This instrument is can be used for determining the structure, crystallinity, or phase composition of a powdered sample. We use this for characterization of materials such as stone, mortar, and brick.

Bruker D2 Phaser XRD

Jason Church preparing a sample of red parge coat for XRD analysis

The Bruker D2 Phaser is a benchtop XRD unit. It uses x-rays to examine short- and long-range molecular structure of a sample. The instrument bombards the powdered sample with a highly focused stream of x-rays, which interact with the material and bounce off of the atoms at angles characteristic of the sample’s molecular geometry, these bounced x-rays are then measured by the detector. The instrument will continue this bombardment while scanning through a range of angles to gather more complete structural data.  The data is presented as a graph of the number of x-ray counts by angle of reflection.  The main drawback to this technique is that it is moderately destructive: it requires a powdered or pressed-pellet sample for analysis.

Training and installation of the Bruker D2 Phaser XRD

These data are complementary to element composition data, such as that collected by x-ray fluorescence or mass spectrometry. For example, when examining glass and quartz, both have the elemental composition of SiO2 but very different long-range molecular structures. Glass has a random arrangement of SiO2 molecules with no long-range order; the XRD pattern for glass is characterized by very broad peak features. Quartz, on the other hand is a crystal and has a highly ordered structure of SiO2 that repeats; the XRD pattern is characterized by specifically spaced, sharp peaks characteristic of the long-range order of the SiO2 molecules.

Research Associate Sarah Hunter using the XRD to look at corroded iron samples

Researchers at NCPTT have used XRD to examine the effects of herbicides on the built environment, and to examine corrosion on metals.

 

 

 

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National Center for Preservation Technology and Training
645 University Parkway
Natchitoches, LA 71457

Email: ncptt[at]nps.gov
Phone: (318) 356-7444
Fax: (318) 356-9119