scholarly journals Surface Crystallization and Thin Film Melting in Normal Alkanes

1994 ◽  
Vol 366 ◽  
Author(s):  
X. Z. Wu ◽  
H. H. Shag ◽  
B. M. Ocko ◽  
M. Deutsch ◽  
S. K. Sinha ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Carbon Number ◽  
Grazing Incidence ◽  
Melting Behavior ◽  
Surface Crystallization ◽  
Surface Phase ◽  
Normal Alkanes ◽  
X Ray ◽  
Rotator Phase ◽  
Surface Freezing

ABSTRACTNormal alkanes of carbon number n>14 exhibit surface crystallization at their liquid-vapor interface. This has been investigated with x-ray reflectivity, grazing incidence scattering and surface tension measurements. The structure and thermodynamics of the surface layer is consistent with a monolayer of the bulk rotator phase occurring at the surface above the bulk melting temperature. On the other hand, thin films of alkanes on SiO2, exhibit a reduction of the melting temperature. The surface crystalline phase is observed for carbon number n>14. The vanishing of surface phase for small n may be due to a transition from surface freezing to surface melting behavior. These measurements can yield the relative surface energies of the various phases.

In situ monitoring of the c( 4 × 4) to the 2 × 4 surface phase transformation on GaAs(001) by grazing incidence X-ray diffraction

1994 ◽  
Vol 320 (3) ◽  
pp. 252-258 ◽  
Author(s):  
V.H. Etgens ◽  
M. Sauvage-Simkin ◽  
R. Pinchaux ◽  
J. Massies ◽  
N. Jedrecy ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Grazing Incidence ◽  
In Situ Monitoring ◽  
Surface Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Phase Transformation

Nature of Stark Rubber

1955 ◽  
Vol 28 (4) ◽  
pp. 1007-1020 ◽  
Author(s):  
Donald E. Roberts ◽  
Leo Mandelkern
Keyword(s):  
Natural Rubber ◽  
Melting Temperature ◽  
Melting Behavior ◽  
X Ray Diffraction ◽  
Equilibrium Melting Temperature ◽  
X Ray ◽  
Melting Temperatures ◽  
Controlled Conditions ◽  
Previous Assignment ◽  
Diffraction Patterns

Abstract The melting behavior and x-ray diffraction patterns of four different samples of stark rubber have been investigated. The melting temperatures, 39° to 45.5° C, are substantially higher than that observed for natural rubber crystallized by cooling. The x-ray diffraction patterns indicate that the crystallites in stark rubber are oriented. This observation can explain the higher melting temperatures. Thus, the previous assignment of an equilibrium melting temperature, 28° (±1°) C, to unoriented crystalline natural rubber is shown to be appropriate. Several different methods that have been used successfully in preparing stark rubber under controlled conditions in the laboratory are outlined.

The Rotator Phases of the Normal Alkanes

1991 ◽  
Vol 248 ◽  
Author(s):  
E. B. Sirota ◽  
H.E. King ◽  
D.M. Singer ◽  
H. Shao
Keyword(s):  
Order Parameters ◽  
Normal Alkanes ◽  
X Ray ◽  
X Ray Scattering ◽  
Rotator Phase ◽  
Scattering Study ◽  
Ray Scattering

AbstractWe present results of an x-ray scattering study on the rotator phases of normal alkanes: CH2-(CH3)n-CH2 (20 ≤ ≤ 33). We have characterized a new tilted rotator phase and measured the distortion and tilt order parameters in all 5 rotator phases. We have shown that there is no strong even-odd chain effect within the rotator phases.

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.

X-Ray Fluorescence Spectrometer with Geometry of Grazing Incidence X-ray Radiation

2012 ◽  
Vol 1 (2) ◽  
pp. 78-82
Author(s):  
N.M. Novikovskii ◽  
◽  
V.M. Raznomazov ◽  
V.O. Ponomarenko ◽  
D.A. Sarychev ◽  
...  
Keyword(s):  
Grazing Incidence ◽  
X Ray ◽  
Fluorescence Spectrometer

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>

Strain Relaxation and In-Situ Observation of Voiding in Passivated Aluminum Alloy Lines.

1993 ◽  
Vol 308 ◽  
Author(s):  
Paul R. Besser ◽  
Thomas N. Marieb ◽  
John C. Bravman
Keyword(s):  
Strain Relaxation ◽  
Grazing Incidence ◽  
Scanning Transmission Electron Microscope ◽  
In Situ Observation ◽  
X Ray ◽  
Scanning Transmission ◽  
Length Width ◽  
Measured Strain ◽  
Ray Geometry

ABSTRACTStrain relaxation in passivated Al-0.5% Cu lines was measured using X-ray diffraction coupled with in-situ observation of the formation and growth of stress induced voids. Samples of 1 μm thick Al-0.5% Cu lines passivated with Si3N4 were heated to 380ºC, then cooled and held at 150ºC. During the test, principal strains along the length, width, and height of the line were determined using a grazing incidence x-ray geometry. From these measurements the hydrostatic strain in the metal was calculated and strain relaxation was observed. The thermal cycle was duplicated in a high voltage scanning transmission electron microscope equipped with a backscattered electron detector. The 1.25 μm wide lines were seen to have initial stress voids. Upon heating these voids reduced in size until no longer observable. Once the samples were cooled to 150ºC, voids reappeared and grew. The measured strain relaxation is discussed in terms of void and θ-phase (Al2Cu) formation.

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