The reactive hydride composite (RHC) LiBH4–MgH2 is regarded as one of the most promising material... more The reactive hydride composite (RHC) LiBH4–MgH2 is regarded as one of the most promising materials for hydrogen storage. Its extensive application is so far limited by its poor dehydrogenation kinetics, due to the hampered nucleation and growth process of MgB2. Nevertheless, the poor kinetics can be improved by additives. This work studied the growth process of MgB2 with varying contents of 3TiCl3AlCl3 as an additive, and combined kinetic measurements, X-ray diffraction (XRD), and advanced transmission electron microscopy (TEM) to develop a structural understanding. It was found that the formation of MgB2 preferentially occurs on TiB2 nanoparticles. The major reason for this is that the elastic strain energy density can be reduced to ~4.7 107 J/m3 by creating an interface between MgB2 and TiB2, as opposed to ~2.9 108 J/m3 at the original interface between MgB2 and Mg. The kinetics of the MgB2 growth was modeled by the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation, describing the kinetics better than other kinetic models. It is suggested that the MgB2 growth rate-controlling step is changed from interface- to diffusioncontrolled when the nucleation center changes from Mg to TiB2. This transition is also reflected in the change of the MgB2 morphology from bar- to platelet-like. Based on our observations, we suggest that an additive content between 2.5 and 5 mol% 3TiCl3AlCl3 results in the best enhancement of the dehydrogenation kinetics.
The hampered kinetics of reactive hydride composites (RHCs) in hydrogen storage and release, whic... more The hampered kinetics of reactive hydride composites (RHCs) in hydrogen storage and release, which limits their use for extensive applications in hydrogen storage S1and energy conversion, can be improved using additives. However, the mechanism of the kinetic restriction and the additive effect on promoting the kinetics have remained unclear. These uncertainties are addressed by utilizing versatile transmission electron microscopy (TEM) on the LiBH4-MgH2 composite under the influence of the 3TiCl3•AlCl3 additives. The formation of the MgB2 phase, as the rate-limiting step, is emphatically studied. According to the observations, the heterogeneous nucleation of MgB2 relies on different nucleation centers (Mg or TiB2 and AlB2). The varied nucleation and growth of MgB2 are related to the in-plane strain energy density at the interface, resulting from the atomic misfit between MgB2 and its nucleation centers. This leads to distinct MgB2 morphologies (bars and platelets) and different performances in the dehydrogenation kinetics of LiBH4-MgH2. It was found that the formation of numerous MgB2 platelets is regarded as the origin of the kinetic improvement. Therefore, to promote dehydrogenation kinetics in comparable RHC systems for hydrogen storage, it is suggested to select additives delivering a small atomic misfit.
In this paper, we introduce our approach in using the web-based application Kadi4Mat (KadiWeb) as... more In this paper, we introduce our approach in using the web-based application Kadi4Mat (KadiWeb) as an electronic laboratory notebook (ELN) combined with an integratedinstrument database to facilitate Findable - Accessible - Interoperable - Reusable (FAIR) research data. Facing transmission electron microscopy (TEM), focused ion beam (FIB), atom probe tomography (APT), or scanning electron microscopy (SEM) tasks, including sample preparation challenges, we developed a strategy to document the complex processes in our user facility KNMFi. To create appropriate records in Kadi4Mat we are comprising one central record for the material/sample to be investigated, a record for the sample preparation, a record for the investigation/experiment, and a record for the data evaluation. Therefore, a set of appropriate templates for the categories ‘sample preparation general,’ ‘sample preparation for TEM,’ ‘Focused Ion Beam and Scanning Electron Microscopy,’ ‘Transmission Electron Microscopy,’ ‘Atom Probe Tomography,’ and ‘Data Evaluation’ was developed in ‘atomistic units.’ The templates can be combined easily and have been designed to be user-friendly, but at the same time requesting the relevant metadata in a structured and standardized way. The documentation process, including MaTeLiS-instrument database, is demonstrated in a use-case with several sample preparation steps and different investigation methods. The developed templates can be exported in JSON-format and might be used as models for other tasks.
