IN-SITU PHASE DIAGRAM DETERMINATION OF THE HFO_2-TA_2O_5 BINARY UP TO 3000C

摘要

Ceramic equilibrium phase diagrams have proven to be difficult to produce for materials above 1500 ℃. We demonstrate that in-situ X-ray diffraction on laser heated levitated samples can be used to elucidate phase fields. In these experiments, solid spherical samples are suspended and rotated by a gas stream through a conical nozzle levitator, heated by a 400 W CO_2 laser at Argonne National Labs beamline 6-ID-D. X-ray diffraction patterns suitable for Rietveld refinement were collected at 100℃ temperature intervals and were used to determine the phase fraction of phases present. The temperature of each phase was determined based on thermal expansion data collected by using powder diffraction in conjunction with the Quadrupole Lamp Furnace (QLF) at beamline 33-BM-C. HFO_2-Ta_2O_5 was used as an example system.