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Electron diffraction patterns from thin amorphous films of SnO2
Abstracts ~,~ l'he Scandinavian Society .for Electron Microscopy
ELECTRON MI2ROSCOPY OF ZEOLITES P. Skjerpe, M. St~cker* and K. P. Lillerud** Department of Physics, University of Oslo, ~Center for Industrial Research, Oslo; **Department of Chemistry, University of Oslo
Zeolites have considerable interest within the field of catalysis. In order to characterize these catalysts, TEM is necessary to describe the microstructure and crystal defects on a fine scale. In the present work, the zeolite ericnite (hexagonal a=13.2~ and c=14.8~) was studied. In order to obtain stable specimens for TEM work, erionite samples were dealuminized four times and finally the powder was dispersed on holey carbon films. Additional stabilization was attempted by keeping the specimen in vacuum prior to TEM observation. Erionite crystals were often plate-shaped and selected area diffraction showed their c/a ratio to be somewhat different compared to the ideal structure. Streaking effects parallel to the c-axis were commonly observed, indicating the presence of faults on {OOO1}. HREM observation and recording at iOO,OO0 X was possible before disintegration of the structural framework took place. Images were recorded mainly in the [lO10] projection. Image simulations for HREM were carried out using the multislice method.
AI20 3 and TiN on, since they are not affected by the high temperature. Cemented carbides are used for wear parts and for metal cutting applications and by applying a thin layer (5-10 ~m) of the above mentioned coatings, the wear resistance can be increased further. In the present work very thin combined TiC-AI203 coatings have been produced using the conventional CVD hot wall deposition technique. The aim was to examine the coatings concerning the morphology and composition and to study the nucleation and growth. The main method for the microanalysis has been AEM. For the analysis very sharp needle-shaped specimens have been used. They are very suitable for studies of the early growth stages of the coatings since they can be used directly after deposition without any further specimen preparation. Composition depth profiles ubtaine~ by EDS are presented and also compared with results from atom probe analyses from the same specimens. Different types of abnormal growth of coatings is also presented. Coated cutting tool inserts have been examined by scanning Auger microscopy (S~4.~). These inserts were also used for preparing thin foils £or AEM. Two different specimen preparation techniques were used. One was Dy electropolishing the specimen until the coating was detached from the substrate and the other was by using a dimpler and ion-beam thinning.
THE FIRST STAGES OF GROWTH OF WEARRESISTANT COATINGS ON CEMENTED CARBIDES
ELECTRON DIFFRACTION PATTERNS FROM ~HIN AMORPHOUS FILMS OF SnO 2
J. Skogsmo and H. Nord6n
E. S@rbr~den and J. Taft@*
Department of Physics, Chalmers University of Technology, S-412 96 G~teborg, Sweden
Chemical vapour deposition (CVD) is a method by which a thin uniform coating can be applied with a very good adherence on many different types of substrates. The deposition is usually per~ o ~ m ~ at reduced pressure and = ~ v ~ d temperature, around lO00°C, which puts some requirements on the substrates. Tool steels, for example, are not so well suited since they have to be quenched after coating, which is rather complicated and easily causes the coating to crack and peel off. Cemented carbide of the WC-Co type is perfect to deposit coatings of TiC,
77
Department of Physics, Universlty of Oslo, Blindern, Oslo 3, Norway; ~Norsk Hydro Research Centre, 3 9 0 1 P o r s g r u n n , Norway
Electron diffraction offers several advantages in structure studies of amorphous films. Often only thin films, of 1 um or less, are available, which may techniques. High precision in determination of interatomic distances will be possible if the high s = 4~sinS/1 values can be exploited: In an electron microscope operating at 200 kV s = 40 ~-i at the maximum diffraction angle of 9° (JEM 2OOOFX). On the other hand multiple scattering may complicate the interpretation if quantitative comparison of
Abstracts of The Scandinavian Society for Electron Microscopy
78
intensities is sought. Diffraction data from thin amorphous films of SnO 2 have been recorded in JEM 2OOCX and JEM 2OOOFX microscopes, using microphotometer traces of photographic films as well as a STEM detector combined with the ASD deflection system. Patterns are also obtained in a gas electron diffraction apparatus with a rotating sector, operating at 38 kV. The diffuse ring patterns which extend out to s = 20 R-I can be interpreted in terms of a local atomic arrangement similar to crystalline u-SnO 2. ELECTRON ENERGY LOSS SPECTROSCOPY AND SYNCHROTRON RADIATION: A COMPARISON J. Taft~ Research Centre, Norsk 3901Porsgrunn, Norway
Hydro,
Electron energy loss spectroscopy (EELS) with a (S)TEM and X-ray absorption with a synchrotron are closely related techniques to study the composition and structure of matter. T]~ese two techniques are based on %h~ ~ , ~ physical phenomenon, namely the ejecuion of an inner shell electron by the incident electron (or X-ray). The ejected electron which thus becomes a photoelectron interacts with the surrounding atoms, giving rise to structure above the absorption edge, i.e., X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) when X-rays are used. Similarly in EELS we observe electron energy loss near edge structure (ELNES) and extended energy loss fine structure (EXELFS). In other respects the two techniques are complementary. EELS is best suited in the low energy region (energy loss from 0-2.5 keY) where the absorption edges of the important elements carbon, nitrogen and oxygen are located. Synchrotron X-ray absorption is superior in the high energy region (above 2.5 keV)° The merits of the two techniques a~e discussed with some emphasis on spatial resolution, and surface and interface sensitivity. TEXTURAL AND GEOCHEMICAL CHANGES RESULTING FROM ALTERATION (PALAGONITIZATION) OF BASIC VOLCANIC GLASSES: APPLICATION OF SEM AND MICROPROBE ANALYSES
Ingunn Hindenes Thorseth, and Ole Tumyr Geologisk 1 Bergen
Institutt,
Harald F u m e s
Avd.
