Phase-separation transformation behaviors in NiO bearing NaO-BO-SiO glass and melt through high-temperature Ni K-edge XAFS and time-resolved SAXS measurements

富田 夏奈*; 岸 哲生*; 大坂 恵一*; 松村 大樹   ; 矢野 哲司*

Tomita, Kana*; Kishi, Tetsuo*; Osaka, Keiichi*; Matsumura, Daiju; Yano, Tetsuji*

High-temperature in-situ Ni-K edge XAFS and SAXS measurements were conducted on borosilicate glasses with low alkali content with/without phase separation tendency, which have been investigated to understand immiscibility into silica-rich phase and borate-rich one on the samples heat-treated at certain temperature followed by fast quenching. In this work, using in-situ analyzing techniques, in-situ time-domain evolution of phases along temperature and time was obtained to understand high-temperature behavior. Ni ion probes phase separation behavior using its high selectivity favoring borate-rich phase and sensitivity to electron donating ability of surrounding oxygens. Taking advantage of these characters, local compositional change was tracked during phase separation under heat treatment. Time-resolved SAXS profiles revealed the speed of phase transformation in addition to changes of morphology at respective temperature. The phase-separation transformation mechanism via different phase separation scheme (homogeneous spinodal binodal homogeneous) was clearly described, revealing effect of NiO clustering at higher temperature.