Analytical Services: X-Ray Powder Diffraction
Raymond P. Goehner, Siemens Corporation and Monte C. Nichols, Sandia National Laboratories
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General Use |
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- Identification of crystalline phases contained in unknown samples |
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- Quantitative determination of the weight fraction of crystalline phases in multiphase materials |
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- Characterization of solid-state phase transformations |
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- Lattice-parameter and lattice-type determinations |
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- Orientation of single crystals |
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- Stereographic projections |
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- Alignment for cutting along crystallographic planes |
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Examples of Applications |
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- Qualitative and quantitative analysis of crystalline phases in coal ash, ceramic powders, corrosion products, and so on |
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- Determination of phase diagrams |
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- Determination of pressure- and/or temperature-induced phase transformations |
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- Quantitative analysis of solid solutions from lattice-parameter measurements |
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- Determination of anisotropic thermal expansion |
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Samples |
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- Form: Crystalline solids (metals, ceramics, geological materials, and so on) |
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- Size: For powder samples 1 mg is usually adequate |
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- Preparation: Sometimes none; sample may require crushing to fit into the sample holder |
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Limitations |
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- Must be crystalline for phase identification |
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- Identification requires existence of standard patterns: JCPDS powder diffraction file of inorganic and organic phases, NBS Crystal Data (contains lattice constants for inorganic and organic phases), and Cambridge File of Organic Single Crystal Structural Data |
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Estimated Analysis Time |
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- Qualitative analysis requires less than 1 h for major phases, up to 16 h for trace phase confirmation |
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- Quantitative analysis, after a procedure is set up, requires several minutes to several hours |
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Capabilities of Related Techniques |
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- X-ray spectrometry, inductively coupled plasma atomic emission spectroscopy, atomic absorption spectrometry, classical wet chemical analysis: Quantitative and qualitative elemental information |
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- Auger electron spectroscopy: Elemental and structural data on small portions of the samples |
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- Single-crystal x-ray diffraction: Crystal structure using small single crystals |
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- Infrared and Raman spectroscopy: Molecular structure and sometimes crystal structure |
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- Neutron diffraction: Similar information, but can be applied in some cases in which x-ray powder diffraction fails |
Reprinted with permission of ASM International®.
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