cycle performance of spinel LiMn2O4 is dependent on the power of the laser and the amount of lithium excess. X-ray diffraction is used to study the phase evolution of laser-annealed LiMn2O4. The morphology of LiMn2O4 particles is observed by scanning electron microscope. Electrochemical tests show that the initial capacity of the laser-annealed LiMn2O4 is less than the untreated LiMn2O4, but the cycle performance improved noticeably.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materiomics
·
2020
·
IF 5.797
Gang Liu,Jia Dong,Leiyang Zhang,Yan Yan,Ruiyi Jing,Li Jin
In the present work, the nature of phase evolution of (1− x )(Na 0.5 Bi 0.5 )TiO 3 - x SrTiO 3 (NBT- x ST) solid solutions with x of 0–0.6 is revealed by characterizing the dielectric and ferroelectric properties. Two unique dielectric anomalies associated with high-temperature nanoregions (PNRs) in the ergodic relaxor (ER) state and low-temperature PNRs in the nonergodic relaxor (NR) state are identified. Characteristic temperatures, including T B , T RT∗ , T m , T d and T T ∗ , are determined in fresh and poled states on the basis of the characteristics of the evolution of these two dielectric anomalies. The whole evolution of the transition from the NR state to the ER state is reflected by the temperature-dependent polarization versus electric field ( P - E ) hysteresis loops, i.e., from the square loops, via the double-like loops, to the slim loops. The characteristic temperatures, including T P-N , T N-R and T R-dis , are determined by the characteristics of the evolution of P - E loops. Accordingly, a phase diagram of NBT- x ST was constructed according to these characteristic temperatures. Most importantly, the relationship between polarization responses and heterogeneous polar phase coexistence has been established and a schematic diagram is given. This work will help to understand the phase evolution and its impact on the macroscopic properties of NBT and the associated NBT-based solid solutions.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2017
·
IF 3.454
Yi Ding,Hui Dan,Xirui Lu,Xiaoyan Shu,Zhihao Hong,Shuai Zhang
A series of Zr 1- x Nd x O 2- x /2 (0 ≤ x ≤ 1) ceramics was prepared by solid-state reaction method. The effects of Nd content on the phase evolution were investigated. The chemical durability of resulting waste forms was also examined. The results show that the ceramics with x < 0.1 show monoclinic and cubic zirconia phase, with 0.2 ≤ x < 0.4 exhibit a single cubic phase, with 0.4 ≤ x ≤ 0.6 exhibit a single pyrochlore phase, with 0.6 < x < 0.8 exhibit a single cubic phase and remain cubic phases and hexagonal Nd 2 O 3 when 0.8 ≤ x ≤ 1. The unit cell parameters of the Nd-doped zirconia samples increase as the Nd content increases. Moreover, the normalized element release rates of Nd element in Nd-doped zirconia ceramics firstly decrease with leaching time and almost no change after 21 days (∼0 −6 g m −2 d −1 ), demonstrating its good chemical durability.
研究领域:
材料科学
·
核废料管理
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2020
·Vol. 31
·期 16
·13496-13502
·
IF 2.22
Fang Weishuang,Ao Laiyuan,Tang Ying,Li Jie,Xiang Huaicheng,Zhang Zhiwei,Du Qianbiao,Fang Liang
Recently, there have been considerable interests in the Li-containing spinel oxides as promising microwave dielectric materials. Li loss at elevated temperatures, however, is known to be inevitable, resulting in deterioration on dielectric performances. Here the influence of Li nonstoichiometry on the microwave dielectric properties of Li 2 ZnGe 3 O 8 , a spinel oxide, was reported. An appropriate level of Li excess enhanced the densification of Li 2 ZnGe 3 O 8 and increased dielectric performances. In contrast, high level of Li excess induced the formation of the secondary phase of Li 2 ZnGeO 4 confirmed by XRD and Raman spectra, which in turn lowered the dielectric properties. Typically, a composition with x = 0.075, in the Li 2(1+ x ) ZnGe 3 O 8 ceramics exhibited the enhanced microwave dielectric properties with ε r = 10.68, Q × f = 77,300 GHz (at 13.3 GHz), and τ f = − 70.35 ppm/°C when sintered at 940 °C for 4 h. Moreover, these compounds have well chemical compatibility with the silver electrodes.
