水热法合成纳米晶SnO_2的气敏特性研究

Gas-sensing properties of crystalline SnO_2 prepared by hydrothermal method

以锡粉和硝酸为主要原料，采用水热法合成了纳米晶SnO2粉体，研究了其厚膜元件对空气中低体积分数H2S气体（2～100μL／L）的敏感特性．结果表明：170℃水热处理3～13h获得的SnO2粉体结晶良好，呈四方相金红石结构，其X射线射峰宽化明显，颗粒尺寸为数纳米且分布窄．随着水热处理时间的延长，颗粒尺寸及结晶程度有所提高．170℃水热处理9h得到的SnO2粉体颗粒尺寸约为4．4nm．利用该粉体制作的厚膜元件晶粒细小均匀，晶粒尺寸约为10．0rim．在最佳工作温度150℃下该元件对低浓度H2S气体具有良好的响应～恢复特性，对50μL／LHzS的灵敏度为20．5，敏感体积分数下限低至2μL／L，而对体积分数高至1000μL／L的CO及CH4两种气体均不敏感．

Nanocrystalline SnO2 was synthesized with tin powder and nitric acid by hydrothermal method, and its sensitivity to low concentrations of H2S gas （2-100 μL/L） in air was studied. The powders synthesized at 170℃ for 3-13 h were tetragonal rutile structured and the X-ray diffraction peaks are significantly broadened where the particle size is several nanometers with narrow distribution. Both the particle size and crystallinity increase slightly with the hydrothermal treatment time. The particle size of the powder synthesized at 170℃ for 9 h is about 4.4 nm. Thick-film sensors based on the as-synthesized SnO2 nanopowder show fine and uniform grains with the size of about 10.0 nm. At the optimal operation temperature of around 150℃, the sensor samples show fast response and recovery properties toward low concentrations of H2S gas, and the sensitivity toward 50 μL/L of H2S is 20. 5. The samples are also sensitive to 2μL/L of HaS in air, while their response to 1 000 μL/L of CO or CH4 in air is negligible.