Hall nanostructures

The study of these systems have become possible thanks to the development of various preparation routes, from sophisticated routes for the preparation of model materials with controlled nanostructures to industrial routes for the production of large quantity of materials. It has benefited as well from the development of new experimental techniques, allowing the properties of matter to be quantitatively examined at the nanometre scale. These include Hall micro-probe [3] or micro-SQUID magnetometry [4], XMCD at synchrotron radiation facilities [5] and scanning probe microscopes [6]. This is not the topic of this chapter to describe in detail these various techniques. They are only quoted in the following sections. The reader may find in the associated references the detailed technical descriptions that he may need. 

W. R. Moser, Advanced Catalysts and Nanostructured Materials Modern Synthetic Methods, Chapman Hall, New York, 1996. 

The author acknowledges the Alexander von Humboldt (AvH) Eoundation for supporting several research visits to Germany. He also thanks Prof. Goerg H. Michler and his research group at Martin Luther University Halle-Wittenberg, Germany for their unconditional support to the author s research missions in the field of nanostructured polymers in Nepal. 

Dense nanostructured monoliths are of interest for a range of applications where materials experience extreme conditions of pressure and temperature. In this case, hardness must be pursued and grain boundaries can enhance such properties, for instance, by the Hall-Petch effect. The management of thermal and electrical behaviors at the same time is also of prime importance in thermoelectricity, for which devices often rely on monolith-shaped materials. In this case, incorporation of grain boundaries may be a mean to fine-tune thermal conductivity independent of electrical conductivity. In both cases, the design of nanostructured monoliths may represent a significant advance in the respective fields. 

X.J. Liu, L.W. Yang, Z.E. Zhou, P.K Chu, C.Q. Sun, Inverse Hall-Petch relationship of nanostructured Ti02 Skin-depth energy pinning versus surface preferential melting. J. Appl. Phys. 108, 073503 (2010)... 

It was well known that Williamson-Hall method is more accurate method to calculate crystallite size as compared to Debye-Scherrer method. The Fig. 2 represents the Williamson-Hall (W-H) plot for YP04 Eu nanostructure phosphor. As shown in Fig. 2, the Y- intercept is 0.0027 taking X as 0.154 nm, the grain size was found to be around 62 nm. The calculated particle size was in good concurrence with the Debye-Scherrer data. The small variation in the size of grains calculated by Debye-Scherrer and W-H method was due to the fact that in Debye-Scherrer formula strain component was assumed to be zero and the diffraction peak broadening was assumed to be due to reduced grain size only. 

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