Twin-Domain Formation in Epitaxial Triangular Lattice Delafossites

Elastic Analysis of Twinning in Misfitting Thin Films

MRS Proceedings ◽

10.1557/proc-389-149 ◽

1995 ◽

Vol 389 ◽

Author(s):

N. Sridhar ◽

J.M. Rickman ◽

D.J. SroIovitz

Keyword(s):

Thin Film ◽

Thin Films ◽

Film Thickness ◽

Misfit Strain ◽

Elastic Analysis ◽

Domain Formation ◽

Linear Elasticity Theory ◽

Periodic Distribution ◽

Twin Domain ◽

Strain Tensors

ABSTRACTWe examine the conditions under which a misfitting thin film on a substrate will twin and the pattern of the twin microstructure that will form. Using linear elasticity theory, we present exact analytical results for the energy released due to the formation of a periodic array of twinned domains as well as that for a single embedded twin domain. While the analysis is applicable to general misfit strain tensors, we specifically analyze the energetics of twinned domain formation for a tetragonal film on a cubic substrate. The analysis shows that for a periodic distribution of twins, the equilibrium width of the domains of the two variants are identical. Our results also show that the equilibrium periodicity of the microstructure scales inversely with film thickness for large film thickness and decays exponentially with increasing film thickness for small film thicknesses.

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Overcoming merohedral twinning in crystals of bacteriorhodopsin grown in lipidic mesophase

Acta Crystallographica Section D Biological Crystallography ◽

10.1107/s0907444909042838 ◽

2009 ◽

Vol 66 (1) ◽

pp. 26-32 ◽

Cited By ~ 11

Author(s):

Valentin Borshchevskiy ◽

Rouslan Efremov ◽

Ekaterina Moiseeva ◽

Georg Büldt ◽

Valentin Gordeliy

Keyword(s):

Crystal Growth ◽

Membrane Protein ◽

Slow Growth ◽

Protein Crystals ◽

Domain Formation ◽

Ratio Distribution ◽

Model Calculations ◽

Growth Defects ◽

Twin Domain ◽

Crystallization Conditions

Twinning is one of the most common crystal-growth defects in protein crystallography. There are neither efficient rational approaches for the growth of nontwinned protein crystals nor are there examples of systematic studies of the dependence of the twinning-ratio distribution on crystallization conditions. The description of the twinning phenomenon has been covered even less for membrane-protein crystals and is non-existent for crystals grown using lipidic phases (in meso). In the present work, possibilities for overcoming merohedral twinning are investigated for crystals of the membrane protein bacteriorhodopsin (bR) grownin meso. It is shown that traditional crystallization additives are not effective in the case of thein mesocrystallization of bR. The twinning ratio was determined for 310 crystals grown under different crystallization conditions. A correlation of the twinning ratio with the growth rate of the crystals was observed. Slow growth indicated that crystals had a noticeable chance of avoiding twinning. Model calculations were performed in order to rationalize this observation. The calculations confirmed the experimental observation that most crystals consist of two twin domains and showed that under this condition small changes in the probability of twin-domain formation lead to dramatic changes in the number of nontwinned crystals, which explains why slow crystal growth results in a considerable number of nontwinned crystals.

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Domain Formation in Synthetic Quartz

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064839 ◽

1971 ◽

Vol 29 ◽

pp. 156-157

Author(s):

Joseph J. Comer

Keyword(s):

Electron Beam ◽

Room Temperature ◽

Domain Formation ◽

Synthetic Quartz ◽

Transmission Electron ◽

Black Spots ◽

Diffraction Mode ◽

Domain Boundaries ◽

Kikuchi Lines ◽

Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

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