Low Temperature Synthesis of Single-crystal Alpha Alumina Platelets by Calcining Bayerite and Potassium Sulfate  

作　　者：Xinghua Su Jiangong Li 

机构地区：[1]School of Materials Science and Engineering, Changtan University, Xi＇an 710061, China [2]Institute of Materials Science and Engineering, Lanzhou University, Lanzhou 730000, China

出　　处：《Journal of Materials Science & Technology》2011年第11期1011-1015,共5页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 51102022 and 50872046);the China Postdoctoral Science Foundation (Grant No. 2011M501413);the Special Fund for Basic Scientific Research of Central Colleges, Changan University (Grant No. CHD2012ZD015);the Special Fund for Basic Research support programs of Chang an Univer sity

摘　　要：Single-crystal alpha alumina （α-Al2O3） platelets were synthesized by calcining a powder mixture of bayerite （α-AI（OH）3） and potassium sulfate （K2SO4） at 900℃. The crystalline phase evolutions and morphologies of the samples were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The synthesized samples mainly consisted of single-crystal α-Al2O3 platelets with a diameter of 0.5-1.5 μm and a thickness of 50-150 nm. Moreover, with 3, 5, and 8 wt% （referred to the obtained alumina） α-Al2O3 seeds adding into the powder mixture of bayerite and potassium sulfate, the average diameter of α-Al2O3 platelets can be reduced to 450, 240, and 220 nm, respectively. It is found that the sequence of the phase transformation is the bayerite （α-Al（OH）3） → boehmite （γ-AIOOH） →γ-Al2O3 → α-Al2O3. Further analysis indicated that K2SO4 can promote the phase transformation from α-Al2O3 to α-Al2O3 and the formation of single-crystal α-Al2O3 platelets might be attributed to the liquid phase K3AI（SO4）3.Single-crystal alpha alumina （α-Al2O3） platelets were synthesized by calcining a powder mixture of bayerite （α-AI（OH）3） and potassium sulfate （K2SO4） at 900℃. The crystalline phase evolutions and morphologies of the samples were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The synthesized samples mainly consisted of single-crystal α-Al2O3 platelets with a diameter of 0.5-1.5 μm and a thickness of 50-150 nm. Moreover, with 3, 5, and 8 wt% （referred to the obtained alumina） α-Al2O3 seeds adding into the powder mixture of bayerite and potassium sulfate, the average diameter of α-Al2O3 platelets can be reduced to 450, 240, and 220 nm, respectively. It is found that the sequence of the phase transformation is the bayerite （α-Al（OH）3） → boehmite （γ-AIOOH） →γ-Al2O3 → α-Al2O3. Further analysis indicated that K2SO4 can promote the phase transformation from α-Al2O3 to α-Al2O3 and the formation of single-crystal α-Al2O3 platelets might be attributed to the liquid phase K3AI（SO4）3.

关 键 词：Alpha alumina PLATELETS Phase transformation CALCINATION 

分 类 号：TB[一般工业技术]