1998 Fiscal Year Final Research Report Summary
Analysis of Structural Transition Phenomena in Amorphous Functional Materials
| Project/Area Number |
09640595
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Chiba University |
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Principal Investigator |
IWADATE Yasuhiko Chiba Univ., Materials Technology, Associate Professor, 工学部, 助教授 (80168583)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIYAMA Shin Chiba Univ., Materials Technology, Research Associate, 工学部, 助手 (90241942)
HATTORI Takeo Chiba Univ., Materials Technology, Professor, 工学部, 教授 (80009539)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Glass / Melt / X-ray diffraction / Radial distribution / Borate / Tellurite / Network structure / Complex ion |
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| Research Abstract |
X-ray diffraction analyses were performed for two B_2O_3-CaO and TeO_2-Li_2O glassy systems and two Na_3ErCl_6 and K_3ErCl_6 ionic melts. The samples of glasses and melts were prepared by rapidly quenching of the starting chemicals. The scattered intensity data were corrected in a conventional manner for background, polarization, absorption and Compton scattering, normalized to the coherent scattering intensity of the stoichiometric unit, and Fourier-transformed to obtain radial distribution functions, from which structural information was extracted. Most probable structural parameters such as coordination number. interatomic distance, and temperature factor were optimized for each atomic pair by the correlation method in the reciprocal lattice space as well as the radial distribution analysis in the real space in order to clarify the effects of oxide modifiers or alkali chlorides on the structure of glasses or melts.
The obtained results were as follows, (1) network structure consisting of boroxol rings was formed in B_2O_3 glass, (2) 4-coordinated borons transformed from 3-coordinated ones existed in B_2O_3-CaO glasses, (3) distortion of boroxol rings and decrease in symmetricity of rings were observed, (4) Ca_<2-> ions in B_2O_3-CaO glasses entered the octahedral cavity composed of six oxygen atoms, (5) network-forming units in TeO_2-Li_2O glasses were trigonal bipyramids TeO_4 and trigonal pyramids TeO_3 in which the former was thought to be transformed, via the transient species of polyhedra with non-bridging oxygens, into the latter with increasing Li_2O contents, (6) there were clustered complex ions in molten pure ErCl_<3+>, but the existence of discrete octahedral complex ions ErCl_6^<3->, due to cluster decomposition, was recognized in Na_3ErCl_6 and K_3ErCl_6 melts according to the geometrical calculations of bond lengths and bond angles.
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