ABSTRACT Influence of surface spins on magnetization of maghemite nanoparticles have been studied... more ABSTRACT Influence of surface spins on magnetization of maghemite nanoparticles have been studied by using SQUID measurements and also comparison done with theoretical simulations. Surface spin disorder arises in these nanoparticles due to the randomness of surface spins. A model of AC-susceptibility has been used to investigate the experimental results. The comparison between experiment and theory signifies the presence of large effective anisotropy and freezing effects on the surface of maghemite nanoparticles. The enhanced effective anisotropy constant of these nanoparticles as compared to bulk maghemite is due to presence of disordered surface spins.
ABSTRACTSuperparamagnetic behavior is characterized by a thermally fluctuating vector of magnetiz... more ABSTRACTSuperparamagnetic behavior is characterized by a thermally fluctuating vector of magnetization, leading to magnetization curves free of hysteresis: it is a property of isolated ferrite particles with sizes below ca. 10 nm. These particles fulfil the condition Kv < kT with K … energy of unisotropy, v … volume of the particle, kT has the usual meaning. To produce a superparamagnetic macroscopic part it is necessary to avoid the interaction of the particles. This can be achieved by coating the particles with a second non-magnetic phase. This special material can be synthesized using the microwave plasma process. Because of the specific interaction of charged particles with an oscillating electrical field, microwave plasmas excel in relatively low reaction temperatures. The low reaction temperature and the electrical charging of the particles in the plasma reduce the probability of agglomeration. Therefore, it is possible to pass the gas stream with the as produced particles ...
ABSTRACTThe microwave plasma process is capable to produce larger quantities of nanoparticulate p... more ABSTRACTThe microwave plasma process is capable to produce larger quantities of nanoparticulate powders with mean particle sizes in the range from 5 to 20 nm. The products may be oxides, nitrides, sulphides, selenides, or even metals. Additional, it is possible to coat these particles with a layer of a second ceramic, a polymer or carbon. Sintered ZrO2-Al2O3 nanocomposites and super-paramagnetic cores of γ-Fe2O3-polymer composites are given as examples.
ABSTRACTIn superparamagnetic materials, the change of the direction of the magnetization is not a... more ABSTRACTIn superparamagnetic materials, the change of the direction of the magnetization is not associated with the movement of Bloch walls, but with thermal fluctuation of the magnetization vector. Therefore, the resonance frequency of the Bloch walls is no longer limiting the maximum frequency for applications. The limit found in superparamagnetic materials is given by the frequency of electron spin resonance. This behavior was verified for spinelle type ferrites made of ceramic or polymer coated oxide nanoparticles produced by the microwave plasma process. By selecting the composition of the spinelle type ferrites the energy of magnetic anisotropy controlling the susceptibility and the maximum frequency for applications can be adjusted. Superparamagnetic materials have their frequency limit beyond 2 GHz. Coating of the particles reduces dipole – dipole interaction destroying superparamagnetism. Even when the susceptibility is in the order of magnitude of today's commercial fe...
Nanocrystalline Cr,O, particles were synthesized in a microwave plasma using chromium hexacarbony... more Nanocrystalline Cr,O, particles were synthesized in a microwave plasma using chromium hexacarbonyl as precursor. Electron microscopy revealed that the particle diameter is, depending on the process parameters, in the range from 7 to 9 nm or from 5 to 6 nm. In the case of the larger particles, additionally elongated ones with a diameter from 6 to 7 nm and a length from 10 to 15 nm, were found. The larger particles were found to be single crystals. The smaller particle fraction showed a granular substructure, resembling to a polycrystalline particle. The size of these granules is in the range from 2 to 3 nm. The structure of the material was determined by electron diffraction to be the rhombohedral corundum structure. In the temperature range from 10 to 300 K the magnetic behavior can be described by a modified Langevin function but with a magnetic moment having a thermally activated component. In any event, in this temperature range the assumption Kc < kT is valid, where K is the anisotropy energy and c' the particle volume. The thermally activated magnetization can be attributed to the material with the granular substructure. The size of the magnetic domains was found to be identical with the electronmicroscopically determined size of the granules.
