University:
York University
Course:
CHEM 1100 | Chemistry and Materials Science for Engineers
Academic year:

2021
Views:

389

Pages:

2
Author:

Nick T.

Interface of CdTe (cubic)/CdS (hexagonal): The interface is where the two materials meet. The materials have different crystalline structures, leading to a non-continuous alignment. 2D Defects: External Surface: No bond from the top. Grain Boundaries: Higher surface energy, more reactive and mobile. Different domains due to different orientations. Discontinuity when orientation changes, leading to voids and longer, weaker bonds. Phase Boundaries: Separate distinct phases within the same material. Example: Rusting in iron (Fe and FeO). Identifying Phases: X-ray diffraction: Can differentiate between crystalline and amorphous materials. Twin Boundaries: Planes that separate a crystal in a way that both sides of the plane have the same atoms mirrored. Polycrystalline Materials: Grain boundaries: Regions between crystals with different orientations. Angle of misalignment: Determines the type of grain boundary. High-angle grain boundary: Large angle of misalignment. Small-angle grain boundary: Small angle of misalignment. Properties: Mobility: More mobile for higher angles. Reactivity: More reactive for higher angles. Resistivity: Higher resistivity for higher angles. Coarse vs. Fine Material: Coarse material: Large grain boundaries. Fine material: Small, many grain boundaries with more voids and longer chemical bonds.