高稳定性的γ－Fe_2O_3的合成及其气敏性能研究

Studies on Synthesis of High Stability α-Fe_2O_3 and Its Gas Sensing Characteristics

本文采用空气氛化Ｆｅ（ＣＯ＿３）＿ｘ（ＯＨ）＿（２（１－ｘ））悬浮液体系，控制体系的ｐＨ和掺入适量的钇元素，合成出纳米级铁黄γ－ＦｅＯＯＨ微晶。由ＤＴＡ－ＴＧ和ＸＲＤ分析得出，由γ－ＦｅＯＯＨ直接脱水得到的γ－Ｆｅ＿２Ｏ＿３样品，具有很好的热稳定性，其γ－α相变温度可达７２５℃，且粒径为纳米级，并具有很好的气敏灵敏度和选择性。６００℃烧结的气敏元件，对液化石油气（ＬＰＧ）的灵敏度Ｓ大于７０；而在７００℃下烧结的元件，对Ｃ＿２Ｈ＿２灵敏度Ｓ大于４０；它们均对选定测试的气体ＣＯ、Ｈ＿２、汽油（Ｐｅｔｒｏｌ）。Ｃ＿２Ｈ＿２和ＬＰＧ有很好的选择性。

The nm grade γ-Fe_2O_3 crystallites weresynthesized using air oxidation in Fe(CO_3)_x(OH)_(2(1-x)) suspension liquids system and controllingpH and adding moderate quantitative Y into reactionsystem, The DTA-TG a nd XRD showed that the γ-Fe_2O_3 obtained by the process of dehydration of γ-FeOOH possessed good thermostability,and itsphase transfer temperature could reach to 725 ℃.The high sensitivity and selectivity were due to itsnm grade grain diameter. The gas sensitivity ofelement sintered at 600℃ for LPG was higher than70, and the sintered element at 700℃ had the gassensitivity for C_2H_2 is higher than 40. Theirselectivity for measured gases, such as CO,H_2,petrol. C_2H_2, LPG were good.