Search results for "Crystal twinning"
showing 6 items of 16 documents
Crystal Inclusions in Diamonds and Other Crystals
2013
Single crystal inclusions in natural single crystals bear a lot of information on the genesis and phase stabilities between host and guest crystals. Not only parameters of the natural environment of crystallization may be elucidated, also the history of up-rise within the earth to the surface and the development during procedures, eventually applied by mankind to enhance the physical properties of crystals, may be detectable. Structural reactions resulting in phase separation due to chemical stress during change of physical parameters shed light on the borders of solid solution and exsolution domains. Natural crystals of proper quality allow us to evaluate a time factor in phase stabilities…
Micro-structure evolution of wall based crystals after casting of model suspensions as obtained from Bragg microscopy.
2012
Growth of heterogeneously nucleated, wall based crystals plays a major role in determining the micro-structure during melt casting. This issue is here addressed using a model system of charged colloidal spheres in deionized aqueous suspension observed by Bragg microscopy which is a combination of light scattering and microscopy. We examine the evolution of the three-dimensional size, shape, and orientation of twin domains in monolithic crystals growing from two opposing planar walls into a meta-stable (shear-) melt. At each wall crystal orientation and twinning emerges during nucleation with small domains. During growth these widen and merge. From image analysis we observe the lateral coars…
Structural factor in bending testing of fivefold twinned nanowires revealed by finite element analysis
2016
In this study, we performed finite element method simulations to investigate the effect of the structure on the elastic response of Ag and Au nanowires (NWs) with a fivefold twinned crystal structure in bending tests. Two different models of a pentagonal NW were created: a 'uniform model' having an isotropic continuous structure and a 'segmented model' consisting of five anisotropic domains. Two asymmetrical mechanical test configurations were simulated: cantilevered beam bending and 3-point bending. The dimensions of the NW, the test configurations, as well as the force and the displacement ranges were based on the previously obtained experimental data. The results of the simulations demon…
Twin coarsening in CdTe(111) films grown on GaAs(100)
2006
Abstract We present a scanning force microscopy study of twin coarsening in CdTe(1 1 1) films grown on GaAs(1 0 0). Two types of CdTe(1 1 1) twins grow epitaxially and with equal probability on the long-range wavy surface structure developed by previous in situ annealing of the GaAs(1 0 0) substrate. Due to this initial substrate wavy structure, the grain coarsening during film growth leads to a quasi-one-dimensional rippled pattern. We propose a coarsening mechanism between twins driven by the formation of stacking faults.
Experimentally Induced Twinning in Plants
1955
IT is well known that characteristic changes in leaf-form and growth habit can be induced by treating shoot apices with synthetic growth substances. The question arises as to whether entire plant embryos also can be induced to develop abnormally by the action of growth regulators. For this purpose the solutions must be applied in a suitable manner to the earliest embryo stages through the growing carpel walls, or it would be necessary to remove the still quite small embryos and to expose them in vitro to the proper influences. Both methods are difficult to apply and have as yet proved unsatisfactory.
Automated electron diffraction tomography – development and applications
2019
Electron diffraction tomography, a potential method for structure analysis of nanocrystals, and, in more detail, the strategies to use automated diffraction tomography (ADT) technique are described. Examples of ADT application are discussed according to the material class.