Difference between revisions of "Incommensurate composite crystal"
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| − | <Font color="blue">Cristal composite</font> (Fr.) | + | <Font color="blue">Cristal composite incommensurable</font> (''Fr''). <Font color="black">Cristallo composito incommensurabile</font> (''It''). <Font color="purple">非整合複合結晶</font> (''Ja''). |
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An ''incommensurate composite crystal'' is a compound with two or more (''N'') subsystems that are | An ''incommensurate composite crystal'' is a compound with two or more (''N'') subsystems that are | ||
Revision as of 05:30, 25 July 2015
Cristal composite incommensurable (Fr). Cristallo composito incommensurabile (It). 非整合複合結晶 (Ja).
An incommensurate composite crystal is a compound with two or more (N) subsystems that are
themselves modulated structures, with basis structures that are mutually incommensurate.
Each subsystem (numbered by ν) has a reciprocal lattice for its basic structure with three basis vectors
[math]a_i^{*\nu}[/math]. There is a basis of the vector module of diffraction spots that has at most
3N basis vectors [math]A_j^*[/math] such that
[math] a_i^{*\nu}~=~\sum_{j=1}^n Z_{ij}^{\nu} A_j^* ~~~(i=1,2,3),[/math]
where [math]Z_{ij}^{\nu}[/math] are integer coefficients. If n is larger than the dimension of space (three), the composite crystal is an aperiodic crystal. n is the rank of the vector module.
Applications
Examples are intergrowth crystals and adsorbed monolayers. To the former belongs Hg3-δAsF6 with two systems of Hg chains inside the host lattice formed by AsF6 octahedra. Another example is nonadecane in the channels of a urea host crystal.