02140nas a2200253 4500008004100000022001400041245008800055210006900143260006900212300001200281490000800293520130500301653002001606653001701626653000801643653001101651653000801662100001901670700001301689700002201702700001901724700002101743856012201764 2007 eng d a0925-400500aLow temperature synthesis and NOx sensing properties of nanostructured Al-doped ZnO0 aLow temperature synthesis and NOx sensing properties of nanostru aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcOCT a382-3860 v1263 a

Although ZnO is studied intensively as a sensing material, there are limited reports available on aluminum-doped ZnO (AZO) as a NO, sensor. This paper reports selective NO, sensing characteristics of M-doped ZnO synthesized in the form of porous pellets sintered at 350 degrees C. The salient feature of our experimental results is that our sensor can detect small concentrations of NO, at lower operating temperature. It is also observed that as compared to gases such as SOx HCl, LPG, H2S, H-2, ammonia, alcohol and acetone it selectively detects NOx due to Al-doping. The amount of Al in ZnO during synthesis is varied between 1 and 10 wt%. Our sensor senses NO, concentration as low as 20ppm at 100 degrees C with a %response of 11 and a %response of 740 at 300 degrees C for 1 wt% Al. Of all the compositions with Al-doping, I wt% is found to give best results. Sensing experiments carried out at 350 C, however. do not show any significant improvement in the gas sensing properties. The phase contents and lattice parameters were determined by XRD and the average particle size was obtained using Scherrer formula. A probable mechanism for sensing NO, involving oxygen ion adsorption and desorption on the surface of sensor has been suggested. (C) 2007 Elsevier B.V. All rights reserved.

10aaluminum doping10ananomaterial10aNOx10aSensor10aZnO1 aNavale, S., C.1 aRavi, V.1 aMulla, Imtiaz, S.1 aGosavi, S., W.1 aKulkarni, S., K. uhttps://library.ncl.res.in/content/low-temperature-synthesis-and-nox-sensing-properties-nanostructured-al-doped-zno-002200nas a2200229 4500008004100000022001400041245009100055210006900146260007300215300001400288490000700302520140100309653001401710653001501724653001901739653002201758653000801780100002401788700001901812700002201831856011701853 2008 eng d a0039-914000aControlled synthesis of ZnO from nanospheres to micro-rods and its gas sensing studies0 aControlled synthesis of ZnO from nanospheres to microrods and it aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUN a1315-13190 v753 a

1D ZnO rods are synthesized using less explored hydrazine method. Here we find, besides being combustible hydrazine can also be used as a structure-directing agent. The ratio of zinc nitrate (ZN) to hydrazine is found to control the morphology of ZnO. At lower concentration of ZN as compared with hydrazine the morphology of ZnO is found to be spherical. As we increase the hydrazine content the morphology changes from spherical (diameter similar to 100 nm) to the elongated structures including shapes like Y, T as well dumbbell (diameter similar to 40 nm and length similar to 150 nm). Interestingly for more than 50% of hydrazine ZnO micro-rods are formed. Such rods are of diameter similar to 120 mn having length of about 1 mu m for ZN to hydrazine ratio of 1:9, isolated as well as bundle of rods are seen in scanning electron microscopy (SEM). The X-ray diffraction (XRD) reveals the phase formation with average particle size of 37 nm as calculated using Scherrer's formula. The high-resolution transmission electron microscopy (HRTEM) is also done to confirm the d-spacing in ZnO. Gas sensing study for these samples shows high efficiency and selectivity towards LPG at all operating temperatures. Photoluminescence (PL) study for these samples is performed at room temperature to find potential application as photoelectric material. (C) 2008 Elsevier B.V. All rights reserved.

10aHydrazine10aLPG sensor10aNanostructures10aphotoluminescence10aZnO1 aNavale, Shalaka, C.1 aGosavi, S., W.1 aMulla, Imtiaz, S. uhttps://library.ncl.res.in/content/controlled-synthesis-zno-nanospheres-micro-rods-and-its-gas-sensing-studies-002154nas a2200265 4500008004100000022001400041245005700055210005600112260006900168300001200237490000800249520136900257653002001626653000801646653000801654653001501662653000801677100002401685700001301709700001701722700002201739700001901761700002101780856008701801 2008 eng d a0925-400500aEPR and DRS evidence for NO2 sensing in Al-doped ZnO0 aEPR and DRS evidence for NO2 sensing in Aldoped ZnO aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcMAR a668-6730 v1303 a