... DV Szab6,* G. H. Campbell,*&amp;#x27; J. Brulely: M. J. Hoffmann? * and M. Ruhle* * ... a... more ... DV Szab6,* G. H. Campbell,*&amp;#x27; J. Brulely: M. J. Hoffmann? * and M. Ruhle* * ... ample is the crystallization of yttrium aluminum garnet,&amp;quot; characterized by thc formation of very large grains, which pass through three-grain pipes and connect many four-grain pockets. ...
Nanoparticulate WO(3) films were prepared using microwave plasma synthesis and studied with respe... more Nanoparticulate WO(3) films were prepared using microwave plasma synthesis and studied with respect to the electrical conductivity in dependence of ambient conditions. The WO(3) films with a monoclinic structure were made from cluster-assembled nanoparticles (diameter 3 nm) by means of dispersion and spin-coating. Above 100 °C a thermally activated decrease of the electrical resistance due to oxygen vacancy donors is found. A reversible increase of the electrical resistance R due to oxygen uptake is observed. The decrease of R in response to reducing H(2)S in the ppm range is studied in dependence of temperature and pre-annealing conditions.
Starting from results from He-pycnometry, electron diffraction, Extended X-ray Absorption Fine St... more Starting from results from He-pycnometry, electron diffraction, Extended X-ray Absorption Fine Structure Spectroscopy and Perturbed Angular Correlation Spectroscopy the phase transformations and structures of zirconia are described. From a comparison of these results with those obtained on other oxide nanoparticles it is concluded that the phases and structure of nanoparticles are different compared to those of coarse-grained material. The difference of the transformation temperature of bare and coated nanoparticles was used to estimate enthalpy and entropy of the tetragonal fi monoclinic transformation for nanoparticulate zirconia. By comparison with results obtained from other nanocrystalline oxides, the following rules were derived: Provided the particles are sufficiently small, particles made of materials showing phase transitions crystallize in the high temperature structure. However, compared to coarse-grained materials of the same structure, the density of nanoparticles is reduced. A first estimation limits this phenomenon to particle sizes well below 10 nm. Those nanoparticles follow the generalized phase diagram postulated by Tammann.
Oxide nanoparticles were used as carrier for organic semiconductor materials. Stable suspensions ... more Oxide nanoparticles were used as carrier for organic semiconductor materials. Stable suspensions of ZrO 2 nanoparticles coated with anthracene, pentacene, or para-hexaphenyl were obtained by microwave plasma synthesis of ZrO 2 cores, subsequent in situ coating with organic compounds, and in situ dispersion in ethylene glycol. Powders of coated oxide nanoparticles were synthesized for comparison. The successful coating and a small uniform size distribution of the ZrO 2 cores were confirmed by comprehensive characterization including photoluminescence, absorption spectroscopy, electron microscopy, electron energy loss spectroscopy, mass spectrometry, and X-ray diffraction. Powder compacts of anthracenecoated ZrO 2 particles showed good air stability and a significant blue shift accompanied by an attenuation of the emission lines at higher vibronic orders in comparison to samples of pure anthracene as received. For para-hexaphenyl-coated nanoparticles, the same photoluminescence characteristics are observed as for pure para-hexaphenyl. In the case of pentacene-coated nanoparticles indication for degradation is found.
Nanocrystalline maghemite, γ–Fe2O3, can be synthesized in a microwave plasma using FeCl3 or Fe3(C... more Nanocrystalline maghemite, γ–Fe2O3, can be synthesized in a microwave plasma using FeCl3 or Fe3(CO)12 as the precursor. Electron microscopy revealed particle sizes in the range of 5 to 10 nm. In general, this material is superparamagnetic. The magnetic properties are strongly dependent on the precursor. In both cases the production process leads to a highly disordered material with the consequence of a low magnetization. The assumption of a disordered structure is also supported by electron energy loss (EEL) and Mössbauer spectroscopy. The structure of this material shows a nearly identical number of cations on tetrahedral and octahedral lattice sites.
