溶胶-凝胶法制备纳米La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3-δ)薄膜及其阻抗谱性能的研究

Synthesis of Nanometer Thin Film La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3-δ) by Sol-gel Method and Study on Impedance Spectroscopy Property

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-δ(LSCM) gel were prepared by sol-gel method using La(NO3)3,Cr(NO3)3·9H2O,Sr(NO3)2,Mn(NO3)2 and citric acid as raw materials.The LSCM nanopowder was obtained by the gel calcining at 700 ℃ for 2 h.The average particle size was about 28 nm.The powders,ethyl cellulose,terpineol and alcohol were mixed in proportion for preparing LSCM slurry by ball milling.LSCM film was coated on YSZ by screen-printing technology.The Effect of the film thickness and temperatures were investigated by EIS.The results show that the La0.75Sr0.25Cr0.5Mn0.5O3-δ exhibits high NO2 sensitivity,the EMF of sensor and the NO2 concentration had almost linear correlation.Below 600 ℃,the 7-layers LSCM sensor had the best linear and sensitivity.