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Letters to Nature
Nature 348, 317 - 319 (22 November 1990); doi:10.1038/348317a0

Geometric effects of deuteration on hydrogen-ordering phase transitions

M. I. McMahon*, R. J. Nelmes*, W. F. Kuhst, R. Dorwarth, R. O. Piltz* & Z. Tun*

*Physics Department, University of Edinburgh, Edinburgh EH9 3JZ, UK
Institut für Kristallographie, Universität (TH) Karlsruhe, Postfach 6980, 7500 Karlsruhe 1, Germany
Present address: Physics Division, Chalk River Nuclear Laboratories, Chalk River, Ontario, Canada, KOJ 1JO.

IT has long been known that the substitution of deuterium for hydrogen in hydrogen-bonded materials can lead to a change in the geometry of the hydrogen bonds—the so-called Ubbelohde effect1. There can also be significant accompanying changes in the physical properties of the material. Among the most striking examples is the increase in the transition temperature, T c, of hydrogen-ordering systems of the KH2PO4 type by >100K on full deuteration. In all of these systems, T c decreases under pressure, making it possible in principle to compare protonated and deuterated forms at the same T c by applying pressure to the latter. Here we report the results of a high-pressure neutron diffraction study of the deuterated H(D)-ordering material PbDPO4. We find that much, and possibly all, of the increase in T c on deuteration is attributable to the accompanying changes in the hydrogen-bond dimensions. This suggests that purely mass-dependent effects on the quantum-mechanical tunnelling between the equivalent H(D) potential minima—an explanation that has been favoured previously—have little or no direct influence on T c. Substantial revisions to the theory of this type of ordering transition are apparently required.

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References

1. Robertson, J. M. & Ubbelohde, A. R. Proc. R. Soc. A170, 222−240 (1939).
2. Blinc, R. J. Phys. Chem. Solids 13, 204−211 (1960). | ChemPort |
3. Tokunaga, M. & Matsubara, T. Ferroelectrics 72, 175−191 (1987). | ChemPort |
4. Tun, Z., Nelmes, R. J., Kuhs, W. F. & Stansfield, R. F. D. J. Phys. C21, 245−258 (1988). | ChemPort |
5. Tibballs, J. E., Nelmes, R. J. & Mclntyre, G. J. J. Phys. C15, 37−58 (1982). | ChemPort |
6. Tibballs, J. E. & Nelmes, R. J. J. Phys. C15, 849−853 (1982).
7. Samara, G. A. Ferroelectrics 71, 161−182 (1987). | ChemPort |
8. Silsbee, H. B., Uehling, E. A. & Schmidt, V. H. Phys. Rev. A133, 165−170 (1964). | Article | ChemPort |
9. Ichikawa, M., Motida, K. & Yamada, N., Phys. Rev. B36, 874−876 (1987). | ChemPort |
10. Samara, G. A. & Semmingsen, D. J. chem. Phys. 71, 1401−1407 (1979). | Article | ChemPort |
11. Nelmes, R. J. J. Phys. C21, L881−L886 (1988). | ChemPort |
12. Katrusiak, A. & Nelmes, R. J. J. Phys. C19, L765−L772 (1986). | ChemPort |
13. Negran, T. J. et al. Ferroelectrics 6, 179−182 (1974). | ChemPort |
14. Mylov, V. P., Shirokov, A. M., Shuvalov, L. A., Kharitonov, V. N. & Brzhezina, B. Soviet Phys. Crystallogr. 24, 738−739 (1979).
15. Kuhs, W. F., Ahsbahs, H., Londono, D. & Finney, J. L. Physica B156/157, 684−687 (1989).
16. Zucker, U. H., Perenthaler, E., Kuhs, W. F., Bachmann, R. & Schulz, H., J. appl. Cryst. 16, 358 (1983). | Article | ChemPort |
17. Piltz, R. O., McMahon, M. I. & Nelmes, R. J. Ferroelectrics 108, 271−276 (1990). | ChemPort |
18. Lawrence, M. C. & Robertson, G. N. J. Phys. C13, 1053−1059 (1980).
19. Matsubara, T. & Matsushita, E. Prog. theor. Phys. 71, 209−11 (1984). | ChemPort |
20. McMahon, M. I., Piltz, R. O. & Nelmes, R. J. Ferroelectrics 108, 277−282 (1990). | ChemPort |
21. Kojyo, N. & Onodera, Y. J. phys. Soc. Japan 57, 4391−4402 (1988). | ChemPort |
22. Lockwood, D. J., Ohno, N., Nelmes, R. J. & Arend, H., J. Phys. C18, L559−L565 (1985). | ChemPort |
23. Motida, K. & Ichikawa, M. J. phys. Soc. Japan 58, 2810−2816 (1989). | ChemPort |



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