Chemical trends of the rattling phonon modes in alloyed germanium clathrates

被引:95
作者
Dong, JJ [1 ]
Sankey, OF
Ramachandran, GK
McMillan, PF
机构
[1] Arizona State Univ, Dept Phys & Astron, Tempe, AZ 85287 USA
[2] Arizona State Univ, Mat Res Ctr, Tempe, AZ 85287 USA
[3] Arizona State Univ, Dept Chem & Biochem, Tempe, AZ 85287 USA
关键词
D O I
10.1063/1.373447
中图分类号
O59 [应用物理学];
学科分类号
摘要
Alloys based on Ge clathrates are promising thermoelectric materials because of their expected "rattling" properties. We have incorporated the elements of columns I and II into the cages of (Ge, Ga)(46) type-I clathrates as cation guests and have theoretically examined their "rattling" behavior using density functional theory. The potential energy curves of guest atoms in the cages are evaluated to understand the nature of the weak guest-framework interaction. Some atoms are unstable at the center of the cages, while others appear to be bonded by weak restoring forces. We calculate the phonon modes and the Raman spectra and find that heavy alkali-earth elements, such as Sr and Ba, induce low-frequency "rattling" phonon modes as predicted by Slack's model, while heavy alkali metal atoms (K, Rb, and Cs) are less "rattler-like" since they interact less with the acoustic modes of the Ge-based clathrate framework. (C) 2000 American Institute of Physics. [S0021-8979(00)06311-8].
引用
收藏
页码:7726 / 7734
页数:9
相关论文
共 66 条
[1]   WIDE-BAND-GAP SI IN OPEN FOURFOLD-COORDINATED CLATHRATE STRUCTURES [J].
ADAMS, GB ;
OKEEFFE, M ;
DEMKOV, AA ;
SANKEY, OF ;
HUANG, YM .
PHYSICAL REVIEW B, 1994, 49 (12) :8048-8053
[2]   Why clathrates are good thermoelectrics:: A theoretical study of Sr8Ga16Ge30 [J].
Blake, NP ;
Mollnitz, L ;
Kresse, G ;
Metiu, H .
JOURNAL OF CHEMICAL PHYSICS, 1999, 111 (07) :3133-3144
[3]   Synthesis and characterization of stable stoichiometric clathrates of silicon and germanium:: Cs8Na16Si136 and Cs8Na16Ge136 [J].
Bobev, S ;
Sevov, SC .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1999, 121 (15) :3795-3796
[4]  
Born M., 1954, DYNAMICAL THEORY CRY, P91
[5]   Superconductivity in germanium clathrate Ba8Ga16Ge30 [J].
Bryan, JD ;
Srdanov, VI ;
Stucky, GD ;
Schmidt, D .
PHYSICAL REVIEW B, 1999, 60 (05) :3064-3067
[6]  
CAHILL DG, 1988, ANNU REV PHYS CHEM, V39, P93, DOI 10.1146/annurev.physchem.39.1.93
[7]   Low-temperature transport properties of the filled skutterudites CeFe4-xCoxSb12 [J].
Chen, BX ;
Xu, JH ;
Uher, C ;
Morelli, DT ;
Meisner, GP ;
Fleurial, JP ;
Caillat, T ;
Borshchevsky, A .
PHYSICAL REVIEW B, 1997, 55 (03) :1476-1480
[8]   Glasslike heat conduction in high-mobility crystalline semiconductors [J].
Cohn, JL ;
Nolas, GS ;
Fessatidis, V ;
Metcalf, TH ;
Slack, GA .
PHYSICAL REVIEW LETTERS, 1999, 82 (04) :779-782
[9]  
CROS C, 1968, B SOC CHIM FR, P2737
[10]  
CROS C, 1965, CR HEBD ACAD SCI, V260, P4764