Study On The Response Of LaVO₄/V₂O₅Sensor To NH₃gas

With the development of modern industry, people require a high living environment in recent years. The detection of flammable, explosive, poisonous and harmful gases timely and accurately detect has become an important issue. Ammonia gas is a colorless, toxic and flammable gas with the chemical reduction ability. Ammonia has strong stimulating and corrosion effects to the respiratory tract organizations of human and animals and can damage cell membrane structures and weaken the body’s resistance to diseases. Therefore, the development of sensors for detecting ammonia and protecting people’s health is of great significance in case of ammonia leakage.In present work, La2O3and V2O5powders were as raw materials and were used to prepare LaVO4/V2O5sensing materials by the high temperature solid reaction after milling, sieving, pressing and sintering process. The constitute of the prepared materials were characterized by X-ray diffraction (XRD). The components in the materials are LaVO4and V2O5in small amount. The preparation conditions were optimized from the aspects of sintering time, sintering temperature and raw material ratio (in molar ratio) as V2O5:La2O3=6:5;24h of ball milling,600℃of sintering temperature and24h of sintering time.We assembled a sensing device and detected the sensing performances of LaVO4/V2O5to ammonia by the DC resistance method in the ammonia concentration range of500ppm-3000ppm in the temperature of475-600℃. We studied the response repeatability, recovery time, selectivity of the sensor to the ammonia. The results showed that the response sensitivity is in the range of13to80%, much higher than the results reported in the literature. The response sensitivity increase with the increase of concentration of NH3The decreasing working temperature improved the response sensitivity and the recovery time. At475℃, the response sensitivity of LaVO4/V2O5for500ppm NH3is67%. In the same experimental conditions, the sensitivity of LaVO4/V2O5sensor to H2and CO gas is much smaller than to ammonia, indicating that LaVO4/V2O5sensor has a good selectivity for NH3gas. The response mechanism of LaVO4/V2O5for NH3gas was also discussed.