研究领域:
材料科学
·
陶瓷学
·
电子材料
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2023
·Vol. 34
·期 13
·1096
·
IF 2.8
Gu Wen,Liu Bingguo,Li Shunzi,Hu Baofu,Xu Jian,Wang Jian,Du Baoli
Cu 2 SnS 3 (CTS), as a potential thermoelectric (TE) material, the electrical and thermal transport properties are heavily determined by its original phase structure and the following phase evolution upon heating. Unlike previous studies that induced CTS phase transition by doping, this study used mechanical alloying powder as the precursor and successfully prepared phase-pure cubic (c-) and monoclinic (m-) CTS samples, as well as two-phase mixed samples with different percentage composition of c-CTS and m-CTS, by simply adjusting the hot pressing temperature. Firstly, phase structures of hot-pressed specimens were determined and confirmed by XRD refinement, SEM, TEM, and Raman spectroscopy. Secondly, thermodynamic property was analysis by DSC analysis, and phase evolution was detailed by analyzing specimens quenched at various temperatures. Then, the electrical and thermal transport properties were measured up to 500 °C, and were correlated with phase evolution analyzed above. Benefiting from cationic disorder, a maximum zT of 0.42 at 500 °C was achieved in c-CTS samples hot-pressed at 575 °C. The phase evolution of CTS was comprehensively investigated by using high-quality samples. The results indicate that phase transition is the potential mechanism for the doping effect in most studies, providing some guidance for improving the performance of environmentally friendly TE sulfides.
研究领域:
材料科学
·
凝聚态物理
·
无机化学
·
能源材料
·
热电转换
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
Shan-Lu Chen,Wei-Ming Guo,Shi-Kuan Sun,Yuji Masubuchi,Ming Lv,Hua-Tay Lin,Cheng-Yong Wang
In this work, nearly single phase SrTaO 2 N powder was directly prepared from strontium carbonate (SrCO 3 ) and tantalum mononitride (TaN), instead of the nitridation of the oxide precursors using NH 3 . The phase evolution and reaction mechanism together with the chemical composition, crystal structure and particle size of SrTaO 2 N product were investigated. Similar to the reactions between SrCO 3 and Ta 3 N 5 , the evolution of CO 2 , CO and N 2 was detected during the reactions. The results revealed that this novel reaction was able to successfully synthesize orange-coloured SrTaO 2 N powder with nearly pure phase at 1200 °C and the powder possessed the uniform size distribution with the mean diameter of 6.63 µm.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Xingyu Chen,Yeqing Guan,Zhaolin Zhong,Fenglin Wang,Wei Li,Haijun Mao,Zhuofeng Liu,Weijun Zhang
The effect of Zr 4+ substitution for Ti 4+ on the phase evolution and microwave dielectric properties of (Cu 1/3 Nb 2/3 ) 0.25 Ti 0.75- x Zr x O 2 (0 = x ≤ 0.35) ceramics prepared via conventional solid-state method has been investigated. With the increase of Zr substitution, the ceramics exhibit a gradual phase transition from a tetragonal rutile phase to an orthorhombic srilankite phase, where the synthesis of the srilankite phase at atmospheric pressure and temperature below 1200 °C in this study is reported for the first time. The crystal structure is tetragonal rutile type for the unsubstituted composition, orthorhombic srilankite type for the compositions with x > 0.30, and the compositions in between is a two-phase region with a mixture of rutile and srilankite. The Zr substitution has a great influence on the microstructure of the ceramics. In particular, for compositions where x > 0.1, the grain boundaries are surrounded by elongated powdery particles. The microwave dielectric properties of the ceramics are closely related to the phase transition process, in which Q × f is significantly improved and τ f decreases almost linearly with the increase of the content of srilankite phase. Optimum microwave dielectric properties with a permittivity of 35.1, a Q × f value of 7270 GHz, and a near-zero τ f of 9.0 ppm/°C are obtained in the ceramics with x = 0.3 sintered at 1150 °C for 4 h, which provides a new option for microwave devices requiring medium-permittivity dielectric ceramics .
