Enhanced long-term stability of SnO2-based CO gas sensors modified by sulfuric acid treatment

Ozaki, Yasutaka; Suzuki, Sachiyo; Morimitsu, Masatsugu; Matsunaga, Masaki

doi:10.1016/s0925-4005(99)00394-9

Cited by 48 publications

(26 citation statements)

References 8 publications

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“…The SnO 2 were in order to improve on the charge carrier concentration and with palladium to improve on their gas. Since passivation is known to improve on the stability of SnO 2 based thin films [14,20,21,22], the main purpose of this study was to gas sensing and study on the optical properties of Procedure microscope glass slides and 1.2mm thick. Cleaning of deposition.…”

Section: Sample Preparationmentioning

confidence: 99%

“…Thin films were passivated by annealing them in a nitrogen atmosphere in a tube furnace for 30 minutes at 450 0 C. Since passivation is known to improve on the stability of doped SnO 2 thin films [13,14,20,21,22], in this study it was done in order to study its effect on optical properties of Pd-F: SnO 2 thin films.…”

Section: Thin Film Passivationmentioning

confidence: 99%

“…The SnO doped with fluorine in order to improve on the charge concentration and with palladium to improve on their stability and sensitivity toward CO 2 gas. Since pas known to improve on the stability of SnO [14,20,21,22], the main purpose of this study was to deposit Pd-F:SnO 2 thin films for CO 2 gas the effect of surface passivation on the optical properties of Pd-F:SnO 2 thin films.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Surface Passivation on Optical Properties of Spray Pyrolysis Deposited Pd-F:SnO2

Mwathe¹

2014

IJMSA

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Pd-F:SnO 2 thin films have been prepared by spray pyrolysis technique using an alcoholic precursor solution consisting of stannic chloride (SnCl 4 .5H 2 0), ammonium fluoride (NH 4 F) and palladium chloride (PdCl 2 ). Optimization on the deposition parameters has been done in order to obtain high quality thin films. The effect of varying the fluorine content on the optical properties of Pd-F:SnO 2 thin films were studied. Data for transmittance and reflectance in the wavelength range from 300nm -2500nm was measured using the solid spec 3700DUV spectrophotometer. The calculated optical band gap of the as prepared thin films has been found to range from 3.8eV to 4.11eV. Fluorine incorporation for Pd-F:SnO 2 has been found to have a narrowing effect on the band gap, but at its higher concentration the band gap has been seen to increase. The band gap narrowing is due to the incorporation of F -ions in the crystal lattice therefore giving rise to donor levels in the SnO 2 band gap which is an essential characteristic for the gas sensor applications. Both annealing and passivation have been found to have very insignificant change in optical band gap of Pd-F:SnO 2 .

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Section: Sample Preparationmentioning

confidence: 99%

Section: Thin Film Passivationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Surface Passivation on Optical Properties of Spray Pyrolysis Deposited Pd-F:SnO2

Mwathe¹

2014

IJMSA

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“…Poseen una velocidad de quimisorción extremadamente lenta a temperatura ambiente, razón por la cual son empleados a temperaturas entre 200-400°C (1). Los sensores basados en SnO 2 son ampliamente empleados para detectar concentraciones muy bajas de CO debido a su alta selectividad y sensibilidad comparada con otros sensores de gases cerámicos (2).…”

Section: Introductionunclassified

“…Un gran número de trabajos referentes a la sensibilidad y selectividad de estos sensores se ha publicado recientemente (6)(7)(8), pero muy pocos explican la estabilidad del sensor al ser expuesto a gases combustibles (2). En la abundante literatura en el tema se discute la capacidad del SnO 2 en detectar pequeñas cantidades de CO u otros gases reductores en aire.…”

Section: Introductionunclassified

Efectos de la exposición de películas gruesas de SnO<sub>2</sub> a vacío, oxígeno y monóxido de carbono

Ponce¹,

Aldao²,

Castro³

2002

Bol. Soc. Esp. Ceram. Vidr.

