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以La(NO3)3、Cr(NO3)3.9H2O、Sr(NO3)2、Mn(NO3)2为原料,用柠檬酸络合溶胶-凝胶法制备了La0.75Sr0.25Cr0.5Mn0.5O3-δ凝胶,在700℃下焙烧2 h得到La0.75Sr0.25Cr0.5Mn0.5O3-δ(LSCM)纯相纳米粉,颗粒呈球形,分散性较好,平均粒径在28 nm左右。将上述粉体、乙基纤维素及松油醇按比例混合,经球磨、加乙醇研磨后制备成具有一定粘稠度的LSCM浆料。采用丝网印刷技术在YSZ片上制成不同厚度的LSCM膜,经1400℃煅烧,制备成厚膜型LSCM质NO2传感器。采用交流阻抗谱技术研究了膜层厚度、工作温度对传感器气敏性能的影响。结果表明:在一定温度条件下,传感器电阻与NO2浓度呈良好的线性关系。在600℃下,刷涂了7层LSCM的传感器线性最佳,灵敏度最高。
La0.75Sr0.25Cr0.5Mn0.5O3-La0.3Sr0.25Cr0.5Mn0.5O3 was prepared by citric acid complex sol-gel method using La (NO3) 3, Cr (NO3) 3.9H2O, Sr (NO3) 2 and Mn (NO3) δ gel, calcined at 700 ℃ for 2 h to obtain La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM) pure phase nano-powder with spherical shape and good dispersibility, and the average particle size is about 28 nm. The above powder, ethyl cellulose and terpineol are mixed in proportion, ball milling and ethanol milling to prepare LSCM slurry with a certain consistency. The LSCM films with different thicknesses were made on YSZ by screen printing technology and calcined at 1400 ℃ to produce thick film type LSCM NO2 sensors. The effects of film thickness and operating temperature on gas sensor performance were studied by AC impedance spectroscopy. The results show that there is a good linear relationship between the resistance of the sensor and the NO2 concentration at a certain temperature. At 600 ° C, sensors coated with seven LSCMs have the best linearity and sensitivity.