“…During the flushing process, it was found that some of the metallic Nb had changed into niobium hydride (NbH) through a reaction with hydrogen ions. Therefore, metallic Nb powder was finally obtained by performing a dehydrogenation heat treatment for the removal of the hydrogen component contained in the produced powder at 973 K and a vacuum pressure of 6 © 10 ¹6 kPa for 2 h. 18) The structure, phase, and components of the obtained metallic Nb powder were investigated using a scanning electron microscope (MIRA3 LM, TESCAN, Brno, Czech), an X-ray diffractometer (Rigaku, Tokyo, Japan), an oxygen/ nitrogen/hydrogen determinator (ELTRA ONH-P, Haan, Germany), a transmission electron microscope (JEOL 2100F, JEOL Ltd, Tokyo, Japan), and an elemental analyzer (Flash 2000, Thermo Fisher Scientific, U.K.).…”