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].

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.

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.

Visualization of the Coalescence of Bismuth Nanoparticles

2014 ◽  
Vol 20 (2) ◽  
pp. 416-424 ◽  
Author(s):  
Kai-Yang Niu ◽  
Hong-Gang Liao ◽  
Haimei Zheng
Keyword(s):  
Precursor Solution ◽  
Growth Trajectories ◽  
Transport Mechanisms ◽  
Bismuth Nanoparticles ◽  
Transmission Electron ◽  
Liquid Cell ◽  
Significant Pathway ◽  
Mass Transport Mechanisms ◽  
Bi Nanoparticles

AbstractCoalescence is a significant pathway for the growth of nanostructures. Here we studied the coalescence of Bi nanoparticles in situ by liquid cell transmission electron microscopy (TEM). The growth of Bi nanoparticles was initiated from a bismuth neodecanoate precursor solution by electron beam irradiation inside a liquid cell under the TEM. A significant number of coalescence events occurred from the as-grown Bi nanodots. Both symmetric coalescence of two equal-sized nanoparticles and asymmetric coalescence of two or more unequal-sized nanoparticles were analyzed along their growth trajectories. Our observation suggests that two mass transport mechanisms, i.e., surface diffusion and grain boundary diffusion, are responsible for the shape evolution of nanoparticles after a coalescence event.

Laser- and  -induced transformations of optical spectra of indium-doped sodium borate glass

2003 ◽  
Vol 15 (23) ◽  
pp. 3919-3929 ◽  
Author(s):  
O V Kopyshinsky ◽  
B A Okhrimenko ◽  
S E Zelensky ◽  
B A Danilchenko ◽  
O P Shakhov
Keyword(s):  
Borate Glass ◽  
Optical Spectra ◽  
Sodium Borate ◽  
Sodium Borate Glass

A hole trapped centre responsible for high temperature thermoluminescence in sodium borate glass

1985 ◽  
Vol 4 (2) ◽  
pp. 247-248 ◽  
Author(s):  
N. Takeuchi ◽  
T. Miyanaga ◽  
K. Inabe ◽  
Y. Fukuda
Keyword(s):  
High Temperature ◽  
Borate Glass ◽  
Sodium Borate ◽  
Sodium Borate Glass

In situstudy of the kinetics of growth of Pb nanoparticles embedded in a PbO–B2O3glass

2018 ◽  
Vol 51 (2) ◽  
pp. 395-405
Author(s):  
Andreia Gorgeski ◽  
Aldo Felix Craievich ◽  
Leonardo Marcon Corrêa ◽  
Luciano Andrei Montoro ◽  
Guinther Kellermann
Keyword(s):  
Isothermal Annealing ◽  
Equilibrium Concentration ◽  
Spherical Shape ◽  
Distribution Functions ◽  
Relative Dispersion ◽  
Droplet Growth ◽  
Temperature Dependences ◽  
Different Temperatures ◽  
Size Dispersion

The process of growth of liquid Pb nanoparticles embedded in a lead borate glass was investigated by transmission electron microscopy (TEM) and byin situsmall-angle X-ray scattering (SAXS) during isothermal annealing at different temperatures within the 649–679 K range. A TEM study at room temperature of the glass–Pb nanoparticle composite, previously subjected to isothermal annealing, showed the presence of a number of nearly spherical Pb nanocrystals with some size dispersion. The analysis of several series of experimental SAXS curves recordedin situ, for increasing periods of time of isothermal annealing at different temperatures, allowed the authors to determine time and temperature dependences of the radius distribution functions of the growing spherical Pb nanoparticles. Since all selected annealing temperatures were higher than the melting temperature of bulk Pb, the Pb nanoparticles were in all cases in the liquid state during the whole growth process. A fast increase in the total volume of Pb droplets was observed during the initial stages of annealing, which indicated that the Pb droplets grow because of the incorporation of Pb atoms dispersed in the glass matrix. For more advanced stages of droplet growth, when the concentration of Pb atoms becomes close to its equilibrium concentration, the time dependences of the average radius, number density and total volume of Pb droplets are those predicted by the classical theory of coarsening proposed by Lifshitz–Slyosov–Wagner. Furthermore, it has been established that the Pb nanodroplets preserve their spherical shape and their relative dispersion in size through the whole coarsening process and that the activation energy for diffusion of Pb atoms and growth of Pb droplets embedded in the studied glass isEa= 2.65 ± 0.09 eV per atom.

