Compact and Portable Hybrid Systems

The Terra provides full phase ID of major, minor, and trace components in rocks and minerals and an XRF system capable of scanning from Ca to U. It has a sample handling system that can sieve powders to 150 pm and requires only 20 mg of sample. To obtain accurate powder XRD spectra, it is generally necessary to finely grind a sample and press a pellet, to ensure sufficient random orientation of the crystals in the sample. To avoid the problems of pressing a pellet, which is difficult to do in the field or on Mars, the Terra has a patented integrated sample vibration chamber. By vibrating the 15-20 mg sample, all orientations of the crystal structure are presented to the 

Using an XRD pattern and looking at the intensity of peaks, it is possible to determine if the crystals of a polymer or a metal are oriented in any particular direction. Preferred orientation can occur after the material has been rolled out into a sheet, for example. This is sometimes a very undesirable property, since the material may be very weak in one direction and strong in another, with 

A search of a computerized database identified the unknown as silicon, based on the match to the stored spectrum for silicon (lower spectrum). 

Powder XRD is nsed for phase analysis and compound identification in a variety of industries, especially mineral, mining, and metal prodnction and for materials such as rocks, minerals, oxide materials, and prodncts. Typical examples inclnde the levels of Fe phases such as FeO, Fc203, Fe304, and FeC determination of free lime in clinker and slags in the cement indnstry phases related to the electrolysis of Al and CaO, CaCOj, and Ca(OH)2 content. 

XRD at different temperatures can be used to study phase transitions between different crystallographic forms of a material (e.g., tetragonal vs. monoclinic forms of yttria-stabilized zirconia). This approach can be used to measure thermal expansion coefficients and to stndy crystalline-to-amorphous transitions in materials. 

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