TABLE OF CONTENTS Many characterization and analytical techniques have been applied for the study of nanomaterials and nanostructures; only a few widely used methods are reviewed in this chapter. Both bulk and surface characterization techniques find applications in the study of nanomaterials. However, bulk methods are used to characterize the collective information of nanomaterials such as XRD and gas sorption isotherms. They do not provide information of individual nanoparticles or mesopores. Since most nanomaterials have uniform chemical composition and structures, bulk characterization methods are extensively used. Surface characterization methods such as SPM and TEM offer the possibilities to study individual nanostructures. For example, the surface and inner crystallinity and chemical compositions of nanocrystals can be studied using high resolution TEM. Bulk and surface characterization techniques are complementary in the study of nanomaterials.
Physical properties of nanomaterials can be substantially different from that of their bulk encounters. The peculiar physical properties of nanomaterials arise from many different fundamentals. For example, the huge surface energy is responsible for the reduction of thermal stability and the superparamagnetism. Increased surface scattering is responsible for the reduced electrical conductivities. Size confinement results in a change of both electronic and optical properties of nanomaterials. The reduction of size favors an increase in perfection and, thus, enhanced mechanical properties of individual nanosized materials; however, the size effects on mechanical properties of bulk nanostructured materials is far more complicated, since there are other mechanisms involved, such as grain boundary phase and stresses.
