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Green culms of bamboo and charcoal of Bambusa multiplex were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) mapping. A dynamic observation of the initial stage of carbonization was also performed in-situ by heating a radial longitudinal section of the bamboo culm at a rate of 20°C/min up to 500°C. EDS mapping of the green bamboo culms detected Si signals in the harder cells such as the epidermis (Ep), cortex (Cor) and vascular bundle sheath (Bs) and between these cells as silicon oxide particles. Appreciable morphological change of the cells occurred in a temperature range of about 300–400°C due to the decomposition of cellulose that is the main component of the bamboo cells. The charcoal of the bamboo culm has a skin layer which originates from the Ep and Cor and the main central cylinder with many openings that originate from the expanded xylem and phloem holes. During carbonization, the Si atoms in the Ep and Cor were segregated as thin silicon oxide layers onto both the sides of the skin layer and the Si included in the Bs fibers and parenchyma cells accumulated near the walls of the openings.
AlN/SiOx nanocomposite coatings fabricated by differential pumping cosputtering (DPCS) were investigated by analytical electron microscopy. The DPCS system consists of two halves of a Chamber, A and B, for radio frequency (RF) magnetron sputtering deposition of different materials, and a substrate holder that rotates through the chambers. Al and SiO2 were sputtered in gas environments with a flow mixture of N2 and Ar gases at RF power of 200 W in the Al Chamber A and a flow of Ar gas at RF powers of 49 W in the SiO2 Chamber B. The substrates of (001) Si wafers heated at 250°C were rotated for 1,080 min at 3 rpm and alternately deposited by AlN and SiO2. AlN columnar crystals grew at a rate of ~0.3 nm/revolution preferentially along the hexagonal [0001] axis. Amorphous silicon oxide (a-SiOx), deposited at a rate of ~0.2 nm/revolution, was coagulated preferentially along the boundaries between the AlN columns and also the interfaces between the subgrains within the AlN columns. The a-SiOx played an important role in the increase in mechanical hardness of the AlN/SiOx composite coating by disturbing deformation of AlN crystal lattices.
In this paper we introduce new methodology for the observation of living biological samples in an environmental scanning electron microscope (ESEM). The methodology is based on an unconventional initiation procedure for ESEM chamber pumping, free from purge–flood cycles, and on the ability to control thermodynamic processes close to the sample. The gradual and gentle change of the working environment from air to water vapor enables the study of not only living samples in dynamic in situ experiments and their manifestation of life (sample walking) but also its experimentally stimulated physiological reactions. Moreover, Monte Carlo simulations of primary electron beam energy losses in a water layer on the sample surface were studied; consequently, the influence of the water thickness on radiation, temperature, or chemical damage of the sample was considered.
The microstructure in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics is strongly affected by the formation of Ruddlesden-Popper fault–rich (RP fault) lamellae, which are coherently intergrown with the matrix of the perovskite grains. We studied the structure and chemistry of RP faults by applying quantitative high-resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy analyses. We showed that the Sr2+ and Ca2+ dopant ions form RP faults during the initial stage of sintering. The final microstructure showed preferentially grown RP fault lamellae embedded in the central part of the anisotropic perovskite grains. In contrast, the dopant Ba2+ ions preferably substituted for Sr2+ in the SrTiO3 matrix by forming a BaxSr1−xTiO3 solid solution. The surplus of Sr2+ ions was compensated structurally in the later stages of sintering by the formation of SrO-rich RP faults. The resulting microstructure showed RP fault lamellae located at the surface of equiaxed BaxSr1-xTiO3 perovskite grains.
SrTiO3-based semiconducting ceramics are widely used to electric devices such as dielectric condensers and varistors due to their properties of high dielectric constant, high dispersion frequency and small temperature dependence of the dielectric constant. The electric properties of these ceramic devices have been studied and found to be deeply influenced by the crystal growth mechanism, the grain boundary layer characteristics and the sintering atmosphere that is represented by such factors as oxygen partial pressure and processing temperature which relate to the atom vacancy formation. Atom vacancies, which play an important role to the electrical properties, have been detected by cathodoluminescence (CL) spectroscopy with scanning electron microscopy (SEM).
A ceramic condenser (Sr0.94Ca0.05Ba0.01)0.99TiO3 was investigated by Hitomi el at: using transmission electron microscopy (TEM). The material is a boundary layer (BL) semiconducting ceramic condenser, having dielectric layers between semiconducting grains. The same condenser material was investigated in this report at the grain boundary region using high resolution (scanning) transmission electron microscope (TEMSTEM) capable of High Angle Annular Dark Field (HAADF) technique.
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