The Gas-sensitivity And Preparation Of Rare Earth Doping Biomorphic Structure SnO₂ Porous Ceramics

The gas sensitive material used at the present stage is poor selectivity, long response time, high working temperature and poor sensitivity. It’s found by research: the biological hierarchical structure especially hierarchical porous structure is an ideal template to construct gas sensitive materials of metal oxide with high sensitivity and fast response-reply. In recent years, the study of metal oxide matrix composite prepared by organism template has got a rapid development, and wide and shape-controlled ramie fiber source, which play a reference role to composite advanced functional materials through the theory of“structure-function coupling”.This paper takes ramie fiber with hierarchical porous structure as the template, synthesizes SnO2 gas-sensing material of biologic form, compares the effect on gas sensitive properties before and after alkali degumming treatment to ramie template; studies the influence to gas sensitive properties from steeping liquor with different level of concentration and doping ratio; discusses doping modification mechanism of rare earth elements and the effect on gas sensitive the properties; analyzes the influence to grain growth of gas sensitive material from sintering molding temperature, heating rate and heat preservation time. The aforesaid items provide a train of thought to synthesize and prepare SnO2 the gas sensitive materials with rare earth doped ceramic-wood structure. The research shows that: the specific surface area and gas-sensing properties of SnO2 gas-sensing material with ceramic-wood structure decline following with the concentration increase of steeping liquor; alkali degumming treatment to ramie template can improve the steeping rate and gas sensitive property; introduction of rare earth elements inhibits the growth and particle aggregation on SnO2 grains and improves the conductivity properties of SnO2. Those improve the sensitivity and selectivity of materials, reduce the best working temperature; sintering molding temperature is a parabola apex. Sintering molding temperature rises further, the loose porosity of ramie template begins to decline, tubular structure begins to collapse, gas sensitive property of material decreases, response-reply time increases and the best working temperature rises. There are 31 Figures,19 Tables,and 51 References in this study.