Development of a compact near-infrared lamp furnace for synchrotron powder diffraction and its application for <i>in situ</i> high-temperature observation of ferrite magnets

The effective development of functional materials requires a thorough understanding of their high-temperature thermodynamic properties under material production process conditions. In this study, we develop high-temperature synchrotron X-ray diffraction (XRD) techniques using a compact near-infrared (NIR) lamp furnace at BL02B2 and BL13XU in SPring-8, enabling heating to ~ 1700 °C at a maximum rate of 1000 °C/min. The compactness of the device allows easy installation within the limited space around a goniometer in the beamline and facilitates simple sample exchange and positioning. The NIR furnace supports various measurement types using two different setups. One setup involves sample holders with flat sapphire sample cells, enabling measurements under various gas atmospheres and precise temperature control through direct temperature measurements near sample positions using a thermocouple. The other involves a capillary rotation system, allowing for sufficient particle statistical measurements even as crystal grain growth progresses. To demonstrate the applicability of the developed system for <i>in situ</i> experiments under various heating conditions, we evaluated the heating process of standard samples and <i>in situ</i> crystalline phase changes of Sr ferrite permanent magnet materials. Specifically, we successfully observed the calcination synthesis of the permanent magnet material, M-type SrFe₁₂O₁₉, from a mixture of SrCO₃ and Fe₂O₃. Moreover, <i>in situ</i> heating observations were utilized to establish a pseudo-binary diagram of the SrFe₁₂O₁₉-Fe₂O₃ system above 1300 °C, including multiple Sr ferrite magnet phases (M-type SrFe₁₂O₁₉, X-type Sr₂Fe₃₀O₄₆, and W-type SrFe₁₈O₂₇). Harnessing NIR lamp furnace adaptability facilitated <i>in situ</i> XRD observations for visualizing diverse high-temperature treatment procedures for functional materials. Newly designed multi-purpose near-infrared furnace for synchrotron X-ray diffraction enables <i>in</i> <i>situ</i> observation of various high-temperature heating processes up to 1700°C, as demonstrated by the permanent magnet material synthesis