Transmission electron microscopy definition

With such a definition, it was found that vfc at 445 K did not change within experimental error as the average Pd particle size, determined by transmission electron microscopy (TEM), was varied between 1.5 and 8.0 nm (Figure 1). Besides, this value of v was also the same as that reported for the ill face of a single crystal of Pd (2), the latter value being itself very much the same on other planes of Pd or on a polycrystalline wire (3). 

Fred M. Allen, Mineral definition by HRTEM Problems and opportunities, ch. 8, 289-333 in Reviews in Mineralogy, Vol. 27, 1992, Minerals and Reactions at the Atomic Scale Transmission Electron Microscopy, Ed. P. R. Buseck. 

The consolidated titanate waste pellets are similar in appearance to their glass counterparts, i.e., both are dense, black and apparently homogeneous. Microscopic analyses, however, reveal important differences between these two waste forms. While little definitive work has been done with glassy waste forms, it is apparent that several readily soluble oxide particulates of various nuclides are simply encapsulated in the glass matrix. The titanate waste form has undergone extensive analyses which includes optical microscopy, x-ray, scanning electron microscopy, microprobe, and transmission electron microscopy (l ) The samples of titanate examined were prepared by pressure sintering and consisted of material from a fully loaded titanate column. Zeolite and silicon additions were also present in the samples. 

The active agents used in antiperspirants are aluminium and zirconium salts. These are designed to block the sweat glands, which they do by reacting with water to form a sticky gel of aluminium hydroxide or zirconium hydroxide which plugs the pores, and we know this is how they work because these tiny plugs have been observed by means of transmission electron microscopy. By definition, an antiperspirant in the US must reduce perspiration by at least 20% in half of all users, but this requirement is easily met. 

Hence, finite size effects on the optical response of metal nanoparticles are very difficult to take into account in an accurate manner. Moreover, in most experiments carried out on thin nanocomposite films or colloidal solutions the particle size distribution is not mono-dispersed but more or less broad, that can be usually determined by analysis of transmission electronic microscopy images. It should be underlined that the relevant quantity for smdying size effects in the optical response of such media can definitely not be the mean cluster radius , although it is often used in the literature [28-33], since the contribution of one nanoparticle to the optical response of the whole medium is proportional to its volume, i.e. to (cf. Eq. 7). The relevant quantity, that we call the optical mean radius , would then rather be the third-order momentum of the size distribution, = / ... 

The term high-temperature requires definition. In contrast to aqueous corrosion, the temperatures considered in this book will always be high enough that water, when present in the systems, will be present as the vapour rather than the liquid. Moreover, when exposed to oxidizing conditions at temperatures between 100 and 500 °C, most metals and alloys form thin corrosion products that grow very slowly and require transmission electron microscopy for detailed characterizahon. While some principles discussed in this book may be applicable to thin films, high temperature is considered to be 500 °C and above. 

No long-range order means not longer than, say, one or two or three times the basic building block of the glass. This definition is consistent with experimental observations [X-ray diffraction (XRD), transmission electron microscopy (TEM), etc.] but it is clearly a little arbitrary since it depends on the size of the building block. 

The classification scheme shown is not definite. For example, the distinction between NPs and clusters cannot be established on the basis of dimensional criteria. Although the term cluster is used for small Au NPs [34], in principle, they are characterized by a well-defined structure [35], while the mobility of the surface atoms in the NPs does not allow one to ascribe them an exact geometrical shape. Similarly, although transmission electron microscopy (TEM) images depict carbon black particles as spherical and they are thus classified as OD nano-objects, they actually consist of disordered graphene sheets. 

There are several ways in which the PSD can be represented, and often this depends on the method used to measure it. Thus, histograms are used when the PSD is determined by transmission electron microscopy. However, the mathematical analysis is simpler if the PSD is defined in terms of the number density of polymer particles of unswollen volume v [m 3j j.jg], n v). The units of n v) are the number of particles per unit of unswollen volume of particle. From this definition, the number of particles with unswollen volumes between and 2 is given by Eq. (67), and the total number of particles by Eq. (68). 

---