@article { ISI:000244008300028, title = {Influence of surfactant on ZnO varistors}, journal = {Ceramics International}, volume = {33}, number = {2}, year = {2007}, month = {MAR}, pages = {289-291}, publisher = {ELSEVIER SCI LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

ZnO varistors with and without surfactant such as sodium dodecyl sulphate (SIDS) are prepared by nitrate-combustion process. The samples were identically heat treated and sintered at 1000 degrees C for 12 h to study the influence of the surfactant on the nonlinear electrical properties of polycrystalline ZnO. It is observed that the nonlinear coefficient decreases marginally (alpha = 35) for samples prepared with surfactant, whereas breakdown field (E-B = 130 V/mm) decreased significantly. The corresponding parameters for the samples synthesized without surfactant are alpha = 45 and E-B = 400 V/mm. Hence, this method can be used for the manufacture of varistors with low to moderate breakdown fields. (c) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

}, keywords = {Chemical synthesis, Semiconductors, X-ray methods, ZnO}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2005.08.010}, author = {Dhage, S. R. and Navale, S. C. and Ravi, V.} } @article { ISI:000250178900006, title = {Low temperature synthesis and NOx sensing properties of nanostructured Al-doped ZnO}, journal = {Sensors and Actuators B-Chemical}, volume = {126}, number = {2}, year = {2007}, month = {OCT}, pages = {382-386}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

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.

}, keywords = {aluminum doping, nanomaterial, NOx, Sensor, ZnO}, issn = {0925-4005}, doi = {10.1016/j.snb.2007.03.019}, author = {Navale, S. C. and Ravi, V. and Mulla, Imtiaz S. and Gosavi, S. W. and Kulkarni, S. K.} } @article { ISI:000255107700017, title = {EPR and DRS evidence for NO2 sensing in Al-doped ZnO}, journal = {Sensors and Actuators B-Chemical}, volume = {130}, number = {2}, year = {2008}, month = {MAR}, pages = {668-673}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

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.

}, keywords = {aluminum doping, DRS, EPR, NO2 sensor, ZnO}, issn = {0925-4005}, doi = {10.1016/j.snb.2007.10.055}, author = {Navale, Shalaka C. and Ravi, V. and Srinivas, D. and Mulla, Imtiaz S. and Gosavi, S. W. and Kulkarni, S. K.} }