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
JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Chao-Qian Liu,Bin Wen,Nan Wang,Shi-Min Liu,Hua-Lin Wang,Wei-Wei Jiang,Wan-Yu Ding,Shi-Chong Xu,Wei-Ping Chai
The mechanochemical process was employed to synthesize Cu 2 ZnSnS 4 (CZTS) powder using elemental powders of Cu, Zn, Sn and S as the source materials. The phase evolution of the synthesized powders dependent on the milling parameters was systematically researched according to Raman and X-ray diffraction measurements . It is noteworthy that the kesterite CZTS phase were observed in the mechanochemical process milling only for 3 h, but some binary metal sulfides always existed in the synthesized powders. Moreover, the formation mechanism of the CZTS phase in the mechanochemical processes was proposed. Further, the sintering behaviors of the synthesized powders were systematically investigated also, i.e., the effects of sintering temperature and milling parameters were discussed on the phase, residual stress, composition, cross-section morphologies and relative densities. It was found that the longer the milling time and/or the higher the milling rotation speed, the better the sintering properties of the synthesized powders.
研究领域:
材料科学
·
无机化学
✓ 已验证
DOI
高影响因子
ACS Materials Au
·
2023
·
IF 0
Dongdong Li,Ning Zhang,Dandan Gao,Ziyu Zhuang,Dewen Zeng
Lithium aluminum layered double hydroxide chlorides (LADH-Cl) have been widely used for lithium extraction from brine. Elevation of the performances of LADH-Cl sorbents urgently requires knowledge of the composition–structure–property relationship of LADH-Cl in lithium extraction applications, but these are still unclear. Herein, combining the phase equilibrium experiments, advanced solid characterization methods, and theoretical calculations, we constructed a cyclic work diagram of LADH-Cl for lithium capture from aqueous solution, where the reversible (de)hydration and (de)intercalation induced phase evolution of LADH-Cl dominates the apparent lithium “adsorption–desorption” behavior. It is found that the real active ingredient in LADH-Cl type lithium sorbents is a dihydrated LADH-Cl with an Al:Li molar ratio varying from 2 to 3. This reversible process indicates an ultimate reversible lithium (de)intercalation capacity of ∼10 mg of Li per g of LADH-Cl. Excessive lithium deintercalation results in the phase structure collapse of dihydrated LADH-Cl to form gibbsite. When interacting with a concentrated LiCl aqueous solution, gibbsite is easily converted into lithium saturated intercalated LADH-Cl phases. By further hydration with a diluted LiCl aqueous solution, this phase again converts to the active dihydrated LADH-Cl. In the whole cyclic progress, lithium ions thermodynamically favor staying in the Al–OH octahedral cavities, but the (de)intercalation of lithium has kinetic factors deriving from the variation of the Al–OH hydroxyl orientation. The present results provide fundamental knowledge for the rational design and application of LADH-Cl type lithium sorbents.
