Laboratory Procedure:

1. Record the diffraction peak positions (2θ) from the XRD pattern.
   

2. Index the diffraction peaks by assigning the appropriate (h k l) planes corresponding to the FCC or BCC crystal structure.
   

3. Calculate the Bragg angle 2θ, θ, θ (in radians), sin θ, sin²θ, & cos²θ, and the interplanar spacing d for each reflection using Bragg's law.
   

4. Determine the lattice parameter a corresponding to each indexed reflection using the cubic lattice relationship:
   a=d√(h²+k²+l² )
   

5. Calculate the Nelson–Riley function F(θ) for each reflection and tabulate all calculated values.
   
   

6. Plot a versus F(θ) and perform linear fitting of the data obtained.
   
7. Extrapolate the best-fit line to F (θ)=0. The y-intercept of the fitted line corresponds to the precise lattice parameter of the material after minimizing systematic errors.
   
   

FCC: The below procedure yields a precise lattice parameter for FCC to be 3.631±0.003 Å.

BCC:The below procedure yields a precise lattice parameter for FCC to be 3.2583±0.003 Å.

Simulation Procedure:

Step 1: Select the preferred language (English or Hindi) from the language selection option.

Step 2: Click on the ON button to switch on the machine.

Step 3: Once the machine is turned on, click on the OFF button to stop the machine if required; otherwise, select the specimen.

Step 4: Click on the OPEN button to open the chamber.

Step 5: Click on the CLOSE button to close the chamber.

Step 6: Click on the STANDBY/ON button and set the required voltage and current.

Step 7: Set the start angle and end angle, then specify the step size and scan rate.

Step 8: Click on the START SCAN button and observe the generated graph and observation table.