掺杂Cs元素的微孔晶体材料C12A7的表征及负离子发射特性(英文)  

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

作　　者：宁珅[1] 沈静[1] 李兴龙[1] 徐勇[1] 李全新[1] 

机构地区：[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

出　　处：《物理化学学报》2011年第4期983-989,共7页Acta Physico-Chimica Sinica

基　　金：supported by the National Natural Science Foundation of China(50772107);National Key Basic Research Program of China(973)(2007CB210206);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.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.

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 

分 类 号：TB383.4[一般工业技术—材料科学与工程]