The reactive hydride composite (RHC) LiBH4–MgH2 is regarded as one of the most promising material... more The reactive hydride composite (RHC) LiBH4–MgH2 is regarded as one of the most promising materials for hydrogen storage. Its extensive application is so far limited by its poor dehydrogenation kinetics, due to the hampered nucleation and growth process of MgB2. Nevertheless, the poor kinetics can be improved by additives. This work studied the growth process of MgB2 with varying contents of 3TiCl3AlCl3 as an additive, and combined kinetic measurements, X-ray diffraction (XRD), and advanced transmission electron microscopy (TEM) to develop a structural understanding. It was found that the formation of MgB2 preferentially occurs on TiB2 nanoparticles. The major reason for this is that the elastic strain energy density can be reduced to ~4.7 107 J/m3 by creating an interface between MgB2 and TiB2, as opposed to ~2.9 108 J/m3 at the original interface between MgB2 and Mg. The kinetics of the MgB2 growth was modeled by the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation, describing the kinetics better than other kinetic models. It is suggested that the MgB2 growth rate-controlling step is changed from interface- to diffusioncontrolled when the nucleation center changes from Mg to TiB2. This transition is also reflected in the change of the MgB2 morphology from bar- to platelet-like. Based on our observations, we suggest that an additive content between 2.5 and 5 mol% 3TiCl3AlCl3 results in the best enhancement of the dehydrogenation kinetics.
The hampered kinetics of reactive hydride composites (RHCs) in hydrogen storage and release, whic... more The hampered kinetics of reactive hydride composites (RHCs) in hydrogen storage and release, which limits their use for extensive applications in hydrogen storage S1and energy conversion, can be improved using additives. However, the mechanism of the kinetic restriction and the additive effect on promoting the kinetics have remained unclear. These uncertainties are addressed by utilizing versatile transmission electron microscopy (TEM) on the LiBH4-MgH2 composite under the influence of the 3TiCl3•AlCl3 additives. The formation of the MgB2 phase, as the rate-limiting step, is emphatically studied. According to the observations, the heterogeneous nucleation of MgB2 relies on different nucleation centers (Mg or TiB2 and AlB2). The varied nucleation and growth of MgB2 are related to the in-plane strain energy density at the interface, resulting from the atomic misfit between MgB2 and its nucleation centers. This leads to distinct MgB2 morphologies (bars and platelets) and different performances in the dehydrogenation kinetics of LiBH4-MgH2. It was found that the formation of numerous MgB2 platelets is regarded as the origin of the kinetic improvement. Therefore, to promote dehydrogenation kinetics in comparable RHC systems for hydrogen storage, it is suggested to select additives delivering a small atomic misfit.
In this paper, we introduce our approach in using the web-based application Kadi4Mat (KadiWeb) as... more In this paper, we introduce our approach in using the web-based application Kadi4Mat (KadiWeb) as an electronic laboratory notebook (ELN) combined with an integratedinstrument database to facilitate Findable - Accessible - Interoperable - Reusable (FAIR) research data. Facing transmission electron microscopy (TEM), focused ion beam (FIB), atom probe tomography (APT), or scanning electron microscopy (SEM) tasks, including sample preparation challenges, we developed a strategy to document the complex processes in our user facility KNMFi. To create appropriate records in Kadi4Mat we are comprising one central record for the material/sample to be investigated, a record for the sample preparation, a record for the investigation/experiment, and a record for the data evaluation. Therefore, a set of appropriate templates for the categories ‘sample preparation general,’ ‘sample preparation for TEM,’ ‘Focused Ion Beam and Scanning Electron Microscopy,’ ‘Transmission Electron Microscopy,’ ‘Atom Probe Tomography,’ and ‘Data Evaluation’ was developed in ‘atomistic units.’ The templates can be combined easily and have been designed to be user-friendly, but at the same time requesting the relevant metadata in a structured and standardized way. The documentation process, including MaTeLiS-instrument database, is demonstrated in a use-case with several sample preparation steps and different investigation methods. The developed templates can be exported in JSON-format and might be used as models for other tasks.
