Transmission Electron Microscopy of Nanomaterials

*Mohammad Jafari Eskandari, Reza Gostariani and Mohsen Asadi Asadabad*

## **Abstract**

Structural and analytical characterization, in the nanometer scale, has become very important for all types of materials in recent years. Transmission electron microscope (TEM) is a perfect instrument for this purpose, which is summarized in this chapter. Parameters such as particle size, grain size, lattice type, morphological information, crystallographic details, chemical composition, phase-type, and distribution can be obtained by transmission electron micrographs. Electron diffraction patterns of nanomaterials are also used to acquire quantitative information containing size, phase identification, orientation relationship and crystal defects in the lattice structure, etc. In this chapter, typical electron diffraction, highresolution transmission and scanning transmission electron microscope imaging in materials research, especially in the study of nanoscience are presented.

**Keywords:** nanomaterials, characterization, transmission electron microscopy, electron diffraction

#### **1. Introduction**

Nanotechnology is considered to be the main technology for all types of materials in the current century. Nowadays, the development and production of nanostructure materials aimed at increasing the strength to weight of structures that led to cost and energy saving were considered by researchers [1, 2]. For studying materials in the nanometer scale, the investigation of nanostructures is needed to discover the properties of nanostructured materials. This purpose will not be achieved except by the use of efficient characterization instruments. Transmission electron microscope (TEM) has evolved over many years into a highly sophisticated instrument that has found widespread application across the scientific disciplines. Due to unparalleled ability to provide structural and chemical information over a range of length scales down to the level of atomic dimensions, TEM has developed into an indispensable tool for understanding the properties of nanostructured materials and in manipulating their behavior. The precise control of nanoparticles size, grain size, size distribution and homogeneity, lattice type, crystal structure, dispersion, chemical and physical property of phases such as number, morphology, and structure of the phases at the nano-level are characterized by TEM. Besides, this investigation attempts to demonstrate the effectiveness of EDP technique to the analysis of nanomaterial properties. Types of diffraction patterns such as ring, spot and Kikuchi patterns, and general and unique indexing diffraction patterns are described. The methods for indexing simple, complicated and imperfect patterns as well as Kikuchi lines and a combination of Kikuchi lines and spots are determined.

In this research, samples of materials such as nanoparticles, nanotubes, bulk metallic, graphene, graphene oxide, and polymer nanocomposites are investigated using an EM208S (PHILIPS) transmission electron microscopy operating at an accelerating voltage of 100 kV and a digital camera. In addition, electron diffraction pattern of several materials are expounded and structure of materials is predicted with electron diffraction pattern results interpretation. On the other hand, TEM/ STEM (STEM, JEOL JEM-2100F) equipped with an energy-dispersive X-ray spectrometry (EDS) and the operating voltage of 200 kV are used to evaluate the in-situ phase characterization, microstructural observation, dislocation pile-up and chemical composition of in-situ nanocomposite fabricated by planetary ball milling of Al/BN composite powders and hot extrusion. This paper discusses the basic principle and applications of the transmission electron microscope (TEM) in the field of nanotechnology research.
