@article { ISI:000228898600009, title = {Co-precipitation method for the preparation of ferroelectric CaBi4Ti4O15}, journal = {Journal of Materials Science-Materials in Electronics}, volume = {16}, number = {4}, year = {2005}, month = {APR}, pages = {229-231}, publisher = {SPRINGER}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

A simple co-precipitation technique has been successfully applied for the preparation of pure single phase CaBi4Ti4O15 (CBT) powders. Ammonium oxalate and ammonium hydroxide were used to precipitate Ca2+, Bi3+ and Ti4+ cations simultaneously. No pyrochlore phase was found while heating powder at 600\° C and pure CBT phase was found to be formed by X-ray diffraction. Particle size and morphology was studied by transmission electron microscopy (TEM). The room temperature dielectric constant at 1 kHz is 400. The ferroelectric hysteresis loop parameters of these samples were also studied. (C) 2005 Springer Science + Business Media, Inc.

}, issn = {0957-4522}, doi = {10.1007/s10854-005-0773-2}, author = {Gaikwad, S. P. and Dhage, S. R. and Ravi, V.} } @article { ISI:000227550500009, title = {Co-precipitation method for the preparation of nanocrystalline ferroelectric SrBi2Nb2O9 ceramics}, journal = {Journal of Electroceramics}, volume = {14}, number = {1}, year = {2005}, month = {JAN}, pages = {83-87}, publisher = {SPRINGER}, type = {Article}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

A simple co-precipitation technique had been successfully applied for the preparation of pure ultrafine single phase SrBi2Nb2O9. Ammonium hydroxide and ammonium oxalate were used to precipitate Sr2+, Bi3+ and Nb5+ cations simultaneously. No pyrochlore phase was found while heating powder at 850 C and pure SrBi2Nb2O9 (SBN) phase was formed as revealed by the X-ray diffraction (XRD) studies. Particle size and morphology was studied by transmission electron microscopy (TEM). The room temperature dielectric constant at 1 kHz is 100. The ferroelectric hysteresis loop parameters of these samples were also studied.

}, keywords = {Ceramics, Chemical synthesis, electronic materials, ferroelectricity, Oxides}, issn = {1385-3449}, doi = {10.1007/s10832-005-6588-y}, author = {Gaikwad, S. P. and Dhage, S. R. and Potdar, H. S. and Samuel, V. and Ravi, V.} } @conference { ISI:000227460600023, title = {Magnetic properties of nanosized ferrite powders synthesized by microwave-hydrothermal method}, booktitle = {Ninth International Conference on Ferrites (ICF-9)}, year = {2005}, note = {9th International Conference on Ferrites (ICF-9), San Francisco, CA, AUG 22-27, 2004}, month = {AUG}, pages = {143-148}, publisher = {Amer Ceramic Soc, 735 Ceramic Place, Westerville, OH 43081-8720 USA}, organization = {Amer Ceramic Soc, 735 Ceramic Place, Westerville, OH 43081-8720 USA}, address = {San Francisco, CA}, abstract = {

Nanosized powders of Fe3O4 and MgFe2O4 are synthesized by microwave-hydrothermal (MH) method. The ferrite powders thus obtained are characterized by powder X-ray diffraction, Mossbauer spectroscopy, scanning and transmission electron microscopies, vibrating sample magnetometer and AC magnetic susceptibility studies. Stoichiometric, nanosized (similar to 34 nm) Fe3O4 particles, having cubic symmetry with a(0) approximate to 8.39 angstrom, are obtained when molar ratio of Fe/NaOH used for the synthesis is 0.133. On the other hand, non-stoichiometric Fe3O4 is obtained when Fe/NaOH molar ratio is increased to 0.4. Though the powder XRD patterns of both stoichiometric and non-stoichiometric Fe3O4 are identical, Mossbauer spectroscopic studies showed different features in terms of asymmetry, intensity, isomer shift, etc. Saturation magnetization, M-s = 70 emu/g and coercivity, H-c = 178 Oe, at room temperature, are obtained for stoichiometric Fe3O4 powders. In the case of MgFe2O4, spherical, nanosized (similar to 3 nm) powders with cubic symmetry (a(0) approximate to 8.30 angstrom) and having very narrow size distribution are obtained under the MH conditions. The temperature and field dependent magnetic measurements on MgFe2O4 powders confirmed the existence of superparamagnetic state in this material with a superparamagnetic blocking temperature of 38 K below which typical magnetic hysteresis behaviour is observed.

