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层状前体法制备的钴尖晶石铁氧体纳米颗粒的磁性能 被引量:3
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作者 祁欣 陈秀霞 +1 位作者 周小多 李峰 《磁性材料及器件》 CAS CSCD 2008年第1期18-20,27,共4页
采用化学共沉淀的层状前(驱)体法制备出不同Co含量的Co尖晶石铁氧体前体,经900℃焙烧制得Co铁氧体纳米粉体。利用X射线衍射(XRD)分析Co铁氧体前体及铁氧体粉末晶体结构,利用振动样品磁强计(VSM)测量了样品的磁性能。结果表明,当Co2+/Fe2... 采用化学共沉淀的层状前(驱)体法制备出不同Co含量的Co尖晶石铁氧体前体,经900℃焙烧制得Co铁氧体纳米粉体。利用X射线衍射(XRD)分析Co铁氧体前体及铁氧体粉末晶体结构,利用振动样品磁强计(VSM)测量了样品的磁性能。结果表明,当Co2+/Fe2+/Fe3摩尔配比分别为(a)1/3/1、(b)3/5/2、(c)1.92/1/2、(d)2/1/1、(e)3/1/1时均可以制得具有层状结构的前驱体,高温焙烧产物亦为尖晶石结构的Co铁氧体。分析样品的Co含量发现,不同投料摩尔比的前体经过高温焙烧后得到的产物相成分并不完全相同,只有当Co2+/(Fe2++Fe3+)接近尖晶石的化学计量比1/2时,制得的样品为单一晶相。且当化学计量比M2+/M3+接近1/2时矫顽力可达最大值166kA/m,饱和磁化强度和剩余磁化强度也出现最大值,分别为72.63A·m2/kg和23.37A·m2/kg。 展开更多
关键词 Co铁氧纳米颗粒 层状() 相成分 磁性能
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Sodium carbonate-assisted synthesis of hierarchically porous single-crystalline nanosized zeolites 被引量:1
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作者 Xiaoxia Zhou Yu Chen +3 位作者 Tongguang Ge Zile Hua Hangrong Chen Jianlin Shi 《Science Bulletin》 SCIE EI CAS CSCD 2017年第14期1018-1024,共7页
Hierarchically porous single-crystalline nanosized zeolites as heterogeneous catalysts show great poten- tial in fine chemistry because they offer more rich hierarchically porous channels for the mass transfer and mol... Hierarchically porous single-crystalline nanosized zeolites as heterogeneous catalysts show great poten- tial in fine chemistry because they offer more rich hierarchically porous channels for the mass transfer and molecular diffusion. However, the synthesis of hierarchically porous nanosized zeolites generally requires the assistance of templates acting as the mesoporogens, which limits its popularity. Herein, we report a one-pot and template-free synthesis of hierarchically porous single-crystalline nanosized zeolite beta only by introducing sodium carbonate in precursor solution. The resulted sample features the extraordinary properties, including the uniform nanocrystal (200-300 nm), high pore volume (0.65 cm3g 1) and the hierarchical pore-size distribution (e.g., 2-8 and 90-150 nm). After slicing pro- cessing, it is interestingly found that a large number of interconnected mesopores penetrate throughout whole material, which enables the hierarchically porous nanosized zeolite beta remarkably superior cat- alytic activity than the conventional zeolite beta in condensation of henzaldehyde with ethanol at room temperature. More importantly, this one-pot sodium carbonate-assisted synthetic strategy is highly ver- satile, which has also been successfully developed to synthesize hierarchically porous nanosized single- crystalline zeolites ZSM-5 and TS. 展开更多
关键词 Hierarchically porous Single-crystalline Beta/ZSM-5/TS Sodium carbonate Template-free Condensation of benzaldehyde
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