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稀土是重要的战略物资资源,有一些已形成产业,在永磁、发光、催化和储氢等方面有着重要的作用. 对稀土及其化合物的研究一直是国内外研究的热点.对稀土原子结构和价电子结构的研究有助于对其的更深刻的理解. 依据固体与分子经验电子理论,对镧系稀土和Sc, Y的价电子结构进行系统地研究, 并以此为基础,对它们的熔点和结合能做进一步分析,分析结果和实验值相符. 研究结果表明:稀土金属的结构与晶格电子和共价电子密切相关,随着晶格电子向共价电子的转换, 稀土金属的熔点趋于增加.稀土的价态变化也是影响电子分布和性能的主因, 如: Sm和Eu的熔点与电子结构的关系不同于其他稀土,外壳层的共价电子之间的转化是其熔点与其他元素之间差别较大的主要原因.稀土的4f电子对结合能的影响大,这是源于其4f电子引发的收缩效应. 此结果揭示了决定稀土熔点和结合能的主要因素是稀土的价电子结构的变化.Rare earth element is one kind of strategic materials. Some rare earth elements have been industrialized. They play major roles in permanent magnetism material, lightening, catalysis and hydrogen storage material. In order to understand the rare earth elements more, it is necessary to study the structures of the valence electrons and atoms of them. The valence electron structures and properties of yttrium, scandium and lanthanum group rare earth elements are studied with the empirical electron theory (EET). Based on the valence electron parameters, the melting points and cohesive energies of these rare earth elements are calculated. The calculations accord with those of the measurements. According to the analyses of EET, the structures and the physical properties of rare earth elements depend on the electron emission or transformation between the lattice-electrons and coherent electrons in outer orbital. It is exhibited that the melting point tends to increase with the lattice electron-covalent electron transformation, however, the valence status of rare earth element affects significantly the electron distribution and property. The covalent electron hoppings occur at divalent europium, ytterbium and samarium, and their melting points are related to the electron transformation covalence-electrons. It is different from the others with trivalent status. The theoretical analysis reveals that the cohesive energy is related to the 4f electrons. The contribution to cohesive energy increases with the number of 4f electrons increasing, which may be due to the shrinking effect of the atomic radius for the lanthanum group. The study implies that the characteriscs of rare earth element are due to the relation between their melt pointing and conhesive energy and electronic structure.
[1] Liang Y C, Guo J T, Zhou L Z, Xie Y, Hu Z Q 2008 Acta Metal. Sin. 44 535 (in Chinese) [梁泳纯, 郭建亭, 周兰章, 谢亿, 胡壮麒 2008 金属学报 44 535]
[2] Wang B, Liu Q Y, Bao X P, Weng Y, Wang X D, Jia S J, Dong H 2008 Acta Metal. Sin. 44 863 (in Chinese) [汪兵, 刘青友, 毛新平, 翁羽, 王向东, 贾书君, 董瀚 2008 金属学报 44 863]
[3] Wu W X, Guo Y Q, Li A H, Li W 2008 Acta Phys. Sin. 57 2486 (in Chinese) [吴文霞, 郭永权, 李安华, 李卫 2008 物理学报 57 2486]
[4] Jin X, Zhang X D, Lei Z F, Xiong S Z, Song F, Zhao Y 2008 Acta Phys. Sin. 57 4580 (in Chinese) [金鑫, 张晓丹, 雷志芳, 熊绍珍, 宋峰, 赵颖 2008 物理学报 57 4580]
[5] Zhang X S, Zheng H R, He E J, Cai X Y, Zhu G Q, Gao D L, Qu S X 2009 Chin. Sci. Bull. 54 1222 (in Chinese) [张喜生, 郑海荣, 何恩节, 蔡晓燕, 朱刚强, 高当丽, 屈世显 2009 科学通报 54 1222]
[6] Wu Y X, Hu X Z, Gu S L, Qu L C, Li T, Zhang H 2011 Acta Phys. Sin. 60 017101 (in Chinese) [吴玉喜, 胡智向, 顾书林, 渠立成, 李腾, 张昊 2011 物理学报 60 017101
[7] Romaka L, Romaka V V, Stadnyk Y, Demchenko P 2010 J. Alloys Compounds. 505 70
[8] Mohanta S K, Mishra S N, Srivastava S K, Rots M 2010 Solid State Commun. 150 1789
