Material science: Imperfections in solids

In summary, for a BCC iron crystal to have a density of 7.87 g/cm^3, it would need approximately 1.12x10^23 vacancies per cm^3. This can be calculated by first finding the number of atoms in a unit cell (2), then multiplying it by the number of unit cells in 1 cm^3 (0.074), and finally dividing the atomic weight of iron (55.847 g/mol) by Avogadro's number (6.022x10^23 atoms/mol). The theoretical mass of a cm^3 of iron can also be calculated using this information, but this value is not given in the problem.
  • #1
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Determine the number of vacancies per cm^3 needed for a BCC iron crystal to have a density of 7.87 g/cm^3. The lattice parameter of the iron is 2.866x10^-8 cm and the atomic weight of the iron is 55.847 g/mol. Given: Avogradro's number, N=6.022x10^23 atoms/mol

Help please? i have no idea how to solve this question :( I am gona have my first test for material science on wednesday!
 
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  • #2
How many atoms in a unit cell? How many unit cells in 1 cm3? What is the average mass of an iron atom?

What is the theoretical mass of a cm3 of Fe?
 
  • #3
theyre not given:( that is why I am having a hard time solving the question now sir
 

1. What are imperfections in solids?

Imperfections in solids refer to structural defects or irregularities in the arrangement of atoms or molecules within a solid material. These imperfections can occur during the formation or processing of the material, and can affect its properties and performance.

2. What are the different types of imperfections in solids?

There are three main types of imperfections in solids: point defects, line defects, and planar defects. Point defects are localized disruptions in the atomic arrangement, such as vacancies, interstitials, and substitutional impurities. Line defects, also known as dislocations, are one-dimensional irregularities in the crystal lattice. Planar defects, such as grain boundaries and stacking faults, are two-dimensional disruptions in the crystal structure.

3. How do imperfections in solids affect material properties?

Imperfections in solids can have a significant impact on material properties. For example, point defects can change the electrical conductivity of a material, while line defects can affect its strength and ductility. Planar defects can also affect properties such as corrosion resistance, surface reactivity, and thermal conductivity.

4. Can imperfections in solids be controlled or manipulated?

Yes, imperfections in solids can be controlled and manipulated through various techniques. For example, annealing can be used to reduce the number of point defects, while alloying can be used to intentionally introduce substitutional impurities. Defects can also be controlled through processing techniques such as hot working and cold working.

5. What are some real-world applications of studying imperfections in solids?

The study of imperfections in solids is crucial for understanding and improving the properties and performance of various materials. It has applications in fields such as metallurgy, semiconductor technology, and nanotechnology. For example, the controlled introduction of imperfections can be used to tailor the properties of materials for specific applications, such as increasing the strength of metals or improving the efficiency of solar cells.

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