Molten-salt assisted synthesis and characterization of Mg<sub>2</sub>B<sub>2</sub>O<sub>5</sub> and Al<sub>18</sub>B<sub>4</sub>O<sub>33</sub> whiskers
Zhaoyang Liu, Jingkun Yu, Xiangnan Wang, Xue Zhang, Jia‐Kang Wang, Danbin Jia, Tianpeng Wen, Zhengguo Yan, Lei Yuan, Beiyue Ma
Abstract
In this work, magnesium borate (Mg2B2O5) and aluminum borate (Al18B4O33) whiskers with a high aspect ratio were successfully synthesized using a molten salt method. The phase transformation and morphology involution of the whiskers were studied by XRD, IR-FT, TG-DSC, and SEM-EDS with different boron/metal ratios and reaction temperatures. The results show a rich boron environment and appropriate reaction temperature to be the crucial factors with respect to the composition and morphology of the borate whiskers. Mg2B2O5 whiskers with a diameter of several hundred nanometers and a 10–60 length–diameter ratio were obtained when the B/Mg ratio was 1.5:1 and the reaction temperature was 800°C. For Al18B4O33 whiskers, a synthesis temperature of 1000°C and a B/Al ratio of 3:9 were found to be optimal with respect to the whisker morphology. A liquid-solid (LS) mechanism is proposed as the growth mechanism of the whiskers on the basis of the experimental phenomena.