Materials Science Schottky defects

In summary, the conversation discusses the calculation of the fraction of lattice sites that are Schottky defects for cesium chloride at its melting temperature. The density of cesium chloride is found to be 3.99 g/cm^3 and the number of lattice sites per cubic meter is calculated to be 1.43 x 10^28. However, when plugged into the equation for equilibrium number, the result is incorrect and the correct answer is 7.87 x 10^-6 for the NS/N ratio. Further assistance is requested.
  • #1
unteng10
10
0

Homework Statement



Calculate the fraction of lattice sites that are Schottky defects for cesium chloride at its melting temperature (645C). Assume an energy for defect formation of 1.86eV.

Homework Equations



Number of lattice sites per cubic meter (N)

N=(NA[tex]\rho[/tex])/(ACS + ACL)
Where NA = Avogadros number, [tex]\rho[/tex] = density, ACS = 132.91 g/mol and ACL = 35.45 g/mol


Equilibrium number (NS)

NS = N * e^(-QS/2kT)
Where QS = Schottky defect, k = Boltzmanns Constant, and T = temp in Kelvin

The Attempt at a Solution



I found the density of Cesium Chloride to be 3.99 g/cm^3

N = (6.02.10^23 atoms/mol)(3.99 g/cm^3)(10^6 cm^3/m^3)/(132.91 g/mol + 35.45 g/mol)
From this is I got 1.43 x 10^28 lattice sites/m^3

When I plug this into the NS equation I get 1.16 x 10^24, and I know this is wrong. I am supposed to solve for a NS/N ratio, and the correct answer is 7.87 x 10^-6.

I am not sure what to do here, any help would be appreciated. Thanks
 
Physics news on Phys.org
  • #2
Nevermind, got it figured out.
 

1. What are Schottky defects in materials science?

Schottky defects are a type of point defect in a crystalline material where a pair of oppositely charged ions are missing from their lattice sites, leaving behind a vacant space known as a Schottky defect. These defects are commonly found in ionic crystals and can significantly affect the material's properties and behavior.

2. How do Schottky defects form in materials?

Schottky defects can form in materials due to a variety of factors, such as thermal energy, radiation, or impurities. When the thermal energy of the material is high enough, ions can break their bonds and leave their lattice sites, creating a Schottky defect. Similarly, radiation or impurities can also cause ions to leave their lattice sites and form Schottky defects.

3. What are the effects of Schottky defects on material properties?

Schottky defects can have significant effects on material properties, such as electrical conductivity, thermal conductivity, and mechanical strength. These defects can create vacant spaces in the material's lattice, which can affect the movement of ions or electrons and alter the material's overall behavior.

4. Can Schottky defects be beneficial in materials?

Yes, Schottky defects can be beneficial in certain materials. For example, in semiconductors, Schottky defects can create more free charge carriers and improve the material's conductivity. In some cases, Schottky defects can also improve the material's mechanical properties by reducing the overall number of defects in the lattice.

5. How can Schottky defects be controlled or prevented in materials?

Schottky defects can be controlled or prevented by carefully controlling the material's composition and processing conditions. For example, reducing impurities in the material can prevent the formation of Schottky defects. Additionally, annealing the material at high temperatures can help to heal or repair any existing Schottky defects.

Similar threads

I Non-Relativistic Bethe-Bloch Calculation for Alpha Particle in Xenon"
    • High Energy, Nuclear, Particle Physics
Replies
7
Views
2K
Materials Science Homework - BIG PROBLEMS
    • Engineering and Comp Sci Homework Help
Replies
1
Views
7K
Material science: Imperfections in solids
    • Materials and Chemical Engineering
Replies
2
Views
3K
What is the density of a unit cell of NaCl crystal?
    • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
Radii of Mg2+ and O2- in MgO
    • Biology and Chemistry Homework Help
Replies
4
Views
13K
Solving Schottky's Defect Homework with 3 States
    • Advanced Physics Homework Help
Replies
1
Views
2K
Problem related to nanotechnology
    • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
Chemistry Determine Weight Percent given molecular weight....
    • Biology and Chemistry Homework Help
Replies
4
Views
3K
Calculating the magnetic field from the Hall Voltage
    • Advanced Physics Homework Help
Replies
2
Views
8K
Help Needed - Solving Physics Problem
    • Introductory Physics Homework Help
Replies
3
Views
3K

Hot Threads

Recent Insights

Back
Top