@article { ISI:000245760900020, title = {Low temperature route to prepare LaFeO3 and LaCoO3}, journal = {Materials Letters}, volume = {61}, number = {10}, year = {2007}, month = {APR}, pages = {2030-2032}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A combination of digestion and further low temperature calcination to crystallize the product was employed to prepare LaFeO3 (LF) and LaCoO3 (LC) powders. Freshly co-precipitated lanthanum and ferric (or cobalt) hydroxide gels by sodium hydroxide were allowed to react at 100 degrees C under refluxing and stirring conditions for 4-6 h. These oven dried powders were heated at 450 degrees C to from crystalline LF (or LC) powders. The phase contents and lattice parameters were investigated by X-ray diffraction (XRD). Transmission electron microscope (TEM) investigations were carried out to examine the morphology and average particle size of these powders. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Chemical synthesis, LaFeO3, Precipitation, transmission electron microscopy, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2006.08.009}, author = {Jadhav, A. D. and Gaikwad, A. B. and Samuel, V. 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:000252474200009, title = {Low voltage varistor ceramics based on SnO2}, journal = {Bulletin of Materials Science}, volume = {30}, number = {6}, year = {2007}, month = {DEC}, pages = {583-586}, publisher = {SPRINGER}, type = {Article}, address = {233 SPRING STREET, NEW YORK, NY 10013 USA}, abstract = {

The nonlinear current (I)-voltage (V) characteristics of tin dioxide doped with either Nb2O5 and CoO or Sb2O3 and CoO show promising values of nonlinear coefficient (alpha) values (similar to 11) with low breakdown voltages (E-B, similar to 40 V mm(-1)). The pentavalent antimony or niobium acts as donor and increases the electronic conductivity. The crucial parameter for obtaining low breakdown voltage is the grain size, which depends upon sintering duration and temperature of these oxide ceramics.

}, keywords = {Chemical synthesis, electronic materials, Microstructure, tin oxide, X-ray diffraction}, issn = {0250-4707}, doi = {10.1007/s12034-007-0092-8}, author = {Dhage, S. R. and Ravi, V. and Yang, O. B.} } @article { ISI:000254820000016, title = {La0.67Ce0.03Sr0.3MnO3-coupled microwave assisted ultra-fast synthesis of nanocrystalline cobalt oxide and Bismuth oxide}, journal = {Materials Letters}, volume = {62}, number = {10-11}, year = {2008}, month = {APR}, pages = {1511-1513}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Bismuth hydroxide and Cobalt hydroxide gels were freshly prepared by adding aqueous sodium hydroxide to their corresponding nitrates under basic conditions. Then they were oven dried at 373 K and found to be amorphous in X-ray diffraction (XRD) study. They crystallized into their respective oxides by microwave irradiation (2.45 GHz) in merely 2 min using La0.67Ce0.03Sr0.3MnO3 (LCSMO) as couplant in a microwave domestic oven (similar to 100 W). This is the lowest temperature treatment and synthesis time so far reported in the literature for the formation of these systems. Formation of nanocrystallites of Bi2O3 (10 nm) and Co3O4 (15 nm) has been confirmed by XRD. Normally these hydroxides produce oxides only on heating at temperature \>673 K or digesting them at 373 K for 4 - 6 hours as reported by us earlier. Microwave assisted heating proves to be a novel technology whose applications can be carefully harnessed due to its unique effects compared to the conventional heating, such as rapid volumetric heating, shortened reaction time and energy saving. (C) 2007 Elsevier B.V. All rights reserved.

}, keywords = {Citrate gel method, Manganites, Microwave, Oxides}, issn = {0167-577X}, doi = {10.1016/j.matlet.2007.09.013}, author = {Rajagopal, Rajashree and Mona, J. and Joshi, Rakesh S. and Kale, Sangeeta N. and Pradhan, Sivararn and Gaikwad, A. B. and Ravi, V.} } @article { ISI:000257367100016, title = {Low temperature synthesis and characterization of BiNbO4 powders}, journal = {Materials Characterization}, volume = {59}, number = {8}, year = {2008}, month = {AUG}, pages = {1083-1087}, publisher = {ELSEVIER SCIENCE INC}, address = {360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA}, abstract = {

BiNbO4 powders, a potential microwave dielectric ceramic were prepared by both coprecipitation and solid state techniques. In the former method, an aqueous ammonium hydroxide was used to precipitate Bi3+ and Ta5+ cations as hydroxides simultaneously under basic conditions. It is observed that the co-precipitation produces BiNbO4 phase on heating at 600 degrees C, whereas complete phase formation occurs only at 800 degrees C in the case of solid state method. The phase contents and lattice parameters were studied by powder X-ray diffraction. The sequence of the reaction and phase evolution of BiNbO4 were also studied by the X-ray diffraction. The samples were characterized by the differential-thermal/thermo-gravimetric analyses and scanning electron microscopy techniques. (C) 2007 Elsevier Inc. All rights reserved.

}, keywords = {BiNbO4, Ceramics, Chemical synthesis, Electron microscopy, Oxides, X-ray diffraction}, issn = {1044-5803}, doi = {10.1016/j.matchar.2007.08.026}, author = {Radha, R. and Muthurajan, H. and Rao, N. Koteswara and Pradhan, Sivaram and Gupta, U. N. and Jha, Ratnesh Kumar and Mirji, S. A. and Ravi, V.} } @article { ISI:000253106100026, title = {Low temperature synthesis of SrNb2O6 and SrTa2O6 using hydroxide precursor}, journal = {Materials Letters}, volume = {62}, number = {6-7}, year = {2008}, month = {MAR}, pages = {892-894}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

SrNb2O6 (SN) or SrTA(2)O(6) (ST) compounds were prepared at low temperatures for the first time from hydroxide precursors. A simple procedure of mixing commercially purchased strontium hydroxide and niobium (or tantalum) hydroxide thoroughly together and heating at a low temperature (\<400 degrees C) produced SrNb2O6 (SN) or SrTa2O6 (ST) powders. This is the lowest temperature so far reported for the formation of these phases. These materials are potential candidates for ferroelectric and electro-optic applications. The reaction sequence and evolution of the phase formation were investigated by X-ray diffraction (XRD) studies. The average particle size and morphology of these powders were studied by scanning electron microscopy (SEM). (C) 2007 Elsevier B.V. All rights reserved.

}, keywords = {Chemical synthesis, Electron microscopy, electronic materials, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2007.07.006}, author = {Muthurajan, H. and Kumar, H. H. and Koteswara Rao, N. and Pradhan, Sivaram and Jha, Ratnesh Kumar and Ravi, V.} }