Nanomaterials: Synthesis, Characterization, and Applications
Introduction to Nanomaterials
Nanotechnology involves manipulating matter at the nanometer scale to create materials, devices, and systems with unique properties. Nanomaterials exhibit novel physical, chemical, and biological characteristics due to their size, which falls between isolated atoms and bulk materials.
Types of Nanomaterials
- Zero-Dimensional (0D): Nanoparticles with all dimensions within the nanoscale (e.g., 1-100 nm).
- One-Dimensional (1D): Nanotubes, nanorods, and nanowires with one dimension outside the nanoscale.
- Two-Dimensional (2D): Plate-like structures such as graphene, nanofilms, and nanocoatings with two dimensions outside the nanoscale.
- Three-Dimensional (3D): Bulk powders, dispersions, and multi-nanolayers not confined to the nanoscale in any dimension.
Synthesis of Nanomaterials
High-Energy Ball Milling
This technique involves grinding materials into nanoparticles using high-speed rotating containers filled with milling balls. Factors such as ball size, milling speed, and duration influence particle size and properties.
Thin Film Deposition
Thin films of nanomaterials can be deposited using techniques like chemical vapor deposition (CVD). Growth rate and film quality depend on gas pressure, substrate temperature, and reaction mechanisms.
Characterization of Nanomaterials
Scanning Electron Microscopy (SEM)
SEM uses a focused electron beam to scan the surface of a sample, generating high-resolution images. It can also provide compositional information through Energy-Dispersive X-ray Spectroscopy (EDAX).
Transmission Electron Microscopy (TEM)
TEM transmits electrons through a thin specimen, enabling the visualization of internal structures and crystallographic analysis through diffraction patterns.
X-ray Diffraction (XRD)
XRD is used to determine the crystal structure and size of nanomaterials. The Scherrer equation relates the broadening of diffraction peaks to crystallite size.
Note: The Scherrer equation provides a lower bound on crystallite size and does not account for other factors that can contribute to peak broadening, such as strain and imperfections.