LiZnVO4添加量对Zn2SnO4系湿敏材料性能的改善

采用共沉淀法制备了Zn2SnO4-LiZnVO4系纳米粉体,考察了液相掺杂LiZnVO4对材料微结构、湿敏性能的影响,分析了材料的复阻抗特性和频率特性。结果表明,适当的LiZnVO4添加量可明显改善Zn2SnO4-LiZnVO4系纳米材料的微结构和感湿特性。采用共沉淀法制备纳米粉体并使LiZnVO4液相掺杂为10%(摩尔分数),可使Zn2SnO4材料具有低湿电阻小、灵敏度适中的湿敏特性,频率特性表明该材料具有较好的频率响应。     

SnO2-LiZnVO4系湿敏材料湿敏特性及介电特性

采用尿素共沉淀法制备SnO2纳米粉体,考察了液相掺杂LiZnVO4对其湿敏性能的影响,测试了材料的电抗特性、电容量特性和响应–恢复特性。结果表明,采用尿素共沉淀法制备SnO2纳米粉体,液相掺杂x(LiZnVO4)为10%时,可使材料具有较好的湿敏性能和响应–恢复特性,响应时间和恢复时间都为55s左右。测试频率对材料的电抗和电容量影响很大。     

K+掺杂对SnO2-LiZnVO4系湿敏陶瓷性能的影响

为了提高 SnO_2-LiZnVO_4系湿敏材料的性能,采用共沉淀法制备出 SnO_2-K_2O-LiZnVO_4系纳米湿敏粉体。考察了液相掺杂 K+对材料湿敏性能、复阻抗特性和电容特性的影响。实验结果表明,采用共沉淀法制备纳米粉体并使K+液相掺杂量为 2.5%(摩尔分数),可使湿敏材料低湿电阻小、灵敏度适中,适当的 K+添加量可明显改善 SnO_2-LiZnVO_4系纳米材料的感湿特性。     

添加剂对SnO_2系湿敏陶瓷影响的研究进展

SnO2是一种优良的气湿敏陶瓷材料,应用十分广泛,是一类十分有前途的湿敏材料。综述了添加剂对SnO2系湿敏陶瓷的微结构和电性能的影响之研究现状。结果表明:添加适量的LiZnVO4和碱金属,可使材料获得规则的棒状晶粒微结构,低湿电阻较小,灵敏度适中等良好的湿敏性能。并阐明了SnO2系湿敏陶瓷未来的研究方向可以结合TiO2,制备TiO2,SnO2,LiZnVO4和碱金属复合材料。     

复合钒钛酸干凝胶薄膜的湿敏特性研究

采用sol-gel法制备了复合钒钛酸干凝胶(H2V10Ti2O30-y·nH2O)薄膜,并对其湿敏特性进行了研究。结果表明:该薄膜为层状结构。用此薄膜制备的湿敏元件,在RH为11%～95%的范围内,感湿特性曲线线性好,其响应、恢复时间分别为5s和20s,湿滞为RH2%,感湿温度系数为RH0.45%/℃,并具有良好的稳定性。H2V10Ti2O30-y·nH2O干凝胶薄膜湿敏元件的灵敏度和湿滞均优于复合钒酸(H2V12O31-y·nH2O)干凝胶薄膜湿敏元件。     

SnO_2-LiZnVO_4系棒状与球形晶粒湿敏陶瓷特性研究

对比研究了尿素共沉淀法和氨水共沉淀法制备出SnO_2-LiZnVO_4系湿敏陶瓷的显微结构和湿敏特性,考察了液相掺杂LiZnVO_4对材料湿敏特性的影响.实验结果表明,采用尿素共沉淀法制备出的SnO_2-LiZnVO_4系湿敏材料具有棒状晶粒的微结构,而采用氨水共沉淀法制备出的该系湿敏材料具有球形晶粒的微结构.湿敏特性表明,2种微结构的湿敏材料都是液相掺杂LiZnVO_4的摩尔分数为10%时可使材料湿敏性能最好.但棒状晶结构的SnO_2-LiZnVO_4系湿敏材料低湿电阻更小,灵敏度更适中.频率特性表明,测试频率对2种试样的阻抗-相对湿度特性曲线影响都较大.稳定性分析表明,棒状晶结构的试样比球形晶粒结构的试样更稳定.     

