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Potentiometric NO2 Sensors Based on Thin Stabilized Zirconia Electrolytes and Asymmetric (La0.8Sr0.2)0.95MnO3 Electrodes.

Zou J, Zheng Y, Li J, Zhan Z, Jian J - Sensors (Basel) (2015)

Bottom Line: Measurements of their sensing characteristics show that reducing the porosity of the supporting LSM95 reference electrodes can increase the response voltages.The best linear coefficient can be as high as 0.99 with a sensitivity value of 52 mV/decade as obtained at 500 °C.Analysis of the sensing mechanism suggests that the gas phase reactions within the porous LSM95 layers are critically important in determining the response voltages.

View Article: PubMed Central - PubMed

Affiliation: Gas Sensors & Sensing Technology Laboratory, College of Information Science and Engineering, Ningbo University, Ningbo 315211, China. ljl2005@mail.sic.ac.cn.

ABSTRACT
Here we report on a new architecture for potentiometric NO2 sensors that features thin 8YSZ electrolytes sandwiched between two porous (La0.8Sr0.2)0.95MnO3 (LSM95) layers-one thick and the other thin-fabricated by the tape casting and co-firing techniques. Measurements of their sensing characteristics show that reducing the porosity of the supporting LSM95 reference electrodes can increase the response voltages. In the meanwhile, thin LSM95 layers perform better than Pt as the sensing electrode since the former can provide higher response voltages and better linear relationship between the sensitivities and the NO2 concentrations over 40-1000 ppm. The best linear coefficient can be as high as 0.99 with a sensitivity value of 52 mV/decade as obtained at 500 °C. Analysis of the sensing mechanism suggests that the gas phase reactions within the porous LSM95 layers are critically important in determining the response voltages.

No MeSH data available.


Schematic illustration of the NO2 sensors.
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sensors-15-17558-f001: Schematic illustration of the NO2 sensors.

Mentions: Commercially available 8YSZ powders (Tosoh, Yamaguchi, Japan) were used as the electrolytes and self-synthesized LSM95 powders were used to prepare the RE substrates using the tape casting technique with carbon (Cancarb, Medicine Hat, AB, Canada) as the pore former. Screen printing was used to prepare SE from LSM95 ink and commercial Pt ink (Sino-platinum, Kunming, China). The tape casting slurries were prepared by a two-step ball milling procedure. In the first step, the targeted ceramic powders were homogeneously dispersed in a planetary mill for 1 h using zirconia balls, acrylic and xylene/butyl acetate as the milling medium, dispersant and solvents, respectively. Then, polyvinylbutyral (PVB) was added as the binder and polyethylene glycol (PEG) as the plasticizer, followed by another planetary milling for 2 h. The content of carbon in the LSM95 slurries were 15, 30, 45 and 60 wt % relative to the ceramic powders, respectively. After de-airing for 10 min under vacuum, the LSM95 and 8YSZ slurries were cast onto Mylar substrates with a doctor blade height of 300 or 75 μm. After drying, the green LSM95 and 8YSZ tapes were about 125 and 30 μm, respectively. In order to fabricate the LSM95 supported sensors, one sheet of 8YSZ green tape was laminated with the six similar sheets of LSM95 green tape. The LSM95 powders were mixed with α-terpineol to prepare print ink. The LSM95 ink was printed onto the top of green 8YSZ tapes. The sensors were denoted as S-15LSM95, S-30LSM95, S-45LSM95 and S-60LSM95. The Pt ink was printed onto the top of green 8YSZ tapes using the thick LSM95 layer with 15 wt % carbon as RE. The resultant sensors were denoted as S-15Pt. These green sensors were co-fired in air at 1225 °C for 4 h with a ramp rate of 3 °C/min. The schematic of NO2 sensors is showed in Figure 1. As the electrode leads, Pt wires were bonded to the electrode surfaces using a small amount of Pt ink. The particle size and pore size distributions were measured by laser particle analyzer (Mastersizer 2000, Malvern, Worcestershire, UK) and mercury intrusion porosimeter (Micromeritics AutoPore IV 9500, Norcross, GA, USA). The phase composition and microstructures of sensors were examined by X-ray diffraction with Cu-Kα radiation (XRD, D8 advance, Bruker, Billerica, MA, USA) and scanning electron microscopy (FE-SEM, SU-70, Hitachi, Tokyo, Japan).


