物理化学学报 >> 2011, Vol. 27 >> Issue (04): 983-989.doi: 10.3866/PKU.WHXB20110410

材料物理化学 上一篇    下一篇

掺杂Cs元素的微孔晶体材料C12A7的表征及负离子发射特性

宁珅, 沈静, 李兴龙, 徐勇, 李全新   

  1. 中国科学技术大学化学物理系, 生物质洁净能源实验室, 合肥 230026
  • 收稿日期:2010-11-26 修回日期:2011-01-17 发布日期:2011-03-29
  • 通讯作者: 李全新 E-mail:liqx@ustc.edu.cn
  • 基金资助:

    国家自然科学基金(50772107), 国家重点基础研究发展规划(973)(2007CB210206)及国家高技术研究发展计划(863)(2009AA05Z435)资助项目

Characterization and Anion Emission Characteristics of the Microporous Crystal Cs-C12A7

NING Shen, SHEN Jing, LI Xing-Long, XU Yong, LI Quan-Xin   

  1. Laboratory of Biomass Clean Energy, Department of Chemical Physics, University of Science & Technology of China, Hefei 230026, P. R. China
  • Received:2010-11-26 Revised:2011-01-17 Published:2011-03-29
  • Contact: LI Quan-Xin E-mail:liqx@ustc.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (50772107), National Key Basic Research Program of China (973) (2007CB210206) and National High-Tech Research and Development Program of China (863) (2009AA05Z435).

摘要:

利用浸渍CsI的方法在微孔晶体材料12CaO·7Al2O3 (C12A7)表面掺杂Cs元素并对其进行场发射扫描电镜、透射电子显微镜、X射线衍射以及电子顺磁共振的表征. 场发射扫描电镜以及透射电子显微镜的结果均证实CsI沉积在C12A7的表面; X射线衍射证明C12A7的结构并没有被破坏; 电子顺磁共振谱说明了浸渍后C12A7中的O-和O2-浓度也无明显变化. 将浸渍后的同原始的C12A7进行比较发现, 掺杂样品在结构和存储特性上均无明显变化. 此外, 对该材料的发射性能与温度和引出场的关系也进行了研究与分析. 结果表明: 浸渍CsI至C12A7表面不仅降低了氧负离子的发射温度, 还大幅增强了发射强度; 氧负离子发射增强的主要原因归结于浸渍CsI后其表观活化能的降低.

关键词: 氧负离子, 掺杂Cs元素的C12A7, 发射特性, 存储特性, 表观活化能

Abstract:

Cesium-12CaO·7Al2O3 (Cs-C12A7) was fabricated by adding CsI to the C12A7 surface using incipient wetness impregnation. The X-ray diffraction (XRD) structure determined for the Cs-C12A7 material is the same as that of the 12CaO·7Al2O3 (C12A7) crystal, which belongs to the I43d] space group. The concentrations of O- and O2- in Cs-C12A7 were about (1.3±0.3)×1020 cm-3 and (1.2±0.2)×1020 cm-3, respectively, according to a simulation of the measured electron paramagnetic resonance (EPR) spectrum. This is similar to the data obtained for fresh C12A7 ([O-]=(1.4±0.3)×1020 cm-3 and [O2-]=(1.4±0.3)×1020 cm-3). The CsI particles from the C12A7 surface were observed using field emission scanning electron microscope (FESEM) and conventional transmission electron microscopy (TEM). The emission features of Cs-C12A7, including the emission distribution, field effect and apparent activation energy were investigated in detail and compared with those of C12A7. The advanced emission behavior was attributed to a reduction in the apparent activation energy.

Key words: Atomic oxygen anion, Cs-C12A7, Emission characteristics, Storage characteristics, Apparent activation energy

MSC2000: 

  • O647