@article { ISI:000227603500004, title = {Co-precipitation method for the preparation of fine ferroelectric BaBi2M2O9}, journal = {Ceramics International}, volume = {31}, number = {3}, year = {2005}, month = {JAN}, pages = {379-381}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

A simple co-precipitation technique had been successfully applied for the preparation of pure fine powders of single phase BaBi2Nb2O9. Ammonium hydroxide and ammonium oxalate were used to precipitate Ba2+, Bi3+ and Nb5+ cations simultaneously. No pyrochlore phase was formed while heating powder at 800 degrees C and pure BaBi2Nb2O9 phase was found to be formed by X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). The room temperature dielectric constant at 1 kHz is 100. The ferroelectric hysteresis loop parameters of these samples were also studied. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

}, keywords = {dielectric properties, Electron microscopy, ferroelectric properties, powders chemical preparation}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2004.05.024}, author = {Gaikwad, S. P. and Potdar, HS and Samuel, V and Ravi, V} } @article { ISI:000227447800012, title = {Coprecipitation technique to prepare BaNb2O6}, journal = {Materials Science and Engineering B-Solid State Materials for Advanced Technology}, volume = {117}, number = {2}, year = {2005}, month = {MAR}, pages = {169-171}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

A mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and niobium ions as barium oxalate and niobium hydroxide under basic conditions. This precursor on calcination at 750degreesC yielded BaNb2O6 ceramics. This is a much lower temperature as compared to that prepared by traditional solid-state method (1000degreesC), as reported for the formation of BaNb2O6. Transmission electron microscope (TEM) investigations 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 1100. The ferroelectric hysteresis loop parameters of these samples were also studied. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {Ammonia, Ceramics, Electron microscopy, niobium oxide, Oxides}, issn = {0921-5107}, doi = {10.1016/j.mseb.2004.11.009}, author = {Natarajan, N and Samuel, V and Pasricha, R and Ravi, V} } @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:000232864800029, title = {Low temperature synthesis of MgTa2O6 powders}, journal = {Materials Letters}, volume = {59}, number = {29-30}, year = {2005}, month = {DEC}, pages = {3926-3928}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A combination of digestion and further low temperature calcination to crystallize the product is employed to prepare MgTa2O6 (MT) ceramics. Freshly prepared niobium hydroxide gel is mixed with magnesium hydroxide thoroughly and allowed to react at 100 degrees C under refluxing and stirring conditions for 6-12 h. The X-ray amorphous product so formed is heated at 550 degrees C to form crystalline MgTa2O6. This is the lowest temperature so far reported for the formation of MgTa2O6. For comparison, MT powders were also prepared by the traditional solid state method. Transmission electron microscope (TEM) investigations revealed that the average particle size is 40 nm for the low temperature calcined powders. (C) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Electron microscopy, magnesium tantalate, Oxides, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2005.07.035}, author = {Navale, SC and Samuel, V and 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:000230877900002, title = {Preparation of nanocrystalline ferroelectric CaBi2Ta2O9 by the urea method}, journal = {Ceramics International}, volume = {31}, number = {6}, year = {2005}, month = {JAN }, pages = {773-775}, publisher = {ELSEVIER SCI LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

A precipitate was formed when a aqueous solution of CaCl2, BiCl3, TaF5 and urea in stoichiometric ratio (total metal cations to urea ratio is 5) is heated on a water bath. This precipitate on decomposition at 600 degrees C yielded the nanocrystallites of ternary oxide CaBi2Ta2O9 (CBT) as confirmed by X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). Ferroelectric hysteresis loop parameters such as remnant polarization (P-r) and coercive field (E-C) were also determined. TEM investigations revealed that the average particle size of the polycrystalline powder is 70 nm. The room temperature dielectric constant was found to be 110. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

}, keywords = {dielectric properties, Electron microscopy, ferroelectric properties, powders : chemical preparation}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2004.08.011}, author = {Gaikwad, S. P. and Pasricha, R and Ravi, V} } @article { ISI:000227447800010, title = {Preparation of nanocrystalline ferroelectric CaBi2TaO9 by citrate gel method}, journal = {Materials Science and Engineering B-Solid State Materials for Advanced Technology}, volume = {117}, number = {2}, year = {2005}, month = {MAR}, pages = {159-161}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

A gel was formed when an aqueous solution of CaCl2, BiCl3, TaF5 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 600degreesC yielded the nano-crystallites of ternary oxide, CaBi2Ta2O9 (CBT) as confirmed by X-ray diffraction study (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). Ferroelectric hysteresis loop parameters such as remnant polarization (P-r) and coercive field (E-C) are also determined. TEM investigations revealed that the average particle size of the polycrystalline powder is 40 nm. The room temperature dielectric constant was found to be 90. (C) 2004 Elsevier B.V All rights reserved.

