On the structure of grain/interphase boundaries and interfaces

• K. Anantha Padmanabhan and
• Herbert Gleiter

Beilstein J. Nanotechnol. 2014, 5, 1603–1615, doi:10.3762/bjnano.5.172

• exact threshold value has not been established yet), the activation energy required to transform them into an “ultra-stable” nano-glassy state is provided. (It may also be possible to supply an equivalent amount of energy by heating. But this hypothesis is yet to be tested.) As noted earlier, in view of

• gets converted into a nano-crystalline or crystalline material above the crystallization temperature, when the required activation energy becomes available. Alternatively, crystalline materials can also be produced directly by casting. Within each state, depending on the experimental conditions, the

Formation of Cu_xAu_1−x phases by cold homogenization of Au/Cu nanocrystalline thin films

• Alona Tynkova,
• Gabor L. Katona,
• Gabor A. Langer,
• Sergey I. Sidorenko,
• Svetlana M. Voloshko and
• Dezso L. Beke

Beilstein J. Nanotechnol. 2014, 5, 1491–1500, doi:10.3762/bjnano.5.162

• results offer an explanation for the linear growth kinetics in this regime: If the front velocity is constant, the amount of the product phase should grow linearly with time and the activation energy obtained from this part should be close to the activation energy of GB/interface diffusion [24][26

Synthesis, characterization, and growth simulations of Cu–Pt bimetallic nanoclusters

• Subarna Khanal,
• Ana Spitale,
• Nabraj Bhattarai,
• Daniel Bahena,
• J. Jesus Velazquez-Salazar,
• Sergio Mejía-Rosales,
• Marcelo M. Mariscal and
• Miguel José-Yacaman

Beilstein J. Nanotechnol. 2014, 5, 1371–1379, doi:10.3762/bjnano.5.150

• obtained during the dynamic simulations could be easily explained by the activation energy for diffusion of Pt atoms on Cu. Both, thermodynamic and kinetic parameter (exchange energy and activation energy) confirms the existence of alloyed CuPt nanoparticles. The morphologies obtained with the simulations

• parameters, the mean square displacement (MSD) of the Pt atoms in the nanoalloy was calculated by taking previous configurations in the recorded trajectory as reference configuration. Moreover, the MSD reflects the relative change of diffusivity of the atoms at different temperatures and the activation

• energy (Ea) for Pt diffusion in Cu NPs can be calculated, plotting the diffusion constant as a function of (k·T)−1 [49]. By means of a linear regression fit, an Ea of 0.009 eV/atom was found (Figure S6 in Supporting Information File 1). If we assume the transition state theory to be valid for the problem

Volcano plots in hydrogen electrocatalysis – uses and abuses

• Paola Quaino,
• Fernanda Juarez,
• Elizabeth Santos and
• Wolfgang Schmickler

Beilstein J. Nanotechnol. 2014, 5, 846–854, doi:10.3762/bjnano.5.96

• evolution region [24]. So the adsorption of the weakly adsorbed species sets in before the coverage with the other one is complete. This is important, because the two species repel each other, and with increasing coverage of upd hydrogen both the energy of the opd species and the activation energy for the

Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

• Xiaohong Wang,
• Heinz C. Schröder and
• Werner E. G. Müller

Beilstein J. Nanotechnol. 2014, 5, 610–621, doi:10.3762/bjnano.5.72

• thermodynamically possible, but are strictly controlled in a biochemical system through the activation energy barriers that prevent a chemical reaction from occurring at physiological temperatures/conditions [30]. A modulation of the activation energy barriers enables an organism to control under which

• physiological conditions a thermodynamically possible reaction can be initiated or prevented [30]. Almost exclusively, alterations of the heights of the activation energy barriers are adjusted by enzymes or by the surface architecture of membranes separating two phases. The recent findings that in animals the

• diameter of about 4 μm and a length greater than 100 µm, show a very fast growth rate of 65 μm/h. Hence it has to be concluded that an acceleration of the velocity of the exergonic reaction at ambient environmental conditions has to occur by lowering the activation energy by an enzyme, or by allowing the

Fabrication of carbon nanomembranes by helium ion beam lithography

• Xianghui Zhang,
• Henning Vieker,
• André Beyer and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2014, 5, 188–194, doi:10.3762/bjnano.5.20

• -linking arise from the activation energy for the DEA process and the entropic barrier to form a covalent bond among adjacent molecules. The activation energy and the above mentioned energy-dependent DEA cross section determine the rate coefficient of the DEA process [33]. The entropic barrier can be

