Determination of the melting and freezing temperatures of Pb nanoparticles embedded in a PbO–B2O3–SnO2glass by using only the SAXS method

2015 ◽  
Vol 48 (2) ◽  
pp. 520-527 ◽  
Author(s):  
G. Kellermann ◽  
A. Gorgeski ◽  
A. F. Craievich ◽  
L. A. Montoro
Keyword(s):  
Metallic Nanoparticles ◽  
Oxide Glass ◽  
Radius Of Gyration ◽  
X Ray ◽  
Nanoparticle Radius ◽  
Saxs Intensity ◽  
Temperature Dependences ◽  
Freezing Temperatures ◽  
Glass Matrices

Melting and freezing of metallic nanoparticles embedded in glass matrices usually occur at temperatures lower than for the same metal in the bulk state.In situsmall-angle X-ray scattering (SAXS) measurements using a synchrotron beamline and a specially designed high-temperature chamber allowed the determination of the temperature dependence of the SAXS intensity produced by a dilute and nearly monodisperse set of spherical Pb nanoparticles, with an average radius 〈R〉 = 16.1 nm, embedded in a homogeneous lead–borate oxide glass. The temperature dependences of the nanoparticle volumeV(T) and nanoparticle radius of gyrationRg(T) derived from SAXS results exhibit clear discontinuities during the cooling and during the heating processes, thus allowing for precise determinations of the melting and freezing temperatures of the studied Pb nanoparticles. Additional features observed in bothV(T) andRg(T) curves showed that during the heating cycle the frozen Pb nanoparticles suffer a transition to a more compact phase at 433 K before melting at 580 K. The results of this work demonstrate that the melting and freezing temperatures of nanoparticles in a very diluted state – for which the X-ray diffraction technique is not sensitive enough – can be precisely determined by applying only the SAXS method.

Experimental Method of Determination of Structural Correlations in Surface Layers of Oxide Glass

1990 ◽  
Vol 216 ◽  
Author(s):  
Zenon BochyŃski
Keyword(s):  
Structural Changes ◽  
Lattice Models ◽  
Molecular Size ◽  
Oxide Glass ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
X Ray ◽  
The Real ◽  
Inorganic Glasses

ABSTRACTA new method of X-ray diffraction analysis of structural inhomogeneities in the quartz/Si02/n based inorganic glasses is presented. The method enables the determination of structural changes occuring in the real nodal lattice in the regions of 10…20 Å or more as well as substructural changes in the regions 5…15 Å comparable to the molecular size of SiO2…SiO4. In consequence these changes can be correlated with approximate nodal lattice models of different degree of ordering. The applied method provided the possibility of constructing structural models of nodal lattices describing the surface and inner layers of the real glasses, changes in the local inhomogeneities as well as boundaries in water-gel associates.

Determination of small alterations in the radius of gyration by small-angle X-ray scattering

1971 ◽  
Vol 4 (4) ◽  
pp. 317-318 ◽  
Author(s):  
I. Simon
Keyword(s):  
Small Angle ◽  
Direct Determination ◽  
Differential Method ◽  
Scattering Data ◽  
Radius Of Gyration ◽  
X Ray ◽  
X Ray Scattering ◽  
Colloid Particles ◽  
Ray Scattering

A differential method is presented for the evaluation of small-angle X-ray scattering data. The direct determination of slight changes in the radius of gyration of colloid particles is rendered possible by the method proposed.

scholarly journals Size dependences of transition temperatures of nanoparticles by SAXS and XRD

2014 ◽  
Vol 70 (a1) ◽  
pp. C1073-C1073
Author(s):  
Guinther Kellermann ◽  
Aldo Craievich
Keyword(s):  
Borate Glass ◽  
Structural Features ◽  
Sodium Borate ◽  
Transition Temperatures ◽  
Intensity Pattern ◽  
Saxs Intensity ◽  
Temperature Dependences ◽  
Freezing Temperatures ◽  
Bi Nanoparticles

SAXS technique alone and combined with XRD can be applied to determine the size dependences of crystal-to-liquid and liquid-to crystal transition temperatures of nanoparticles in dilute state. Since the volume of nanoparticles at the transition temperatures are expected to exhibit (weak) discontinuities, SAXS can be applied to determine the melting and freezing temperatures of nanoparticles as functions of their size. For this purpose, a set of samples, each of them with different nanoparticle size, is studied by in situ SAXS at varying temperatures. The variations in nanoparticle volume at the transitions lead to discontinuities in the 3D integral of SAXS intensity, ΔQ, in the slope of Guinier plots, ΔS, and in SAXS intensity at any q except at q=0, ΔI(q>0). Thus, the transition (melting and freezing) temperatures of a nearly monodisperse set of nanoparticles, can be derived from the discontinuities observed in the temperature dependence of V, S or I(q>0). Since the transition temperatures are strongly dependent on the size of the nanoparticles, for samples containing nanoparticles with a wide size distribution the size dependences of the melting and freezing temperatures cannot be determined by applying the method outlined above. However, in the particular case of systems consisting of a dilute set of spherical nanoparticles with a broad radius distribution, N(R), the combined use of SAXS and XRD makes it possible to determine the radius dependences of the melting and freezing temperatures, MT(R) and FT(R), respectively. This is achieved by studying a single sample in situ, along a heating/cooling cycle, and simultaneously determining the temperature dependences of the SAXS intensity pattern and the area of XRD Bragg peaks. A few applications of these procedures will be described, namely the determination of the radius dependences MT(R) and FT(R) of (i) a nearly monodisperse set of Pb nanoparticles embedded in a lead-borate glass (Gorgeski et al, 2014) and (ii) a polydisperse set of Bi nanoparticles embedded in a sodium-borate glass [Kellermann and Craievich, 2002). Other relevant structural features of Bi nanoparticles embedded in borate glass could also be derived from the analysis of the same experimental results [Kellermann and Craievich, 2008].

