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无机材料学报

无机材料学报

• 研究论文 • 上一篇    下一篇

锂修饰钙掺杂钛酸铅纳米薄膜的显微结构与湿敏机理

左霞1,2, 王智民1, 刘静波1, 张艳熹1, 韦永德2   

  1. 1. 黑龙江大学化学化工与材料科学学院, 哈尔滨 150080; 2. 哈尔滨工业大学应用化学系, 哈尔滨 150001
  • 收稿日期:2003-12-01 修回日期:2004-01-15 出版日期:2005-01-20 网络出版日期:2005-01-20

Microstructure and Humidity-sensing Mechanism of Both Ca2+-doped and Li+-modified PbTiO3 Nano-film

ZUO Xia1,2, WANG Zhi-Min1, LIU Jing-Bo1, ZHANG Yan-Xi1, WEI Yong-De2   

  1. 1. College of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; 2. Department of Applied Chemistry, Harbin
    Institute of Technology, Harbin 150001, China
  • Received:2003-12-01 Revised:2004-01-15 Published:2005-01-20 Online:2005-01-20

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摘要： 利用溶胶-旋涂镀膜技术, 以Li2CO3, Ca(OAc)2, Pb(OAc)2, 和Ti(O-nBu)为起始物, 制备了锂修饰的钙掺杂钛酸铅湿敏纳米薄膜(Li+-CaxPb1-xTiO3, 缩写为Li-CPT, 在 850℃/1h条件下烧结成瓷), 其中x=0.35, Li/Ti=1/100(mol/mol), 获得了很好的电阻-湿敏性能. 采用原子力显微镜(AFM)技术, 并与激光拉曼光谱仪(LRS)形貌观测相结合的方法, 表征了该薄膜的显微结构, 探讨了钙掺杂和锂修饰的协同作用对湿敏性能极差的纯钛酸铅 (PbTiO3, 缩写为PT)进行湿敏改性的可能机理. Li-CPT 表面的晶粒平均面积为5μm×10μm, 具有网状晶界和较大的表面积, 表面粗糙度为(+0.5μm)～(-1.2μm), 形成了多晶陶瓷结构和晶格缺陷. Pauling离子半径较小的Ca2+掺杂取代了Pb2+, 降低了四方晶相畸变度c/a和不对称性导致的各向异性, 消除了冷却过程中内应力引起的薄膜开裂和脱落. 少量Li+用作表面修饰, 其半径比Ca2+的更小, 电荷密度更大, 对水分子具有很强的极化作用和吸附作用, 在很宽的湿度范围内和外电场的诱导下, 水分子被解离, OH-与氧空位结合产生出自由电子参与导电. 因而钙掺杂和锂修饰的协同作用使薄膜表现出灵敏度和线性均好的电阻-湿敏性能.

关键词: 锂修饰的钙掺杂钛酸铅(Li-CPT), 阻-湿敏感纳米薄膜, 原子力显微镜(AFM), 显微结构

Abstract: A good humidity-sensitive Li+-modified and Ca2+-doped PbTiO3 nano-film (Li+-CaxPb1-xTiO3, x=0.35, Li/Ti=1/100 mol/mol, sintered
at 850℃/1h; abbreviated as Li-CPT) was prepared by the sol-spin-coating process using Ca(OAc)2, Pb(OAc)2, Li2CO3 and Ti(O-nBu)4 as starting materials. Li-CPT microstructure was studied by means of AFM. AFM observation
of both morphology and linear surface roughness indicates marked reticulate grain boundaries, the linear surface roughness is within (+0.5μm)～
(-1.2μm), and hence large surface area: The film surface shows the presence of polycrystalline grains with an average area of
5μm×10μm. Such a microstructure is favorable for having a good humidity sensitivity. The crystal geometry and electron structure will change greatly
after the equate-valence substitution of Ca2+ with smaller Pauling ion radius for Pb2+. The substitution decreases the lattice distortion
(c/a), the non-symmetry and film cracks. There is a probable mechanism for electrical resistance-humidity sensitivity. H2O molecules polarized and adsorbed on the Li-CPT
film surface, due to the doping of Li+ ions with smaller radius, dissociate into H+ and OH-, H+ ions combine with lattice oxygen,
OH- ions fill up the oxygen hole (defect site) and release free electrons which participate in electric conduction in the external electric field; hence electrical
resistance will decrease with the increase of relative humidity.

Key words: Li+-modified and Ca2+-doped PbTiO3(Li-CPT), humidity sensitive nano-film, AFM, microstructure

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