ABSTRACT Influence of surface spins on magnetization of maghemite nanoparticles have been studied... more ABSTRACT Influence of surface spins on magnetization of maghemite nanoparticles have been studied by using SQUID measurements and also comparison done with theoretical simulations. Surface spin disorder arises in these nanoparticles due to the randomness of surface spins. A model of AC-susceptibility has been used to investigate the experimental results. The comparison between experiment and theory signifies the presence of large effective anisotropy and freezing effects on the surface of maghemite nanoparticles. The enhanced effective anisotropy constant of these nanoparticles as compared to bulk maghemite is due to presence of disordered surface spins.
ABSTRACTSuperparamagnetic behavior is characterized by a thermally fluctuating vector of magnetiz... more ABSTRACTSuperparamagnetic behavior is characterized by a thermally fluctuating vector of magnetization, leading to magnetization curves free of hysteresis: it is a property of isolated ferrite particles with sizes below ca. 10 nm. These particles fulfil the condition Kv < kT with K … energy of unisotropy, v … volume of the particle, kT has the usual meaning. To produce a superparamagnetic macroscopic part it is necessary to avoid the interaction of the particles. This can be achieved by coating the particles with a second non-magnetic phase. This special material can be synthesized using the microwave plasma process. Because of the specific interaction of charged particles with an oscillating electrical field, microwave plasmas excel in relatively low reaction temperatures. The low reaction temperature and the electrical charging of the particles in the plasma reduce the probability of agglomeration. Therefore, it is possible to pass the gas stream with the as produced particles ...
ABSTRACTThe microwave plasma process is capable to produce larger quantities of nanoparticulate p... more ABSTRACTThe microwave plasma process is capable to produce larger quantities of nanoparticulate powders with mean particle sizes in the range from 5 to 20 nm. The products may be oxides, nitrides, sulphides, selenides, or even metals. Additional, it is possible to coat these particles with a layer of a second ceramic, a polymer or carbon. Sintered ZrO2-Al2O3 nanocomposites and super-paramagnetic cores of γ-Fe2O3-polymer composites are given as examples.
ABSTRACTIn superparamagnetic materials, the change of the direction of the magnetization is not a... more ABSTRACTIn superparamagnetic materials, the change of the direction of the magnetization is not associated with the movement of Bloch walls, but with thermal fluctuation of the magnetization vector. Therefore, the resonance frequency of the Bloch walls is no longer limiting the maximum frequency for applications. The limit found in superparamagnetic materials is given by the frequency of electron spin resonance. This behavior was verified for spinelle type ferrites made of ceramic or polymer coated oxide nanoparticles produced by the microwave plasma process. By selecting the composition of the spinelle type ferrites the energy of magnetic anisotropy controlling the susceptibility and the maximum frequency for applications can be adjusted. Superparamagnetic materials have their frequency limit beyond 2 GHz. Coating of the particles reduces dipole – dipole interaction destroying superparamagnetism. Even when the susceptibility is in the order of magnitude of today's commercial fe...
Nanocrystalline Cr,O, particles were synthesized in a microwave plasma using chromium hexacarbony... more Nanocrystalline Cr,O, particles were synthesized in a microwave plasma using chromium hexacarbonyl as precursor. Electron microscopy revealed that the particle diameter is, depending on the process parameters, in the range from 7 to 9 nm or from 5 to 6 nm. In the case of the larger particles, additionally elongated ones with a diameter from 6 to 7 nm and a length from 10 to 15 nm, were found. The larger particles were found to be single crystals. The smaller particle fraction showed a granular substructure, resembling to a polycrystalline particle. The size of these granules is in the range from 2 to 3 nm. The structure of the material was determined by electron diffraction to be the rhombohedral corundum structure. In the temperature range from 10 to 300 K the magnetic behavior can be described by a modified Langevin function but with a magnetic moment having a thermally activated component. In any event, in this temperature range the assumption Kc < kT is valid, where K is the anisotropy energy and c' the particle volume. The thermally activated magnetization can be attributed to the material with the granular substructure. The size of the magnetic domains was found to be identical with the electronmicroscopically determined size of the granules.
