| Project/Area Number |
09650725
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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 | Tohoku University |
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Principal Investigator |
ONO Yasuhiro Tohoku University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (30211832)
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| Co-Investigator(Kenkyū-buntansha) |
KAJITANI Tsuyoshi Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (80134039)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | non-linear optical crystal / second harmonic generation / borate group / colquiriite / UV-laser / phase matching / reflactive index / structure determination / SHG / 自己逓倍レーザー / 強誘電体 / スティルウェライト / 単結晶育成 |
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| Research Abstract |
We have first determined absolute structures of new non-linear optic crystals, LiKB_4O_7 and LiRbB_4O_7, by means of single crystal X-ray diffraction. These crystals with space group P2 _12_12_1(No.19) are isomorphous. Rietveld analysis of powder neutron diffraction data also supports these resolved crystal structures. The framework consists of (B_3O_8)^<7-> chains parallel to [100] direction which are interconnected by (B_5O_<10>)^<5-> groups. According to the anionic group theory by Chen et al., both borate groups are highly active for non-linear optic effects such as second harmonic generation (SHG). Refractive index mesurements indicated that non-critical phase-matching for SHG can be realized for incident light propagating parallel to each crystallographic axis.
New UV-laser crystals, Ce^<3+> : LiCaAlF_6, Ce^<3+> : LiSrAlF_6, Ce^<3+> : LiSrGaF_6, have been also studied by means of single crystal X-ray diffraction and optical measurements. The Ce^<3+> dopant substitutes for divalent cations, Ca^<2+> or Sr^<2+>, at an octahedral site. We found a correlation between 5d-4f transition energy of Ce^<3+> and the distortion of MF_6 octahedra, where M represents divalent cations, Ca^<2+> or Sr^<2+>. The distortion in octahedral crystal-field at the Ce^<3+> site is responsible for the 5d-4f transition energy.
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