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Study on Properties of Resistive-type Humidity Sensors Based Nano-oxides

Author: WangZhuYi
Tutor: WuFengQing
School: Jilin University
Course: Physical and chemical
Keywords: Resistive Humidity sensor Humidity sensitive mechanism LaCoxFe1-xO3 TiO2
CLC: TP212
Type: PhD thesis
Year: 2009
Downloads: 164
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Abstract


Humidity monitoring and control by the more and more attention in industry, agriculture , daily life , scientific research and other aspects of the resistive type humidity sensor is a widely used class of chemical sensors , it is a work based on the adsorption of moisture-sensitive materials , i.e. , adsorption and desorption of the moisture sensitive material after the water molecules can cause a change in the impedance of the material occurs , causing the element output signal changes . Synthesis and characterization of two types of humidity sensitive material of this paper , based on the electrical properties of these two types of functional materials resistance-type humidity sensing element and sensitive mechanism . Citric acid were prepared with different X values ??LaCo in x Fe 1 - x O 3 < / sub > nano- powder materials as a thick-film technology to prepare sensitive devices sensitive slurry , its moisture-sensitive performance parameter test results showed that the sensitivity relative best material for LaCo 0.3 Fe 0.7 O 3 < / sub>. This material alkali metal physical doping , chemical doping modification effectively reduces the resistivity of the material , so that the humidity sensor of the material be able to work within the entire humidity range , the sensitivity of the moisture-sensitive element is greatly improved . Tetrabutyl titanate as the precursor, after TEOS is added in the sol-gel synthesis process of the sample HF treatment obtained TiO 2 a specific surface area is greatly improved, significantly improved the traditional methods of preparation of TiO2 poor sensitivity phenomenon in low humidity , humidity sensor humidity changes in the entire humidity area has a good response . Dielectric physical theory sensitive mechanism used to explain the humidity sensitive element of the types of materials , according to the experiment, the obtained complex impedance spectrum of the element in a different humidity environment , designed DC instantaneous polarity reversal experiments wet sensitive elements in a different humidity environment , the specific conductive particles. That these two types of moisture-sensitive materials in the entire humidity range by the two types of particles involved in electrical conductivity , namely electrons and ions . With increasing humidity , the role of e-participation conductive gradually weakened , while the ions involved in the role of conductivity gradually increased , the experimental results obtained with the more popular electronic - ionic conductivity theory coincide . Of these studies is to find new humidity and humidity sensitive material modification of certain significance.

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CLC: > Industrial Technology > Automation technology,computer technology > Automation technology and equipment > Automation components,parts > Transmitter ( converter),the sensor
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