Stacking Faults and Twinning in Homoepitaxial Thin Films on Ir(111)

The growth and annealing behavior of thin Iridium films on the Ir(111) surface was studied with respect to stacking fault and twin formation by means of scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and surface X-ray diffraction (SXRD). It was found that by heterogeneous nucleation of new faults at phase boundaries between areas of regular and faulted stacking, initial faulted areas spread into their surrounding (proliferation effect). In the process, the phase boundary is stabilized and evolves to a persistent fault structure, and a transition from layer-by-layer growth to a defect dominated growth with a fixed length scale takes place. During this transition, the majority of the surface area becomes twinned. A step-influenced enhancement of the stacking fault probability initially supports the effect. By the supply of additional energy in the order of 50 eV per deposited atom using ion beam assisted deposition (IBAD), stacking fault and twin formation can be effectively lifted. Various strategies of IBAD have been tested. The strongly twinned Ir/Ir(111) films exhibit a high stability against thermal annealing. Annealing is found to take place in a two step process: At 800 K-1000 K the boundaries between areas of different stacking are diminished. Only beyond 1200 K also the twins themselve heal. Structure models of the boundaries involved are presented. The boundaries between different stacking areas are identified to consist of {111}/{115} boundaries dissociated into coherent {111}/{111} and {112}/{552} boundaries. The influence of adsorbates on the growth of Ir/Ir(111) was studied for CO and O. It was found that exposure of the sample to CO or O during deposition prevents coalescence, leads to columnar growth and multiple twinning. For both adsorbates, the island number density is increased, indicating a reduced mobility on the surface

Twins and their boundaries during homoepitaxy on Ir(111)

The growth and annealing behavior of strongly twinned homoepitaxial films on Ir(111) has been investigated by scanning tunneling microscopy, low energy electron diffraction and surface X-ray diffraction. In situ surface X-ray diffraction during and after film growth turned out to be an efficient tool for the determination of twin fractions in multilayer films and to uncover the nature of side twin boundaries. The annealing of the twin structures is shown to take place in a two step process, reducing first the length of the boundaries between differently stacked areas and only then the twins themselves. A model for the structure of the side twin boundaries is proposed which is consistent with both the scanning tunneling microscopy and surface X-ray diffraction data.Comment: 13 pages, 11 figure

Two Dimensional Ir-Cluster Lattices on Moir\'e of Graphene with Ir(111)

Lattices of Ir clusters have been grown by vapor phase deposition on graphene moir\'{e}s on Ir(111). The clusters are highly ordered, spatially and thermally stable below 500K. Their narrow size distribution is tunable from 4 to about 130 atoms. A model for cluster binding to the graphene is presented based on scanning tunneling microscopy and density functional theory. The proposed binding mechanism suggests that similar cluster lattices might be grown of materials other than Ir.Comment: Submitted to PRL on 27Apr0

Исследование состава донных отложений реки Кисловки в составе инженерно-экологических изысканий на территории перспективной застройки (Томский район)

На изменение состояния и развития природно-антропогенных водных объектов оказывают влияние различные факторы. Данная работа направлена на выявление пространственных изменений и факторов формирования эколого-геохимического состояния донных отложений р. Кисловки. В работе исследованы донные отложения и речные воды р. Кисловки. На основе аналитических исследований были построены диаграммы пространственного распределения химических элементов и выявлены закономерности их изменения.Changes in the state and development of natural-anthropogenic water bodies are influenced by various factors. This work is aimed at identifying spatial changes and factors in the formation of the ecological and geochemical state of bottom sediments of the river Kislovka. The study investigated bottom sediments and river waters of the river Kislovka. On the basis of analytical studies, diagrams of the spatial distribution of chemical elements were constructed and the patterns of their change were revealed

Biaxially textured Ag films by grazing ion beam assisted deposition

The effect of grazing incidence 4 key Ar+ ion irradiation on the early stage of Ag thin film growth on amorphous Si was investigated The double effect of axial and surface channeling resulted in grains oriented along the axis in-plane while the (111) out-of-plane texture was maintained A slight average tilt of the (111) out-of-plane texture axis towards the ion beam direction is proposed to result from the difference between terrace and step edge sputtering yield The observed tilt is consistent with a minimum erosion orientation of the surface profile (C) 2010 Elsevier B V All rights reserve