本研究採鐵酒石酸鹽爲起始原料,以熱處理方式先獲得一微粒的γ-Fe2O3(~15nm),然後在γ→α-Fe2O3相轉換過程中,經由適當的熱處理,可生成一微粒的α-Fe2O3。實驗中,分別以XRD及BET來量測結晶粒徑與BET粒徑,觀察相轉換與γ-Fe2O3及α-Fe2O3晶粒成長的關係。研究結果發現,將熱處理的條件控制在γ→α-Fep3相轉換剛結束的溫度(450-500℃),此時可得一微粒的α-Fe2O3,其平均晶徑約爲30nm。若高於此溫度,則α-Fe2O3晶粒會快速成長,並產生指狀成長,不利於微粒α-Fe2O3的生成。同時在γ→α-Fe2O3相轉換的過程,會產生一defect α-Fe2O3,此defect α-Fe2O3,可能是引發指狀成長的原因。
An important concern for processing nano-sized powders is the control of grain growth during synthesis. In this study, the crystal size of γ and α-Fe2O3 during phase transformation was investigated using Fe-tartrate precursor. Various physicochemical techniques e.g. XRD, BET, and TEM have been employed to characterize the crystallite particle size of γ- and α-Fe2O3. Finally, based on the size characteristics, preparation of a nano-sized α-Fe203 powder was obtaind.