You have a single crystal of 100% pure gold. Identify which of the following defects you would expect to be present at room temperature.

Free surface
Grain boundaries
Vacancies
Inclusions
Substitutional impurity atoms
Interstitial impurity atoms

Noted.

Free Surface

Vacancies

thanks

To determine which defects would be present in a single crystal of 100% pure gold at room temperature, we need to understand the nature of these defects and their likelihood of occurring in different materials.

1. Free surface: A free surface defect refers to the area of a crystal where atoms are missing due to the termination of the lattice. In a single crystal of gold, it can be expected to have free surfaces since it is just a single piece of the material.

2. Grain boundaries: Grain boundaries are the interfaces or boundaries between different crystal grains in a polycrystalline material. Since we are considering a single crystal of gold, it will not have grain boundaries.

3. Vacancies: Vacancies occur when atoms are missing from the regular crystal lattice. Even in 100% pure materials, vacancies are present due to thermal vibrations. Therefore, a single crystal of gold is likely to have vacancies at room temperature.

4. Inclusions: Inclusions refer to foreign materials that are trapped inside the crystal lattice. Since we are considering a single crystal of 100% pure gold, there should not be any inclusions present.

5. Substitutional impurity atoms: Substitutional impurity atoms are foreign atoms that replace the host atoms in the crystal lattice. In the case of 100% pure gold, there should not be any substitutional impurity atoms since it is assumed to be pure without any intentional impurities.

6. Interstitial impurity atoms: Interstitial impurity atoms are foreign atoms that occupy the interstitial sites between the host atoms in the crystal lattice. Similar to substitutional impurity atoms, a single crystal of 100% pure gold would not have interstitial impurity atoms.

To summarize, the defects that would be expected to be present in a single crystal of 100% pure gold at room temperature are free surfaces and vacancies. There should not be grain boundaries, inclusions, substitutional impurity atoms, or interstitial impurity atoms in this case.