1990 Fiscal Year Final Research Report Summary
X-Ray Study of Structural Anomalies in 2D Layered Compounds
| Project/Area Number |
01460028
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | University of Tsukuba |
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Principal Investigator |
OHSHIMA Ken-ichi Univ. of Tsukuba, Inst. of Appl. Phys., Asso. Prof., 物理工学系, 助教授 (70109271)
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| Co-Investigator(Kenkyū-buntansha) |
OHBA Takuya Teikyo Univ., Fac. of Sci. & Eng., Asso. Prof., 理工学部, 助教授 (00211110)
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| Project Period (FY) |
1989 – 1990
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| Keywords | X-ray study / 2D layered compound / Structural anomaly / In-plane correlation / Interlayer correlation |
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| Research Abstract |
X-ray measurements have been performed on the development of in-plane and interplanar correlations of intercalated Ag atoms in stage-2 and-1 Ag<@D2X@>D2 TiS<@D22@>D2 single crystls. The abrupt change of the c-axis parameter for stage-2 Ag<@D20.15@>D2 TiS<@D22@>D2 at around 250 K, due to the structural transformation of the stacking sequence, was observed, although the a-axis parameter changes continuously. Rodlike diffuse scattering parallel to c<@D1*@>D1 at <@D71(/)3@>D7<@D71(/)3@>D7.0,<@D72(/)3@>D7<@D72(/)3@>D7.0, and their equivalent positions is observed for stage-2 Ag<@D20.15@>D2 TiS<@D22@>D2 above 250 K and shows the two-dimensional (2D) feature of the disordered state. Such a diffiuse rod is modulated below 250 K, with maxima appearing at every half-integer. This reveals an enhancement of the three-dimensional natture and a stacking sequence alphabetaalphageta... . By analyzing rodlike diffuse scattering at 350, 300, 280, and 250 K for stage-2 Ag<@D20.15@>D2TiS<@D22@>D2, the 2D short-range-order parameters were determined. By comparing the 2D short-range-order parameters with the 2D Ornstein-Zernike correlation function, it was obtained that the correlation length varies from 4.1(] SY.+-.[)0.6 A<@D40@>D4 at 350 K to 37.1(] SY.+-[)1.6 A<@D40@>D4 at 250 K. These results can be interpreted with the use of the Daumas-He<@D4'@>D4rold island model. On the other hand, for stage-1 Ag<@D2X@>D2TiS<@D22@>D2, the modulation of the diffuse rod parallel to the c<@D2*@>D2 axis at <@D71(/)3@>D7<@D71(/)3@>D7.0, <@D72(/)3@>D7<@D72(/)3@>D7.0, and their equivalent positions was observed at room temperature, which shows the 3D nature.
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