A. Univ.
Basic volcanic glasses alter to palagonite, given aqueous conditions. A SEM and microprobe study of fresh basalt and basaltic andesite glasses and associated palagonites, all from Icelandic hyaloclastites, have been carried out. The microprobe analyses of palagonite give highly variable results with respect to all oxides, and the total sums of individual analyses vary between less than 50% to more than 90%. Even though palagonite may be considered as a hydrated glass from which major elements predominantly have been lost, and H20 gained, relative to the fresh parental glass, itisdoubtful, however, on the basis of this study, that H20 alone can compensate for the generally low and variable totals of the microprobe analyses. The SEM studies reveal that palagonite consists of a spongy material, in which the empty pores are usually much less than 1 micron in .diameter, and with a variable spacing between the pores. The vaz!ation in the ' percentage of pores, presumably a function of the degree of alteration, may account for the pronounced variations in the absolute concentrations of oxides and their total sums. Thus, when considering the texture of palagonite, previously suggested relationships of progressive loss of elements with decreasing totals may, to some extent (as yet unspecified),be in error. MICROANALYSIS AND IMAGE ANALYSIS IN METALLURGICAL APPLICATIONS T. Thorvaldsson R & D Centre, AB S a n d v i k S-811
81 Sandviken,
Steel, Sweden
Image analysis has shown great potential in electron microscopy, especially in combination with microanalysis. Although image analysis has been extensiw ~ ely used for some time for the characterizatio!a of inclusions in metals, it has only :recently been used in the metal industry for research and development. Mechanical, corrosion and magnetic properties are highly sensitive to the
ELECTRON MI2ROSCOPY OF ZEOLITES P. Skjerpe, M. St~cker* and K. P. Lillerud** Department of Physics, University of Oslo, ~Center for Industrial Research, Oslo; **Department of Chemistry, University of Oslo
Zeolites have considerable interest within the field of catalysis. In order to characterize these catalysts, TEM is necessary to describe the microstructure and crystal defects on a fine scale. In the present work, the zeolite ericnite (hexagonal a=13.2~ and c=14.8~) was studied. In order to obtain stable specimens for TEM work, erionite samples were dealuminized four times and finally the powder was dispersed on holey carbon films. Additional stabilization was attempted by keeping the specimen in vacuum prior to TEM observation. Erionite crystals were often plate-shaped and selected area diffraction showed their c/a ratio to be somewhat different compared to the ideal structure. Streaking effects parallel to the c-axis were commonly observed, indicating the presence of faults on {OOO1}. HREM observation and recording at iOO,OO0 X was possible before disintegration of the structural framework took place. Images were recorded mainly in the [lO10] projection. Image simulations for HREM were carried out using the multislice method.
AI20 3 and TiN on, since they are not affected by the high temperature. Cemented carbides are used for wear parts and for metal cutting applications and by applying a thin layer (5-10 ~m) of the above mentioned coatings, the wear resistance can be increased further. In the present work very thin combined TiC-AI203 coatings have been produced using the conventional CVD hot wall deposition technique. The aim was to examine the coatings concerning the morphology and composition and to study the nucleation and growth. The main method for the microanalysis has been AEM. For the analysis very sharp needle-shaped specimens have been used. They are very suitable for studies of the early growth stages of the coatings since they can be used directly after deposition without any further specimen preparation. Composition depth profiles ubtaine~ by EDS are presented and also compared with results from atom probe analyses from the same specimens. Different types of abnormal growth of coatings is also presented. Coated cutting tool inserts have been examined by scanning Auger microscopy (S~4.~). These inserts were also used for preparing thin foils £or AEM. Two different specimen preparation techniques were used. One was Dy electropolishing the specimen until the coating was detached from the substrate and the other was by using a dimpler and ion-beam thinning.
