Nano Research
·
2021
·Vol. 15
·期 1
·446-451
·
IF 8.897
Yu Yongsheng,He Lin,Xu Junjie,Li Jiaming,Jiang Sida,Han Guanghui,Jiang Baojiang,Lei Wenjuan,Yang Weiwei,Hou Yanglong
The ordered Pt-based intermetallic nanoparticles (NPs) with small size show superior magnetic or catalytic properties, but the synthesis of these NPs still remains a great challenge due to the requirement of high temperature annealing for the formation of the ordered phase, which usually leads to sintering of the NPs. Here, we report a simple approach to directly synthesize monodisperse ordered L1 0 -FePt NPs with average size 10.7 nm without further annealing or doping the third metal atoms, in which hexadecyltrimethylammonium chloride (CTAC) was found to be the key inducing agent for the thermodynamic growth of the Fe and Pt atoms into the ordered intermetallic structure in the synthetic process. In particular, 10.7 nm L1 0 -FePt NPs synthesized by the proper amount of CTAC show a coercivity of 3.15 kOe and saturation magnetization of 45 emu/g at room temperature. The current CTAC-assisted synthetic strategy makes it possible to deeply understand the formation of the ordered Pt-based intermetallic NP in solution phase synthesis.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yinyin Zhang,Fangzhong Liu,Ting Song,Yong Pei,Xianyou Wang,Xiongwei Wu,Manjun Xiao,Qi Deng,Bei Long
The electrochemical performances of LiNi 0.5 Mn 1.5 O 4 (LNMO) materials are strongly correlated with the ratio of disordered to ordered phases. Nevertheless, there are few reports on the adjustment of ordered and disordered phase ratio. In this paper, the ratio of ordered to disordered phases in LNMO is successfully adjusted by using a quaternary molten salt, which is proven by XRD refinement, FT-IR, and XPS. Reductive quaternary molten salt and Co doping are favorable for Ni/Mn cation disorder, leading to the increased disordered phase. LNMO with an appropriate ratio of ordered to disordered phases can exhibit enhanced electronic/ionic transfer rate and structural stability, revealed by electrochemical tests and ex situ characterizations. Therefore, the optimized material delivers a reversible capacity of 121 mA h g −1 at 20 mA g −1 and a long cyclic life with 61 mA h g −1 at 1000 mA g −1 over 1200 cycles. The present work offers a new idea for achieving a regulated ratio of ordered to disordered phases in LNMO.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
Nature Communications
·
2024
·Vol. 15
·期 1
·1-10
·
IF 14.7
Zhang Wencong,Li Fan,Li Yi,Song Anran,Yang Kun,Wu Dongchang,Shang Wen,Yao Zhenpeng,Gao Wenpei,Deng Tao,Wu Jianbo
Intermetallic phases with atomic ordering are highly active and stable in catalysts. However, understanding the atomistic mechanisms of disorder-to-order phase transition, particularly in multi-component systems, remains challenging. Here, we investigate the atom diffusion and phase transition within Pd@Pt-Co cubic nanoparticles during annealing, using in-situ electron microscopy and ex-situ atomic resolution element analysis. We reveal that initial outward diffusing Pd partially substitutes Pt, forming a (Pt, Pd)-Co ternary system in the surface region, enabling the phase transition at a low temperature of 400 °C, followed by shape-preserved inward propagation of the ordered phase. At higher temperatures, excessive interdiffusion across the interface changes the stoichiometric ratio, diminishing the atomic ordering, leading to obvious change in morphology. Calculations indicate that the Pd-substitute in (Pt, Pd)-Co system leads to a significantly lower phase transition temperature compared to that of Pt-Co alloy and thus a lower activation energy for atomic diffusion. These insights into atomistic behavior are crucial for future design of multi-component systems.
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
POLYMER
·
2019
·
IF 3.771
Chao Lv,Ruiyang Wang,Jia Gao,Ning Ding,Shunni Dong,Jingjing Nie,Junting Xu,Binyang Du
Enhanced phase separation and inverse order-to-order phase transition with increasing temperature was observed for a series of poly (acrylic acid)- b -poly (propylene oxide)- b -poly (acrylic acid) triblock copolymers with various block lengths by temperature-variable synchrotron small-angle X-ray scattering (SAXS). This abnormal phase behavior was attributed to the change of hydrogen (H)-bonding interaction in block copolymers upon increasing temperature and theoretically explained from thermodynamic viewpoint. The temperature-dependent FTIR analysis revealed that increasing temperature led to the weakening of overall H-bonding interactions and the increase of free C O and C–O–C groups. The Flory-Huggins interaction parameter χ of PAA and PPO blocks was positive and increased with increasing temperature as determined from the SAXS profiles of disordered block copolymer. The thermodynamic calculation indicated that the increase of Δ H was larger than the decrease of – T Δ S with increasing temperature because of the relatively large value of χ , leading to the increase of overall Δ G mix and hence the enhanced phase separation at higher temperature.
研究领域:
高分子科学
·
材料科学
·
热力学
·
物理化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）