Passivation of Ge Nanocrystals in SiO2

2005 ◽  
Vol 108-109 ◽  
pp. 33-38 ◽  
Author(s):  
Jesper Skov Jensen ◽  
Tom P. Leervad Pedersen ◽  
Rui Pereira ◽  
Pia Bomholt ◽  
Jacques Chevallier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Paramagnetic Resonance ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Potential Applications ◽  
Electron Paramagnetic ◽  
Ge Nanocrystals

Nanocrystals have attracted considerable attention in recent years because of their potential applications as a light source in Si technology. From theory Ge nanocrystals are expected to have better luminescence properties than Si nanocrystals. In this study we have compared Ge nanocrystals produced both in PE-CVD deposited and magnetron sputtered SiO2 doped with Ge during deposition to concentrations between 3-9 at.%, followed by high temperature treatment at temperatures between 600 and 1100°C. The nanocrystals were structurally characterized by Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR). The interface of the nanocrystals was passivated by use of alnealing, while the effect of the passivation was monitored by photoluminescence (PL)

Study on Electrospun-Membrane-Based Filter to Rapidly Remove Reactive Yellow 2 from Wastewater

2013 ◽  
Vol 726-731 ◽  
pp. 707-711
Author(s):  
Wen Peng Zhang ◽  
Da Yong Wu ◽  
Ya Kun Wang
Keyword(s):  
Electron Microscopy ◽  
Mesoporous Silica ◽  
Adsorption Capacity ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Electrospun Membrane ◽  
Transmission Electron ◽  
Prepared Material

Uniform highly ordered mesoporous silica nanofiber membrane was successfully prepared onto copper mesh via coaxial electrospinning combining with the solvent evaporation and extraction induced surfactant assembly process. After a high temperature treatment and amination, it was employed to remove reactive yellow 2 (RY2) in wastewater showing remarkable adsorption capacity. The maximum adsorption capacity can reach up to 371.7 mg/g. The structural properties of synthesized mesoporous silica were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectrum (FTIR). And the adsorption behavior of prepared material was analyzed through three kinds of isotherm models.

scholarly journals Influence of Conditioning Temperature on Defects in the Double Al2O3/ZnO Layer Deposited by the ALD Method

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1038
Author(s):  
Katarzyna Gawlińska-Nęcek ◽  
Mateusz Wlazło ◽  
Robert Socha ◽  
Ireneusz Stefaniuk ◽  
Łukasz Major ◽  
...  
Keyword(s):  
High Temperature ◽  
Photoelectron Spectroscopy ◽  
Atomic Layer ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Defect States ◽  
Paramagnetic Resonance ◽  
Transmission Electron ◽  
Conditioning Temperature ◽  
Defects Analysis

In this work, we present the results of defects analysis concerning ZnO and Al2O3 layers deposited by atomic layer deposition (ALD) technique. The analysis was performed by the X-band electron paramagnetic resonance (EPR) spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) methods. The layers were either tested as-deposited or after 30 min heating at 300 °C and 450 °C in Ar atmosphere. TEM and XPS investigations revealed amorphous nature and non-stoichiometry of aluminum oxide even after additional high-temperature treatment. EPR confirmed high number of defect states in Al2O3. For ZnO, we found the as-deposited layer shows ultrafine grains that start to grow when high temperature is applied and that their crystallinity is also improved, resulting in good agreement with XPS results which indicated lower number of defects on the layer surface.

scholarly journals Mineral-polymer composites based on hydroxyapatite with polyvynylpyrrolidon for medicine

2019 ◽  
Vol 487 (3) ◽  
pp. 270-274
Author(s):  
I. V. Fadeeva ◽  
F. I. Grabovenko ◽  
A. S. Fomin ◽  
S. M. Barinov ◽  
F. F. Murzakhanov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Epr Spectroscopy ◽  
Coherent Scattering ◽  
Coherent Scattering Region ◽  
Paramagnetic Resonance ◽  
Transmission Electron ◽  
Electron Paramagnetic ◽  
Photoinduced Epr

Composites of hydroxyapatite (HA) with polyvinylpyrrolidone (PVP) were synthesized by precipitation in water solutions, mass relations of HA/PVP varied in region 3,6-14,5. The composite materials were investigated using XRD, IR, electron paramagnetic resonance (EPR) spectroscopy and transmission electron microscopy (TEM). Based on the TEM results it was found that during calcination of composites at 400 °C small agglomerates consisting of individual crystalline HA particles were formed, resulting in a particle size (according to TEM) slightly larger than coherent scattering region. Using the method of photoinduced EPR spectroscopy confirmed the presence of interaction between HA and PVP. The resulting composites can be used as materials for reconstructive surgery.

Synthesis, structure, and magnetic properties of iron-oxide nanowires

2006 ◽  
Vol 21 (11) ◽  
pp. 2955-2962 ◽  
Author(s):  
Matej Pregelj ◽  
Polona Umek ◽  
Boštjan Drolc ◽  
Boštjan Jančar ◽  
Zvonko Jagličič ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Iron Oxide ◽  
Quantum Interference ◽  
Superconducting Quantum Interference Device ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Oxide Nanowires ◽  
Transmission Electron ◽  
Electron Paramagnetic

Iron-oxide nanowires were synthesized by a hydrothermal treatment of Fe(OH)3 dispersion in NaOH. The obtained materials were first structurally investigated by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, and thermogravimetric analysis techniques. Their magnetic properties were then examined by superconducting quantum interference device and electron paramagnetic resonance methods. A typical nanowire measured 10–15 nm in diameter and 600 nm in length. All the structural and magnetic investigations were consistent with the nanowire goethite structure. The nanowire Neél transition temperature occurred at 375 K; i.e., it was lowered by 25 K with respect to the corresponding goethite bulk value. The shift in the ordering temperature was suggested to be a consequence of a growing importance of strains and surface effects at the nanoscale. We were also able to irreversibly convert goethite nanowires into hematite, by warming the sample to temperatures exceeding 530 K.

scholarly journals A study of radicals in industrial raw cristobalite powders

2021 ◽  
Vol 48 (2) ◽  
Author(s):  
Francesco Di Benedetto ◽  
Andrea Giaccherini ◽  
Maurizio Romanelli ◽  
Giordano Montegrossi ◽  
Elena Belluso ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Raw Materials ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Energy Dispersive Microanalysis ◽  
Structural Coherence ◽  
Artificial Stone ◽  
Electron Paramagnetic

AbstractWe report the results of an experimental multianalytical characterisation of industrial cristobalite powders, used as raw materials for artificial stone production. Cristobalite is considered a serious threat to human health. The study was carried out through X-ray diffraction (XRD), scanning electron microscopy with energy dispersive microanalysis (SEM/EDS), continuous-wave (cw) and pulse electron paramagnetic resonance (EPR) spectroscopy. Our results point out a sub-micrometric size of the structural coherence in cristobalite, associated with numerous stacking defects. Moreover, the material was found characterised by the presence of superoxide radicals, whose persistence appears conceivably long. Radicals in a material synthesized through a high-temperature treatment were generated during the grinding step in the industrial production of cristobalite. During this process, in fact, both superoxide generation and structural defectivity are induced. Indeed, cristobalite powders already result activated by a radical population, before any kind of process in artificial stone production.

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