Xps measurement results exhibited that no detectable fe2 + existed in the compound of a ~ fe2os doped with sn4 + , which suggest that oxygen anions or cation vacancies not only can compensate the charge balance but also significantly enhance the gas - sensitivity of a - fe2o3 based gas sensors . ( 3 ) conductive type of a - fe2o3 doped with sn4 + is showed in the n - type by hall measurement and gas - sensitivity measurement . the results of measurements and characterizations suggest that the sensitive mechanism of the a - fe2o3 based nano - materials prepared by this work be the surface resistance controlled mode ( 3 )首次進行了霍爾測量,并結合氣敏測試結果,從不同方面證實了摻錫- fe _ 2o _ 3納米半導體的導電類型是n型;綜合粉體的電導率?溫度曲線、元件的電阻?加熱電流特征曲線、元件在不同氣氛下的電阻特性以及比表面積等測試表征結果,得出本文所制成的- fe _ 2o _ 3基氣敏元件的氣敏機理特征屬于表面控制型。