Hostname: page-component-78c5997874-ndw9j Total loading time: 0 Render date: 2024-11-09T03:35:48.218Z Has data issue: false hasContentIssue false
  • English
  • Français

Semiconducting Molybdenum Pyrochlores for high Temperature Applications

Published online by Cambridge University Press:  10 February 2011

V. Ponnambalam  and
U. V. Varadaraju
V. Ponnambalam
Affiliation:
Materials Science Research Centre, Indian Institute of Technology Madras 600 036. INDIA.
U. V. Varadaraju
Affiliation:
Materials Science Research Centre, Indian Institute of Technology Madras 600 036. INDIA.
Get access

Abstract

The solid solutions (Y1-xYbx)2Mo2O7 were prepared and the systematic changes in the electrical resistivity (ρ=l/σ), thermopower (S) and power factor (S2σ) have been studied in the temperature range 300–900 K. The lattice parameters ‘a’ and ‘c’ are smaller for higher Yb3+ content phases due to smaller Yb3+ radius and a small tetragonality is observed for all the phases. Semiconducting behaviour is seen for all compositions with systematic increase in activation energy with increasing Yb content. All compositions show negative thermopower indicating electrons are the majority charge carriers in the temperature range of measurements. The calculated power factor values S2σ increase with increasing temperature in the low temperature region and a maximum power factor of ∼0.76×10−7 Wcm−1K−2 is observed at 650K.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 512: Symposium F – Wide Bandgap Semiconductors for High Power, High Frequency , 1998 , 249
Copyright
Copyright © Materials Research Society 1998

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. Sato, Mineo, Yan, Xu and Greedan, J.E., Z. anorg. allg. Chem., 540/541, 177 (1986); J.E. Greedan, M. Sato, Xu Yan, F.S. Razavi, Solid State. Commun., 59, 895 (1986); N.P. Raju, E. Gmelin, and R.K. Kremer, Phy. Rev. B, 46, 5405 (1992).Google Scholar
2. Ali, Naushad, Hfill, N.P., Lambo, Sunil, Greedan, J.E., I. Solid State Chem. 83, 178 (1989).Google Scholar
3. Greedan, J.E., Sato, M., Ali, Naushad and Datars, W.R.. I. Solid State Chem., 68, 300 (1987); N.P. Raju and G. Rangarajan, J. Phy.: Condens. Matter 2, 3539 (1990); N. Gao, T. Timusk, N.P. Raju, J.E. Greedan, P.Gougeon, I. Phy.: Condens. Matter, 7, 2489 (1995).Google Scholar
4. Subramanian, M.A., Aravamudan, G. and Rao, G.V. Subba, Met. Res. Bull., 15, 1401 (1980).Google Scholar
5. Subramanian, M.A.. Aravamudan, G., and Rao, G.V. Subba, Progress in Solid state Chem. 15, 55 (1983); M.A. Subramanian and A.W. Sleight, “Hand Book on the Physics and Chemistry of Rare Earths” Chapter 107, 16, Elsevier Science Publishers B.V, 1993.Google Scholar
6. Chanara, K., Ohno, Y., Kasai, M., and Kozono, Y., Appl.Phy. Lett, 63, 1990 (1993); R.Mahendiran, A.K. Raychaudhuri, A. Chainani and D.D. Sharma, Appl. Phy. Lett., 66, 233 (1995); R.Mahendiran, RMahesh, A.K. Raychaudhuri and C.N.R. Rao, J. Phy. D: Appl.Phys. 28, 1743 (1995).Google Scholar
7. Ranganathan, , Rangarajan, G., Srinivasan, R., Subramanian, M.A. and Rao, G.V. Subba, J. Low Temp. Phys., 52, 481 (1983).Google Scholar
8. Rao, V. Vasudeva, Rangarajan, G., and Srinivasan, R, J. Phys. Chem. Solids, 47, 395 (1986).Google Scholar