• barriers due to steric hindrance. Note that the orientation of the 1D structures appears to be closer to the horizontal (scan) direction than to the vertical direction, which implies that the activation energy could be slightly brought down by the helium ion beam scanning due to the local electronic field

The role of electron-stimulated desorption in focused electron beam induced deposition

• Willem F. van Dorp,
• Thomas W. Hansen,
• Jakob B. Wagner and
• Jeff T. M. De Hosson

Beilstein J. Nanotechnol. 2013, 4, 474–480, doi:10.3762/bjnano.4.56

• it is observed that the growth rate is lower at higher substrate temperatures. From Arrhenius plots we calculated the activation energy for desorption, Edes, of W(CO)6. We found an average value for Edes of 20.3 kJ or 0.21 eV, which is 2.5–3.0 times lower than literature values. This difference

• are affected by the electron irradiation, the majority desorbs from the surface rather than dissociates to contribute to the deposit. It is important to take this into account during FEBIP experiments, for instance when determining fundamental process parameters such as the activation energy for

• gas flux at the sample, etc. If we want to understand and model FEBIP, we need to understand how these parameters contribute to the final product. In this paper we determined the activation energy for desorption, Edes, from a FEBIP experiment. The desorption energy plays a significant role in FEBIP

Digging gold: keV He⁺ ion interaction with Au

• Vasilisa Veligura,
• Gregor Hlawacek,
• Robin P. Berkelaar,
• Raoul van Gastel,
• Harold J. W. Zandvliet and
• Bene Poelsema

Beilstein J. Nanotechnol. 2013, 4, 453–460, doi:10.3762/bjnano.4.53

• of interlayer diffusion by the step edge or Ehrlich–Schwoebel barrier [14][20][24][25][26][27][28]. The activation energy for vacancy diffusion on Au{111} is much higher than the one for adatoms [29], hence we can suppose that at room temperature adatoms are dominantly responsible for the pattern

Functionalization of vertically aligned carbon nanotubes

• Eloise Van Hooijdonk,
• Carla Bittencourt,
• Rony Snyders and
• Jean-François Colomer

Beilstein J. Nanotechnol. 2013, 4, 129–152, doi:10.3762/bjnano.4.14

• provides a highly reactive environment compared with thermal CVD, allowing lower synthesis temperatures. An activation energy of about 1.2–1.8 eV [44][45] characterizes the thermal CVD while a lower activation energy of ≈0.3 eV [46] was reported for the PECVD. These energies are defined taking into account

• structure. Hoffman et al. [47] demonstrated that the limiting step in the determination of the activation energy for thermal CVD is the dissociation of the precursor molecule and, for PECVD, is the carbon diffusion on the catalyst. Thanks to the low temperatures in PECVD compared to the temperatures in

Plasmonics-based detection of H₂ and CO: discrimination between reducing gases facilitated by material control

• Gnanaprakash Dharmalingam,
• Nicholas A. Joy,
• Benjamin Grisafe and
• Michael A. Carpenter

Beilstein J. Nanotechnol. 2012, 3, 712–721, doi:10.3762/bjnano.3.81

• and YSZ could also induce a change in the dielectric function, and while the adsorption of hydrogen is an activated process, the activation energy is typically less than 1 eV [25]. The uptake of hydrogen as an OH species by a zirconia matrix at temperatures between 673 and 873 K has been confirmed

Enhancement of the critical current density in FeO-coated MgB₂ thin films at high magnetic fields

• Andrei E. Surdu,
• Hussein H. Hamdeh,
• Imad A. Al-Omari,
• David J. Sellmyer,
• Alexei V. Socrovisciuc,
• Andrei A. Prepelita,
• Ezgi T. Koparan,
• Ekrem Yanmaz,
• Valery V. Ryazanov,
• Horst Hahn and
• Anatolie S. Sidorenko

Beilstein J. Nanotechnol. 2011, 2, 809–813, doi:10.3762/bjnano.2.89

• reported at higher temperatures and higher fields (Jc ~ 102 A/cm2 at 6 T and 20 K). In our previous study of the resistive transitions of MgB2 films in an external magnetic field [7], we showed that the rapid decrease of the activation energy of the flux flow for MgB2 in the field region B > 1 T represents

Femtosecond time-resolved photodissociation dynamics of methyl halide molecules on ultrathin gold films

