Inquiry-Based Experiment with Powder XRD and FeS2 Crystal: 'Discovering' the (400) Peak

摘要

We discuss how a powder X-ray diffraction (XRD) system can be used to probe large pyrite (FeS2) crystals to reveal a peak generally not documented in the literature. The ability to detect this peak is attributed to the use of a large crystal, which gives large signal intensities. This type of experiment provides a research-like experience and gives students the opportunity to deepen their understanding of diffraction orders. In this experiment students are first challenged to be creative and determine how to mount a mineral crystal in a powder XRD system and then practice critical thinking in order to determine the origin of the unknown XRD peak. This experiment may also be generalized to crystals other than pyrite.