[9] Yu R H 1978 Chin. Sci. Bull. 23 217 (in Chinese) [余瑞璜 1978 科学通报 23 217]
[10] Pauling L 1966 The Nature of the Chemical Bond (New York: Comell University Press) p384
[11] Zhang R L 1993 The Empirical Electron Theory of Solids and Molecules (Changchun: Jilin Science and Technology Press) p68 (in Chinese) [张瑞林 1993 固体与分子经验电子理论(长春:吉林科学技术出版社) 第68页]
[12] Guo Y Q, Yu R H, Zhang R L, Zhang X H, Tao K 1998 Phys. Chem. B 102 9
[13] Fu B Q, Liu W, Li Z L 2010 Appl. Surf. Sci. 256 6899
[14] Mi G B, Li P J, He L J 2011 Rare Metal Mater. Eng. 39 11
[15] Ye Y C, Li P J, He L J 2010 Intermetallics 18 465
[16] Fu B Q, Liu W, Li Z L 2009 Appl. Surf. Sci. 255 9348
[17] Huang K 1985 Solid State Physics (Beijing: Higher Education Press) p16 (in Chinese) [黄昆 1985 固体物理学(北京:高等教育出版社) 第16页]
[18] Kittel C 2005 Introduction to Solid State Physics (Beijing: Chemical Industry Press) pp94-114 (in Chinese) [基泰尔著, 项金钟, 吴兴惠译 2005 固体物理导论(北京:化学工业出版社) 第94-114页]
[19] Nagasaki S 2004 Binary Alloy State Atlas (Beijing: Metallurgical Industry Press) p79 (in Chinese) [长崎诚三著, 刘安生译 2004 二元合金状态图集(北京: 冶金工业出版社) 第79页]
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[1] Liang Y C, Guo J T, Zhou L Z, Xie Y, Hu Z Q 2008 Acta Metal. Sin. 44 535 (in Chinese) [梁泳纯, 郭建亭, 周兰章, 谢亿, 胡壮麒 2008 金属学报 44 535]
[2] Wang B, Liu Q Y, Bao X P, Weng Y, Wang X D, Jia S J, Dong H 2008 Acta Metal. Sin. 44 863 (in Chinese) [汪兵, 刘青友, 毛新平, 翁羽, 王向东, 贾书君, 董瀚 2008 金属学报 44 863]
[3] Wu W X, Guo Y Q, Li A H, Li W 2008 Acta Phys. Sin. 57 2486 (in Chinese) [吴文霞, 郭永权, 李安华, 李卫 2008 物理学报 57 2486]
[4] Jin X, Zhang X D, Lei Z F, Xiong S Z, Song F, Zhao Y 2008 Acta Phys. Sin. 57 4580 (in Chinese) [金鑫, 张晓丹, 雷志芳, 熊绍珍, 宋峰, 赵颖 2008 物理学报 57 4580]
[5] Zhang X S, Zheng H R, He E J, Cai X Y, Zhu G Q, Gao D L, Qu S X 2009 Chin. Sci. Bull. 54 1222 (in Chinese) [张喜生, 郑海荣, 何恩节, 蔡晓燕, 朱刚强, 高当丽, 屈世显 2009 科学通报 54 1222]
[6] Wu Y X, Hu X Z, Gu S L, Qu L C, Li T, Zhang H 2011 Acta Phys. Sin. 60 017101 (in Chinese) [吴玉喜, 胡智向, 顾书林, 渠立成, 李腾, 张昊 2011 物理学报 60 017101
[7] Romaka L, Romaka V V, Stadnyk Y, Demchenko P 2010 J. Alloys Compounds. 505 70
[8] Mohanta S K, Mishra S N, Srivastava S K, Rots M 2010 Solid State Commun. 150 1789
[9] Yu R H 1978 Chin. Sci. Bull. 23 217 (in Chinese) [余瑞璜 1978 科学通报 23 217]
[10] Pauling L 1966 The Nature of the Chemical Bond (New York: Comell University Press) p384
[11] Zhang R L 1993 The Empirical Electron Theory of Solids and Molecules (Changchun: Jilin Science and Technology Press) p68 (in Chinese) [张瑞林 1993 固体与分子经验电子理论(长春:吉林科学技术出版社) 第68页]
[12] Guo Y Q, Yu R H, Zhang R L, Zhang X H, Tao K 1998 Phys. Chem. B 102 9
[13] Fu B Q, Liu W, Li Z L 2010 Appl. Surf. Sci. 256 6899
[14] Mi G B, Li P J, He L J 2011 Rare Metal Mater. Eng. 39 11
[15] Ye Y C, Li P J, He L J 2010 Intermetallics 18 465
[16] Fu B Q, Liu W, Li Z L 2009 Appl. Surf. Sci. 255 9348
[17] Huang K 1985 Solid State Physics (Beijing: Higher Education Press) p16 (in Chinese) [黄昆 1985 固体物理学(北京:高等教育出版社) 第16页]
[18] Kittel C 2005 Introduction to Solid State Physics (Beijing: Chemical Industry Press) pp94-114 (in Chinese) [基泰尔著, 项金钟, 吴兴惠译 2005 固体物理导论(北京:化学工业出版社) 第94-114页]
[19] Nagasaki S 2004 Binary Alloy State Atlas (Beijing: Metallurgical Industry Press) p79 (in Chinese) [长崎诚三著, 刘安生译 2004 二元合金状态图集(北京: 冶金工业出版社) 第79页]
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