湿度和频率对湿敏元件电学特性的影响

在印有梳状电极的石英玻璃表面涂覆氧化钛纳米薄膜制备湿敏元件,研究不同湿度、不同频率下的电学特性。结果表明,随着湿度的增大,湿敏元件的电阻值、阻抗值减小,电容增大;当湿度一定时,电阻值、电容值都随频率的增大而减小;工作频率为0.01 kHz、相对湿度高于40%时,具有较好的湿敏特性。实验说明湿敏元件中不仅电子、离子浓度发生变化,材料的极化也发生了变化。     

复合钒钼酸干凝胶薄膜湿敏元件的感湿机理

采用sol-gel法,制备了复合钒钼酸H2V8.5Mo3.5O32.nH2O干凝胶薄膜湿敏元件。测试频率为1 kHz时,元件全湿范围内线性响应好,灵敏度高,最大湿滞约为RH 2.74%,响应、恢复时间分别为8 s和20 s,283~303 K温度范围内的感湿温度系数为RH 0.4%/℃;H2V8.5Mo3.5O32.nH2O干凝胶薄膜湿敏元件的导电机理为电子和离子导电共存,低湿时以电子导电为主,湿度增加,离子导电增强。     

氧化镓纳米棒的超声法制备及湿敏特性研究

以商业氮化镓(GaN)粉末为原料,经简单超声辅助的方法成功制备出氧化镓(Ga_2O_3)纳米棒。通过X射线衍射(XRD)、场发射扫描电镜(FE-SEM)和透射电子显微镜(TEM)等对其结构、形貌及成分进行表征分析。结果表明材料为纳米棒状多孔结构,直径和长度范围分別在100 nm和2μm左右,并且Na~+和K~+被成功地掺杂。湿敏材料旋涂在预先涂覆有Ag-Pd叉指电极的Al_2O_3陶瓷基片上制作成湿敏测试元件。对其湿敏性能进行测试,結果表明:Ga_2O_3纳米棒传感器的阻抗随着湿度的变化曲线表现出良好的线性响应和稳定性,在100 Hz频率下,当环境中的相对湿度(RH)从11%到95%变化时,该湿度传感器阻抗变化超过四个数量级,响应和恢复时间分別为1 s和6 s,其最大湿滞为3%RH。优异的湿敏特性可能源于一维Ga_2O_3纳米结构和离子掺杂的协同效应。     

掺Sm2O3的SnO2纳米粉体对C2H2气敏特性的研究

用化学沉淀法制备了SnO2纳米材料,利用XRD和SEM对合成产物进行了表征.采用旁热式结构制成了以SnO2为基体材料,掺杂Sm2O3的气体传感器.通过元件对C2H2气敏特性的测试表明:Sm2O3的掺杂可以明显地提高SnO2气敏材料对C2H2气体的灵敏度,当工作温度为180℃,C2H2浓度为1000ppm时,元件的灵敏度为64,响应恢复时间分别为3和20s.讨论了不同相对湿度对元件气敏特性的影响.     

Novel capacitance-type humidity sensor based on multi-wall carbon nanotube/SiO2 composite films

A novel capacitance-type relative humidity (RH) sensor based on multi-wall carbon nanotubc/SiO2 (MWCNTs/SiO2) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteristics,such as linearity and sensitivity,are described.The capacitance of the MWCNTs/SiO2 composite film shows typical concentration percolation behavior with increasing MWCNT loading.At loadings below the percolation threshold (1.842wt％),the sensor capacitance increases obviously with increasing MWCNTs.The water condensed in the MWCNTs/SiO2 layer can lower the percolation threshold and increase the sensor capacitance.The sensor with MWCNT concentration of 1 wt％ has the best properties.The sensor has a humidity sensitivity of about 673 pF/％ RH and a linearity correlation of 0.98428.The response time of the sensor to RH is about 40 s and the recovery time is about 2 s.     

