鈧酸鹽陰極發(fā)射物質(zhì)相的研究
STRUCTURE ANALYSIS STUDIES IN EMISSIVE MATERIALS OF THE BARIUM SCANDATE DISPENSER CATHODE
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摘要: 用多晶X射線衍射方法,研究鈧酸鹽陰極發(fā)射材料在燒結(jié)過程中物理化學(xué)變化。由BaO-CaO-Al2O3-Sc2O3組成的發(fā)射材料中,在10001300℃內(nèi),是Ba-Al-O和Ba-Sc-O體系與CaO的混合物;在13001500℃內(nèi),是Ba-Al-O和Ba-Sc-O體系互溶生成熱力學(xué)上的亞穩(wěn)定態(tài)的Ba-Al-Sc-O固溶體。先形成組成約為5BaO-Al2O3-Sc2O3物相,屬正交晶系,a=9.725(2),b=8.698(3),c=6.152(3);最后生成組成約為4BaO-Al2O3-0.5Sc2O3物相,屬四方晶系,a=14.4996(19),b=4.4996(19),c=5.0265(8).CaO呈游離狀態(tài)。
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關(guān)鍵詞:
- 熱陰極; 鈧酸鹽陰極; 發(fā)射材料; X射線衍射分析
Abstract: Physio-chemical reactions in emissive materials of the barium scandate dispenser cathode during the sintering process are investigated by X ray analysis with the aid of an X-ray diffractometer using CuK radiation. The emissive materials of barium scandate are the compounds resulting from the reaction and sintering of BaO-CaO-Al2O3-Sc2O3 with a specified proportion. During the course of the investigation, it became clear that the formation of different compounds is very dependent on the firing temperature.The results of experiments indicate that the phases present at 1000--1600℃ are the compounds of Ba-Al-O system, Ba-Sc-O system and CaO; at 1300--1500℃ a solid solution of Ba-al-Sc-O system is found, which is formed from Ba-Al-O and Ba-Sc-O system by their mutual solubility and belongs to a quasistable state of thermodynamics. the solid solution is first formed to be an orthorhombic unit cell for about 5BaO-Al2O3-Sc2O3 with a=9.725(2), b=8.698(3), c=6.152(3), and finally a tetragonal unit cell for about 4BaO-Al2O3-0.5Sc2O3 with a=14.4996(19), c=5.0265(8), and CaO is in the form of free state. -
曾昭俟等,電子管技術(shù),1984年,第3期,p.14.[2]陳明業(yè),電子情報(bào),1984年,第1期,p.19.[3]G. M. Wolfen, An Appraisal of the Ternary System BaO-CaO-Al2O3, SO-TR-80-67, Space Division Air[4]Force Systems Command, Los Angeles, Oct., 1980.[5]M. L. Kovba, et al., Dokl.Akad, Nauk SSSR, 260(1981)4, 924-927.[6]W. Kwestroo, et al., Res. Bull, 17(1982)5, 641-646.[7]S. J. Schneider, et al., J. Research N. B. S., 65A(1961), 345-375.[8]J. W. Visser, J. Appl. Cryst, 2(1969)4, 89.[9]A. van Osstron, L. Augustus, Appl. of Surf. Science, 2(1979), 173-186. -
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