【作者】 闫晓娜；

【导师】 别利剑；

【作者基本信息】 天津理工大学 ， 材料物理与化学， 2007， 硕士

【摘要】 传统的纳米粉体或薄膜制备的半导体气敏元件由于颗粒易发生团聚或在高温工作时出现晶粒吞并、长大的陶瓷化过程,难以满足高灵敏度和选择性要求。将一维纳米材料制备成阵列作为气敏元件可能有效提高气敏元件性能。本文利用两步溶液化学法在不同基体上制备出氧化锌纳米阵列,通过对气体的灵敏度、响应时间等测量评价了氧化锌纳米阵列的气敏性能,并对包覆有二氧化钛纳米粒子的氧化锌纳米阵列气敏性能进行了研究;另外还研究了氧化锌纳米阵列的光致发光和浸润性,主要研究结果如下:1、通过两步溶液化学法制备出氧化锌纳米阵列。首先乙酸锌水解制备出ZnO纳米粒子的胶体溶液,然后将胶体溶液涂到玻璃或Al2O3陶瓷管基体上,在300~500℃之间热处理,获得了粒径在5~20nm之间的ZnO纳米薄膜,利用所得到的薄膜为前体,通过适当溶液化学反应获得了直径为20~200nm,长度为50 nm~2μm的ZnO纳米阵列。研究结果表明,两步溶液化学法可以在较低温度下大面积生长氧化锌纳米阵列,所得到的氧化锌纳米阵列分布均匀,呈c轴取向,晶体结构为六方纤维锌矿结构。2、对乙醇和氢气的气敏性能测试表明,工作温度为350℃时,所制备的氧化锌纳米阵列气敏元件对2500ppm乙醇的灵敏度为71.104,即使乙醇的浓度低至50ppm,其灵敏度仍然为10.573;氢气浓度为2500ppm时,氧化锌纳米阵列气敏元件的灵敏度也达到30.076。与氧化锌纳米粉体材料所制备的传感元件相比,这些结果都有较大提高。以氧化锌为基体的ZnO-TiO2复合材料在工作温度为350℃时,气敏元件对2500ppm乙醇的灵敏度为74.949,对相同浓度的氢气的灵敏度也达到52.09。研究结果还表明,无论纯氧化锌纳米阵列还是ZnO-TiO2复合材料气敏元件对乙醇的灵敏度都比对相同浓度的氢气灵敏度要高。3、光致发光性能研究结果表明,氧化锌纳米阵列的紫外发光峰位于399.8nm,与氧化锌纳米薄膜相比,纳米阵列的紫外发光明显的红移,且发光强度明显减弱;但纳米阵列的发光峰在蓝光部分相对增强。4、通过接触角测量评价了氧化锌纳米阵列的浸润性,重点研究了粒径大小对氧化锌纳米阵列的亲水性能的影响。对氧化锌纳米膜前体在300℃时进行不同时间的热处理,随热处理时间的增加,所得到的氧化锌纳米阵列中纳米棒的平均直径逐渐增加,亲水性逐渐减弱。更多还原

【Abstract】 The sensitivity and selectivity of traditional semiconductor metal oxide sensors prepared using powders with grain size in micron or nano range were not high enough to detected very low concentration gases due to their grain growth when they were working at relatively high temperature, It should be possible to increase the sensing properties of these sensors with 1-D nanostructures array.ZnO nanorods array on different kinds of substrates were prepared by a two-step solution method. The corresponding gas sensitivity, photoluminescence and wettability were investigated, and the gas sensitivity of ZnO nanorods covered with TiO2 was studied as well. The main findings are as following:1. Preparation of ZnO nanorods array via a two-step solution approach. The ZnO sol was prepared through Zn(Ac)12 hydrolysis, then the ZnO sol prepared was coated onto glass or Al2O3 tubes , annealed at 200~600℃, ZnO film precursor with the diameter of 5~20nm was obtained.Large-area, well-aligned ZnO nanorods can be obtained by further reaction on the ZnO precursors, the diameters and lengths of the obtained ZnO nanorods array are in the range of 20~200nm and 50nm~2μm respectively. The as-prepared ZnO nanorods are wurtzite structure with preferentially c-axis orientation.2. Sensitivity measurement of ethanol and hydrogen showed that at the temperature of 350℃, the aligned ZnO nanorods gas sensor exhibited a sensitivity of 71.104 and 30.076 to 2500ppm ethanol and hydrogen respectively, the sensitivity achieved 10.573 even being exposed to the gas concentration as low as 50ppm ethanol. The sensitivity test of ethanol and hydrogen showed that the aligned zinc oxide nanorods devices had an improved sensing performance compared with the reported ZnO nanoparticle sensors.An investigation on the gas sensor of ZnO-TiO2 composite showed that at 350℃, the sensitivity of ZnO-TiO2 composite are 74.949 and 52.09 to 2500ppm ethanol and hydrogen respectively. Either pure ZnO nanorods or ZnO-TiO2 composite gas sensors showed relatively higher sensitivity to ethanol than to hydrogen.3. In contrast to the photoluminescence spectra gathered from ZnO film, the emission band of ZnO nanorods red-shifted to the position around 399.8nm, and the intensity of violet luminescence decreased greatly compared with that of ZnO film sample. Nevertheless, the intensity of blue luminescence was relatively increased.4. The wettability of ZnO nanorods array was evaluated via contact angular measurement. Results showed that the hydrophilicity of ZnO nanorods array decresed as the heat-treatment time increased at the temperature of 300℃.更多还原