... DV Szab6,* G. H. Campbell,*&amp;#x27; J. Brulely: M. J. Hoffmann? * and M. Ruhle* * ... a... more ... DV Szab6,* G. H. Campbell,*&amp;#x27; J. Brulely: M. J. Hoffmann? * and M. Ruhle* * ... ample is the crystallization of yttrium aluminum garnet,&amp;quot; characterized by thc formation of very large grains, which pass through three-grain pipes and connect many four-grain pockets. ...
Nanoparticulate WO(3) films were prepared using microwave plasma synthesis and studied with respe... more Nanoparticulate WO(3) films were prepared using microwave plasma synthesis and studied with respect to the electrical conductivity in dependence of ambient conditions. The WO(3) films with a monoclinic structure were made from cluster-assembled nanoparticles (diameter 3 nm) by means of dispersion and spin-coating. Above 100 °C a thermally activated decrease of the electrical resistance due to oxygen vacancy donors is found. A reversible increase of the electrical resistance R due to oxygen uptake is observed. The decrease of R in response to reducing H(2)S in the ppm range is studied in dependence of temperature and pre-annealing conditions.
Starting from results from He-pycnometry, electron diffraction, Extended X-ray Absorption Fine St... more Starting from results from He-pycnometry, electron diffraction, Extended X-ray Absorption Fine Structure Spectroscopy and Perturbed Angular Correlation Spectroscopy the phase transformations and structures of zirconia are described. From a comparison of these results with those obtained on other oxide nanoparticles it is concluded that the phases and structure of nanoparticles are different compared to those of coarse-grained material. The difference of the transformation temperature of bare and coated nanoparticles was used to estimate enthalpy and entropy of the tetragonal fi monoclinic transformation for nanoparticulate zirconia. By comparison with results obtained from other nanocrystalline oxides, the following rules were derived: Provided the particles are sufficiently small, particles made of materials showing phase transitions crystallize in the high temperature structure. However, compared to coarse-grained materials of the same structure, the density of nanoparticles is reduced. A first estimation limits this phenomenon to particle sizes well below 10 nm. Those nanoparticles follow the generalized phase diagram postulated by Tammann.
Oxide nanoparticles were used as carrier for organic semiconductor materials. Stable suspensions ... more Oxide nanoparticles were used as carrier for organic semiconductor materials. Stable suspensions of ZrO 2 nanoparticles coated with anthracene, pentacene, or para-hexaphenyl were obtained by microwave plasma synthesis of ZrO 2 cores, subsequent in situ coating with organic compounds, and in situ dispersion in ethylene glycol. Powders of coated oxide nanoparticles were synthesized for comparison. The successful coating and a small uniform size distribution of the ZrO 2 cores were confirmed by comprehensive characterization including photoluminescence, absorption spectroscopy, electron microscopy, electron energy loss spectroscopy, mass spectrometry, and X-ray diffraction. Powder compacts of anthracenecoated ZrO 2 particles showed good air stability and a significant blue shift accompanied by an attenuation of the emission lines at higher vibronic orders in comparison to samples of pure anthracene as received. For para-hexaphenyl-coated nanoparticles, the same photoluminescence characteristics are observed as for pure para-hexaphenyl. In the case of pentacene-coated nanoparticles indication for degradation is found.
Nanocrystalline maghemite, γ–Fe2O3, can be synthesized in a microwave plasma using FeCl3 or Fe3(C... more Nanocrystalline maghemite, γ–Fe2O3, can be synthesized in a microwave plasma using FeCl3 or Fe3(CO)12 as the precursor. Electron microscopy revealed particle sizes in the range of 5 to 10 nm. In general, this material is superparamagnetic. The magnetic properties are strongly dependent on the precursor. In both cases the production process leads to a highly disordered material with the consequence of a low magnetization. The assumption of a disordered structure is also supported by electron energy loss (EEL) and Mössbauer spectroscopy. The structure of this material shows a nearly identical number of cations on tetrahedral and octahedral lattice sites.
