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The effect of fluorine and tungsten co-doping on optical, electrical and structural properties of tin (IV) oxide thin films prepared by sol–gel spin coating method

Keskenler E F, Turgut G, Aydin S., Dogan S, Duzgun B

Optica Applicata

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2013

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Vol. 43, nr 4

663--677

EN

Fluorine and tungsten co-doped tin (IV) oxide (WFTO) thin films have been prepared first time by a sol–gel spin coating method. The effect of F and W co-dopant ratio on optical, electrical and structural properties of SnO2 was investigated. It was found that the optical properties of the films were obviously affected by the co-dopant ratio. When the F:W co-dopant ratio increases from 0.25:0.25 to 0.75:0.50, the transmittance in the short wavelengths slightly increases and transmittance edge shifts towards shorter wavelength. With an increase in the co-dopant ratio, the reduction and red shifts in the optical transmittance edge are very obvious at all wavelengths. Transmittance values at 550 nm for the films have varied between 79.64% and 50.20%. The indirect and direct band gap values for WFTO-1, WFTO-2, WFTO-3 and WFTO-4 samples were calculated to be 3.73, 3.79, 3.48, 3.40 eV and 4.03, 4.04, 3.98, 3.97 eV, respectively. The crystal structure of the films has been investigated by X-ray diffraction patterns. It has been observed that WFTO-1 and WFTO-2 samples have (111) preferential orientation corresponding to SnO2 cubic phase. This orientation almost disappears and changes to tetragonal phase (110) orientation for WFTO-3 and WFTO-4. To the best of our knowledge, this is the first cubic structure observation for SnO2 grown by the sol–gel technique. The electrical properties were also changed with co-doping ratio. The best optical, electrical and structural properties were obtained for mole ratio 0.75:0.50 (F:W).

2

Experimental phase studies in the TeO2–CdO system

Karaduman G., Celikbilek M., Ersundu A. E., Solak N., Tatar D., Aydin S.

Materiały Ceramiczne

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2011

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T. 63, nr 1

40-43

EN

In the present study, phase equilibrium in the TeO2–CdO system has been investigated. Different compositions of (1-x)TeO2–xCdO, where x = 0.10, 0.20, 0.25, 0.30 and 0.40 in molar ratio were prepared. The samples waited at 750°C in a platinum crucible for 30 minutes and then quenched in a water bath. DTA studies performed on as-cast samples. According to the DTA results, all samples were heat-treated at 550°C for 24 hours to obtain phase equilibrium. XRD and SEM/EDS studies were performed on the crystallized samples for microstructural analysis.

PL

W prezentowanej pracy zbadano równowagę fazową w układzie TeO2–CdO. Przygotowano różne składy (1-x)TeO2 – xCdO, gdzie x = 0,10, 0,20, 0,25, 0,30 i 0,40 mol.%. Próbki przetrzymywano w 750°C w tyglu platynowym przez 30 min., a następnie szybko chłodzono w kąpieli wodnej. Badania DTA przeprowadzono na świeżo wytopionych próbkach. Zgodnie z wynikami DTA, wszystkie próbki wygrzewano w 550°C przez 24 h, aby uzyskać stan równowagi fazowej. Badania XRD i SEM/EDS przyprowadzono na wykrystalizowanych próbkach w przypadku analizy mikrostrukturalnej.

3

Microstructural and thermal characterization of the TeO2–WO3 system

Celikbilek M., Karaduman G., Ersundu A. E., Solak N., Tatar D., Aydin S.

Materiały Ceramiczne

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2010

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T. 62, nr 4

556-559

EN

In the present study, thermal behaviour and microstructure of the TeO2–WO3 system have been investigated. Different compositions of (1-x)TeO2 – xWO3 system (x = 0.02, 0.05, 0.15, 0.25 and 0.40 in molar ratio) were prepared. The samples waited at 750°C in a platinum crucible for 30 min and then quenched in a water bath. DTA studies were performed on glassy samples. Afterwards, all samples were heat-treated at 550°C for 24 h and furnace cooled to obtain phase equilibrium. XRD and SEM/EDS studies were performed on the crystallized samples for microstructural analysis.

PL

W prezentowanej pracy zbadano zachowanie cieplne i mikrostrukturę tworzyw w układzie TeO2-WO3. Przygotowano różne składy układu (1-x)TeO2 – xWO3, gdzie x = 0.02, 0.05, 0.15, 0.25 i 0.40 w stosunku molowym. Próbki przebywały w 750°C w tyglu platynowym przez 30 min a potem szybko chłodziły się w wodzie. Badania DTA przeprowadzono na próbkach szklistych. Następnie, wszystkie próbki zostały wygrzane w . 550°C przez 24 h i schłodzone z piecem w celu osiągnięcia równowagi fazowej. Badania XRD i SEM/EDS przeprowadzono na krystalizowanych próbkach w przypadku analizy mikrostrukturalnej.

4

Sequential Versus Parallel Grammar Formalisms with Respect to Measures of Descriptional Complexity

Aydin S., Bordihn H.

Fundamenta Informaticae

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2003

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Vol. 55, nr 3,4

243-254

EN

For tabled Lindenmayer systems and their languages, the degree of synchronization and the degree of nondeterminism are well investigated measures of descriptional complexity. In this paper the sequential counterparts of tabled Lindenmayer systems, namely cooperating distributed grammar systems and their pure variant (working in the so-called t-mode of derivation) are treated with respect to these complexity measures. In the pure case, where no distinction between terminal and nonterminal symbols is made, the sequential mechanisms are compared with the parallel ones, investigating whether one mechanism may have a better descriptional complexity than the other one when the same language is described.