}, keywords = {Bismuth, diffraction, Electron microscopy}, issn = {0921-5107}, doi = {10.1016/j.mseb.2004.11.006}, author = {Gaikwad, S. P. and Pasricha, R and Ravi, V} } @article { ISI:000230275100022, title = {Preparation of nanocrystalline LiNbO3 by citrate gel method}, journal = {Materials Letters}, volume = {59}, number = {19-20}, year = {2005}, month = {AUG}, pages = {2476-2478}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A gel was formed when an aqueous solution of Li(NO3) NbF5 and citric acid in stoichiometric ratio is heated in a water bath at 100 degrees C. This gel on decomposition at 700 degrees C produced the fine crystallites of ternary oxide, LiNbO3 (LN). 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). (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Electron microscopy, electronic materials, lithium niobate, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2005.03.028}, author = {Navale, SC and Samuel, V and Ravi, V} } @article { ISI:000229379000010, title = {Preparation of nanocrystalline MgNb2O6 by citrate gel method}, journal = {Materials Letters}, volume = {59}, number = {17}, year = {2005}, month = {JUL}, pages = {2146-2148}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A gel was formed when a aqueous solution of Mg(NO3)(2), NbF5 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 700 degrees C produced the fine crystallites of ternary oxide, MgNb2O6 (MN). The formation of MN phase and lattice parameters were determined by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Citrate gel, Electron microscopy, magnesium niobate, powders, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2005.02.050}, author = {Pasricha, R and Ravi, V} } @article { ISI:000231605600002, title = {Preparation of ultrafine LiTaO3 powders by citrate gel method}, journal = {Bulletin of Materials Science}, volume = {28}, number = {5}, year = {2005}, month = {AUG}, pages = {391-393}, publisher = {INDIAN ACADEMY SCIENCES}, type = {Article}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

A gel was formed when a aqueous solution of Li(NO3), TaF5 and citric acid in stoichiometric ratio was heated in a water bath. This gel on decomposition at 700 degrees C produced fine crystallites of ternary oxide, LiTaO3 (LT). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM).

}, keywords = {Ceramics, Electron microscopy, electronic materials, X-ray diffraction}, issn = {0250-4707}, doi = {10.1007/BF02711224}, author = {Navale, SC and Samuel, V 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:000231592300006, title = {Synthesis of Sr0.5Ba0.5Nb2O6 by citrate gel method}, journal = {Materials Chemistry and Physics}, volume = {94}, number = {1}, year = {2005}, month = {NOV}, pages = {34-36}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

A gel was formed when an aqueous solution of BaCl2, SrCl2, NbF5 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 700 degrees C yielded the nanocrystallites of ternary oxide, Sr0.5Ba0.5Nb2O6 (SBN) as confirmed by X-ray diffraction study (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). The room temperature dielectric constant at I kHz is 1000. The ferroelectric hysteresis loop parameters of these samples were also studied by a home built Sawyer-Tower circuit. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Electron microscopy, ferroelectricity, Oxides}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2005.04.003}, author = {Pasricha, R and Ravi, V} } @article { ISI:000234951400014, title = {Coprecipitation technique to prepare LiTaO3 powders}, journal = {Materials Letters}, volume = {60}, number = {8}, year = {2006}, month = {APR}, pages = {1047-1048}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A simple coprecipitation technique had been successfully applied for the preparation of pure ultrafine single phase LiTaO3 (LT). An aqueous mixture of ammonium carbonate and ammonium hydroxide was used to precipitate Li+ and Ta5+ cations as carbonate and hydroxide respectively. This precursor oil heating at 750 degrees C produces LT powders. For comparison, LT powders were also prepared by the traditional solid state method. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Electron microscopy, electronic materials, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2005.10.074}, author = {Navale, SC and Gaikwad, A. B. 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} }