Morphological determination of face-centered-cubic metallic nanoparticles by X-ray diffraction

2012 ◽  
Vol 369 (1) ◽  
pp. 129-133 ◽  
Author(s):  
Chi-Feng Lee ◽  
Chia-Lun Chang ◽  
Jing-Cyuan Yang ◽  
Hsiang-Yu Lai ◽  
Chun-Hua Chen
Keyword(s):  
Metallic Nanoparticles ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Face Centered

Determination of the melting temperature of spherical nanoparticles in dilute solution as a function of their radius by exclusively using the small-angle X-ray scattering technique

2020 ◽  
Vol 53 (2) ◽  
pp. 455-463
Author(s):  
Guinther Kellermann ◽  
Felipe L. C. Pereira ◽  
Aldo F. Craievich
Keyword(s):  
Thermal Expansion ◽  
Melting Temperature ◽  
Glass Matrix ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
X Ray Scattering ◽  
Saxs Intensity ◽  
Expansion Coefficients ◽  
Bi Nanoparticles

In this investigation the dependence on radius of the melting temperature of dilute sets of spherical nanocrystals with wide radius distributions was determined by a novel procedure exclusively using the results of small-angle X-ray scattering (SAXS) measurements. This procedure is based on the sensitivity of the SAXS function to small and rather sharp variations in the size and electron density of nanocrystals at their melting temperature. The input for this procedure is a set of experimental SAXS intensity functions at selected q values for varying sample temperatures. In practice, the sample is heated from a minimum temperature, lower than the melting temperature of the smallest nanocrystals, up to a temperature higher than the melting temperature of the largest nanocrystals. The SAXS intensity is recorded in situ at different temperatures during the heating process. This novel procedure was applied to three samples composed of dilute sets of spherical Bi nanocrystals with wide radius distributions embedded in a sodium borate glass. The function relating the melting temperature of Bi nanocrystals with their radius – determined by using the procedure proposed here – agrees very well with the results reported in previous experimental studies using different methods. The results reported here also evidence the predicted size-dependent contraction of Bi nanocrystals induced by the large surface-to-volume ratio of small nanocrystals and an additional size-independent compressive stress caused by the solid glass matrix in which liquid Bi nanodroplets are initially formed. This last effect is a consequence of the increase in the volume of Bi nanoparticles upon crystallization and also of differences in the thermal expansion coefficients of the crystalline phase of Bi and the glass matrix. This additional stress leads to a depression of about 10 K in the melting temperature of the Bi nanocrystals confined in the glass. The procedure described here also allowed the determination of the specific masses and thermal expansion coefficients of Bi nanoparticles in both liquid and crystalline phases.

Melting and freezing temperatures of confined Bi nanoparticles over a wide size range

2017 ◽  
Vol 50 (6) ◽  
pp. 1590-1600 ◽  
Author(s):  
Hermann Franz Degenhardt ◽  
Guinther Kellermann ◽  
Aldo Felix Craievich
Keyword(s):  
Structural Model ◽  
Sodium Borate ◽  
Experimental Procedure ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
Freezing Temperatures ◽  
Bi Nanoparticles ◽  
Ray Scattering

The size dependences of the melting and freezing temperatures,TmandTf, respectively, of spherical Bi nanoparticles embedded in a sodium borate glass were determined by applying a new experimental procedure based on the combined and simultaneous use of small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). This experimental procedure is particularly useful for materials in which a widely polydisperse set of nanoparticles are embedded. The results provide additional and stronger evidence supporting the main previous conclusions: (i) the melting and freezing temperatures both decrease linearly for increasing reciprocal radius (1/R); and (ii) the effect of undercooling is suppressed for Bi nanoparticles with radii smaller than a critical value equal to 1.8 nm. These results confirm a previously proposed low-resolution structural model for Bi nanocrystals below their melting temperature and with radiusR> 1.8 nm, which consists of a crystalline core surrounded by a disordered shell. In the present work, a number of samples with different and partially overlapping radius distributions were studied, allowing the determination ofTm(R) andTf(R) functions over a wide range of radii (1 <R< 11 nm). Comparison of the experimentally determinedTm(R) andTf(R) functions corresponding to different samples indicates good reproducibility of the experimental results. This allowed the verification of the robustness of the experimental procedure based onin situcombined use of SAXS and WAXS for determination of the radius dependence of the melting and freezing temperatures of spherical nanoparticles in dilute solution.

Lateral resolution of the electron microbeam analysis

1978 ◽  
Vol 36 (1) ◽  
pp. 542-543
Author(s):  
H.J. Dudek
Keyword(s):  
Quantitative Analysis ◽  
Depth Resolution ◽  
Lateral Resolution ◽  
Cylindrical Particle ◽  
Correction Procedure ◽  
X Ray ◽  
Element Concentrations ◽  
Microbeam Analysis ◽  
The Matrix

The chemical inhomogenities in modern materials such as fibers, phases and inclusions, often have diameters in the region of one micrometer. Using electron microbeam analysis for the determination of the element concentrations one has to know the smallest possible diameter of such regions for a given accuracy of the quantitative analysis.In th is paper the correction procedure for the quantitative electron microbeam analysis is extended to a spacial problem to determine the smallest possible measurements of a cylindrical particle P of high D (depth resolution) and diameter L (lateral resolution) embeded in a matrix M and which has to be analysed quantitative with the accuracy q. The mathematical accounts lead to the following form of the characteristic x-ray intens ity of the element i of a particle P embeded in the matrix M in relation to the intensity of a standard S

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

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