@article { ISI:000230160700011, title = {Coprecipitation technique to prepare SrNb2O6}, journal = {Materials Characterization}, volume = {55}, number = {1}, year = {2005}, month = {JUL}, pages = {92-95}, publisher = {ELSEVIER SCIENCE INC}, type = {Article}, address = {360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA}, abstract = {

A mixture of ammonium oxalate and ammonium hydroxide was used to co-precipitate strontium and niobium ions as strontium oxalate and niobium hydroxide under basic conditions. This precursor yielded SrNb2O6 ceramics on calcining at 650 degrees C. This is a much lower temperature compared to preparation of SrNb2O6 by the traditional solid state method (900 degrees C). Transmission electron microscopy (TEM) revealed that the average particle size is 100 nm for the calcined powders. The room temperature dielectric constant at 1 kHz is found to be 550. The ferroelectric hysteresis loop parameters of these samples were also studied. (c) 2005 Elsevier Inc. All rights reserved.

}, keywords = {Ceramics, Electron microscopy, ferroelectric, Oxides, X-ray methods}, issn = {1044-5803}, doi = {10.1016/j.matchar.2005.04.002}, author = {Ravi, V} } @article { ISI:000228794300014, title = {Preparation of fine MgTa2O6 and Mg4Ta2O9 powders by chemical methods}, journal = {Materials Science and Engineering B-Solid State Materials for Advanced Technology}, volume = {119}, number = {2}, year = {2005}, month = {MAY}, pages = {189-191}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

Two different chemical methods are applied to prepare MgTa2O6 (MT2) and Mg4Ta2O9 (M4T2) powders. A gel was formed when a aqueous solution of Mg(NO3)(2), TAF(5) and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 750 degrees C produced the fine crystallites of ternary oxide, M4T2. A simple co-precipitation technique had been successfully applied for the preparation of pure ultrafine single phase MT2. Ammonium hydroxide was used to precipitate Mg2+ and Ta5+ cations as hydroxides simultaneously. This precursor on heating at 750 degrees produces MT2 powders. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron microscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Electron microscopy, powders-chemical preparation, X-ray methods}, issn = {0921-5107}, doi = {10.1016/j.mseb.2005.02.058}, author = {Navale, SC and Ravi, V} } @article { ISI:000230877900020, title = {Synthesis of bismuth oxide nanoparticles by citrate gel method}, journal = {Ceramics International}, volume = {31}, number = {6}, year = {2005}, month = {JAN}, pages = {889-891}, publisher = {ELSEVIER SCI LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

A mixture of bismuth nitrate and citric acid solution is taken in 1: 1 molar ratio and heated on hot water bath. A gel is formed on evaporation of the water, which on decomposition at 400 degrees C produces nanocrystalline Bi2O3 particles. Formation of nanocrystallites of Bi2O3 is confirmed by X-ray diffraction (XRD) study. Transmission electron microscope (TEM) investigations revealed that the average particle size is 50 nm for these powders. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

}, keywords = {Electron microscopy, powders : chemical preparation, X-ray methods}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2004.09.002}, author = {Anilkumar, Mettu and Pasricha, R. and Ravi, V.} } @article { ISI:000227603500020, title = {Synthesis of bismuth oxide nanoparticles using bismuth nitrate and urea}, journal = {Ceramics International}, volume = {31}, number = {3}, year = {2005}, month = {JAN}, pages = {495-497}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

A mixture of bismuth nitrate and urea is taken in 1:5 molar ratio and heated on hot water bath. A precipitate is formed on evaporation of the water which on decomposition at 400 degrees C produces nanocrystalline Bi2O3 particles. Formation of nano crystallites of Bi2O3 is confirmed by X-ray diffraction (XRD) study. Transmission electron microscopy (TEM) investigations revealed for these powders an average particle size of 50 nm. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

}, keywords = {calcination, Electron microscopy, X-ray methods}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2004.006.013}, author = {Jha, Ratnesh Kumar and Pasricha, R. and Ravi, V.} } @article { ISI:000225856600034, title = {Synthesis of Ce0.75Zr0.25O2 at 100 degrees C}, journal = {Ceramics International}, volume = {31}, number = {1}, year = {2005}, month = {JAN}, pages = {211-213}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

A simple gel to crystal conversion route has been used for the preparation of Ce0.75Zr0.25O2 phase at 80-100degreesC under refluxing conditions. Freshly prepared metal hydroxides gel from cerium and zirconium salt solution is allowed to crystallize under refluxing and stirring conditions for 4-10 h. Formation of nano crystallites of Ce0.75Zr0.25O2 is confirmed by X-ray diffraction (XRD). Transmission electron microscopy (TEM) investigations revealed the average particle size of these powders to be 5 nm. (C) 2004 Elsevier Ltd and Techna S.r.l. All rights reserved.

