一种修饰钙掺杂钛酸铅湿敏纳米薄膜的新方法──钾修饰薄膜的制备、湿敏特性和结构表征

A New Method for Modification of Ca^(2+) doped PbTiO_3 Humidity Sensitive Nano-Film: Preparation, Humidity Sensitivity and Structure of K^+-Modified Thin Film

为了使感湿性能很差的钛酸铅湿敏改性 ,选取Ti(O n Bu) 4 ,Pb(OAc) 2 和Ca(OAc) 2 为起始物 ,采用溶胶 -旋涂法以及烧结晶化过程 ,在镀有Ag Pd合金叉指电极的α Al2 O3 基片上制备了钾修饰的钙掺杂钛酸铅纳米湿敏薄膜 (K+ CaxPb1 -xTiO3 ,缩写为K CPT) .在 ( 2 0± 0 .1)℃的常温下、相对湿度RH =8.0 %～ 93 .6%之间 5个检测点上测试了K CPT的阻 -湿特性 ,并与纯钛酸铅薄膜 (PT)、钙掺杂钛酸铅薄膜 (CPT)以及锂修饰的钙掺杂钛酸铅薄膜 (Li CPT)进行了比较 ,对工艺进行了正交实验和研究 .结果表明 :在x =0 .3 5 ,K+ 含量为 1%(K/Ti,mol/mol) ,以及 85 0℃ /1h的烧结晶化成瓷条件下 ,所制得的陶瓷薄膜在RH =8.0 %～ 93 .6%的实测范围内 ,灵敏度S =3 .3× 10 3 ,感湿响应时间τ =15s,湿滞≤± 2 %;而在RH =0 %～ 10 0 %的全湿范围内 ,总的电阻值降低值约为 10 4kΩ ,即全湿范围内的灵敏度可达四个数量级 :S =10 4kΩ/10 0ΔRH ( %) .通过XRD ,SEM和TEM手段对薄膜的晶相结构及显微结构进行了表征 ,薄膜为四方多晶 ,具有网状孔道和岛形晶界 ,晶粒呈极化定向排列的电畴结构 ,粒度为 10nm ,岛的平均面积为 4μm× 5 μm .

In order to increase the humidity sensitivity of PbTiO3, using Ti(O-n-Bu)(4)(or (n-BuO)(4)Ti), Pb(OAc)(2) and Ca(OAc)(2) as the starting materials, K+-modified and Ca2+-doped PbTiO3 nano-film (K+-Ca-x Pb1-xTiO3, abbreviated as K-CPT) was prepared by sol-gel method, namely, spin-coating sol on alpha-Al2O3 substrate plated with Ag-Pd alloy interdigital electrode and then sintered at 850 degreesC/1 h for crystallization. Its property of resistance-relative humidity was tested at the constant temperature of (20 +/- 0.1)degreesC, and compared with pure PbTiO3 (PT), Ca2+-doped PbTiO3(CPT) and Li+-modified Ca2+-doped PbTiO3 nano-film (Li+-CaxPb1-xTiO3, Li-CPT for short). Process parameters were investigated by orthogonal design. The results indicated that the film prepared with formula of x = 0.35 and K+ content= 1.0% (K/Ti, mol/mol), and sintered at 850 degreesC/1 h, displayed the sensitivity S = 3.3 x 10(3) in the range of RH = 8.0% similar to 93.6%, response time tau = 15 s and humidity hysteresisless than or equal to +/- 2%; the total sensitivity Scongruent to10(4) in the extrapolation range of RH = 0.0% similar to 100.0%. The film was characterized by XRD, SEM and TEM, which showed the tetragonal nano-polycrystalline with 10 nm of grain size and electric domain structure reticulated pores and obvious grain boundary like island with 4 mum x 5 mum area.