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

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-Al_2O_3基片上制备了钾修饰的钙掺杂钛酸铅纳米湿敏薄膜(K~+-Ca_xPb_ (1-x)TiO_3，缩写为K-CPT)。在(20 ± 0.1) ℃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-温特性，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 = 0.35，K~+含量为1%(K/Ti, mol/mol)，以及 850 ℃/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%～ 100%的全湿范围内，总的电阻值降低值约为10~4 kΩ，即全湿范围内的灵敏度可达 四个数量级；S=10~4kΩ/100△RH(%)。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，晶粒呈极度 化定向排列的电畴结构，粒度为10nm，岛的平均面积为4μm*5μm。

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

In order to increase the humidity sensitivity of PbTiO_3 , using Ti (0-n-Bu)_4(or (n-BuO)4Ti), Pb(OAc)_2 and Ca(OAc)_2 as the starting materials, K+-modified and Ca~(2+)-doped PbTiO_3 nano-film ( K+-Cat Pbi_x TiO_3, abbreviated as K-CPT) was prepared by sol-gel method, namely, spin-coating sol on a-Al_2O_3 substrate plated with Ag-Pd alloy interdigital electrode and then sintered at 850 TV1 h for crystallization. Its property of resistance-relative humidity was tested at the constant temperature of (20 ±0.1) °C , and compared with pure PbTiO_3(PT), Ca~(2+)-doped PbTiO_3(CPT) and Li+-modified Ca~ (2+)-doped PbTiO_3 nano-film (Li+-CaA:Pbi_;TiO3) 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 t/l h, displayed the sensitivity S = 3.3 X 103in the range of RH = 8.0% -93.6%, response time r = 15 s and humidity hysteresis sg ±2%; the total sensitivity S^IO4 in the extrapolation range of RH = 0.0% - 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 pan X 5 f*m area.