Instruments and Procedures
Powder X-Ray Diffraction
- Technique: Powder X-Ray Diffraction.
- Instrument Name: Rigaku MiniFlex 6G benchtop.
- ODR Instrument Name: Rigaku.
- Location: ARES, NASA Johnson Space Center, Houston, TX
- Principle Laboratory Contact: Nikole Haney (nikole.c.haney@nasa.gov)
- Procedure: Powder XRD patterns were acquired under ambient laboratory conditions and were normally collected between 3 º2θ and 70 º2θ at a scan rate of 1.0 º2θ/min using a Co Kα source operated at 40 kV and 15 mA. Silicon metal sample holders with 0.2 mm diameter wells were used to accommodate the small sample volumes available for analysis. Sample holders were not rotated during º2θ scanning because of a tendency of powder samples to slide off the holders during rotation, because 2θ scanning is achieved by rotating the sample holder assembly relative to the fixed location for the x-ray beam. The scan rate employed (1.0 º2θ/min) was selected to minimize pattern acquisition time at the expense of minor shifts in the positions of diffraction peak maxima, because of concerns of temporal phase stability (e.g., with respect to hydration state) of samples equilibrated relatively low relative humidity and then analyzed at relatively high laboratory relatively humidity. Diffraction patterns were analyzed for phase identification by JADE 9.6 software (Materials Data, Inc.) and JADE 10 software (ICDD) coupled with PDF-4/Minerals database (ICDD).