Allotwinning: oriented crystal association of polytypes – some warnings on consequences
Abstract
The oriented association of two or more polytypes of the same compound enters neither in the Friedel's definition of twinning nor in that of epitaxy/syntaxy; for it the term allotwinning is here introduced and the relevant laws of formation are established. The appearance of allotwins is in principle recognizable from the diffraction pattern, but allotwins involving polytypes with the same number of layers and the same lattice symmetry may produce complete overlap of the lattice nodes of the individuals, i.e. as in case of twinning by merohedry. Differently from that case, however, the observed intensities are the sum of non-equivalent diffractions. This characteristic, if not recognized, may in principle lead to mistake the allotwin for a single crystal and possibly to find a reasonable, but wrong, stacking sequence.
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Articles in the same Issue
- Uniqueness of rotationally invariant polyhedra classification
- Allotwinning: oriented crystal association of polytypes – some warnings on consequences
- Orientational disorder at growing surfaces of molecular crystals: general comments on polarity formation and on secondary defects
- Complex surface structures studied by low-energy electron diffraction
- The crystal structures of synthetic KSb5S8 and (Tl0.598, K0.402)Sb5S8 and their relation to parapierrotite (TlSb5S8)
- 8,11-Diaza[4.3.3]propell-6-enium Oxalate 2.5 hydrate
- Crystal structure of aquabis(dimethylglyoximato)nitrocobalt(III) based on neutron diffraction data
Articles in the same Issue
- Uniqueness of rotationally invariant polyhedra classification
- Allotwinning: oriented crystal association of polytypes – some warnings on consequences
- Orientational disorder at growing surfaces of molecular crystals: general comments on polarity formation and on secondary defects
- Complex surface structures studied by low-energy electron diffraction
- The crystal structures of synthetic KSb5S8 and (Tl0.598, K0.402)Sb5S8 and their relation to parapierrotite (TlSb5S8)
- 8,11-Diaza[4.3.3]propell-6-enium Oxalate 2.5 hydrate
- Crystal structure of aquabis(dimethylglyoximato)nitrocobalt(III) based on neutron diffraction data
