1996 Fiscal Year Final Research Report Summary
SYNTHESIS OF AMORPHOUS GeO_2 WITH HIGH DENSITY
| Project/Area Number |
07651022
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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 |
無機工業化学
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| Research Institution | RYUKOKU UNIVERSITY |
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Principal Investigator |
KUME Shoichi RYUKOKU UNIVERSITY,DEPARTMENT OF SCIENCE AND TECHNOLOGY,PROFESSOR, 理工学部, 教授 (00029604)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Keisuke RYUKOKU UNIVERSITY,DEPARTMENT OF SCIENCE AND TECHNOLOGY,PROFESSOR, 理工学部, 教授 (20234817)
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| Project Period (FY) |
1995 – 1996
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| Keywords | pressure-induced amorphization / sol-gel method / germanium oxide / dense amorphous |
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| Research Abstract |
This research aimed the synthesis of amorphous GeO_2 with high density whose local structure mainly consists of octa-hedrally coordinated GeO_6.
In the first experiment, hydroysis of germanium isopropoxide [Ge(OiPr)_4] was undertaken by adding acetylacetone. When the reaction rate was properly cntrolled, it sometimes happened that the syneresis of the solution took place and the solution solidified into transparent gel. A broad halo pattern of X-ray powder diffraction indicated that the sample was in the amorphous state and [Ge(OiPr)_4] was proved as a starting material suitable to prepare gel, although the reproducibility of the reaction was not so excellent.
To obtain reproducible result, the second experiment was attemped. Proper amounts of NH_4OH and H_2O were added into the mixture of [Ge(OiPr)_4] and isopropanol prepared in advance. A few drops of N-N dimethylbenzilamine was dripped to the above-stated mixed solution. When dried, the syneresis occurred and the sample turned to tran
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sparent gel. The halo pattern of the X-ray diffraction of the gel showed the sample in an amorphous state. On heating the gel in air, this state was preserved up to 500ﾟC.The commencement of crystallization to alpha-quartz type was observed on further heating beyond this temperature.
The transparent gel of starting material was sealed in a Ag tube and submitted to high temperature-pressure conditions. Crystallization began above 150ﾟC.The crystallographic structure of the appeared phase depended on the magnitude of compression. When the applied pressure was lower than 200MPa, alpha-quartz type was produced. In the case when the pressures exceeded this, the rutile type crystallized.
In the final experiment, the gel was compressed to 200MPa at RT and then heated at 500ﾟC in air. It was confirmed that the gel crystallized to rutile type phase. This result indicated that the gel compressed beyond 200MPa at RT included GeO_6 octahedra in its local structure. In other words, the high density gel was synthesized without applying very high pressures. Less
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