• Mihai E. Vaida,
• Robert Tchitnga and
• Thorsten M. Bernhardt

Beilstein J. Nanotechnol. 2011, 2, 618–627, doi:10.3762/bjnano.2.65

• adsorbed molecules. Due to this lateral repulsion between the adsorbate molecules, the activation energy for desorption decreases with increasing coverage and, hence, the desorption temperature decreases. The completion of the first monolayer of CD3I molecules appears for doses just below 4.75 L, in

Nanostructured, mesoporous Au/TiO₂ model catalysts – structure, stability and catalytic properties

• Matthias Roos,
• Dominique Böcking,
• Kwabena Offeh Gyimah,
• Gabriela Kucerova,
• Joachim Bansmann,
• Johannes Biskupek,
• Ute Kaiser,
• Nicola Hüsing and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2011, 2, 593–606, doi:10.3762/bjnano.2.63

• layer volume, and can be normalized accordingly. Lateral transport of product molecules within the film can be neglected considering that the diameter of the sampled surface area (2.5 mm) is large in comparison to the film thickness of 200–400 nm. CO oxidation: Apparent activation energy and reaction

• orders A third aspect deals with inherent reaction properties such as the apparent activation energy (temperature dependence of the reaction rate) and the reaction orders (partial pressure dependence of the reaction rate). Here it is of interest whether the model systems exhibit characteristics that are

• comparable to those of realistic dispersed catalysts, in this case to those of dispersed Au/TiO2 catalysts. The apparent activation energy EA was determined on a 280 nm thick Au/TiO2 film by varying the temperature during the measurement between 70 and 130 °C while recording the CO2 production (CO:O2 = 1:1

Formation of precise 2D Au particle arrays via thermally induced dewetting on pre-patterned substrates

• Dong Wang,
• Ran Ji and
• Peter Schaaf

Beilstein J. Nanotechnol. 2011, 2, 318–326, doi:10.3762/bjnano.2.37

• interaction with SiO2 substrate, which results in low activation energy for metal atom migration [12]. Dewetting is a well known spontaneous physical phenomenon describing the rupture of a thin liquid film on a substrate and the formation of droplets. Dewetting dynamics of liquid polymer films have been

Studies towards synthesis, evolution and alignment characteristics of dense, millimeter long multiwalled carbon nanotube arrays

• Pitamber Mahanandia,
• Jörg J. Schneider,
• Martin Engel,
• Bernd Stühn,
• Somanahalli V. Subramanyam and
• Karuna Kar Nanda

Beilstein J. Nanotechnol. 2011, 2, 293–301, doi:10.3762/bjnano.2.34

• the furnace temperature allows us to calculate the activation energy for the CVD synthesis process and was found to be 0.68 eV [29]. It is noteworthy that the activation energy (EA) was reported to be 1.2–1.8 eV for a thermally activated CVD process and significantly lower, at ~0.3 eV, for a plasma

• enhanced CVD process (PECVD) [30]. A higher activation energy indicates that the growth of CNTs is mainly by bulk diffusion, while a lower activation energy is due to a surface diffusion limited process. The calculated value of EA in the CVD process employed herein, suggests that the increase in length is

Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle–substrate chemistry and morphology, and of operating conditions

• Samer Darwich,
• Karine Mougin,
• Akshata Rao,
• Enrico Gnecco,
• Shrisudersan Jayaraman and
• Hamidou Haidara

Beilstein J. Nanotechnol. 2011, 2, 85–98, doi:10.3762/bjnano.2.10

• corresponds to an exponential decay of the dissipated power with T which points to a thermally activated process [44]. The slopes of these linear fits correspond to (ΔEact/kB), where ΔEact represents an activation energy barrier with respect to a reference state E0: ΔEact = (E0−Eact) where Eact(T) is the

• well as a more extensive interpretation. Indeed, we assumed in our treatment (Figure 5b) ideal Arrhenius behavior where the activation energy is independent of the temperature in both systems. This is an assumption which may not be the case for the complex water bridging hydrophilic contact. 4

Kinetic lattice Monte-Carlo simulations on the ordering kinetics of free and supported FePt L1₀-nanoparticles

• Michael Müller and
• Karsten Albe

Beilstein J. Nanotechnol. 2011, 2, 40–46, doi:10.3762/bjnano.2.5

• activation energy of for Pt self-diffusion. As predicted by our Ising-type Hamiltonian, the average formation energy of a vacancy in FePt alloys is 1.8 eV. Therefore, an attempt frequency ν0 = 4 × 1013 s−1 and a migration energy Emig = 1 eV should provide realistic estimates for the present simulations

Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

• Ulf Wiedwald,
• Luyang Han,
• Johannes Biskupek,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2010, 1, 24–47, doi:10.3762/bjnano.1.5