Investigation And Preparation ZrO₂ Based Material Sensitive To N(CH₃)₃ Working At Low Temperature And Resistance

Trimethylamine (TMA) gas is the one of major odor gases existing in urban sewer. Recent researches in TMA gas sensor focus on inspecting freshness of fish. In this paper, ultrafine zirconia powder is synthesized and adulterated with other metal oxides trying to develop a ZrO₂ based gas sensor sensitive to TMA gas, which can work at low temperature and low resistance, to inspect the concentration of TMA gas in urban sewer. The work consists three parts below.We choose a simple-prepared, economic and environmental method (super alkaline at low temperature). ZrO₂ yield is 87.7% and XRD pattern shows the average of particle calcined in 700℃ is about 18nm and it exists two kinds of crystal(monoclinic and cubic ,which make up of 60% and 40% respectively). TEM image shows the particle calcined in 700℃ is about 30nm and disperses well. It seems no obvious agglomeration phenomenon. ZrO₂'s IEP (iso-eletron point) is pH 2.75 according to the electrophoresis testing. Secondly, we use homogenous deposition to prepare the ultrafine SnO₂ particle. SnO₂ yield is 87.6% and XRD pattern shows the average of particle calcined in 400℃ is about 9 nm and the crystal phase is tetragonal. SEM image shows the particle calcined in 400℃ is about 15nm and disperses well. It seems no obvious agglomeration phenomenon. SnO₂'s IEP is pH 3.08.The sample of gases used in experiment is prepared by static preparation method. That's injecting certain volume of TMA solution, ethanol or formalin solution into an empty glass with fresh air to prepare the gas of each concentration.Based on ZrO₂, we choose V₂O₅ to low down the resistance and SnO₂ or Nb₂O₅ to raise the sensibility of gas sensor. Then three series (ZrO₂-V₂O₅, ZrO₂-V₂O₅-SnO₂, ZrO₂-V₂O₅-Nb₂O₅) of gas sensor were synthesized. The heating power of gas sensor is about 624mW and its surface temperature is about 100℃. We test the three series sensor in TMA gas of low concentration(below 100 ppm) to study the relationship between the ratio of adulterated metal oxide and resistance of gas sensor, the relationship among the ratio of adulterated metal oxide, sensibility and gas concentration and the relationship of the ratio of adulterated metal oxide andresponded time. We also test the gas sensors in ethanol and formalin gas respectively to study its ability of gas-choosing. All experiments show that gas sensor of ZrO₂-V₂O₅-Nb₂O₅ (12:1:0.512:1:1) is more sensitive to TMA gas than other two series. Its sensibility increases as the concentration of gas increases. It is also sensitive to TMA gas compared with other two kinds of gas and the gas sensor's resistance reaches equilibrium within 50 seconds.