Aristotype

From Online Dictionary of Crystallography

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== Definition ==
== Definition ==
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An aristotype is a high-symmetry structure type that can be viewed as an idealized version of a lower-symmetry structure.  It was introduced by Helen Megaw in relation to perovskites, where it is still mostly used. The cubic perovskite structure (which is adopted at most by half a dozen compounds) is regarded as the aristotype for the vast array of other lower-symmetry perovskites.
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An aristotype is a high-symmetry structure type that can be viewed as an idealized version of a lower-symmetry structure.  It was introduced by Helen Megaw in relation to perovskites, where it is still mostly used. The cubic perovskite structure (which is adopted at most by half a dozen compounds) is regarded as the aristotype for the vast array of other lower-symmetry perovskites. The lower-symmetry structure is called '''hettotype'''.
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After Buerger, aristotypes are also known as basic structures and hettotypes as '''derivative structures'''.  
Originally, an aristotype is a printing-out process using paper coated with silver chloride in gelatin; now, any such process using silver salts in either collodion or gelatin; also, a print so made.
Originally, an aristotype is a printing-out process using paper coated with silver chloride in gelatin; now, any such process using silver salts in either collodion or gelatin; also, a print so made.
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== References ==
== References ==
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Megaw H. (1973). ''Crystal Structures'', London: W.B. Saunders,  p. 216, 282
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*Buerger, M.J. (1947). ''Derivative Crystal Structures'', J. Chem. Phys., '''15''', 1-16.
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*Megaw H. (1973). ''Crystal Structures'', London: W.B. Saunders,  p. 216, 282
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[[Category:Fundamental crystallography]]
[[Category:Fundamental crystallography]]

Revision as of 13:31, 14 June 2007

Aristotype (Fr). Aristotipo (It).


Definition

An aristotype is a high-symmetry structure type that can be viewed as an idealized version of a lower-symmetry structure. It was introduced by Helen Megaw in relation to perovskites, where it is still mostly used. The cubic perovskite structure (which is adopted at most by half a dozen compounds) is regarded as the aristotype for the vast array of other lower-symmetry perovskites. The lower-symmetry structure is called hettotype.

After Buerger, aristotypes are also known as basic structures and hettotypes as derivative structures.

Originally, an aristotype is a printing-out process using paper coated with silver chloride in gelatin; now, any such process using silver salts in either collodion or gelatin; also, a print so made.

References

  • Buerger, M.J. (1947). Derivative Crystal Structures, J. Chem. Phys., 15, 1-16.
  • Megaw H. (1973). Crystal Structures, London: W.B. Saunders, p. 216, 282