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Papers by D. V Szabó
the poor kinetics can be improved by additives. This work studied the growth process of MgB2 with varying contents of 3TiCl3AlCl3 as an additive, and combined kinetic measurements, X-ray diffraction (XRD), and advanced transmission electron microscopy (TEM) to develop a structural
understanding. It was found that the formation of MgB2 preferentially occurs on TiB2 nanoparticles. The major reason for this is that the elastic strain energy density can be reduced to ~4.7 107 J/m3 by creating an interface between MgB2 and TiB2, as opposed to ~2.9 108 J/m3 at the original interface between MgB2 and Mg. The kinetics of the MgB2 growth was modeled by the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation, describing the kinetics better than other kinetic models.
It is suggested that the MgB2 growth rate-controlling step is changed from interface- to diffusioncontrolled when the nucleation center changes from Mg to TiB2. This transition is also reflected in the change of the MgB2 morphology from bar- to platelet-like. Based on our observations, we suggest that an additive content between 2.5 and 5 mol% 3TiCl3AlCl3 results in the best enhancement of the dehydrogenation kinetics.
atom probe tomography (APT), or scanning electron microscopy (SEM) tasks, including sample preparation challenges, we developed a strategy to document the complex processes in our user facility KNMFi. To create appropriate records in Kadi4Mat we are comprising one central record for the material/sample to be investigated, a record for the sample preparation, a record for the investigation/experiment, and a record
for the data evaluation. Therefore, a set of appropriate templates for the categories ‘sample preparation general,’ ‘sample preparation for TEM,’ ‘Focused Ion Beam and Scanning Electron Microscopy,’ ‘Transmission Electron Microscopy,’ ‘Atom Probe Tomography,’ and ‘Data Evaluation’ was developed in ‘atomistic units.’ The templates can be combined easily and have been designed to be user-friendly, but at the same time requesting the relevant metadata in a structured and standardized way. The
documentation process, including MaTeLiS-instrument database, is demonstrated in a use-case with several sample preparation steps and different investigation methods. The developed templates can be exported in JSON-format and might be used as models for other tasks.
the poor kinetics can be improved by additives. This work studied the growth process of MgB2 with varying contents of 3TiCl3AlCl3 as an additive, and combined kinetic measurements, X-ray diffraction (XRD), and advanced transmission electron microscopy (TEM) to develop a structural
understanding. It was found that the formation of MgB2 preferentially occurs on TiB2 nanoparticles. The major reason for this is that the elastic strain energy density can be reduced to ~4.7 107 J/m3 by creating an interface between MgB2 and TiB2, as opposed to ~2.9 108 J/m3 at the original interface between MgB2 and Mg. The kinetics of the MgB2 growth was modeled by the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation, describing the kinetics better than other kinetic models.
It is suggested that the MgB2 growth rate-controlling step is changed from interface- to diffusioncontrolled when the nucleation center changes from Mg to TiB2. This transition is also reflected in the change of the MgB2 morphology from bar- to platelet-like. Based on our observations, we suggest that an additive content between 2.5 and 5 mol% 3TiCl3AlCl3 results in the best enhancement of the dehydrogenation kinetics.
atom probe tomography (APT), or scanning electron microscopy (SEM) tasks, including sample preparation challenges, we developed a strategy to document the complex processes in our user facility KNMFi. To create appropriate records in Kadi4Mat we are comprising one central record for the material/sample to be investigated, a record for the sample preparation, a record for the investigation/experiment, and a record
for the data evaluation. Therefore, a set of appropriate templates for the categories ‘sample preparation general,’ ‘sample preparation for TEM,’ ‘Focused Ion Beam and Scanning Electron Microscopy,’ ‘Transmission Electron Microscopy,’ ‘Atom Probe Tomography,’ and ‘Data Evaluation’ was developed in ‘atomistic units.’ The templates can be combined easily and have been designed to be user-friendly, but at the same time requesting the relevant metadata in a structured and standardized way. The
documentation process, including MaTeLiS-instrument database, is demonstrated in a use-case with several sample preparation steps and different investigation methods. The developed templates can be exported in JSON-format and might be used as models for other tasks.