研究领域:
材料化学
·
环境科学
✓ 已验证
DOI
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2019
·Vol. 103
·期 4
·2674-2685
·
IF 3.094
Panpan Du,Jing Ma,Qi Zhu,Ji-Guang Li
Garnet-type Li 6 Ca(La 0.97 Yb 0.02 RE 0.01 ) 2 Nb 2 O 12 (RE = Ho, Er, Tm) new phosphors were successfully synthesized via solid reaction at 900°C for 5 hours, whose course of phase evolution, macroscopic/local crystal structure and up-/down-conversion (UC/DC) photoluminescence were clarified. Mechanistic study and materials characterization were attained via XRD, Rietveld refinement, DTA/TG, electron microscopy (FE-SEM/TEM), and Raman/reflectance/fluorescence spectroscopies. The phosphors were shown to exhibit UC luminescence dominated by a ~ 553 nm green band ( 5 F 4 / 5 S 2 → 5 I 8 transition) for Ho 3+ , a ~ 568 nm green band ( 4 S 3/2 → 4 I 15/2 transition) for Er 3+ and a ~ 806 nm near-infrared band ( 3 H 4 → 3 H 6 transition) for Tm 3+ under 978 nm laser excitation, with CIE chromaticity coordinates of around (0.31, 0.68), (0.38, 0.60) and (0.17, 0.24), respectively. Analysis of the pump-power dependence of UC intensity indicated that all the emissions involve a two-photon mechanism except for the ~ 486 nm blue emission of Tm 3+ ( 1 G 4 → 3 H 6 ), which requires a three-photon process. The DC luminescence of these phosphors is featured by dominant bands at ~ 553 nm for Ho 3+ (green, 5 F 4 / 5 S 2 → 5 I 8 transition), ~568 nm for Er 3+ (green, 4 S 3/2 → 4 I 15/2 transition) and ~ 464 nm for Tm 3+ (blue, 1 D 2 → 3 F 4 transition). The UC and DC properties were also comparatively discussed.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
ADVANCED MATERIALS
·
2024
·Vol. 36
·期 35
·2404046
·
IF 27.4
Xiaoling Hong,Qiao Zhao,Yanping Chen,Zhibin Yu,Mengzhen Zhou,Yan Chen,Wenhao Luo,Chang Wang,Na Ta,Haitao Li,Runping Ye,Xiaotao Zu,Wei Liu,Jian Liu
Cobalt carbide (Co 2 C) possesses high catalytic efficiency Fischer–Tropsch synthesis (FTS), while the products selectivity appears sensitive to crystallography geometry. Since the Anderson–Schulz–Flory (ASF) distribution in FTS is broken through fabricating facetted Co 2 C nanocrystals, yet the underlying mechanism of Co 2 C crystallization remains unclarified suffering from sophisticated catalyst composition involving promoter agents. Herein, the synthesis of high-purity single-crystal nanoprisms (Co 2 C-p) for highly efficient FTS is reported to lower olefins. Through comprehensive microstructure analysis, e.g., high-resolution TEM, in situ TEM and electron diffraction, as well as finite element simulation of gas flow field, for the first time the full roadmap of forming catalytic active cobalt carbides is disclosed, starting from reduction of Co 3 O 4 precursor to CoO intermediate, then carburization into Co 2 C-s and subsequent ripening growth into Co 2 C-p. This gas-induced engineering of crystal phase provides a new synthesis strategy, with many new possibilities for precise design of metal-based catalyst for diverse catalytic applications.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POWDER TECHNOLOGY
·
2017
·
IF 2.942
Yuanbo Zhang,Zijian Su,Bingbing Liu,Jun Chen,Guanghui Li,Tao Jiang
An investigation on the behavior of SnO 2 in the tin-bearing iron concentrates during the reduction sintering process (RSP) has been conducted by the authors' group. It was found that only about 30 wt.% of tin was removed under the optimal conditions. However, the underlying reason why it was so difficult to remove tin by the RSP was not understood. In this study, the phase evolution of tin oxide, iron oxide and calcium oxide under simulative sintering conditions was investigated by varying the gas compositions , sintering temperature and basicity (CaO/SiO 2 ). The results indicated that the Ca-Sn oxides were prior formed at 900 °C–1000 °C in the reduction atmosphere with CO / (CO + CO 2 ) = 10–40 vol.%, while the phases of Fe-Sn spinel (Fe 3 − x Sn x O 4 ) and Ca-Fe-Sn oxides were easily generated as the temperature increased to 1100 °C–1200 °C. The phases of Fe 2 − 4x/3 Sn x O 3 and Ca-Fe-Sn-Si oxides began to generate at 1100 °C in an oxidative atmosphere with O 2 /(O 2 + CO 2 ) = 25–100 vol.%. In addition, increasing alkalinity accelerated the formation of Ca-Sn oxides under reduction atmosphere, which brought about an adverse effect on the tin removal in the sintering process.
研究领域:
冶金学
·
材料科学
✓ 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）