How to calculate XRD peak intensity percentage

To calculate the XRD peak intensity percentage for a given diffraction pattern, you compare the intensity of a specific peak to the total intensity of all peaks or to the highest intensity peak (depending on your analysis goals). Here's a step-by-step guide:

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1. Understand the Basis for Calculation

The percentage intensity can be calculated in two common ways:

1. Relative to Total Intensity:
• I_{peak percentage} = (I_{specific peak}/∑I_all peaks)× 100

 

• Where ∑I_all peaks is the sum of all peak intensities in the pattern.
1. Relative to Maximum Intensity:
• I_{peak percentage}=(I_{specific peak} / I_max peak)× 100

 

• Where I_max peak is the intensity of the highest peak in the pattern.

The method depends on whether you're analyzing all peaks collectively or normalizing to the strongest peak.

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2. Gather Required Data

• Obtain the intensity values for all peaks from the XRD diffraction pattern (usually provided in data files exported from XRD software or manually read from the graph).
• Identify the peak of interest, its corresponding intensity (I_{specific peak}), and other peaks' intensities (∑I_all peaks).

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3. Perform the Calculation

Example 1: Relative to Total Intensity

Suppose you have the following peak intensities from an XRD pattern:

• Peak 1: I₁=100
• Peak 2: I₂=300
• Peak 3: I₃=200

Step 1: Compute the total intensity:

Total Intensity=I₁+I₂+I₃=100+300+200=600

Step 2: Calculate the percentage for each peak:

• For I₁: (100/600)×100=16.67%
• For I₂: (300/600)×100=50%
• For I₃: (200/600)×100=33.33%

Example 2: Relative to Maximum Intensity

Using the same data:

• Maximum intensity (I_max peak) is 300 (from I₂).

Step 1: Calculate the percentage for each peak relative to I_max peak:

• For I1I_1: (100/300)×100=33.33%
• For I2I_2: (300/300)×100=100%
• For I3I_3: (200/300)×100=66.67%

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4. Automate with Software

Many XRD software tools like:

• Origin, MATLAB, X'Pert HighScore, and GSAS-II allow automatic computation of peak intensities and percentages.
• Export the intensity data as a table for further manual calculation if needed.

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5. Considerations

• Normalize intensities if needed, especially if patterns are collected under different conditions.
• Consider baseline correction to ensure accurate intensity values.
• Clearly specify which method you used when reporting results (relative to total intensity or maximum peak).