Crystallography

A general term for the academic field that studies crystals. Historically, it began with research into the optical properties of crystals, and in the 19th century, research progressed into group theoretical treatment, which mathematically discusses the geometric characteristics that appear in the external appearance of crystals, and into the classification of crystal forms based on symmetry. In the 20th century, with the development of crystal structure analysis methods using X-ray diffraction and the elucidation of the atomic arrangement within crystals, the physical and chemical properties of crystals began to be studied microscopically in relation to the properties of atoms and molecules. In terms of applications, research and development is being conducted into the relationship between the properties of bulk materials such as metals and polymer materials and their crystal structures, and the relationship between the functions of micro-materials such as semiconductors and their crystal structures.

Crystallography that focuses on the diffraction phenomenon of X-rays and the like is called X-ray crystallography, but there are also other fields such as crystal physics, which studies the mechanical, electrical, magnetic, and optical properties of crystals, crystal chemistry or chemical crystallography, which deals with the chemical bonds, chemical composition, and the arrangement and mobility of atoms and molecules within crystals, and crystal growth theory, which deals with the dynamics of crystal growth. However, it is difficult to completely distinguish between these, and crystallography can be said to be located on the border between physics, chemistry, mineralogy, biology, etc.

[Iwamoto Shinbu]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

結晶を研究対象とする学問分野の総称。歴史的には結晶の光学的性質の研究から始まり、19世紀に至って、結晶外形に現れる幾何学的特徴を数学的に論ずる群論的取扱いと、対称に基づく結晶形態の分類の研究が進められた。20世紀に入り、X線回折を利用する結晶構造解析法が創始され、結晶内の原子配列が解明されるようになると、結晶の物理的・化学的性質が原子・分子の性質と関連して微視的に研究され始めた。応用面では、金属材料、高分子材料のようなバルク材料の性質と結晶構造との関係、半導体のようなミクロ材料の機能と結晶構造との関係などが研究開発されている。

　X線などの回折現象に重点を置く結晶学はとくにX線結晶学とよばれるが、結晶の機械的、電気的、磁気的、光学的性質などを研究する結晶物理学、結晶内での化学結合、化学組成、原子や分子の配列と運動性を扱う結晶化学あるいは化学結晶学、また、結晶の成長を動的に扱う結晶成長論などの分野もある。しかし、これらを完全に区別することは困難であり、結晶学は物理学、化学、鉱物学、生物学などの境界に位置するものといえる。

［岩本振武］

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