Crystal Structure and Thermal Expansion of Synthetic Fluor-phlogopite

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  • 合成フッ素金雲母の結晶構造と熱膨脹
  • 合成フッ素金雲母の結晶構造と熱膨張
  • ゴウセイ フッソキン ウンモ ノ ケッショウ コウゾウ ト ネツ ボウチョウ

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The thermal expansion (%) of the synthesized fluor-phlogopite crystal of 1 M type was measured by the X-ray powder method, the X-ray single crystal method and the differential dilatometer. The thermal expansion curve was obtained as well as the expansion ellipsoid. There was the breaking point on the thermal expansion curve of the direction parallel to the cleavage plane in any method. The temperature at the breaking point (290℃) on the thermal expansion curve agreed well with that at the breaking point on the (log ρc - 1/T) curve obtained at the perpendicular direction to the cleavage plane. It seemed that thermal expansion had influence on electrical insulation resistance to some extent. The mean thermal expansion coefficient (α) of the 1 M type crystal to an optional direction is expressed in the following equations (1) and (2), α (R.T. -290℃) = (9.6C²₁₃+12C²₂₃+17C²₃₃) × 10⁻⁶ degree⁻¹ (1) α (290℃-940℃) = (4.0C²₁₃+9.9C²₂₃+17C²₃₃) × 10⁻⁶ degree⁻¹ (2) where C₁₃; cosine of optional direction [3] and a axis C₂₃; cosine of optional direction [3] and b axis C₂₃; cosine of optional direction [3] and the direction perpendicular to the cleavage plane (001). The expansion ellipsoid of the 3 T type single crystal is estimated from that of 1 M type as in the following equations (3) and (4). α(R.T. -290℃) = (11C²₁₃+11C²₂₃+17C²₃₃) × 10⁻⁶ degree⁻¹ (3) α (290℃-940℃) = (7.0C²₁₃+7.0C²₂₃+17C²₃₃) ×10⁻⁶ degree⁻¹ (4) Because an optic axial angle is closely related to the way of layer stacking, thermal expansion of crystals both of the large optic axial angle (2V = 14°) and smaller one (2V = 0°) have been measured by the X-ray powder method, the X-ray single crystal method and the differential dilatometer. Discussions based on equations (3) and (4) were made about the results. An interesting relation shown below was observed between the result of the X-ray method and that of the differential dilatometer. (ax+bx)/2≑α The relation between optic axial angle and Laue patterns was also discussed referring the crystal structure of fluor-phlogopite.

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