Synthesis And Gas Sensing Properties Of Ferrite Bismuth Compounds

Nowadays, with the fast development of technology and economy, the living levelof people has changed with each passing day. At the same time, that deterioration of theenviroment pollution, air pollution from chemical industry production, automobileexhaust, and the toxic gas emissions of home decoration, seriously threat to humanhealth. Under such circumstance, gas sensitive materials has developed rapidly in recentyears. Various oxide semiconductor based gas sensors have been used to detect harmfuland toxic gases. The most representative sensor materials are SnO2and ZnO, whichexhibit n-type oxide semiconductivity, and other n-type oxide semiconductors such asTiO2, WO3, In2O3,and Fe2O3are being widely explored to find new functionalities ofchemiresistivity. The research of n-type oxide semiconductor has got an outstandingachievement and made notable effect in actual application. In contrast, thechemiresistors fabricated using p-type oxide semiconductors such as NiO, CuO,Co3O4,Cr2O3, and Mn3O4to date have received ralatively little attention, and the relatedresearch to fabricate such chemiresistors is still in the early stages of development. Forboth n-type oxide semiconductor gas sensor and p-type oxide semiconductor, manyfactors govern the feasibility of commercial success and include, but are not limited to,sensitivity, selectivity, response and recovery times, limits of detection and powerconsumption and these issues have all been considered to varing degrees. Thereforeexploring new types of gas sensor and expanding the scope of applications of gassensitve materials are particularly important. Thus, we synthesized1D BiFeO3andBi25FeO40with orzo structure by hydrothermal method and the gas sensitivity ofmaterials is detected. The specific work is as follows:Firstly, using one-dimensional Bi2O3as template, prepare one-dimensional BiFeO3with hydrothermal method and remove the impurities with dilute nitric acid. The effectsof PH, the molar ratio of Bi and Fe, reaction time and template on the morphology of1D BiFeO3are also investigated. Further explore the structural formation process of onedimensional BiFeO3. At the same time, test the gas sensitive performance of BiFeO3powder and investigate the influence of sintering temperature on gas-sensing propertiesof1D BiFeO3, and describe the gas sensing mechanisms of one-demensional BiFeO3.The experimental results show that the sensors of1D BiFeO3show stronger responsesto ethanol, methanol and acetone, and that the sensitivity increases with the increase ofgas concentrations. But sintering BiFeO3shows the performance degradation.Secondly, using one-dimensional Bi2O3as precursors, Bi25FeO40with orzostructures are fabricated by the hydrothermal method. The influence of reaction time, reaction temperature, template on the morphology structure of Bi25FeO40are alsodiscussed. The gas sensitivity of Bi25FeO40with orzo structure is detected in themeantime. The experimental results show that the sensor of Bi25FeO40with orzostructure has much stronger responses to ethanol, methanol, acetone, toluenedichloroethane and formaldehyde, while the sensors of Bi25FeO40with othermicrostructures show little or no responses to all gases.