A new approach to characterization of the transition temperatures of thin film NiTi shape memory alloys

2004 ◽  
Vol 19 (6) ◽  
pp. 1762-1767
Author(s):  
Nicholas W. Botterill ◽  
David M. Grant ◽  
Jianxin Zhang ◽  
Clive J. Roberts
Keyword(s):  
Thin Film ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Transition Temperatures ◽  
New Approach ◽  
Novel Approach ◽  
Potential Applications ◽  
Niti Shape Memory Alloys

A novel approach in determining the transition temperatures of NiTi shape memory alloys was investigated and compared with conventional techniques. The technique is based on microthemal analysis using a scanning thermal microscope (SThM). In particular, this method has the potential to allow the transformation temperatures of thin films to be investigated in situ. Thin film shape memory alloys have potential applications, such as microactuators, where conventional analysis techniques are either not directly applicable to such samples or are difficult to perform.

Histology and fine structure of the pre-optic nucleus and hypothalamic tracts of the European eel Anguilla anguilla L

1969 ◽  
Vol 256 (804) ◽  
pp. 135-145 ◽  
Keyword(s):  
Electron Microscopy ◽  
Anterior Margin ◽  
Third Ventricle ◽  
Anguilla Anguilla ◽  
Structural Features ◽  
Ependymal Cells ◽  
European Eel ◽  
The Third ◽  
Secretory Products

The pre-optic nucleus and hypothalamic tracts of intact and hypophysectomized specimens of the European eel Anguilla anguilla L. have been studied in situ and by optical and electron microscopy. The in situ technique reveals a hitherto unsuspected degree of segregation of the neurosecretory axons which form up to five discrete tracts having separate origins and following distinct paths before converging, at the level of the anterior margin of the pituitary, to form a median tract. The structure of the pre-optic neurons, as revealed by several different techniques, is described and it is shown that their synthetic poles, identified by a prominent cap of endoplasmic reticulum, are precisely orientated towards the third ventricle and are separated from it by, at most, two or three layers of ependymal cells. Electron microscopy shows that the secretory products lie mainly in the axonal ends of the cells though in Bouin-fixed, wax-embedded material the entire perikaryon stains with neurosecretory dyes and this, and their proximity to the third ventricle, gives the impression that they secrete into the latter, as well as centripetally. This may well be so, but from the work described below it seems more likely that these neurons receive nutrients, or stimuli, or both, from the third ventricle. Two types of pre-optic neurons, separable by structural features as well as by the size of the elementary granules they contain have been identified; these probably give rise to two of the fibre types identified in the neurohypophysis of the eel by Knowles & Vollrath. Aggregations of neurosecretion, common in the fish pre-optic nucleus, and also, much rarer, colloid vesicles, are described and discussed.

In-situ TEM Study of Bismuth Nanostructures

2007 ◽  
Vol 1044 ◽  
Author(s):  
Xiaoting Jia ◽  
Vincent Berube ◽  
Shuo Chen ◽  
Bed Poudel ◽  
Son Hyungbin ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Structural Behavior ◽  
In Situ Tem ◽  
Electrical Measurements ◽  
Dimensionless Figure Of Merit ◽  
Bi Nanoparticles ◽  
Nanostructured Thermoelectric Materials

AbstractNanostructured thermoelectric materials have attracted lots of interest in recent years, due to their enhanced performance determined by their thermoelectric dimensionless figure of merit. However, because of equipment limitations, not much work has been done on combining simultaneous transport measurements and structural characterization on individual nanostructured thermoelectric materials. With an integrated TEM-STM system, we studied the structural behavior and electrical properties of bismuth (Bi) nanobelts and nanoparticles. Results showed that clean Bi nanostructures free of oxides can be produced by in-situ high temperature electro-migration and Joule annealing processes occurring within the electron microscope. Preliminary electrical measurements indicate a conductivity of two orders of magnitude lower for Bi nanoparticles than that for bulk Bi. Such in-situ studies are highly advantageous for studying the semimetal-semiconductor transition and how this transition could enhance thermoelectric properties.

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