Preparation of micrometer-sized α-Al2O3 platelets by thermal decomposition of AACH

Fabrication of high-surface-area γ-alumina by thermal decomposition of AACH precursor using low-temperature solid-state reaction

“…Ammonium aluminum carbonate hydroxide (AACH) is one of alumina precursors, which is widely used to synthesize a-alumina nanostructure [5,[23][24][25]. Up to now, no research has been referred to the synthesis of high-surface-area g-alumina by thermal decomposition of AACH.…”

“…g-Al 2 O 3 . However, the following series of phase transformations of low-crystallized AACH (NH 4 HCO 3 / Al = 6:1) with cluster structure morphologies[8,24,25,34]: AACH ! amorphous Al 2 O 3 !…”

Preparation of Alumina from Heated Kaolin Leached by Citric Acid with AACH as an Intermediate

“…That is, the AACH particles grew in a constantly steady environment, forming crystals of nanorods and then agglomerating into a spherical shape. According to some studies on AACH, , the temperature range of AACH thermal decomposition is around 200 °C, and AACH is transformed into Al 2 O 3 as NH 3 and CO 2 are released, thereby forming pore channels. Then, after roasting at 700 °C, the synthesized product was transformed into γ-Al 2 O 3 .…”

“…According to some studies on AACH, 28,30 the temperature range of AACH thermal decomposition is around 200 °C, and AACH is transformed into Al 2 O 3 as NH 3 and CO 2 are released, thereby forming pore channels. Then, after roasting at 700 °C, the synthesized product was transformed into γ-Al 2 O 3 .…”

Effect of nano-TiO 2 and nano-SiO 2 addition on the morphological control of α-Al 2 O 3 platelets via solid-state reaction

“…However, in the presence of fluorides, Fions disrupt the regular atomic packing and thereby result in Al 3+ vacancies. These vacancies are conducive for mass transport and therefore lead to a decrease in the α phase transformation temperature and the formation of disk-shaped α-Al 2 O 3 particles [41]. Chen [42] used various fluoride additives in the preparation of α-Al 2 O 3 platelets, and concluded that NH 4 F was the most effective in accelerating the phase transformation and forming the regular plate-like particles; this effectiveness stemmed from the low thermal-decomposition temperature of NH 4 F. When NH 4 F is added to the alumina precursor, defects are formed through the following reactions [34]:…”