为了研究MgO晶体和二次电子发射效率间的关系,分析了直接沉淀镁盐法生成Mg(OH)2以及三段式温度煅烧Mg(OH)2制备MgO晶体的过程,并使用扫描电镜和XRD对制成的MgO晶体进行了表征.在此基础上,采用第一性原理对MgO晶体的能带结构和态密度进行了计算,分析了晶体表面的结晶取向对MgO二次电子发射系数的影响.实验结果表明,本方法制备的MgO为立方晶体,且晶粒尺寸均匀分布在40.65 nm附近,晶面取向为(200)、(111)、(220),并沿(200)取向择优生长.常见的(110)、(100)和(111)三种晶面取向中,表面(110)取向的MgO晶体禁带宽度最低,材料表面的二次电子发射系数相对较高.
In this work, the direct precipitation method was used to generate magnesium salt Mg(OH)2, the process of preparing MgO crystal by calcining Mg (OH)2 in three stage temperature was studied, and MgO crystal was characterized by scanning electron microscope and XRD.On this basis, the energy band structure and states density of MgO crystal were calculated by the first principle theory, the influence of crystal orientation on MgO secondary electron emission was analyzed.The experimental results show that the MgO prepared by this method is cubic crystal.The grain size is evenly distributed in the vicinity of 40.65 nm.The crystal orientation is of (200), (111), (220) and along the (200) orientation preferential growth.Among three kinds of common crystal orientation which are (110), (110) and (111), the surface (110) orientation of the MgO crystal with the lowest band gap, the two electron emission coefficient of the material surface is relatively high.
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