A high-speed capacitive humidity sensor with on-chip thermal reset

This paper reports a high-speed capacitive humidity sensor integrated on a polysilicon heater. A response time of 1.0 s and a sensitivity of 30.0 fF/%RH have been obtained. High speed is achieved using multiple polyimide columns having diameters of a few microns and allowing moisture to diffuse into them circumferentially. Using structures that eliminate the air-gap capacitance between the columns, the simulated sensor output drifts by only 1% when the relative dielectric constant in the air region changes from 1 to 10. A polysilicon heater is used to measure relative humidity levels >80% RH. An accuracy of ±3% RH has been obtained using this method, with measurement errors of ±0.5°C and ±2% RH in temperature and relative humidity, respectively. The heater also reduces the recovery time after wetting, enables the sensor to recover from contamination and aging, and allows the sensing film to be reset on demand during self-test protocols     

基于多壁碳纳米管/SiO2复合材料检测的新型电容型碳纳米管湿度传感器

A novel capacitance-type relative humidity(RH) sensor based on multi-wall carbon nanotube/SiO_2 (MWCNTs/SiO_2) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteristics,such as linearity and sensitivity,are described.The capacitance of the MWCNTs/SiO_2 composite film shows typical concentration percolation behavior with increasing MWCNT loading.At loadings below the percolation threshold(1.842wt%),the sensor capacitance increases obviously with i...     

一种新型的CMOS集成湿度传感器

利用MEMS技术 ,对一种新型CMOS湿度传感器进行理论分析、模拟以及结果讨论。该湿度传感器采用标准CMOS工艺制造 ,采用梳状铝电极结构、梳状多晶硅加热结构 ,衬底接地 ,感湿介质采用聚酰亚胺 ,利用商业软件Coventor进行模拟绘制出敏感电容与相对湿度的曲线图。接口电路采用开关电容电路 ,输出可测电压信号 ,利用Microsim公司的Pspice模拟电路得到相对湿度与输出电压曲线关系     

基于倾斜光纤光栅的相对湿度传感器

提出了一种基于倾斜光纤光栅(TFBG)的包层上覆盖着聚乙烯醇(PVA)的空气相对湿度传感器,成功实现了对相对湿度在20～98%RH范围内的监测。研究发现,TFBG的透射功率在20～74%RH和74～98%RH2个相对湿度区域内分别呈现不同的线性变化,敏感度分别为2.52 dBm/%RH和14.95 dBm/%RH,并且在高湿度区有更高的敏感性。     

Application research on the sensitivity of porous silicon

Applications based on sensitive property of porous silicon (PSi) were researched. As a kind of porous material, the feasibility of PSi as a getter material was studied. Five groups of samples with different parameters were prepared. The gas-sensing property of PSi was studied by the test system and suitable parameters of PSi were also discussed. Meanwhile a novel structure of humidity sensor, using porous silicon as humidity-sensitive material, based on MEMS process has been successfully designed. The humidity-sensing properties were studied by a test system. Because of the polysilicon layer deposited upon the PSi layer, the humidity sensor can realize a quick dehumidification by itself. To extend service life and reduce the effect of the environment, a passivation layer (Si₃N₄) was also deposited on the surface of electrodes. The result indicated the novel humidity sensor presented high sensitivity (1.1 pF/RH%), low hysteresis, low temperature coefficient (0.5%RH/℃) and high stability.     

Effect of surfactant on performance of ZnO humidity sensor

In this study, using surfactant monoethanolamine (MEA), zinc oxide (ZnO)-MEA humidity sensor based on ZnO was successfully prepared by hydrothermal method. MEA makes the surface of the ZnO-MEA have more oxygen vacancy and hydrophilic functional groups, which improves the performance of ZnO humidity sensor. ZnO-MEA achieved a change of 4 orders of magnitude at room temperature in the relative humidity (RH) from 11% to 95%, and it shows better linearity, shorter response/recovery time (20 s/15.9 s), smaller humidity lag and long-term stability. In addition, the distribution of ZnO-MEA particles is more uniform and provides more active sites for adsorption of water molecules to enhance humidity sensing performance.