Hostname: page-component-78c5997874-j824f Total loading time: 0 Render date: 2024-11-02T23:00:32.902Z Has data issue: false hasContentIssue false
  • English
  • Français

Framework Stoichiometry and Electrical Conductivity of Si-Ge Based Structure-I Clathrates

Published online by Cambridge University Press:  01 February 2011

Ganesh K. Ramachandran ,
Paul F. McMillan ,
Jianjun Dong ,
Jan Gryko  and
Otto F. Sankey
Ganesh K. Ramachandran
Affiliation:
Department of Chemistry & Biochemistry, and Materials Research Center, Arizona State University, AZ 85287–1604
Paul F. McMillan
Affiliation:
Department of Chemistry & Biochemistry, and Materials Research Center, Arizona State University, AZ 85287–1604 Center for Solid State Science, Arizona State University, AZ 85287–1504
Jianjun Dong
Affiliation:
Department of Physics & Astronomy, and Materials Research Center, Arizona State University, AZ 85287–1704
Jan Gryko
Affiliation:
Department of Earth & Physical Sciences, Jacksonville State University, AL 36265
Otto F. Sankey
Affiliation:
Department of Physics & Astronomy, and Materials Research Center, Arizona State University, AZ 85287–1704
Get access

Abstract

We report the synthesis and structural characterization of two Structure I clathrates in the KSi and Rb-Si systems. The alkali-Si clathrates are fully stoichiometric at the framework sites, i.e., devoid of framework vacancies. This is in sharp contrast to the analogous K-Ge, Rb-Ge and Rb-Sn, Cs-Sn systems, where vacancies are formed at one-third of the crystallographic 6c tetrahedral sites. This is rationalized in terms of Zintl-Klemm rules to remove the tetrahedral atom of its hypervalency. The contrasting behavior is understood in terms of weaker Tt-Tt (Tt – tetrelide, Si, Ge, Sn) bonding as one descends the periodic table, and results in poorly metallic conductivities for vacancy-free K7Si46 and Rb6Si46, but semiconducting behavior of K8Ge44. The observation suggests tuning of the electronic properties of Tt clathrates by substitution of (Si,Ge,Sn) on framework sites, for thermoelectric applications. We describe preliminary results designed to synthesize “mixed” Si-Ge clathrate structures. Thermal decomposition of K2SiGe results in formation of a Structure I clathrate with mixing of Si and Ge on framework sites. The lattice constant ao = 10.523(6) Å, is intermediate between those of K8Si46 and K8Ge44.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 626: Symposium Z – Thermoelectric Materials 2000 - The Next Generation Materials for Small-Scale Refrigeration and Power Generation Applications , 2000 , Z13.2
Copyright
Copyright © Materials Research Society 2000

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Cros, C., Pouchard, M. and Hagenmuller, P., J. Solid State Chem. 2, 570 (1970);Google Scholar
Kasper, J. S., Hagenmuller, P., Pouchard, M. and Cros, C., Science 150, 1713 (1965)Google Scholar
2. Adams, G. B., O'Keeffe, M., Demkov, A. A., Sankey, O. F. and Huang, Y., Phys. Rev. B 49, 8048 (1994);Google Scholar
O'Keeffe, M., Adams, G. B. and Sankey, O. F., Phil. Mag. Letts. 78, 21 (1998)Google Scholar
3. Slack, G. A., Mat. Res. Soc. Symp. Proc. 478, 47 (1997)Google Scholar
4. Nolas, G., Cohn, J. L., Slack, G. A. and Schujman, S. B., Appl. Phys. Lett. 73, 178 (1998)Google Scholar
5. Cohn, J. L., Nolas, G. S., Fessatidis, V., Metcalf, T. H. and Slack, G. A., Phys Rev Lett. 82, 779 (1999)Google Scholar
6. Shujman, S. B., Nolas, G. S., Young, R. A., Lind, C., Wilkinson, A. P., Slack, G. A., Patschke, R., Kanatzidis, M. G., Ulutagay, M. and Hwu, S-J., J. Appl. Phys. 87, 1529 (2000);Google Scholar
Iversen, B. B., Palmqvist, A. E. C., Cox, D. E., Nolas, G. S., Stucky, G. D., Blake, N. P. and Metiu, H., J. Solid State Chem. 149, 455 (2000);Google Scholar
Chakoumakos, B. C., Sales, B. C., Mandrus, D. G. and Nolas, G. S., J. Alloys Comp. 296, 80 (2000)Google Scholar
7. Chemistry, Structure and Bonding of Zintl Phases and Ions, ed. Kauzlarich, Susan M., (VCH Publishers, NY, 1996 Google Scholar
8. von Schnering, H. G., Nova Acta Leopoldina 59, 168 (1985);Google Scholar
Zhao, J-T. and Corbett, J. D., Inorg. Chem. 33, 5721 (1994)Google Scholar
9. Ramachandran, G. K., McMillan, P. F., Diefenbacher, J., Gryko, J., Dong, J. and Sankey, O. F., Phys. Rev. B 60, 12294 (1999);Google Scholar
Shimizu, , Maniwa, Y., Kume, K., Kawaji, H., Yamanaka, S. and Ishikawa, M., Phys. Rev. B 54, 13242 (1996);Google Scholar
Yamanaka, S., Enishi, E., Fukuoka, H. and Yasukawa, M., Inorg. Chem. 39, 56 (2000)Google Scholar
10. Eisenmann, B., Schafer, H., and Zagler, R., J. Less-Comm. Metals 118, 43 (1986);Google Scholar
Cordier, G., and Woll, P., J. Less-Comm. Metals 169, 291 (1991)Google Scholar
11. Chu, T. L., Chu, S. S., Ray, R. L., J. Appl. Phys. 53, 7102 (1982);Google Scholar
Shatruk, M. M., Kovnir, K. A., Shevelkov, A. V., Presniakov, I. A., Popovkin, B. A., Inorg. Chem. 38, 3455 (1999)Google Scholar
12. Bobev, S., and Sevov, S. C., J. Am. Chem. Soc. 121, 3795 (1999)Google Scholar
13. Witte, J. and Schnering, H. G., Z. Anorg. Chem. 327, 260 (1964);Google Scholar
Busmann, E., Z. Anorg. Chem. 313, 90 (1961).Google Scholar