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En este trabajo se estudia la dependencia de la conductividad eléctrica en aire y en monóxido de carbono de películas de SnO 2 . El proceso de conducción, al cambiar la atmósfera de vacío a aire y de vacío a monóxido de carbono, puede ser explicado si consideramos cómo la adsorción de estos gases altera las barreras de potencial formadas en los bordes de grano. La exposición de las películas a estos gases a temperaturas mayores que 300°C favorece la difusión interna del oxígeno lo que provoca la aniquilación de vacantes de oxígeno.Palabras claves: SnO 2 , mecanismos de conducción, monóxido de carbono, oxígeno. Oxygen and carbon monoxide adsorption in SnO 2 thick films gas sensorsIn this work the dependence of the electrical conductivity in air and in carbon monoxide of SnO 2 films is studied. The conduction mechanism when the atmosphere is changed from vacuum to air and vacuum to carbon monoxide can be explained considering the modification of the intergranular potential barriers. The films exposure at temperatures higher than 300°C favors the oxygen indiffusion that causes the annihilation of oxygen vacancies. INTRODUCCIÓNLos óxidos semiconductores como SnO 2 e In 2 O 3 son reconocidos como excelentes materiales para aplicaciones en la detección de gases. Poseen una velocidad de quimisorción extremadamente lenta a temperatura ambiente, razón por la cual son empleados a temperaturas entre 200-400°C (1). Los sensores basados en SnO 2 son ampliamente empleados para detectar concentraciones muy bajas de CO debido a su alta selectividad y sensibilidad comparada con otros sensores de gases cerámicos (2).Generalmente se acepta que la quimisorción de oxígeno produce la transferencia de electrones desde el interior de los granos de SnO 2 a sus superficies lo que da lugar a la modificación de las barreras formadas en los bordes de grano. Las características de estas barreras dependen del contenido de oxígeno intergranular lo que se refleja en un cambio en la resistividad del sensor (3). En este sentido, diferentes factores, tales como química de defectos, propiedades morfológi-cas, influencia de aditivos y efectos catalíticos en las reacciones superficiales, contribuyen a modificar la respuesta eléctri-ca del sensor (4).Actualmente, existen tres modelos teóricos que permiten explicar el comportamiento de estos dispositivos (5): el modelo de barreras dobles de Schottky, el modelo de cuellos, y el modelo de partículas ultrafinas. Al respecto, se ha determinado que el tamaño de grano de los sensores afecta el mecanismo de detección. Se ha propuesto que cuando el tamaño de grano es mayor que el ancho de la zona de deserción de las barreras intergranulares, los bordes de grano controlan la conducción. Cuando el tamaño de grano es comparable con el ancho de las dos zonas de agotamiento, la conducción es controlada por la presencia de cuellos. En cambio, cuando los tamaños de las partículas son menores que el ancho de las dos zonas de agotamiento, la conducción es controlada por el grano.Un gran número de trabajos referentes a...

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Improved Long‐Term Stability and Reduced Humidity Effect in Gas Sensing: SiO₂ Ultra‐Thin Layered ZnO Columnar Films

Postica

Lupan

Gapeeva

et al. 2021

Adv Materials Technologies

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The undoped and metal‐doped zinc oxide columnar films (ZnO:Sn, ZnO:Fe, ZnO:Ag, and ZnO:Cu) are covered with an ultra‐thin layer of SiO2 (10–20 nm). The electrical, UV, and volatile organic compounds (VOCs) sensing properties are evaluated under different ambient conditions for ≈7 months to investigate the impact of the top SiO2‐layer on the long‐term stability of samples. The obtained results show a high immunity of sensing properties of SiO2‐coated samples to humidity. Furthermore, gas sensing measurements show that the loss in response after 203 days is significantly lower for coated samples indicating higher stability of sensing performance. For ZnO:Fe the gas response is reduced by about 90% after 203 days, but for SiO2‐coated ZnO:Fe columnar films the gas response is slightly reduced by only 38%. The density functional theory (DFT) calculations show that water species bind strongly with the surface SiO2 layer atoms with a −0.129 e− charge transfer, which is, much higher compared to the interaction with ethanol and acetone. Calculations show strong binding of water species on the SiO2 layer indicating preferential absorption of water molecules on SiO2. The obtained results demonstrate an important role of the top SiO2 ultra‐thin layer in order to produce humidity‐tolerant sensitive devices.

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Enhanced long-term stability of SnO2-based CO gas sensors modified by sulfuric acid treatment

Cited by 48 publications

References 8 publications

Influence of Surface Passivation on Optical Properties of Spray Pyrolysis Deposited Pd-F:SnO2

Influence of Surface Passivation on Optical Properties of Spray Pyrolysis Deposited Pd-F:SnO2

Efectos de la exposición de películas gruesas de SnO<sub>2</sub> a vacío, oxígeno y monóxido de carbono

Improved Long‐Term Stability and Reduced Humidity Effect in Gas Sensing: SiO₂ Ultra‐Thin Layered ZnO Columnar Films

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Enhanced long-term stability of SnO2-based CO gas sensors modified by sulfuric acid treatment

Cited by 48 publications

References 8 publications

Influence of Surface Passivation on Optical Properties of Spray Pyrolysis Deposited Pd-F:SnO2

Influence of Surface Passivation on Optical Properties of Spray Pyrolysis Deposited Pd-F:SnO2

Efectos de la exposición de películas gruesas de SnO<sub>2</sub> a vacío, oxígeno y monóxido de carbono

Improved Long‐Term Stability and Reduced Humidity Effect in Gas Sensing: SiO2 Ultra‐Thin Layered ZnO Columnar Films

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Product

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Improved Long‐Term Stability and Reduced Humidity Effect in Gas Sensing: SiO₂ Ultra‐Thin Layered ZnO Columnar Films