Structural Transformations Due to Intermixing During Deposition oF Fe/Pt(001) Epitaxial Multilayers

1996 ◽  
Vol 441 ◽  
Author(s):  
T. C. Hufnagel ◽  
M. C. Kautzky ◽  
V. Ramaswamy ◽  
A. Leming ◽  
B. M. Clemens
Keyword(s):  
Grazing Incidence ◽  
Initial Growth ◽  
X Ray Scattering ◽  
Bcc Structure ◽  
Bulk Chemical ◽  
Fundamental Reflection ◽  
Chemical Free Energy ◽  
Fcc Phase ◽  
Epitaxial Multilayers ◽  
Bcc Phase

AbstractPrevious studies of the structure of epitaxial Fe/Pt(001) multilayers have shown that the structure of the Fe layers depends on the Fe layer thickness. For small thicknesses (< 12 Å) the Fe is fcc, while for greater thicknesses (> 22 Å) the Fe has a bcc structure. We speculated that this transition of the Fe structure is a result of intermixing with subsequently deposited Pt. We explore this transition further by examining superlattice satellite peaks around the (111) fundamental reflection, and by using grazing incidence x-ray scattering (GIXS) to examine the structure of epitaxial Fe/Pt(001) multilayers during sputter deposition. The GIXS observations show that the initial growth of Fe is in the bcc structure; thin bcc Fe layers are partially transformed to fcc by subsequent deposition of Pt. The transformation is thermodynamically favorable because the intermixed fcc phase has lower epitaxial mismatch and bulk chemical free energy than the bcc phase.

Structural Transformations During Growth of Epitaxial Fe(001) Thin Films on Cu(001) and Pt(001)

1996 ◽  
Vol 436 ◽  
Author(s):  
B. M. Clemens ◽  
T. C. Hufnagel ◽  
M. C. Kautzky ◽  
J.-F. Bobo
Keyword(s):  
Thin Films ◽  
Structural Evolution ◽  
Grazing Incidence ◽  
Structural Transformations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bulk Chemical ◽  
Sputter Deposited ◽  
Fcc Phase ◽  
Bcc Phase

AbstractWe have used grazing incidence x-ray diffraction to observe the structural evolution during growth of sputter-deposited epitaxial Fe films on Cu(001) and Pt(001). We find that on Cu(001), Fe is fcc up to a thickness of 10–12 monolayers, whereupon bcc Fe is observed in first the Pitsch and then the Bain orientations. The fcc Fe shows some relaxation of the misfit from the Cu, as do the Pitsch orientation bcc, which is in tension, and the Bain orientation bcc, which is in compression. All three Fe variants exist in a 40 monolayer thick film. On Pt(001) the Fe grows as bcc with the Bain orientation. However, a thin (20 å) bcc Fe film is transformed to fcc Fe with cube-on-cube orientation by subsequent deposition of Pt. This behavior is consistent with intermixing of Pt into the Fe layer, which lowers the mismatch and bulk chemical energies of the fcc phase relative to that of the bcc phase.

The Study of Nanosized Cu-Mn Precipitates Contribution to Hardening in Bcc Fe Matrix

2017 ◽  
Author(s):  
YanKun Dou ◽  
XinFu He ◽  
DongJie Wang ◽  
Wu Shi ◽  
LiXia Jia ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Attractive Interaction ◽  
Rapid Decline ◽  
Shear Stresses ◽  
Dislocation Glide ◽  
Bcc Structure ◽  
Fcc Phase ◽  
Increasing Temperature ◽  
Edge Dislocations ◽  
Bcc Phase

In order to study the contribution of Mn atoms in Cu precipitates to hardening in bcc Fe matrix, the interactions of a (111){110} edge dislocations with nanosized Cu and Cu-Mn precipitates in bcc Fe have been investigated by using of molecular dynamics. The results indicate that the critical resolved shear stresses (τc) of the Cu-Mn precipitates are larger than that of Cu precipitates. Meanwhile, τc of the Cu-Mn precipitates show a much more significant dependence on temperature and size, compared to Cu precipitates. Mn atoms exhibit strong attractive interaction with <111> crowdion and improve the fraction of transformed atoms from body centred cubic (bcc) phase to face centred cubic (fcc) phase for big size precipitates. Those all lead to the higher resistance to the dislocation glide. The increasing temperature can assist the Cu atoms rearrange back towards a bcc structure, resulting in the rapid decline of τc. Similar to Cu precipitate, Cu-Mn precipitate with equator planes on the dislocation glide plane is proved to be the strongest obstacle. Eventually, these features are confirmed that the appearance of Mn atoms in Cu precipitates greatly facilitates the hardening in bcc Fe matrix.

scholarly journals Dodecagonal quasicrystalline order in a diblock copolymer melt

2016 ◽  
Vol 113 (19) ◽  
pp. 5167-5172 ◽  
Author(s):  
Timothy M. Gillard ◽  
Sangwoo Lee ◽  
Frank S. Bates
Keyword(s):  
Transition Temperature ◽  
Diblock Copolymer ◽  
Icosahedral Symmetry ◽  
Temperature Dependent ◽  
X Ray Scattering ◽  
Aperiodic Order ◽  
Seed Growth ◽  
Bcc Structure ◽  
The Times ◽  
Bcc Phase

