Nanocrystal superlattices that exhibit improved order on heating: an example of inverse melting?

2015 ◽  
Vol 181 ◽  
pp. 181-192 ◽  
Author(s):  
Yixuan Yu ◽  
Avni Jain ◽  
Adrien Guillaussier ◽  
Vikas Reddy Voggu ◽  
Thomas M. Truskett ◽  
...  
Keyword(s):  
Structural Transition ◽  
Grazing Incidence ◽  
Melting Transition ◽  
Transition Temperatures ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Dsc Measurements ◽  
X Ray Scattering ◽  
Nanocrystal Superlattices ◽  
Melting And Solidification

Grazing incidence small angle X-ray scattering (GISAXS) measurements reveal that superlattices of 1.7 nm diameter, gold (Au) nanocrystals capped with octadecanethiol become significantly more ordered when heated to moderate temperatures (50–60 °C). This enhancement in order is reversible and the superlattice returns to its initially disordered structure when cooled back to room temperature. Disorder–order transition temperatures were estimated from the GISAXS data using the Hansen–Verlet criterion. Differential scanning calorimetry (DSC) measurements of the superlattices exhibited exotherms (associated with disordering during cooling) and endotherms (associated with ordering during heating) near the transition temperatures. The superlattice transition temperatures also correspond approximately to the melting and solidification points of octadecanethiol. Therefore, it appears that a change in capping ligand packing that occurs upon ligand melting underlies the structural transition of the superlattices. We liken the heat-induced ordering of the superlattices to an inverse melting transition.

An instrument for time-resolved and anomalous simultaneous small- and wide-angle X-ray scattering (SWAXS) at NSRRC

2006 ◽  
Vol 39 (6) ◽  
pp. 871-877 ◽  
Author(s):  
Ying-Huang Lai ◽  
Ya-Sen Sun ◽  
U-Ser Jeng ◽  
Jhih-Min Lin ◽  
Tsang-Lang Lin ◽  
...  
Keyword(s):  
Lipid Membrane ◽  
Quantum Wires ◽  
Grazing Incidence ◽  
Anomalous Scattering ◽  
Wide Angle ◽  
Scanning Calorimetry ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

A SWAXS (small- and wide-angle X-ray scattering) instrument was recently installed at the wiggler beamline BL17B3 of the National Synchrotron Radiation Research Center (NSRRC), Taiwan. The instrument, which is designed for studies of static and dynamic nanostructures and correlations between the nano (ormeso) structure (SAXS) and crystalline structure (WAXS), provides a flux of 1010–1011photon s−1at the sample at energies between 5 and 14 keV. With a SAXS area detector and a WAXS linear detector connected to two data acquisition systems operated in master–slave mode, the instrument allows one to perform time-resolved as well as anomalous scattering measurements. Data reduction algorithms have been developed for rapid processing of the large SWAXS data sets collected during time-resolved measurements. The performance of the instrument is illustrated by examples taken from different classes of ongoing projects: (i) time-resolved SAXS/WAXS/differential scanning calorimetry (DSC) with a time resolution of 10 s on a semicrystalline poly(hexamethylene terephthalate) sample, (ii) anomalous SAXS/WAXS measurements on a nanoparticulate PtRu catalyst, and (iii) grazing-incidence SAXS of a monolayer of oriented semiconductor quantum wires, and humidity-controlled ordering of Alamethicin peptides embedded in an oriented lipid membrane.

The formation and characterization of three-dimensional gold nanocrystal superlattices

2007 ◽  
Vol 222 (11/2007) ◽  
Author(s):  
Michael G. Constantinides ◽  
Heinrich M. Jaeger ◽  
Xuefa Li ◽  
Jin Wang ◽  
Xiao-Min Lin
Keyword(s):  
Thermal Stability ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Gold Nanocrystals ◽  
X Ray ◽  
X Ray Scattering ◽  
Drop Drying ◽  
Nanocrystal Superlattices ◽  
Gold Nanocrystal

Highly-ordered, three-dimensional superlattices were self-assembled from dodecanethiol-ligated gold nanocrystals using a simple drop-drying technique. The superlattices had the shape of truncated pyramids (frustums) and reached lateral dimensions of several micrometers. The formation and thermal stability were studied by grazing-incidence small-angle x-ray scattering. We found that the superlattice frustums adopt a

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>

scholarly journals Effect of tungsten disulfide nanotubes on crystallization of polylactide under uniaxial deformation and annealing

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Fausta Loffredo ◽  
Loredana Tammaro ◽  
Tiziana Di Luccio ◽  
Carmela Borriello ◽  
Fulvia Villani ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Structural Evolution ◽  
Tungsten Disulfide ◽  
Fine Tuning ◽  
Nanocomposite Films ◽  
Uniaxial Deformation ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering

