Search

Your search keyword '"Bovin, J.-O."' showing total 135 results
Start Over Author "Bovin, J.-O."
135 results on '"Bovin, J.-O."'

3. Structure-Activity relationship in HC-SCR of NO2 by TEM, O2-chemisorption, and EDXS study of Ag/Al2O3

Author

Arve, K., Svennerberg, K., Klingstedt, F., Eranen, K., Wallenberg, L.R., Bovin, J.-O., Capek, L., and Marzin, Yu. D.

Subjects
Silver compounds -- Electric properties, Aluminum oxide -- Electric properties, Chemicals, plastics and rubber industries
Abstract

The difference in mean particle sizes (MPS), particle size distribution and dispersion for four fresh Ag/Al2O3 catalysts with different metal loadings were determined by means of HRTEM, high angle annular dark field (HAADF), O2-chemisorption and X-ray energy dispersive spectroscopy (EDXS). The MPS values determined by HRTEM resulted in increasing MPS value with increasing metal loading as expected.

Published
2006

13. Dynamic atomic-level rearrangements in small gold particles

Author

Smith, David J., Petford-Long, Amanda K., Wallenberg, L.R., and Bovin, J.-O.

Subjects
Electron microscopy -- Research, Gold -- Research, Metallography -- Research, Science and technology, Research
Abstract

Dynamic Atomic-Level Rearrangements in Small Gold Particles DEVELOPMENT IN INSTRUMENTATION for the high-resolution electron microscope (HREM) have facilitated the observation and recording of dynamic events at the atomic level directly [...]

Published
1986

38. The structure of an iron oxide cluster incorporated into zeolite Y, determined by HRTEM and SAED.

Author

Carlsson, A., Karlsson, G., Bovin, J.-O., Oku, T., Okamoto, Y., Ohnishi, N., and Terasaki, O.

Abstract

The atom positions of an iron cluster (Fe6O n) inside the framework of a zeolite (FAU, Na48(Fe2O3)38Al48Si144O384) were determined through the use of electron crystallography methods for three-dimensional reconstruction of atomic positions within the cluster from high-resolution electron micrographs and selected-area electron diffraction. The iron-containing FAU structure was determined in the space group Fd3m ( a=24.7 Å) by the use of 42 unique reflections. The Fe6O n molecule is situated in the sodalite cage with the iron atoms facing the square windows of the cage. The iron–iron distance is 3.6 Å and the distances between iron atoms and the nearest oxygen atoms in the sodalite cage are close to 2.2 Å. As a verification of the method, the same technique was used for the dermination of the structure of Na48Al48Si144O384 without iron, and the Si/Al atom positions of the zeolite framework were found to coincide with those determined from single crystal X-ray diffraction methods. [ABSTRACT FROM AUTHOR]

Published
2000
Full Text
View/download PDF

39. Characterization of III-V semiconductor nanoparticles using TEM techniques.

Author

Malm, J.-O., Svensson, C., Magnusson, M.H., Deppert, K., Bovin, J.-O., and Samuelson, L.

Abstract

Nanoparticles of GaAs and InP have been prepared by aerosol techniques and characterized by electron microscopy methods. Through variation of the reaction temperature, it has been possible to follow how the reaction proceeds when the group-III aerosol reacts with the group-V precursor to form III-V semiconductor nanoparticles. The reaction can be followed both by the measurement of the change in particle size and the determination of the increase in the group-V element content in the particles. [ABSTRACT FROM AUTHOR]

Published
2000
Full Text
View/download PDF

41. Structure, Luminescence, and Dynamics of Eu<INF>2</INF>O<INF>3</INF> Nanoparticles in MCM-41

Author

Chen, W., Joly, A. G., Kowalchuk, C. M., Malm, J.-O., Huang, Y., and Bovin, J.-O.

Abstract

The structure, luminescence spectroscopy, and lifetime decay dynamics of Eu2O3 nanoparticles formed in MCM-41 have been investigated. Both X-ray diffraction and high-resolution transmission electron microscopic observations indicate that Eu2O3 nanoparticles of monoclinic structure are formed inside channels of MCM-41 by heating at 140 °C. However, heat treatment at 600 or 700 °C causes migration of Eu2O3 from the MCM-41 channels, forming nanoparticles of cubic structure outside the MCM-41 channels. After heating to 900 °C, some of the cubic Eu2O3 particles change to monoclinic Eu2O3, and the MCM-41 structure breaks down and a different or disordered phase is formed. The feature of the hypersensitive 5D0 → 7F2 emission profile of Eu3+ is used to follow the structural changes. In the luminescence spectrum of the sample prepared at 140 °C, the emission spectrum is dominated by peaks at 615 and 623 nm, while in the other samples a peak at 612 nm is prevalent. Photoluminescence lifetimes show the existence of short (&lt;1 μs) and long (microsecond to millisecond) components for each sample. The fast decay is attributed to quenching by surface states of the nanoparticles or energy transfer to the MCM-41, while the longer time decays show the effects of concentration quenching. The monoclinic sample prepared at 140 °C shows a higher luminescence intensity than the cubic samples or the bulk powder. These observations indicate that MCM-41 as a template can be used for making and stabilizing monoclinic rare earth oxides, which normally are stable only at high temperatures and high pressures. More importantly, the nanophase Eu2O3/MCM-41 composite materials formed at low temperatures might represent a new type of efficient luminescence material with fast response, with potential applications in lighting and displays.

Published
2002
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results