OD character and twinning – Selective merohedry in class II merohedric twins of OD polytypes
Abstract
In twinning by merohedry, the twin operations belong to the crystal lattice point group. When twinning concerns an OD structure, i.e. a polytype in which layer pairs are geometrically equivalent, the definition of merohedry should take into account not only the point group of the crystal and that of the lattice, but also the point group of the family structure. If the latter is a subgroup of the point group of the twin, some of the twin laws restore only a part of the reciprocal lattice nodes corresponding to the family reflections (the reflections common to all the OD structures of a family). For this kind of twinning the definition of selective merohedry is introduced: it can occur when the Laue point group of the crystal is lower than the twin point group, i.e. in the so-called “class II twins”. Detection of selective merohedry from the diffraction pattern is discussed.
© 2015 Oldenbourg Wissenschaftsverlag GmbH, Rosenheimer Str. 145, 81671 München
Articles in the same Issue
- Structure analysis of thiouracil on Ag(111) and graphite (0001) by x-ray diffraction and scanning tunneling microscopy
- OD character and twinning – Selective merohedry in class II merohedric twins of OD polytypes
- Trihalogenochalcogenonium-halogenometallates [EX3][MXn] – Synthesis and crystal structures of [TeX3][MX6] (X=Cl, Br; M=W, Nb, Ta) and a suggestion for a structure designation code for the various structure types in this family of compounds
- Structural aspects of spin-chain and spin-ladder oxides
- Restoration of the missing cone in protein electron crystallography by direct methods: bacteriorhodopsin
- Structural properties of garnets under pressure: An ab initio study
- An investigation of microporous cetineite-type phases A6[B12O8][CX3]2[Dx(H2O,OH,O)6−y]
- Crystal structure, phase transitions, anomalous thermal and elastic properties of bis (butylammonium) zirconium bis(nitrilotriacetate) dihydrate and bis(butylammonium) hafnium bis(nitrilotriacetate) dihydrate, [NH3(CH2)3CH3]2X[N(CH2COO)3]2 · 2 H2O, (X=Zr, Hf)
- High-temperature phase transitions of gallium orthophosphate (GaPO4)
- Crystal and molecular structure of 2,6-dimethyl-3,5-di[N-methyl]carbamoyl-4-[3,4-methoxy]phenyl-l,4-dihydropyridine hemihydrate and 2,6-dimethyl-3,5-di[N-methyl]carbamoyl-4-[furan]1,4-dihydropyridine
- Crystal and molecular structure of N-(p-chlorobenzylidene)-3-chloro-4-fluoroaniline
Articles in the same Issue
- Structure analysis of thiouracil on Ag(111) and graphite (0001) by x-ray diffraction and scanning tunneling microscopy
- OD character and twinning – Selective merohedry in class II merohedric twins of OD polytypes
- Trihalogenochalcogenonium-halogenometallates [EX3][MXn] – Synthesis and crystal structures of [TeX3][MX6] (X=Cl, Br; M=W, Nb, Ta) and a suggestion for a structure designation code for the various structure types in this family of compounds
- Structural aspects of spin-chain and spin-ladder oxides
- Restoration of the missing cone in protein electron crystallography by direct methods: bacteriorhodopsin
- Structural properties of garnets under pressure: An ab initio study
- An investigation of microporous cetineite-type phases A6[B12O8][CX3]2[Dx(H2O,OH,O)6−y]
- Crystal structure, phase transitions, anomalous thermal and elastic properties of bis (butylammonium) zirconium bis(nitrilotriacetate) dihydrate and bis(butylammonium) hafnium bis(nitrilotriacetate) dihydrate, [NH3(CH2)3CH3]2X[N(CH2COO)3]2 · 2 H2O, (X=Zr, Hf)
- High-temperature phase transitions of gallium orthophosphate (GaPO4)
- Crystal and molecular structure of 2,6-dimethyl-3,5-di[N-methyl]carbamoyl-4-[3,4-methoxy]phenyl-l,4-dihydropyridine hemihydrate and 2,6-dimethyl-3,5-di[N-methyl]carbamoyl-4-[furan]1,4-dihydropyridine
- Crystal and molecular structure of N-(p-chlorobenzylidene)-3-chloro-4-fluoroaniline
