1989 Fiscal Year Final Research Report Summary
Structure and Phase Transitions in M_3H(XO_4)_2-Type Hydrogen-Bonded Crystals
| Project/Area Number |
63044002
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| Research Category |
Grant-in-Aid for Overseas Scientific Survey.
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Hokkaido University |
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Principal Investigator |
ICHIKAWA Mizuhiko Faculty of Science, Hokkaido University, Instructor, 理学部, 助手 (00000878)
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| Co-Investigator(Kenkyū-buntansha) |
TORBJORN Gus ウプサラ大学, 化学部, 講師
IVAR Olovsso ウプサラ大学, 化学部, 教授
MOTIDA Kiyosi Faculty of Science, Hokkaido University, Instructor, 理学部, 助手 (50001863)
GUSTAFSSON Torbjorn Institute of Chemistry, Uppsala University, Docent
OLOVSSON Ivar Institute of Chemistry, Uppsala University, Professor
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| Project Period (FY) |
1988 – 1989
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| Keywords | Slater model / Trirubidium hydrogen diselenate / Trirubidium deuterium diselenate / Structural phase transition / Lattice constants / (Hydrogen) Isotope effect / Hydrogen-bonded crystals / Crystal-structure analysis |
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| Research Abstract |
1. In view of the investigation of possible phase-transition mechanism in M_3H(XO_4)_2-type crystals, the configuration energy of H_2PO_4-group in Slater model in typical hydrogen(H)-bonded ferrpelectric KH_2PO_4-type crystals has been interpreted microscopically. The correlation between the tansition temperature and O-H(D) distance could be explained semiquantitatively.
2.1) The lattice constants of Rb_3H(SeO_4)_2 has been measured in the temperature range 20K-297K and no anomaly was found, consistent with the dielectric-constant measurement. 2)The lattice constants in Rb_3D(SeO_4)_2 showed no significant change at the transition temperature (92K), but a very slight anomaly was found in some of the 2rheta angles. These results were discussed in the relation to the characteristic of 'O-dimensional' H-bond network in M_3H(XO_4)_2-type crystals. 3) X-ray crystal-structure analysis of Rb_3H(SeO_4)_2 and Rb_3D(SeO_4)_2 have been done at 25, 110 and 297K. It has been shown that the phase transition in Rb_3D(SeO_4)_2 is such that the heavy-atom structure in the low-temperature phase is almost the same as that in the high-temperature phase, but the hydrogen-bond system and the structural part directly related with it change slightly owing to the ordering of the proton.
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