Negative Thermal Sensitivity of La1-xSrxFeO3 Films Prepared by Screen-Printing Method

2017 ◽  
Vol 898 ◽  
pp. 1617-1624
Author(s):  
Xin De Zhu ◽  
Yu Zhou ◽  
Sheng Li Li
Keyword(s):  
Activation Energy ◽  
High Performance ◽  
Screen Printing ◽  
Small Polaron ◽  
Thermal Sensitivity ◽  
Negative Temperature ◽  
Electric Transport ◽  
Polaron Hopping ◽  
Screen Printing Method ◽  
Printing Method

The impacts of different Sr content on the phase structure, negative temperature coefficient (NTC) characteristic and conduction mechanism at high temperature of lanthanum strontium ferrite (La1-xSrxFeO3, x=0.1~0.6) (LSFO) films were systematically discussed. The LSFO films were prepared on the alumina substrate by the screen printing method. The results showed that the crystal structure transformed from orthorhombic (x=0.1~0.3) to rhombohedral (x=0.4~0.6). All the samples presented NTC performance. With increasing the Sr content, B values increased to the maximum 3885 K (x=0.4) and then decreased. Non-adiabatic small polaron hopping mechanism was dominant for their electric transport in the temperature range from 450 K to 873 K. The activation energy was calculated between 0.37 eV and 0.57 eV, and the sample La0.7Sr0.3FeO3 showed the minimum value of the activation energy. Therefore the La1-xSrxFeO3 (x=0.3, 0.4, 0.5) films have the potential to be developed into high-performance NTC resistors.

Synthesis and Electrical Transport Property of Sr and Cu-Doped LaFeO3-Based Cathode Material for IT-SOFC

2013 ◽  
Vol 710 ◽  
pp. 33-36
Author(s):  
Jie Zhao ◽  
Jiang Fu ◽  
Yong Fu ◽  
Yong Chang Ma
Keyword(s):  
Cathode Material ◽  
Electrical Transport ◽  
High Performance ◽  
Small Polaron ◽  
Negative Temperature ◽  
Rare Earth Oxide ◽  
Intermediate Temperature ◽  
Charge Balance ◽  
Mixed Conductivity ◽  
Polaron Hopping

In order to accelerate the commercialization of SOFCs technology, the key is the development of high performance cathode materials operated at intermediate temperature. Sr and Cu doped rare earth oxide La1-xSrxFe1-yCu.yO3-δ (x=0.1, 0.3 ; y=0.1, 0.2, denoted as LSFCu-11, LSFCu-31 and LSFCu-32 ) were synthesized by solid state reaction method (SSR). The formation process, phase structure and microstructure of the synthesized samples were characterized using TG/DSC, XRD and SEM. The thermal expansion coefficients (TEC) of the samples were analyzed by thermal dilatometry. The electrical conductivities of the samples were measured with DC four-terminal method from 25 to 950 °C. The results indicate that the samples exhibit a single phase with orthorhombic and hexagonal perovskite structure after sintered at 1200 °C for 4h. The electrical conductivity of the samples increases with temperature up to a maximum value, and then decreases gradually. The small polaron hopping is regarded as the conducting mechanism for synthesized samples at T 550 °C. The negative temperature dependence occurring at higher temperature is due to the creation of oxygen vacancies for charge balance. LSFCu-32 has higher mixed conductivity (> 100 S·cm-1) at intermediate temperature and can meet the demand of cathode material for IT-SOFC. In addition, the average TECs of LSFCu-11, LSFCu-31 and LSFCu-32 are 1.22 × 10-6 K-1 , 1.30 × 10-6 K-1 and 1.34 × 10-6 K-1 respectively.

scholarly journals Enhancing Formaldehyde Selectivity of SnO2 Gas Sensors with the ZSM-5 Modified Layers

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3947
Author(s):  
Wei Wang ◽  
Qinyi Zhang ◽  
Ruonan Lv ◽  
Dong Wu ◽  
Shunping Zhang
Keyword(s):  
Gas Sensors ◽  
Indoor Air ◽  
High Performance ◽  
Screen Printing ◽  
Gas Sensing ◽  
Oxide Semiconductors ◽  
Screen Printing Method ◽  
Gas Sensing Properties ◽  
Zeolite Films ◽  
Insufficient Knowledge

High performance formaldehyde gas sensors are widely needed for indoor air quality monitoring. A modified layer of zeolite on the surface of metal oxide semiconductors results in selectivity improvement to formaldehyde as gas sensors. However, there is insufficient knowledge on how the thickness of the zeolite layer affects the gas sensing properties. In this paper, ZSM-5 zeolite films were coated on the surface of the SnO2 gas sensors by the screen printing method. The thickness of ZSM-5 zeolite films was controlled by adjusting the numbers of screen printing layers. The influence of ZSM-5 film thickness on the performance of ZSM-5/SnO2 gas sensors was studied. The results showed that the ZSM-5/SnO2 gas sensors with a thickness of 19.5 μm greatly improved the selectivity to formaldehyde, and reduced the response to ethanol, acetone and benzene at 350 °C. The mechanism of the selectivity improvement to formaldehyde of the sensors was discussed.

scholarly journals Synthesis of NTC thermistors with screen printing method from natural yarosite minerals

2021 ◽  
Vol 1053 (1) ◽  
pp. 012012
Author(s):  
Iga Purwitasari Aningratri ◽  
Nazriati Nazriati ◽  
Dani Gustaman Syarif
Keyword(s):  
Screen Printing ◽  
Screen Printing Method ◽  
Ntc Thermistors ◽  
Printing Method

Structural and Dielectric Properties of Screen Printed PZT(70/30) Multilayered Thick Films

2007 ◽  
Vol 124-126 ◽  
pp. 663-666 ◽  
Author(s):  
Sung Gap Lee ◽  
Sang Man Park ◽  
Young Jae Shim ◽  
Young Chul Rhee
Keyword(s):  
Screen Printing ◽  
Remanent Polarization ◽  
Thick Films ◽  
Sol Gel ◽  
Relative Dielectric Constant ◽  
Polycrystalline Structure ◽  
Coating Solution ◽  
Screen Printing Method ◽  
Xrd Patterns ◽  
Printing Method

PZT(70/30) powder was prepared by a sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The coating and drying procedure was repeated 4 times. And then the PZT(30/70) precusor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5 mol/L and the number of coating was varied from 0 to 6. The porosity decreased and the grain size increased with increasing the number of coatings. The thickness of the PZT-6(6: number of coatings) films was about 60~65μm. All PZT thick films showed the typical XRD patterns of a typical perovskite polycrystalline structure. The relative dielectric constant of the PZT-6 thick film was 540. The remanent polarization and coercive field of the PZT-6 film were 23.6 μC /cm2, 12.0 kV/cm, respectively.

Fabrication and Sensing Behavior of NASICON Thick Film SO2 Gas Sensor by Screen-Printing Method

2003 ◽  
Vol 439 ◽  
pp. 352-357
Author(s):  
Sang Tae Lee ◽  
Jae Chul Bae ◽  
Hee-Kwon Jun ◽  
Duk-Dong Lee ◽  
Jeung Soo Huh
Keyword(s):  
Thick Film ◽  
Gas Sensor ◽  
Screen Printing ◽  
Screen Printing Method ◽  
Printing Method
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