Material characterization methods transition types

We previously described some methods used to obtain an array of unstrained Ge quantum dots (QD) on heteroepitaxial ZnSe layers. The examined ZnSe/Ge heterosystem is characterized by similar type of the lattice and small mismatch value for their constants, w 0.2%, which excludes occurrence of the mechanical stress in the substrate-nanoobject system When studying the islets formation in this system, we observed a low-temperature recrystallization of Ge - the transition from the amorphous state to the polycrystalline one, and then into the continuous epitaxial layer (Suprun Fedosenko, 2007). The temperature was significantly below the melting temperature of the bulk material. Later we conducted experiments in situ for direct observation of this process using RHEED and XPS methods, and the results were analyzed in terms of BOLS model. 

Wachter ( ) have presented a very clear example of this behaviour in their studies of the moment formation in TmSe Te under pressure where both mixed valency, or intermediate valence (IV), and semiconductor to metal transition are found. The particular interest of this case is not only that these materials have been extensively characterized, but also because they show, from comparison of valences determined by two different experimental methods, that a unique picture which considers only one type of... 

DTA is a widely used tool for studying and characterizing polymers. Figure 31-7 illustrates the types of physical and chemical changes in polymeric materials that can be studied by differential thermal methods. Note that thermal transitions for a polymer often take place over an extended temperature range because even a pure polymer is a mixture of homologs and not a single chemical species. 

Specific volume and I is the sample length). Therefore, DMA is the most frequently used technique in the fiber/film technology field. A single measurement will provide the temperature dependence of the modulus and the glass transition temperature and will characterize possible second-order transitions of the material. It is important to remember, however, that the glass transition temperature measured by DSC always will be different from that determined by relaxation methods, such as DMA or DEA (due to the frequency excitation effect). Details of DMA measurements of fibers and films can be found in several references [e.g., Murayama (1978), Jaffe et al. (1997) Menczel et al. (1997b)]. Here we briefly summarize the most important aspects of this type area of DMA measurement. 

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