High-aspect-ratio single-crystalline (Hf_xZr_(1−x))B₂ micron-rods: low-temperature, highly-efficient synthesis and oriented growth mechanism

Abstract

By taking advantage of microwave and molten-salt co-assisted boro/carbothermal reduction method (MSM-BCTR) and cheap raw materials of HfO2/ZrO2, B4C and amorphous carbon, three types of (HfxZr(1-x))B2 (x = 0.25, 0.50...

Low temperature controllable synthesis of transition metal and rare earth borides mediated by molten salt

“…[215][216][217][218] It also has been introduced by the corresponding author's group to an MSS process to replace the conventional furnace heating, leading to the development of an improved MSS technique, referred to as 'microwave-assisted molten salt synthesis (MA-MSS)'. [219][220][221][222][223][224][225] Table 7 summarises the studies on MA-MSS of metal boride-based powders. [219][220][221][222][223][224][225] As shown, by using microwave heating combined with MSM-BCRS, phase pure ZrB 2 nanorods, TiB 2 microplatelets and TaB 2 nanoflowers were successfully prepared in the NaCl-KCl eutectic salt after only 20 min at 1100-1200 °C.…”

“…[219][220][221][222][223][224][225] Table 7 summarises the studies on MA-MSS of metal boride-based powders. [219][220][221][222][223][224][225] As shown, by using microwave heating combined with MSM-BCRS, phase pure ZrB 2 nanorods, TiB 2 microplatelets and TaB 2 nanoflowers were successfully prepared in the NaCl-KCl eutectic salt after only 20 min at 1100-1200 °C. Such a condition was milder than that in the MSM-CRS/BCRS and even MSM-MRS using conventional heating (Sections 'Conventional and molten salt mediated borothermal reduction synthesis' and 'Conventional and molten salt mediated carbo-and boro/carbo-thermal reduction synthesis'), and further milder than in the conventional CRS/BCTR.…”

“…Under the conditions listed in Table 7, the reaction extent in the case of either without using a molten salt or without using microwave heating was much lower, demonstrating the synergistic effect from the combination of molten salt with microwave heating. [219][220][221][222][223][224][225] Apart from a single metal boride, a metal boride solid solution or composite powder comprising a boride and another component such as a carbide can be prepared similarly under milder conditions by using MA-MSS. As shown in Table 7, (Hf x Zr 1−x )B 2 microrods were synthesised from oxide precursors, B 4 C and amorphous carbon, in NaCl-KCl after only 20 min at as low as 1100 °C.…”

“…215–218 It also has been introduced by the corresponding author's group to an MSS process to replace the conventional furnace heating, leading to the development of an improved MSS technique, referred to as ‘microwave-assisted molten salt synthesis (MA-MSS)’. 219–225…”

“…Under the conditions listed in Table 7, the reaction extent in the case of either without using a molten salt or without using microwave heating was much lower, demonstrating the synergistic effect from the combination of molten salt with microwave heating. 219–225…”