Mobile electromagnetic levitator for time-resolved in situ X-ray diffraction studies of high-temperature phase transformations.

In situ observations of high-temperature transformations, not compromised by reactivity with a crucible, have recently become accessible by integrating containerless processing with the time-resolved diffraction of synchrotron X-rays. The presented electromagnetic levitator (EML) has been designed for mobility and ease of operation during beamline experiments while enabling stable processing of a wide range of materials. Developed to work with area detectors, the facility's capabilities are demonstrated by measurements of the structural changes during melting and solidification of pure Fe and Fe-Co samples. The direct observations of the metastable phase formation in the Fe-Co system, accessible through containerless processing, have been accomplished for the first time due to the improved acquisition rate of modern area detectors. The diffraction patterns and associated artifacts characteristic of crystal structure measurements during levitation are examined. Moreover, an analytical description of the measured instrumental resolution of the diffraction setup is presented along with a survey of the corrections and associated measurements necessary for an accurate total scattering analysis of the disordered states, such as liquids or glasses. This provides a base for the conceptual planning of diffraction experiments suitable for various levitation methods, including electrostatic, aerodynamic and acoustic levitation.