Page 47 - Book Hosokawa Nanoparticle Technology Handbook

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FUNDAMENTALS CH. 1 BASIC PROPERTIES AND MEASURING METHODS OF NANOPARTICLES

(a) Core shell (b) Internal dispersion

(g) Bulk body from (h) Porous body from (i) Nano thin film
nanograins nanograins

Figure 1.7.1
Images of composite structure fabricated from nanoparticles.

classification of composite structures of nanoparticles ite structure becomes clearer by combining the elec-
and their images. These composite structures are clas- tron microscopic observation with the elemental
sified not only by the situation of agglomeration of analysis. Specific surface area measurement, pore size
nanoparticles but also by the pore structure. It can be distribution measurement in micro to nano area by gas
thought that dispersibility, cohesive property, porosity adsorption method, and that in mm to m area by mer-
and compact density are basic physical properties of cury porosimetry will quantitatively supplement the
the composite structures. In addition, these composite evaluation by the electron microscopy observation for
structures can be divided into the particle composite evaluating surface and internal pore structure. The
structure formed with more than two different kinds of specific surface area and pore size distribution meas-
particles, the element composite structure with various urements are already introduced in the previous chap-
different elements, and the composite structure with ter, and then, the present chapter explains the electron
various different composition grains. In short, the ele- microscope observation which is an effective means to
ment and composition of the grains as well as their evaluate the composite structure.
morphology become basic physical properties to form In electron microscope observation, sample prepa-
the composite construction. ration can play a key role to the success. Especially, for
evaluating the composite structure of the nanoparti-
cles, it is necessary to evaluate its internal microstruc-
1.7.2 Evaluation method of composite structure using ture, and accurate observation is impossible even
electron microscopy using high-performance electron microscope if the
sample preparation is inapposite. The sample prepara-
It is important for evaluating the composite structure tion methods for the electron microscope observation
of the nanoparticles to observe its morphology and are as follows : (1) Dispersion method in which the
microstructure that are the most basic physical proper- sample is directly on a sample holder after dispersing
ties. Scanning electron microscopy (SEM) and trans- in a solution by ultrasonic vibration, (2) Crushing
mission electron microscopy (TEM) generally are method where the sample is set on a holder after being
used for observation of the morphology and crushed with mortar etc., (3) Embedding method that
microstructure, and can capture the composite forms observation side of the sample embedded in
structure in the sight directly. In addition, the compos- epoxy resin etc. by polishing, (4) Ultramicrotomy that

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