What Is X-ray Diffraction (XRD)?
X-ray Diffraction (XRD) is a non-destructive scattering technique that measures how X-rays diffract through a crystal lattice. The resulting patterns reveal information about the phases, structures, and textures of crystalline materials.
Texture Analysis
Lattice Measurement
Phase Fingerprinting
Why Use XRD?
The advantage of XRD analysis is its nondestructive nature, which also allows for the identification and quantification of phase differences within a material.
It is recommended that some input on sample chemistry be included for XRD analyses. Techniques like SEM/EDS, FTIR, WDXRF/EDXRF or XPS can help identify chemical information to aid XRD phase determination.
Accurate Phase Identification
Detailed Structural Insights
Stress and Size Evaluation
How X-ray Diffraction Analysis Works
The basis of XRD comes from Bragg's law, which demonstrates that when X-rays encounter 3D arrangements of atoms in a crystal, most X-rays will interfere destructively, but at specific angles, they will interfere constructively. This constructive interference produces an XRD pattern that gives information on the crystalline lattice and helps identify a material's phase.
XRD is especially good at nondestructively identifying and quantifying differences in phases within a material, which it can do on bulk, thin-film materials, epitaxial films, and crystalline powders. XRD is often used to determine whether there are impurities or starting material within the final product and helps determine the weight percentages of each phase identified. It also assesses the percentage of crystallinity and crystallite size within a material.
Equipment Used for XRD
Covalent has a 9kW rotating anode Rigaku SmartLab that allows for higher energy X-rays than other labs.
Rigaku SmartLab
- HyPix-3000 X-ray Detector.
- Rotating Anode X-ray Source.
- X-ray Source Tube Voltage: 20 to 40 kV.
- X-ray Source Tube Current: 10 to 20 mA.
- Triaxial Sample Stage.
- Biaxial Goniometer Head.
Key differentiators
Strengths
- Covalent optimizes each XRD scan to the specific sample to allow for the best possible measurements.
- An invaluable tool for better understanding materials present within a sample.
- Non-destructive way of characterizing and quantifying the phases within a material.
- Can be used to learn about a material’s residual stress and even texture orientation.
Limitations
- XRD does not work with materials that are not flat or amorphous.
- A completely unknown sample can not be identified using XRD.
- Amorphous material tends to result in large halos at low angles in XRD patterns. Due to the width of the halos, XRD cannot identify what the material is, and the halos may even hide some crystalline peaks within them.
- Regular XRD scans can take around 20-30 minutes; however, more complex scans or samples with limited materials can lead to much longer scan times.
Example outputs
Sample requirements
- For in-house XRD scans, samples must be solid and crystalline. External XRD sites can accommodate liquid samples for transmission XRD.
- For solid materials, 5mm minimum in length and width, 25mm typical, 150mm max.
- 0.5g powder minimum, 1-2g powder typical, no maximum amount of powder.
- 8-inch wafers are the maximum wafer size possible, but only for measuring the center of the wafer. Specific locations on an 8” wafer is not possible without breaking the wafer.
X-ray Diffraction Applications by Industry
Semiconductor / Battery / Materials Industries
XRD is used for phase identification and quantification. There are some thin film materials which are sputtered and annealed that can be characterized by XRD for even film growth on the wafer from all parts of the sputter chamber and throughout each annealing step.
Pharmaceutical Industry
Relies on XRD analysis for phase identification and quantification.
Graphitic Material
XRD is used for crystallite size analysis and for understanding Lc (graphite thickness, for c-axis (002) direction), La (graphite width in the layer sheet (100 and (110)) and degree of graphitization.
Techniques That Complement XRD
Any technique with chemical or elemental analysis is a great complement to XRD. Though XRD is good for phase determination, it cannot determine a sample’s chemical makeup.
Why Choose Covalent for Your XRD Needs?
At Covalent, our expert team can help you better understand materials using XRD and develop methodology within the technique to help shape a comprehensive knowledge of a material.