X-ray Diffraction (XRD)

X-ray Diffraction (XRD) is a nondestructive analytical technique that can measure the physical and chemical properties of crystalline powders, thin films, epitaxial films, and bulk solid materials.

At Covalent, we use the newest in XRD technology, utilizing a high-brilliance Rotating Anode Cu source, Hypix-3000 Hybrid Pixel Array detector, and a variety of high-resolution optics.

Strengths

• Nondestructive
• Sensitivity to the crystallographic structure
• Quantitatively measures crystalline phase and texture orientation
• Minimal sample preparation required

Limitations

• XRD without a pair distribution function has limited capabilities when applied to amorphous materials
• Elemental composition of the samples should be known in advance

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Example Outputs Instruments Used How XRD Works

• Powder, film, or crystalline bulk solids
• Flat surface required for analysis
• Maximum Sample Thickness: 20 mm

X-ray diffraction results when an monochromatic, collimated X-Ray beam strikes a crystalline sample and the lattice spacings between atomic planes produce constructive interference with the incident beam at specified angles, in accordance with Bragg’s Law.

The XRD system scans over a range of diffraction angles, yielding diffraction peaks that can be correlated to distinct families of atomic planes in crystalline specimens. By analyzing the XRD peak pattern, one can: identify and quantify crystalline phases, calculate residual stress (macrostrain) in the material from measured lattice parameters, characterize the crystallite size and microstrain from peak broadening effects, and map the measured lattice parameters in reciprocal space to analyze pseudo-morphic growth of epitaxial films.

Additionally, advanced modeling can be performed from high-resolution XRD data to obtain layer composition and thickness information for epitaxial films, and rocking-curves procedures can be used to show the quality of the films.