2006 Fiscal Year Final Research Report Summary
Local Structure of Alkaline-Earth Borate Glasses: The Study of Unique Glass Formation Physical Properties
| Project/Area Number |
16560599
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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 |
Inorganic materials/Physical properties
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| Research Institution | Japan Synchrotron Radiation Research Institute |
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Principal Investigator |
UMESAKI Norimasa Japan Synchrotron Radiation Research Institute, Industrial Application Division, Chief Scientist, 産業利用推進室, 主席研究員 (70127190)
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| Co-Investigator(Kenkyū-buntansha) |
OHTORI Norikazu Niigata University, Graduate School of Science and Technology, Associated Professor, 大学院自然科学研究科, 助教授 (20272859)
HANDA Katsumi Ritsumeikan University, Synchrotron Radiation Center, Research Staff, SRセンター, 契約職員(専門職) (70411246)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Alkaline-Earth Borate Glasses / Glass Formation / Glass Structure / Molecular Dynamics / Neutron Diffraction / XAFS |
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| Research Abstract |
Neutron diffraction (ND) measurements and molecular dynamics (MD) calculations have been carried out for xRO.(1-x)B_2O_3 glasses with high content RO : Mg, Ca, Sr and Ba : 0.4【less than or equal】x【less than or equal】0.55, complementing the previous results, in order to discuss for the whole glass-forming range of alkaline-earth borate glasses. The experimental structure functions were in good agreement with those from the MD calculation using fully ionic interaction model. Being focused on the nearest B-O correlation, the experimental radial distribution functions and simulated pair distribution functions were analyzed mainly for the purpose of examining the constitutional units in the glasses. The behavior of the positional and asymmetry of peak corresponding to the B-O correlation in these functions shows the presence of well-defined BO_3 triangle and of BO_4 tetrahedral units. It was found that both the experimental and simulated fraction of BO_4 unit, N_4, showed the same dependenc
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e on RO content and the kind of cation up to x=0.33. Regarding the behavior of N_4, the ND results agreed with the IR results for the whole glass-forming range. The simulation results showed that, with increasing RO, the fraction of BO_3 with non-bridging oxygen increases. The Mg-O correlation was analyzed in the real space, which gave the coordination number of oxygen around Mg approximately four for ND and somewhat larger than four for MD. Taking in ionic radii into account, the ND results suggest the Mg-O correlation has somewhat ill-defined coordination shell.
Barium borate xBaO-(1-x)B_2O_3 and lithium borate xLi_2O-(1-x)B_2O_3 glasses were investigated by X-ray absorption spectroscopy at the boron K-edge and barium Lm-edge. This is the first XAS work at the K-edge of boron in lithium borate and barium borate glasses. A resonant peak at the B K-edge was observed at around 194.6eV ; its intensity and area decrease with increasing the amount of four-coordinated B changed by increasing the modifier oxide content and reach their minima at 45mo1%BaO and 40mol%Li2O. Ba Idiredge were also observed. With increasing BaO content in barium borate glasses, the local structure around Ba changes from a single structure of six-coordinated O atoms at a Ba-O interatomic distance of 2.77Å to a two-shell 2.67 and 2.90Å and coordination number four and 3-4, respectively. Less
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Research Products
(12 results)