We report the discovery of a dodecagonal quasicrystalline state (DDQC) in a sphere (micelle) forming poly(isoprene-b-lactide) (IL) diblock copolymer melt, investigated as a function of time following rapid cooling from above the order–disorder transition temperature (TODT = 66 °C) using small-angle X-ray scattering (SAXS) measurements. Between TODT and the order–order transition temperature TOOT = 42 °C, an equilibrium body-centered cubic (BCC) structure forms, whereas below TOOT the Frank–Kasper σ phase is the stable morphology. At T < 40 °C the supercooled disordered state evolves into a metastable DDQC that transforms with time to the σ phase. The times required to form the DDQC and σ phases are strongly temperature dependent, requiring several hours and about 2 d at 35 °C and more than 10 and 200 d at 25 °C, respectively. Remarkably, the DDQC forms only from the supercooled disordered state, whereas the σ phase grows directly when the BCC phase is cooled below TOOT and vice versa upon heating. A transition in the rapidly supercooled disordered material, from an ergodic liquid-like arrangement of particles to a nonergodic soft glassy-like solid, occurs below ∼40 °C, coincident with the temperature associated with the formation of the DDQC. We speculate that this stiffening reflects the development of particle clusters with local tetrahedral or icosahedral symmetry that seed growth of the temporally transient DDQC state. This work highlights extraordinary opportunities to uncover the origins and stability of aperiodic order in condensed matter using model block polymers.

Structural properties and thermal stability of Fe/Al2O3 multilayers

1995 ◽  
Vol 10 (12) ◽  
pp. 3062-3067 ◽  
Author(s):  
O. Lenoble ◽  
J.F. Bobo ◽  
H. Fischer ◽  
Ph. Bauer ◽  
M.F. Ravet ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Magnetron Sputtering ◽  
Grazing Incidence ◽  
Rf Magnetron Sputtering ◽  
Tubular Furnace ◽  
Phase Determination ◽  
X Ray ◽  
X Ray Scattering ◽  
Bcc Phase ◽  
Thermal Stability Of

Iron/alumina multilayers have been deposited on sapphire wafers using RF magnetron sputtering. To study the interdiffusion, the multilayers were annealed in a tubular furnace under a 10−7 mbar vacuum, and the samples examined by using a combination of classical diffractometry (θ/2θ) and Grazing Incidence Scattering (GIS) for the phase determination, and Small Angle X-ray Scattering (SAXS) for the superstructure of the multilayers. In all cases, in the as-deposited state the alumina is amorphous and the iron is crystalline in the bcc phase. Thermal anneals at temperatures between 573 and 873 K give evidence for segregation to the interfaces. At higher temperatures, interdiffusion occurs, leading to the formation of different phases. The Fe-Al2O3 interdiffusion coefficient has been evaluated in the temperature range from 873 to 1273 K.

New Structure of CTAB Templated Silica Films as revealed by GISAXS coupled to HRTEM

2000 ◽  
Vol 628 ◽  
Author(s):  
Sophie Besson ◽  
Catherine Jacquiod ◽  
Thierry Gacoin ◽  
André Naudon ◽  
Christian Ricolleau ◽  
...  
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Grazing Incidence ◽  
Hexagonal Structure ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
Silica Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Hexagonal Arrangement ◽  
Spherical Micelles

ABSTRACTA microstructural study on surfactant templated silica films is performed by coupling traditional X-Ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM) to Grazing Incidence Small Angle X-Ray Scattering (GISAXS). By this method it is shown that spin-coating of silicate solutions with cationic surfactant cetyltrimethylammonium bromide (CTAB) as a templating agent provides 3D hexagonal structure (space group P63/mmc) that is no longer compatible with the often described hexagonal arrangement of tubular micelles but rather with an hexagonal arrangement of spherical micelles. The extent of the hexagonal ordering and the texture can be optimized in films by varying the composition of the solution.

Quantifying Multiple Crystallite Orientations and Crystal Heterogeneities in Complex Thin Film Materials

2019 ◽  
Author(s):  
Jonathan Ogle ◽  
Daniel Powell ◽  
Eric Amerling ◽  
Detlef Matthias Smilgies ◽  
Luisa Whittaker-Brooks
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Structural Design ◽  
Grazing Incidence ◽  
Crystallite Orientation ◽  
Miller Index ◽  
X Ray ◽  
X Ray Scattering ◽  
Orientation Distributions ◽  
Orientation Information

<p>Thin film materials have become increasingly complex in morphological and structural design. When characterizing the structure of these films, a crucial field of study is the role that crystallite orientation plays in giving rise to unique electronic properties. It is therefore important to have a comparative tool for understanding differences in crystallite orientation within a thin film, and also the ability to compare the structural orientation between different thin films. Herein, we designed a new method dubbed the mosaicity factor (MF) to quantify crystallite orientation in thin films using grazing incidence wide-angle X-ray scattering (GIWAXS) patterns. This method for quantifying the orientation of thin films overcomes many limitations inherent in previous approaches such as noise sensitivity, the ability to compare orientation distributions along different axes, and the ability to quantify multiple crystallite orientations observed within the same Miller index. Following the presentation of MF, we proceed to discussing case studies to show the efficacy and range of application available for the use of MF. These studies show how using the MF approach yields quantitative orientation information for various materials assembled on a substrate.<b></b></p>

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