}, keywords = {CeO2, chemical preparation, Electron microscopy, powders, X-ray methods}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2004.04.009}, author = {Dhage, S. R. and Gaikwad, S. R. and Muthukumar, P. and Ravi, V.} } @article { ISI:000228771600009, title = {Synthesis of nanocrystalline rutile}, journal = {Ceramics International}, volume = {31}, number = {4}, year = {2005}, month = {JAN}, pages = {555-557}, publisher = {ELSEVIER SCI LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Nanocrystalline titanium dioxide (TiO2) in the rutile phase has been obtained by homogeneous precipitation using urea and TiOCl2. A mixture of urea and TiOCl2 is heated on a hot water bath at 65-75 degrees C to precipitate rutile powders. X-ray diffraction (XRD) studies on these oven-dried powders indicated the formation of single-phase rutile. Raman scattering experiments were also performed to confirm the formation of the rutile phase. Transmission electron microscopy (TEM) investigations revealed the average particle size of these powders to be 40 nm. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

}, keywords = {chemical preparation, Electron microscopy, powders, TiO2, X-ray methods}, issn = {0272-8842}, author = {Samuel, V and Pasricha, R and Ravi, V} } @article { ISI:000235860500029, title = {Chemical methods to synthesize FeTiO3 powders}, journal = {Materials Letters}, volume = {60}, number = {11}, year = {2006}, month = {MAY}, pages = {1425-1427}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Three different techniques were used to synthesize FeTiO3 powders. The first method is simple coprecipitation of both Fe and Ti ions under basic conditions using standard ammonia solution from aqueous ferric nitrate and titanium oxy chloride. This precipitate on heating at 400 degrees C produces ilmenite phase. The second method is to digest hydroxide precipitates at 100 degrees C to form FeTiO3 phase. The third technique is to make use of citrate process to form FeTiO3 powders. The phase contents and lattice parameters were Studied by powder X-ray diffraction (XRD). Particle size and morphology were studied by Transmission Electron Microscopy (TEM). (c) 2005 Elsevier B.V. All tights reserved.

}, keywords = {Chemical synthesis, Electron microscopy, electronic materials, X-ray methods}, issn = {0167-577X}, doi = {10.1016/j.matlet.2005.11.041}, author = {Mona, J. and Kale, Sangeeta N. and Gaikwad, A. B. and Murugan, A. Vadivel and Ravi, V.} } @article { ISI:000237439300005, title = {Coprecipitation technique to prepare NaNbO3 and NaTaO3}, journal = {Bulletin of Materials Science}, volume = {29}, number = {2}, year = {2006}, month = {APR}, pages = {123-125}, publisher = {INDIAN ACADEMY SCIENCES}, type = {Article}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

A simple coprecipitation technique has been used successfully for the preparation of pure, ultrafine, single phases of NaNbO3 (NN) and NaTaO3 (NT). An alcoholic solution of ammonium carbonate and ammonium hydroxide was used to precipitate Na+ and Nb5+ (or Ta5+) cations under basic conditions as carbonate and hydroxide, respectively. On heating at 700 degrees C, these precursors produce respective products. For comparison, both NN and NT powders were also prepared by the traditional solid state method. The phase purity and lattice parameters were studied by powder X-ray diffraction (XRD). The particle size and morphology were studied by scanning electron microscopy (SEM).

}, keywords = {Ceramics, Chemical synthesis, Electron microscopy, electronic materials, Oxides, X-ray methods}, issn = {0250-4707}, doi = {10.1007/BF02704604}, author = {Samuel, V and Gaikwad, A. B. and Ravi, V} } @article { ISI:000246158300001, title = {Coprecipitation technique to prepare CoTa2O6 and CoNb2O6}, journal = {Materials Letter}, volume = {61}, number = {11-12}, year = {2007}, month = {MAY}, pages = {2127-2129}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

