掺杂Cs元素的微孔晶体材料C12A7的表征及负离子发射特性

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.

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

Cesium-12CaO·7Al2O3 (Cs-Cl2A7) was fabricated by adding CsI to the Cl2A7 surface using incipient wetness impregnation. The X-ray diffraction (XRD) structure determined for the Cs-Cl2A7The concentrations of O- and O2- in Cs-Cl2A7 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 Cl2A7 (O-]=(1.4+0.3)×1020 cm-3 and O2-]=(1.4+0.3)× 1020 cm-3). The CsI particles from the Cl2A7 surface were observed using field emission scanning electron microscope (FESEM) and conventional transmission electron microscopy (TEM). The emission features of Cs-Cl2A7, including the emission distribution, field effect and apparent activation energy were investigated in detail and compared with those of Cl2A7. The advanced emission behavior was attributed to a reduction in the apparent activation energy.