Ceramic samples, electron microscopy

Figure 13.11—Scanning electron microscopy (SEM) accompanied by X-ray fluorescence analysis. Secondary electron image of a cross-section of a supraconducting polycrystalline ceramic with oriented grains of oxide BiPbiSriCaiCurO, (Philips instrument, model XL30FEG). Energy emission spectra corresponding to the matrix and to a 5 pm-long inclusion (bottom). It should be noted that it is possible with this technique to obtain the composition at a precise point on the sample (Link-Oxford analyser) (study by V. Rouessac, reproduced by permission of CRISMAT. University of Caen).

To answer the question whether heterotopically formed bone, induced by hydroxyapatite, oc- and [3-TCP and biphasic HAp/TCP (BCP), would disappear over time due to the absence of mechanical stresses and whether this heterotopically formed bone would give rise to uncontrolled growth, a long-time investigation over 2.5 years was conducted (Yuan et al., 2001). Porous hydroxyapatite ceramic (HAp), porous biphasic calcium phosphate ceramic (TCP/HAp, BCP), porous a-TCP ceramic and porous P-TCP ceramic were implanted in the dorsal muscles of dog with an observation time of 2.5 years. Histological observation, backscattered scanning electron microscopy observation and histomorphometric analysis were performed on thin non-decalcified sections of retrieved samples. Normal compact bone with bone marrow was found in... 

Powder morphology was investigated using a transmission electron microscope (TEM, Model JEM-IOOCXII). Crystallite size of the powders and grain size of Nd YAG ceramics calcined at different temperatures were calculaied by X-ray diffraction (XRD, model D/maxrA, using nickel-filtered Cu-Ka radiation) patterns from the Scherrer s equation. Microstructures of the fractured and the thermal etched mirror-polished surfaces of Nd YAG specimens were observed by scanning electron microscopy (SEM, Model S-4800). Densities of the samples were measured by the Archimedes draining method. 

When smrface coating of ceramic materials is not appropriate environmental scanning electron microscope (ESEM) can be used. Whereas conventional scanning electron microscopy requires a relatively high vacuum in the specimen chamber to prevent atmospheric interference with primary or secondary electrons, an ESEM instrument uses a thin membrane to separate the specimen chamber from the vacuum system. Thus, nonconducting samples can be analyzed without charging, and hydrated specimens can be analyzed without fear of dehydration in the vacuum. 

Transmission electron microscopy of samples with <30 wt % PCL showed no evidence of segregation of components. However, samples with higher PCL contents did show evidence of fine-scale segregation. The results of image analysis were consistent with a ceramer with 46 wt % PCL having co-continuous microphases [176]. 

Nishibori M, Shin W, Tajima K, Houlet LF, Izu N, Itoh T, Matsubara I (2008) Long-term stability of Pt/alumina catalyst combustors for micro-gas sensor application. J Eur Ceram Soc 28 2183-2190 Nowotny J (1988) Surface segregation of defects in oxide ceramic materials. Solid State Ion 28-30 1235-1243 Oudet F, Vejux A, Courtine P (1989) Evolution during thermal treatment of pure and lanthanum-doped Pt/Al O, and Pt-Rh/AljO, automotive exhaust catalysts transmission electron microscopy studies on model samples. Appl Catal 50 79-86... 

Since electron microscopy requires minute samples, the crystallography of materials that are available only as small particles (e.g., catalysts) can be studied in direct and reciprocal space. The early crystallographic studies on Cuy and C70 crystals were for instance, performed by electron diffraction (194. Even fine powders or finegrained ceramics contain single crystal particles large enough to produce a single crystal electron... 

Scanning electron microscopy (SEM) pictures of composite samples ceramized slowly under heating from room temperature to 1000 °C during 2 h demonstrate good adhesion between ceramic phase components in the composites filled with mica (MIC - Cl, C2), wollastonite (WOL - El, E2) and aluminum hydroxide (ALOH - Al, A2). Far worse adhesion is observed for the samples containing calcined kaolin (C-KAO - Bl, B2) and surface modified montmorillonite (M-MMT - Dl, D2) (Fig. 8.8). 

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