An aqueous solution of sodium hydroxide was used to coprecipitate cobalt and tantalum (or niobium) ions from their precursors as hydroxides under basic conditions. This precipitate yielded CoTa2O6 (CT) or CoNb2O6 (CN) ceramics on calcining at 700 degrees C, i.e. at a temperature much lower than 900 degrees C, reported for the formation of these powders prepared by the traditional solid state method. The X-ray diffraction (XRD) studies were employed to investigate phase contents and lattice parameters. The morphology of the synthesized powders was investigated by transmission electron microscopy (TEM). (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Chemical synthesis, electronic materials, Oxides, X-ray methods}, issn = {0167-577X}, doi = {10.1016/j.matlet.2006.08.024}, author = {Mulla, Imtiaz S. and Natarajan, N. and Gaikwad, A. B. and Samuel, V. and Guptha, U. N. and Ravi, V.} } @article { ISI:000246158300058, title = {Coprecipitation technique to prepare NiNb2O6}, journal = {Materials Letter}, volume = {61}, number = {11-12}, year = {2007}, month = {MAY}, pages = {2354-2355}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A mixture of ammonium carbonate and ammonium hydroxide was used to coprecipitate nickel and niobium ions as nickel carbonate and niobium hydroxide under basic conditions. This precursor yielded NiNb2O6 (NN) ceramics on calcining at 700 degrees C (at a temperature lower than 800 degrees C which is necessary for the formation of NiNb2O6 when prepared by the traditional solid state method). The average particle size and morphology of these powders were investigated by transmission electron microscope (TEM). (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Chemical synthesis, Electron microscopy, electronic materials, Oxides, X-ray methods}, issn = {0167-577X}, doi = {10.1016/j.matlet.2006.09.010}, author = {Samuel, V. and Gaikwad, A. B. and Jadhav, A. D. and Natarajan, N. and Ravi, V.} } @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:000246260000011, title = {Preparation of nanocrystalline ferroelectric CaBi4Ti4O15 by citrate gel method}, journal = {Ceramics International}, volume = {33}, number = {4}, year = {2007}, month = {JAN}, pages = {569-571}, publisher = {ELSEVIER SCI LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

A gel was formed when an aqueous solution of CaCl2, BiNO3, TiOCl2 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 700 degrees C produced nano crystallites of the ternary oxide, CaBi4Ti4O15 (CBT). The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). The room temperature dielectric constant at 1 kHz is 390. The ferroelectric hysteresis loop parameters of these samples were also studied by a home-built Sawyer-tower circuit. (c) 2006 Elsevier Ltd and Techna Group S.H. All rights reserved.

}, keywords = {Ceramics, Chemical synthesis, Electron microscopy, Oxides, X-ray methods}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2005.11.006}, author = {Murugan, A. Vadivel and Gaikwad, A. B. and Samuel, V. and Ravi, V.} } @article { ISI:000254698300034, title = {Novel hydroxide precursors to prepare NaNbO3 and KNbO3}, journal = {Ceramics International}, volume = {34}, number = {3}, year = {2008}, month = {APR}, pages = {671-673}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Firstly, fresh niobium, hydroxide was precipitated from NbF5 solution using an aqueous ammonium hydroxide under basic conditions. Then a simple procedure of mixing potassium (or sodium) and niobium hydroxides together and heating at a low temperature (\<400 degrees C) produced KNbO3 (KN) or NaNbO3 (NN) powders. This is the lowest temperature so far reported for the formation of these phases. The phase content and lattice parameters are determined by X-ray diffraction (XRD). The average particle size and morphology were studied by scanning electron microscopy (SEM). (c) 2007 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

}, keywords = {chemical preparation, niobates, Perovskites, powders, X-ray methods}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2006.12.014}, author = {Muthurajan, H. and Kumar, H. H. and Samuel, V. and Gupta, U. N. and Ravi, V.} } @article { ISI:000255612400002, title = {Preparation of ferroelectric CaBi(4)Ti(4)O(15) powders from novel hydroxide precursors}, journal = {Materials Letters}, volume = {62}, number = {12-13}, year = {2008}, month = {APR}, pages = {1751-1753}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Ferroelectric CaBi(4)Ti(4)O(15) (CBT) powders were prepared for the first time from their respective hydroxides. Commercially purchased Ca(OH)(2) is mixed thoroughly with freshly prepared Bi(OH)(3) and Ti(OH)(4) in stoichiometrie ratio and heated at different temperatures ranging from 100 to 600 degrees C. The CBT phase found to be formed at 500 degrees C by the X-ray diffraction studies. This is the lowest temperature so far reported in the literature for the formation of CBT phase. The advantage of this method is that it also avoids the formation of calcium carbonate phase during synthesis. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD) method. The average particle size and morphology were studied by scanning electron microscopy (SEM) technique. (c) 2007 Elsevier B.V All rights reserved.

}, keywords = {CaBi(4)Ti(4)O(15), Ceramics, Chemical synthesis, Electron microscopy, Oxides, X-ray methods}, issn = {0167-577X}, doi = {10.1016/j.matlet.2007.09.080}, author = {Deshmukh, Rupali G. and Vaishampayan, Mukta V. and Darshane, Sonali L. and Mulla, Imtiaz S. and Gaikwad, A. B. and Rao, N. Kotaserwara and Ravi, V.} }