AbstractTungsten disulfide (WS2) nanotubes (NTs) are examined here as a filler for polylactide (PLA) for their ability to accelerate PLA crystallization and for their promising biocompatibility in relevant to biomedical applications of PLA-WS2 nanocomposites. In this work, we have studied the structural and thermal properties of PLA-WS2 nanocomposite films varying the concentration of WS2 NTs from 0 (neat PLA) to 0.6 wt%. The films were uniaxially drawn at 90 °C and annealed at the same temperature for 3 and 10 min. Using wide angle x-ray scattering, Raman spectroscopy and differential scanning calorimetry, we probed the effects of WS2 NT addition on the structure of the PLA films at various stages of processing (unstretched, stretching, annealing). We found that 0.6 wt% of WS2 induces the same level of crystallinity in as stretched PLA-WS2 as annealing in neat PLA for 10 min. These data provide useful insights into the role of WS2 NTs on the structural evolution of PLA-WS2 composites under uniaxial deformation, and extend their applicability to situations where fine tuning of PLA crystallinity is desirable.

Strain Analysis in Thin La1−xCaxMnO3 Films by Grazing Incidence X-ray Scattering

1999 ◽  
Vol 602 ◽  
Author(s):  
M. Petit ◽  
L. J. Martinez-Miranda ◽  
M. Rajeswari ◽  
A. Biswas ◽  
D. J. Kang ◽  
...  
Keyword(s):  
Film Thickness ◽  
Lattice Mismatch ◽  
Compressive Strain ◽  
Strain Analysis ◽  
Grazing Incidence ◽  
Relaxation Processes ◽  
Near Surface ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

AbstractWe have performed depth profile analyses of the lattice parameters in epitaxial thin films of La1−xCaxMno3 (LCMO), where x = 0.33 or 0.3, to understand the evolution of strain relaxation processes in these materials. The analyses were done using Grazing Incidence X-ray Scattering (GIXS) on films of different thicnesses on two different substrates, (100) oriented LaAlO3 (LAO), with a lattice mismatch of ∼2% and (110) oriented NGO, with a lattice mismatch of less than 0.1%. Films grown on LAO can exhibit up to three in-plane strained lattice constants, corresponding to a slight orthorhombic distortion of the crystal, as well as near-surface and columnar lattice relaxation. As a function of film thickness, a crossover from a strained film to a mixture of strained and relaxed regions in the film occurs in the range of 700 Å. The structural evolution at this thickness coincides with a change in the resistivity curve near the metalinsulator transition. The in-plane compressive strain has a range of 0.2 – 1.5%, depending on the film thickness for filsm in the range of 400 - 1500 A.

Evolution of Interfacial Roughness Correlations of Fe Au Films Grown on Mgo(001) Substrates

1996 ◽  
Vol 440 ◽  
Author(s):  
P. C. Chow ◽  
R. Paniago ◽  
R. Forrest ◽  
S. C. Moss ◽  
S. S. P. Parkin ◽  
...  
Keyword(s):  
Thin Films ◽  
Diffuse Scattering ◽  
Perfect Match ◽  
Grazing Incidence ◽  
Interface Roughness ◽  
Metallic Structures ◽  
X Ray ◽  
Dimensional Image ◽  
X Ray Scattering ◽  
Image Plate Detector

AbstractThe growth by sputtering of a series of thin films of Fe/Au on MgO(001) substrates was analyzed using Bragg and diffuse X-ray scattering. The Fe (bcc) layer grows rotated by 45° with respect to the MgO – Au(fcc) (001) epitaxial orientation, resulting in an almost perfect match between the two metallic structures. By collecting the X-ray diffuse scattering under grazing incidence using a 2-dimensional image plate detector, we mapped the reciprocal space of these films. We characterized the correlated interface roughness starting with a buffer of Fe in which only three interfaces are present. The propagation of the roughness was subsequently characterized for Fe/Au multilayers with 40 and 100 bilayers. We observe an enlargement of the surface features as a function of time, evidenced by the longer lateral cutoff length measured for thicker films.

An X-ray scattering study on inverted Ge–Si huts grown at low temperatures

2004 ◽  
Vol 19 (4) ◽  
pp. 347-351
Author(s):  
J. Xu ◽  
X. S. Wu ◽  
B. Qian ◽  
J. F. Feng ◽  
S. S. Jiang ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Lattice Strain ◽  
Lattice Mismatch ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Large Lattice ◽  
Scattering Study

Ge–Si inverted huts, which formed at the Si∕Ge interface of Si∕Ge superlattice grown at low temperatures, have been measured by X-ray diffraction, grazing incidence X-ray specular and off-specular reflectivities, and transmission electron microscopy (TEM). The surface of the Si∕Ge superlattice is smooth, and there are no Ge–Si huts appearing on the surface. The roughness of the surfaces is less than 3 Å. Large lattice strain induced by lattice mismatch between Si and Ge is found to be relaxed because of the intermixing of Ge and Si at the Si∕Ge interface.

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