Potentiometric NO2 Sensors Based on Thin Stabilized Zirconia Electrolytes and Asymmetric (La0.8Sr0.2)0.95MnO3 Electrodes.

Zou J, Zheng Y, Li J, Zhan Z, Jian J - Sensors (Basel) (2015)

Schematic illustration of the NO2 sensors.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541949&req=5

sensors-15-17558-f001: Schematic illustration of the NO2 sensors.
Mentions: Commercially available 8YSZ powders (Tosoh, Yamaguchi, Japan) were used as the electrolytes and self-synthesized LSM95 powders were used to prepare the RE substrates using the tape casting technique with carbon (Cancarb, Medicine Hat, AB, Canada) as the pore former. Screen printing was used to prepare SE from LSM95 ink and commercial Pt ink (Sino-platinum, Kunming, China). The tape casting slurries were prepared by a two-step ball milling procedure. In the first step, the targeted ceramic powders were homogeneously dispersed in a planetary mill for 1 h using zirconia balls, acrylic and xylene/butyl acetate as the milling medium, dispersant and solvents, respectively. Then, polyvinylbutyral (PVB) was added as the binder and polyethylene glycol (PEG) as the plasticizer, followed by another planetary milling for 2 h. The content of carbon in the LSM95 slurries were 15, 30, 45 and 60 wt % relative to the ceramic powders, respectively. After de-airing for 10 min under vacuum, the LSM95 and 8YSZ slurries were cast onto Mylar substrates with a doctor blade height of 300 or 75 μm. After drying, the green LSM95 and 8YSZ tapes were about 125 and 30 μm, respectively. In order to fabricate the LSM95 supported sensors, one sheet of 8YSZ green tape was laminated with the six similar sheets of LSM95 green tape. The LSM95 powders were mixed with α-terpineol to prepare print ink. The LSM95 ink was printed onto the top of green 8YSZ tapes. The sensors were denoted as S-15LSM95, S-30LSM95, S-45LSM95 and S-60LSM95. The Pt ink was printed onto the top of green 8YSZ tapes using the thick LSM95 layer with 15 wt % carbon as RE. The resultant sensors were denoted as S-15Pt. These green sensors were co-fired in air at 1225 °C for 4 h with a ramp rate of 3 °C/min. The schematic of NO2 sensors is showed in Figure 1. As the electrode leads, Pt wires were bonded to the electrode surfaces using a small amount of Pt ink. The particle size and pore size distributions were measured by laser particle analyzer (Mastersizer 2000, Malvern, Worcestershire, UK) and mercury intrusion porosimeter (Micromeritics AutoPore IV 9500, Norcross, GA, USA). The phase composition and microstructures of sensors were examined by X-ray diffraction with Cu-Kα radiation (XRD, D8 advance, Bruker, Billerica, MA, USA) and scanning electron microscopy (FE-SEM, SU-70, Hitachi, Tokyo, Japan).

Bottom Line: Measurements of their sensing characteristics show that reducing the porosity of the supporting LSM95 reference electrodes can increase the response voltages.The best linear coefficient can be as high as 0.99 with a sensitivity value of 52 mV/decade as obtained at 500 °C.Analysis of the sensing mechanism suggests that the gas phase reactions within the porous LSM95 layers are critically important in determining the response voltages.

View Article: PubMed Central - PubMed

Affiliation: Gas Sensors & Sensing Technology Laboratory, College of Information Science and Engineering, Ningbo University, Ningbo 315211, China. ljl2005@mail.sic.ac.cn.

ABSTRACT
Here we report on a new architecture for potentiometric NO2 sensors that features thin 8YSZ electrolytes sandwiched between two porous (La0.8Sr0.2)0.95MnO3 (LSM95) layers-one thick and the other thin-fabricated by the tape casting and co-firing techniques. Measurements of their sensing characteristics show that reducing the porosity of the supporting LSM95 reference electrodes can increase the response voltages. In the meanwhile, thin LSM95 layers perform better than Pt as the sensing electrode since the former can provide higher response voltages and better linear relationship between the sensitivities and the NO2 concentrations over 40-1000 ppm. The best linear coefficient can be as high as 0.99 with a sensitivity value of 52 mV/decade as obtained at 500 °C. Analysis of the sensing mechanism suggests that the gas phase reactions within the porous LSM95 layers are critically important in determining the response voltages.

No MeSH data available.