THE FIRST STAGES OF GROWTH OF WEARRESISTANT COATINGS ON CEMENTED CARBIDES
ELECTRON DIFFRACTION PATTERNS FROM ~HIN AMORPHOUS FILMS OF SnO 2
J. Skogsmo and H. Nord6n
E. S@rbr~den and J. Taft@*
Department of Physics, Chalmers University of Technology, S-412 96 G~teborg, Sweden
Chemical vapour deposition (CVD) is a method by which a thin uniform coating can be applied with a very good adherence on many different types of substrates. The deposition is usually per~ o ~ m ~ at reduced pressure and = ~ v ~ d temperature, around lO00°C, which puts some requirements on the substrates. Tool steels, for example, are not so well suited since they have to be quenched after coating, which is rather complicated and easily causes the coating to crack and peel off. Cemented carbide of the WC-Co type is perfect to deposit coatings of TiC,
77
Department of Physics, Universlty of Oslo, Blindern, Oslo 3, Norway; ~Norsk Hydro Research Centre, 3 9 0 1 P o r s g r u n n , Norway
Electron diffraction offers several advantages in structure studies of amorphous films. Often only thin films, of 1 um or less, are available, which may techniques. High precision in determination of interatomic distances will be possible if the high s = 4~sinS/1 values can be exploited: In an electron microscope operating at 200 kV s = 40 ~-i at the maximum diffraction angle of 9° (JEM 2OOOFX). On the other hand multiple scattering may complicate the interpretation if quantitative comparison of
Abstracts of The Scandinavian Society for Electron Microscopy
78
intensities is sought. Diffraction data from thin amorphous films of SnO 2 have been recorded in JEM 2OOCX and JEM 2OOOFX microscopes, using microphotometer traces of photographic films as well as a STEM detector combined with the ASD deflection system. Patterns are also obtained in a gas electron diffraction apparatus with a rotating sector, operating at 38 kV. The diffuse ring patterns which extend out to s = 20 R-I can be interpreted in terms of a local atomic arrangement similar to crystalline u-SnO 2. ELECTRON ENERGY LOSS SPECTROSCOPY AND SYNCHROTRON RADIATION: A COMPARISON J. Taft~ Research Centre, Norsk 3901Porsgrunn, Norway
Hydro,
Electron energy loss spectroscopy (EELS) with a (S)TEM and X-ray absorption with a synchrotron are closely related techniques to study the composition and structure of matter. T]~ese two techniques are based on %h~ ~ , ~ physical phenomenon, namely the ejecuion of an inner shell electron by the incident electron (or X-ray). The ejected electron which thus becomes a photoelectron interacts with the surrounding atoms, giving rise to structure above the absorption edge, i.e., X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) when X-rays are used. Similarly in EELS we observe electron energy loss near edge structure (ELNES) and extended energy loss fine structure (EXELFS). In other respects the two techniques are complementary. EELS is best suited in the low energy region (energy loss from 0-2.5 keY) where the absorption edges of the important elements carbon, nitrogen and oxygen are located. Synchrotron X-ray absorption is superior in the high energy region (above 2.5 keV)° The merits of the two techniques a~e discussed with some emphasis on spatial resolution, and surface and interface sensitivity. TEXTURAL AND GEOCHEMICAL CHANGES RESULTING FROM ALTERATION (PALAGONITIZATION) OF BASIC VOLCANIC GLASSES: APPLICATION OF SEM AND MICROPROBE ANALYSES
Ingunn Hindenes Thorseth, and Ole Tumyr Geologisk 1 Bergen
Institutt,
Harald F u m e s
Avd.
A. Univ.
Basic volcanic glasses alter to palagonite, given aqueous conditions. A SEM and microprobe study of fresh basalt and basaltic andesite glasses and associated palagonites, all from Icelandic hyaloclastites, have been carried out. The microprobe analyses of palagonite give highly variable results with respect to all oxides, and the total sums of individual analyses vary between less than 50% to more than 90%. Even though palagonite may be considered as a hydrated glass from which major elements predominantly have been lost, and H20 gained, relative to the fresh parental glass, itisdoubtful, however, on the basis of this study, that H20 alone can compensate for the generally low and variable totals of the microprobe analyses. The SEM studies reveal that palagonite consists of a spongy material, in which the empty pores are usually much less than 1 micron in .diameter, and with a variable spacing between the pores. The vaz!ation in the ' percentage of pores, presumably a function of the degree of alteration, may account for the pronounced variations in the absolute concentrations of oxides and their total sums. Thus, when considering the texture of palagonite, previously suggested relationships of progressive loss of elements with decreasing totals may, to some extent (as yet unspecified),be in error. MICROANALYSIS AND IMAGE ANALYSIS IN METALLURGICAL APPLICATIONS T. Thorvaldsson R & D Centre, AB S a n d v i k S-811
81 Sandviken,
Steel, Sweden
Image analysis has shown great potential in electron microscopy, especially in combination with microanalysis. Although image analysis has been extensiw ~ ely used for some time for the characterizatio!a of inclusions in metals, it has only :recently been used in the metal industry for research and development. Mechanical, corrosion and magnetic properties are highly sensitive to the