Zinc oxide (ZnO) is a well-known semiconducting multifunctional material wherein properties right from the morphology to gas sensitivity can be tailor-made by doping or surface modification. Aluminum (Al)-incorporated porous zinc oxide (AI:ZnO) exhibits good response towards NO2 at low-operating temperature. The NO2 gas concentration as low as 20 ppm exhibits S = 17% for 5 wt. % Al-incorporated ZnO. The NO2 response increases with operating temperature and concentration and reaches to its maximum at 300 degrees C without any interference from other gases such as SO3, HCl, LPG and alcohol. Physico-chemical characterization likes differential thermogravimetric analysis (TG-DTA) electron paramagnetic resonance (EPR) and diffused reflectance spectroscopy (DRS) have been used to understand the sensing behavior for pure and A]-incorporated ZnO. The TG-DTA depicts formation of ZnO phase at 287 degrees C. The EPR study reveals distinct variation for O- (g=2.003) and Zn interstitial (g = 1.98) defect sites in pure and Al:ZnO. The DRS studies elucidate signature of adsorbed NO, species in aluminium-incorporated zinc oxide indicating its tendency to adsorb these species even at low temperatures. This paper is an attempt to correlate the gas sensing behavior with the physico-chemical studies such as EPR and DRS. (c) 2007 Published by Elsevier B.V.

10aaluminum doping10aDRS10aEPR10aNO2 sensor10aZnO1 aNavale, Shalaka, C.1 aRavi, V.1 aSrinivas, D.1 aMulla, Imtiaz, S.1 aGosavi, S., W.1 aKulkarni, S., K. uhttps://library.ncl.res.in/content/epr-and-drs-evidence-no2-sensing-al-doped-zno-002342nas a2200265 4500008004100000022001400041245006100055210006000116260009200176300001200268490000600280520146300286653001901749653002601768653001901794653000801813100002401821700002601845700002201871700002201893700002001915700002301935700002301958856009501981 2009 eng d a1662-525000aField emission properties of Al-doped ZnO nanostructures0 aField emission properties of Aldoped ZnO nanostructures aLAUBISRUTISTR 24, STAFA-ZUERICH, CH-8712, SWITZERLANDbTRANS TECH PUBLICATIONS LTDcJAN a231-2370 v53 a

Field emission from Al-doped ZnO nanostrcutures has been investigated in planar diode configuration under ultra high vacuum conditions. The Al-doped ZnO nanostructures were synthesized by co-precipitation method with varying aluminium concentrations. The as- synthesized product was characterized by x-ray diffraction, scanning electron microscope and energy dispersive x-ray analysis. The threshold field required to draw a current density of similar to 1 mu A/cm(2) was observed to be similar to 2.0 V/mu m and similar to 2.3 V/mu m for Al-doped ZnO nanostructures synthesized with aluminium concentrations of 1% and 3%, respectively. The Fowler- Nordheim (F-N) plots for both the specimens exhibit non-linear behaviour, which is observed to be specimen dependent. The nonlinearity observed in the F-N plots has been interpreted on the basis of the theory of electron emission from semiconductor emitters. The field enhancement factors, estimated from the slope of the F-N plots, are found to be similar to 9.3 x 10(3) and 3.9 x 10(3) for 1% and 3% Al-doped ZnO emitters, respectively. The high values of the field enhancement factor Suggest that the emission is from the nanostructures. The emission current stability measured at the preset value of similar to 2 mu A over a period of more than three hours is found to be fairly stable. The results indicate use of Al-doped ZnO nanostructures as promising emitters for field emission based devices.

10afield emission10aFowler-Nordheim plots10aNanostructures10aZnO1 aNavale, Shalaka, C.1 aSheini, Farid, Jamali1 aPatil, Sandip, S.1 aMulla, Imtiaz, S.1 aJoag, Dilip, S.1 aMore, Mahendra, A.1 aGosavi, Suresh, W. uhttps://library.ncl.res.in/content/field-emission-properties-al-doped-zno-nanostructures-001602nas a2200253 4500008004100000022001400041245010500055210006900160260007100229300001400300490000600314520069700320653001901017653002501036653001901061653001701080653000801097100002601105700002301131700002001154700002201174700003001196856012201226 2010 eng d a1936-085100aFowler-nordheim plot behavior and mechanism of field electron emission from ZnO tetrapod structures 0 aFowlernordheim plot behavior and mechanism of field electron emi a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a5585-55900 v43 a

Field emission measurements of current-voltage characteristics are reported for tetrapod structures of ZnO. The nonlinear Fowler-Nordheim (FN) plot is analyzed according to a model of calculation based on saturation of conduction band current and predominance of valence band current at high-field values. The simulated FN plot exhibits similar features to those observed experimentally. The model of calculation suggests that the slope variation of the FN plot, in the high-field and low-field regions, does not depend on the magnitude of saturation. Instead, it is a characteristic of the energy band structure and voltage-to-barrier-field conversion factor of the emitting material.

10afield emission10aFowler-Nordheim plot10aNanostructures10anonlinearity10aZnO1 aAl-Tabbakh, Ahmed, A.1 aMore, Mahendra, A.1 aJoag, Dilip, S.1 aMulla, Imtiaz, S.1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/fowler-nordheim-plot-behavior-and-mechanism-field-electron-emission-zno-tetrapod-0