Wyniki wyszukiwania - Biblioteka Nauki

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Surface acoustic wave hydrogen gas sensor based on layered structure of palladium/metal-free phthalocyanine

100%

Jakubik W. P. , Urbańczyk M. , Maciak E. , Pustelny T.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2008

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tom Vol. 56, nr 2

133-138

EN

A layered sensor structure of metal-free phthalocyanine H2PC (160 nm) with a very thin film of palladium (Pd-20 nm) on the top, has been studied for hydrogen gas-sensing application at relatively low temperatures of about 30°C and about 40°C. The layered structure was obtained by vacuum deposition (first the phthalocyanine Pc and than the Pd film) onto a LiNbO3Y- cut Z-propagating substrate, making use of the Surface Acoustic Wave method, and additionally (in this same technological processes) into a glass substrate with a planar microelectrode array for simultaneous monitoring of the planar resistance of the layered structure. In such a layered structure we can detect hydrogen in a medium concentration range (from 0.5 to 3% in air) even at about 30°c. At elevated tem-perature up to about 40°C the differential frequency increases proportionally (almost linearly) to the hydrogen concentration and the response reaches its steady state very quickly. The response times are about 18 s at the lowest 0.5% hydrogen concentration to about 42 s at 4% (defined as reaching 100% of the steady state). In the case of the investigated layered structure a very good correlation has been observed between the two utilized methods - the frequency changes in the SAW method correlate quite well with the decreases of the layered structure resistance.

2

Effective hydrogen gas sensor based on palladium nanoparticles dispersed on graphene sheets by spin coating technique

100%

Inpaeng S. , Muangrat W. , Tedsree K. , Pfeiler W. , Chodjarusawad T. , Issro C.

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tom Vol. 38, No. 2

305--311

EN

A room-temperature hydrogen gas (H2) sensor was successfully fabricated by dispersion of palladium nanoparticles (Pd NPs) on graphene sheets (GRs) (hereafter referred to as “Pd NPs/GRs”). GRs and Pd NPs were synthesized by chemical vapor deposition technique and by polyol process, respectively. A colloidal solution of Pd NPs with an average diameter of 11 nm was then dispersed onto the GRs by spin coating technique. The density of dispersed Pd NPs on GRs was controlled by varying the volume of the dispersed solution within the range of 50 – 150 μL. The fabricated Pd NPs/GRs sensors exhibited a high sensitivity for H2 gas with a concentration of 1500 – 6000 ppm at room temperature. Upon H2 exposure, the Pd NPs/GRs sensors showed an increase in electrical resistance, which could easily be measured. The relationship between sensor response and H2 concentration is in correspondence with the Langmuir adsorption model. The H2 detection limit is estimated to be 1 ppm. The results demonstrate that the Pd NPs/GRs sensor is an easily fabricated, but very effective means for room-temperature detection of H2 at ppm level.

3

Fast UV detection and hydrogen sensing by ZnO nanorod arrays grown on a flexible Kapton tape

88%

Hassan J. J. , Mahdi M. A. , Kasim S. J. , Ahmed N. M. , Hassan H. A. , Hassan Z.

Materials Science Poland

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2013

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tom Vol. 31, No. 2

180--185

EN

ZnO nanorod arrays were grown on a flexible Kapton tape using microwave-assisted chemical bath deposition. High crystalline properties of the produced nanorods were proven by X-ray diffraction patterns and field emission scanning electron microscopy. Additionally, the photoluminescence spectrum showed higher UV peaks compared with visible peaks, which indicates that the ZnO nanorods had high quality and low number of defects. The metal-semiconductor-metal (MSM) configuration was used to fabricate UV and hydrogen gas detectors based on the ZnO nanorods grown on a flexible Kapton tape. Upon exposure to 395 nm UV light, the UV device exhibited fast response and decay times of 37 ms and 44 ms, respectively, at a bias voltage of 30 V. The relative sensitivities of the gas sensor made of the ZnO nanorod arrays, at hydrogen concentration of 2 %, at room temperature, 150 C, are 0.42, 1.4 and 1.75 respectively.

4

Właściwości sensorowe cienkich warstw mieszanin tlenków miedzi i tytanu

63%

Mańkowska E. , Mazur M.

