Qualitative Phase Analysis

Methodologies

Qualitative Phase Analysis Overview

Lambda Technologies provides x-ray diffraction qualitative phase analysis using diffractometer techniques. Qualitative phase analysis software has been written for data collection and preprocessing to strip background and detect diffraction peaks using first and second derivative algorithms.

Commercial search/match software distributed by Materials Data, Inc. (MDI) is used for searching the full Joint Committee for Powder Diffraction Standards (JCPDS) data file system including organic, inorganic, mineral and alloy systems. The characteristic lattice spacings and intensities are used to search the 60,000 JCPDS cards for known phases using the elemental chemistry obtained by semi-quantitative x-ray fluorescence to bound the search to plausible elemental constituents.

While elemental analysis obtained by spectroscopy or wet chemistry can identify the elemental constituents of a component or mixture, x-ray diffraction provides far more information. The molecular components and crystalline structures are determined, allowing individual components of a mixture such as an oxide and sulfide to be identified. From the knowledge of the crystalline structure, the temperatures, pressures, and other aspects of formation can often be deduced.

Large and small samples of polycrystalline materials down to fractions of grams can be analyzed using the diffractometer systems.

Features

• Samples may be tested nondestructively.
• Corrosion products and coatings may be identified in-situ on the surface of substrates using the bulk mounting capability.
• Graphite monochromators provide virtual immunity to fluorescence from the sample for optimum detection limits and precision.
• All diffractometers are calibrated to the NIST mica and silicon standards (SRM 675 and 640) and corrected for angular error using algorithms unique to Lambda Research's data collection software.
• The data collection and reduction software developed at Lambda can be tailored for specific applications allowing detection of extremely broad peaks and deconvolution of overlapping peaks.

• Identification of unknown corrosion products or contaminants.
• Verfication of raw materials, such as ores, minerals, etc.
• Analysis of cements and concretes..
• Process development for ceramic materials and alloys.

Lambda provides energy dispersive x-ray fluorescence analysis using a thin window Si(Li) detector system. Qualitative and semi-quantitative analyses are performed in a vacuum using a white radiation excitation source. The system is designed for bulk sample analysis irradiating a nominally 5 mm circular zone. Detection of elemental constituents from aluminum to uranium is possible. Samples may be in the form of solids, alloys, powders, or liquids and are usually either analyzed "as is" or using Mylar film mountings.