Using electron microscopy,
K0.5Na0.5NbO3 (KNN) ceramics sintered at
1030°C for 8 h and 1100°C for 2 and 24 h was studied. The scanning
electron microscopy and X-ray spectrometry revealed that the ...materials
consisted of a matrix phase in which the (Na+K)/Nb ratio corresponded
closely to the nominal composition and a small amount of Nb-rich secondary
phase. A bimodal microstructure of cube-shaped grains was revealed in the
fracture and thermally-etched surfaces of the KNN. In the ceramics
sintered at 1100°C, the larger grains (up to 30 μm across),
contained angular trapped pores. The transmission electron microscopy
analysis revealed that the crystal planes of the grains bordering the
intragranular pore faces were of the {100} family with respect to the
simple perovskite cell. Ferroelectric domains were observed in the grains
of this material.
In this article, the secondary electron-emission properties of both
vertically and laterally inhomogeneous samples are discussed. To study the
effect of surface coverage, the total electron-emission ...yield of tungsten
and niobium samples was measured as a function of primary electron energy
and oxide thickness. A method is suggested to avoid charging difficulties
during AES measurements of samples that consist of both metal and various
insulator parts.
Surface-sensitive electron spectroscopies, like Auger electron
spectroscopy, X-ray photoelectron spectroscopy and elastic peak electron
spectroscopy (EPES) are suitable techniques to investigate ...surfaces and
thin layers. A theoretical model for electron transport is needed to
process the observed electron spectra. Electron transport descriptions are
based on the differential elastic cross sections for the sample atoms and
the inelastic mean free path (IMFP) of backscattered electrons. An
electron impinging on the sample can lose energy either due to surface or
volume excitations. In the present work a Monte Carlo (MC) simulation of
the elastic peak of Si, Ag, Ni, Cu, and Au for surface analysis is
presented. The IMFP of Si was determined applying the EPES method. The
integrated elastic peak ratio of Si with the standard metal reference
samples corrected for surface excitation provided IMFP values of Si in the
energy range E = 0.2–2.0 keV. Experiments were made with
the ESA 31 HSA (ATOMKI) and with the DESA-100 (Staib) spectrometers.
Surface correction was based on the application of Chen's model and
material parameters. The Monte Carlo simulations of elastically
backscattered electron trajectories were made using new EPESWIN software
of Jablonski. An improvement of IMFP experimental results was achieved
applying the presented procedure.
The surfaces of crystalline samples of 3d-metals (Mn, Fe, Co, Ni, and
Cu) and their stoichiometric oxides have been studied by Auger
spectroscopy. A correlation between the change in the LVV (L-inner
...level-valence-valence electron transition) Auger intensities and the
change of the squares of the corresponding atomic-magnetic moments has
been observed. This is because of the complicated nature of the Auger
process. That is, the Auger electron emission is a result of the inner
atomic level excitation by electron impact and Auger annihilation of the
inner-level hole. Therefore, the Auger process has been considered a
second-order process, and spin polarization of the valence states has been
taken into account for the LMM (L-inner level-M-inner level-M-inner level
electron transition) Auger spectra of 3d-metals.
Microfacies types (predominantly intrabioclastic grainstones) and microfossils (predominantly dasycladacean algae and diverse foraminifera) characterize the Anisian carbonates near Bled (Castle Hill) ...and in the area westnorthwest of Bled as subtidal to intertidal shelf sediments deposited in the irmer part ofthe Julian carbonate platform. The age of the carbonates is Middle Anisian (Pelsonian) according to the biozonation based on foraminifera and dasycladaceans.
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