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以硝酸铝、硝酸锌和柠檬酸为原料,采用溶胶–凝胶法制备纳米锌铝尖晶石粉体,研究了热处理条件(温度和气氛)对纳米锌铝尖晶石颗粒尺寸的影响。结果表明:在空气气氛下,600℃热处理后即可制备出纳米锌铝尖晶石颗粒,纳米颗粒团聚严重,其颗粒尺寸在20~30 nm之间;随热处理温度升高,纳米锌铝尖晶石颗粒尺寸快速增加,1 000℃开始出现微米尺寸颗粒,1 400℃大部分颗粒尺寸在微米级别,且呈烧结状。在还原性气氛下,柠檬酸分解残留部分碳,碳分布在锌铝尖晶石颗粒间,可阻碍纳米锌铝尖晶石团聚和烧结,进而抑制高温下纳米锌铝尖晶石颗粒长大,1 000℃热处理后,纳米尖晶石颗粒尺寸较小(约10 nm)。然而,在还原性气氛下,当热处理温度≥1 200℃时,锌铝尖晶石与CO或柠檬酸分解残留的碳反应,使锌以气态的形式逸出,只有α-Al_2O_3晶相。
Zinc nitrate aluminum spinel powders were prepared by sol - gel method using aluminum nitrate, zinc nitrate and citric acid as raw materials, and the effects of heat treatment conditions (temperature and atmosphere) on the particle size of nano zinc aluminum spinel were studied. The results show that the nano zinc-aluminum spinel particles can be prepared by heat treatment at 600 ℃ in the air atmosphere. The agglomeration of the nanoparticles is serious with particle size of 20-30 nm. With the increase of heat treatment temperature, The size of spodumene increased rapidly, and microscopic size particles appeared at 1 000 ℃. Most of the particle sizes at 1 400 ℃ were in the micron level and were sintered. Under the reductive atmosphere, the remaining part of carbon and carbon in the decomposition of citric acid are distributed between the zinc-aluminum spinel particles, which can hinder the agglomeration and sintering of the nano-zinc-aluminum spinel, and further inhibit the growth of nano zinc-aluminum spinel particles at high temperature, After heat treatment at 1 000 ℃, the size of nanocrystalline spinel is smaller (about 10 nm). However, under the reducing atmosphere, Zn-Al spinel reacts with the residual carbon in the decomposition of CO or citric acid when the heat treatment temperature is more than 1200 ℃, which causes the zinc to escape in gaseous form, only the α-Al 2 O 3 crystal phase.