Biuletyn Wojskowej Akademii Technicznej

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2023

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tom Vol. 72, nr 1

37--46

PL

Przedmiotem badań były cienkie warstwy mieszanin tlenków miedzi i tytanu o różnym składzie pierwiastkowym, wytworzone za pomocą rozpylania magnetronowego i wygrzane poprocesowo. Wpływ składu pierwiastkowego oraz temperatury wygrzewania na morfologię cienkich warstw określono na podstawie zdjęć ze skaningowego mikroskopu elektronowego. Strukturę krystaliczną i skład chemiczny mieszanin tlenków miedzi i tytanu (CuTi)Ox zbadano za pomocą dyfrakcji promieni rentgenowskich. Przeprowadzono również badania czujnikowe na wodór o stężeniach od 100 do 1000 ppm. Rezystancja wytworzonych mieszanin (CuTi)Ox rosła podczas ekspozycji na wodór, co świadczy o możliwości stosowania tych tlenków w czujnikach wodoru. Dodatkowo dla mieszanin uzyskano lepsze odpowiedzi sensorowe niż dla pojedynczych tlenków miedzi lub tlenków tytanu. Mieszaniny tlenków miedzi oraz tytanu mogą być obiecującymi materiałami do zastosowań jako czujniki wodoru.

EN

The subject of the current studies were mixtures of copper and titanium oxide thin films, with various elemental compositions, deposited by magnetron sputtering and annealed in the postprocess. The effect of elemental composition and annealing temperature on the morphology of thin films was determined using scanning electron microscope images. The crystal structure and chemical composition of copper-titanium oxide (CuTi)Ox mixtures were investigated by X-ray diffraction. Hydrogen gas sensing experiments were performed for hydrogen with concentrations ranging from 100 to 1,000 ppm. The resistance of the prepared (CuTi)Ox mixtures increased during hydrogen exposure, demonstrating the applicability of these oxides in hydrogen sensing. In addition, better sensor responses were obtained for the mixtures in comparison to single copper oxides or titanium oxides. Mixtures of copper oxides and titanium oxides may be promising materials for hydrogen sensor applications.

5

Wpływ wygrzewania na wybrane właściwości mieszanych tlenków miedzi i tytanu

63%

Mańkowska E. , Mazur M.

Biuletyn Wojskowej Akademii Technicznej

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2022

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tom Vol. 71, nr 2

41--48

PL

Praca poświęcona jest badaniom wpływu wygrzewania poprocesowego na morfologię mieszanych tlenków miedzi i tytanu, a także na ich właściwości elektryczne i czujnikowe. Cienkie warstwy (Cu,Ti)Ox naniesiono za pomocą rozpylania magnetronowego na podłoża z krzemionki amorficznej oraz na podłoża ceramiczne ze zintegrowanymi elektrodami. Dodatkowo zastosowano termiczną obróbkę poprocesową w temperaturach 200°C oraz 250°C. Zmianę struktury w procesie utleniania termicznego badano za pomocą dyfrakcji rentgenowskiej, natomiast dzięki profilometrowi optycznemu określono morfologię powierzchni cienkich warstw. W celu określenia właściwości elektrycznych zmierzono charakterystyki prądowo-napięciowe oraz termoelektryczne, na podstawie których wyznaczono rezystancję oraz typ przewodnictwa. Cienkie warstwy (Cu,Ti)Ox poddane obróbce poprocesowej charakteryzowały się dziurowym typem przewodnictwa, a co więcej silnie reagowały na obecność wodoru w atmosferze pomiarowej.

EN

This work presents an investigation of the effects of post-process annealing on the morphology of mixed copper and titanium oxides and on their electrical and hydrogen sensing properties. (CuTi)Ox thin films were deposited by magnetron sputtering on amorphous silica and ceramic substrates with interdigitated electrodes. In addition, post-process thermal treatment was applied at the temperatures of 200°C and 250°C. The transformation of the thin film structure during the thermal oxidation process was studied by X-ray diffraction, while the morphology of the thin films was determined using an optical profilometer. Current-voltage and thermoelectric characteristics were measured to determine electrical properties, from which the resistance and conduction type were determined. The post-treatment (CuTi)Ox thin films exhibited hole-type conduction and, additionally, strongly responded to hydrogen atmosphere.