منابع مشابه
Crystal Engineering Studies: polymorphs and co-crystals
We review the key topics of one of the areas with the biggest impact of the last years in the chemical and pharmaceutical industry that is Crystal Engineering. The relevance of polymorphs and co-crystals from different points of view is been highlighted and broadly illustrated by means of several recent examples of studies carried out in this field. In addition, the most suitable instrumental t...
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X線 回折 法 に よる結 晶構 造 解 析 は,大 き さ0 .1 ~1mmの 単 結 晶 が あ れ ば ,原 子 の三 次 元 配 列 を 決 定 す る こ とが で き,原 子 間 距 離,結 合 角,配 位 数 な どの化 学 結 合 に 関 す る知 識 が 直 接 得 られ る非 常 に 優 れ た 方法 で あ る。 結 晶構 造 を決 定 す る過 程 は,次 の二 つ の段 階 に分 け られ る。 第1は ,単 結 晶 を 選 んで ワイ セ ンベ ル グ写 真 法 な どに よ って 晶 系,格 子 定 数,空 間 群 を 決 め,比 重 測 定 に よ って 単 位 格 子 内 の 化 学 単 位 数 を 決 定 す る過程 で あ る。 第2は,単 結 晶 のX線 回 折 強 度 か ら各原 子 の座 標 を 決 定 す る過 程 で あ る。 こ の過...
متن کاملCrystal Chemistry of Boehmite
-Thirty two boehmites, synthesized at temperatures ranging from room temperature to 300~ were examined by scanning electron microscopy, transmission electron microscopy, electron diffraction, X-ray powder diffraction, differential thermal analysis, and infrared spectroscopy. The results show that boehmite exhibits a continuous gradation in crystallite size ranging from single octahedral layers ...
متن کاملUsing magnetic levitation to separate mixtures of crystal polymorphs.
The crystallization of an organic compound can produce a mixture of crystalline solids with different solid-state structures (polymorphs). No convenient method now exists to separate crystals of a single polymorph from a mixture of crystals of different polymorphs. Of the physical properties that might be used to separate polymorphs, density is attractive for two reasons: 1) Different packings ...
متن کاملCrystal Polymorphs of Barbital: News about a Classic Polymorphic System
Barbital is a hypnotic agent that has been intensely studied for many decades. The aim of this work was to establish a clear and comprehensible picture of its polymorphic system. Four of the six known solid forms of barbital (denoted I(0), III, IV, and V) were characterized by various analytical techniques, and the thermodynamic relationships between the polymorph phases were established. The o...
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ژورنال
عنوان ژورنال: Journal of the Mineralogical Society of Japan
سال: 1980
ISSN: 1883-7018,0454-1146
DOI: 10.2465/gkk1952.14.special3_158