}, isbn = {1-57498-218-4}, author = {Khollam, Y. B. and Dhage, S. R. and Verma, S. and Potdar, H. S. and Deshpande, S. B. and Joy, Pattayil Alias and Date, Sadgopal K.}, editor = {Soohoo, R. F.} } @article { ISI:000228797100048, title = {Preparation of ferroelectric BaNb2O6 the urea method}, journal = {Materials Letters}, volume = {59}, number = {14-15}, year = {2005}, month = {JUN}, pages = {1929-1931}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A precipitate was formed when an aqueous solution of BaCl2, NbF5 and urea in required ratio (the ratio of total metal cations to the urea is five) is heated on a water bath at 100 degrees C. This precipitate on decomposition at 600 degrees C yielded the nanocrystallites of BaNb2O6 (BN), as confirmed by X-ray diffraction study (XRD). This is a much lower temperature as compared to that prepared by traditional solid state method (1000 degrees C) as reported for the formation of BaNb2O6. Transmission electron microscope (TEM) investigations revealed that the average particle size is 85 nm for the calcined powders. The room temperature dielectric constant at 1 kHz is found to be 900. The ferroelectric hysteresis loop parameters of these samples were also studied. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Chemical synthesis, electronic material, ferroelectricity, Oxides}, issn = {0167-577X}, doi = {10.1016/j.matlet.2005.02.028}, author = {Dhage, S. R. and Pasricha, R. and Ravi, V.} } @article { ISI:000230275100032, title = {Synthesis of bismuth oxide nanoparticles at 100 degrees C}, journal = {Materials Letters}, volume = {59}, number = {19-20}, year = {2005}, month = {AUG}, pages = {2523-2525}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A simple gel to crystal conversion route has been followed for the preparation of ultrafine Bi2O3 particles at 80-100 degrees C under refluxing conditions. Freshly prepared bismuth hydroxide gel is allowed to crystallize under refluxing and stirring conditions for 6-12 h. Formation of nanocrystallites of Bi2O3 is confirmed by X-ray diffraction (XRD) study. The thermal decomposition of bismuth hydroxide yields Bi2O3 only at 400 degrees C. This shows the advantage of the present method. Transmission electron microscope (TEM) investigations revealed that the average particle size is 50 nm for these oven-dried powders. (c) 2005 Elsevier B.V All rights reserved.

}, keywords = {Ceramics, Chemical synthesis, Electron microscopy, Oxides, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2005.03.037}, author = {Patil, M. M. and Deshpande, V. V. and Dhage, S. R. and Ravi, V.} } @article { ISI:000225588700025, title = {Synthesis of bismuth titanate by the urea method}, journal = {Materials Letters}, volume = {59}, number = {4}, year = {2005}, month = {FEB}, pages = {514-516}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A simple urea precipitation route was adopted for the preparation of bismuth titanate (Bi4Ti3O12) powders. Stoichiometric quantities of BiCl3 and TiOCl2 were mixed with the required amount of urea (the ratio of total metal cations to urea is five), and the mixture was heated on a water bath. This leads to the formation of precipitate, which was decomposed at 973 K. The formation of bismuth titanate was observed on calcining powders at 973 K by X-ray diffraction studies. The average particle size is found to be 100 nm by microscopy. The room temperature dielectric constant is found to be 150 at 1 kHz. The hysteresis loop parameters were also obtained by home-built Sawer-Tower circuit. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Chemical synthesis, dielectric properties, ferroelectricity, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2004.10.038}, author = {Anilkumar, Mettu and Dhage, S. 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:000226803200008, title = {Synthesis of fine particles of ZnO at 100 degrees C}, journal = {Materials Letters}, volume = {59}, number = {7}, year = {2005}, month = {MAR}, pages = {779-781}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A simple gel to crystal conversion route has been followed for the preparation of fine ZnO at 80-100 degreesC under refluxing conditions. Freshly prepared zinc hydroxide gel is allowed to crystallize under refluxing and stirring conditions for 4-6 It. Formation of fine crystallites of ZnO is confirmed by X-ray diffraction (XRD) study. Transmission electron microscope (TEM) investigations revealed that the average particle size is 100 nm for these powders. (C) 2004 Elsevier B.V All rights reserved.

}, keywords = {Ceramics, Chemical synthesis, Electron microscopy, Oxides, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2004.11.019}, author = {Dhage, S. R. and Pasricha, R. and Ravi, V.} } @article { ISI:000227164000044, title = {Synthesis of Sr0.5Ba0.5Nb2O6 by urea method}, journal = {Materials Letters}, volume = {59}, number = {8-9}, year = {2005}, month = {APR}, pages = {1053-1055}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A precipitate was formed when an aqueous solution of SrCl2, BaCl2, NbF5 and urea in stoichiometric ratio (total metal cations to urea ratio is 5) is heated on a water bath.. This precipitate on decomposition at 750 degreesC yielded the nanocrystallites of ternary oxide, Sr0.5Ba0.5Nb2O6 (SBN) as confirmed by X-ray diffraction study (XRD). This is much lower temperature as compared to that prepared by traditional solid state method (1000 degreesC as reported for the formation of SBN ceramics. 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 1050. The ferroelectric hysteresis loop parameters of these samples were also studied. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Electron microscopy, ferroelectricity, Oxides}, issn = {0167-577X}, doi = {10.1016/j.matlet.2004.12.003}, author = {Dhage, S. R. and Pasricha, R. and Ravi, V.} } @article { ISI:000238298100027, title = {Co-precipitation technique for the preparation of ferroelectric BaBi2Ta2O9}, journal = {Materials Chemistry and Physics}, volume = {98}, number = {2-3}, year = {2006}, month = {AUG}, pages = {344-346}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

A simple co-precipitation technique had been successfully applied for the preparation of pure ultrafine single phase BaBi2Ta2O9 (BBT). Ammonium hydroxide and ammonium oxalate were used to precipitate Ba2+, Bi3+ and Ta5+ cations simultaneously. No pyrochlore phase was found while heating powder at 800 degrees C and pure BaBi2Ta2O9 phase was found to be formed by X-ray diffraction. Particle size and morphology was studied by transmission electron spectroscopy (TEM). The room temperature dielectric constant at 1 kHz is 350. The ferroelectric hysteresis loop parameters of these samples were also studied. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Chemical synthesis, electronic material, ferroelectricity, Oxides}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2005.09.036}, author = {Dhage, S. R. and Pasricha, R. and Murugan, A. Vadivel 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: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:000260483400085, title = {Varistor property of SnO2 center dot CoO center dot Ta2O5 ceramic modified by barium and strontium}, journal = {Journal of Alloys and Compounds}, volume = {466}, number = {1-2}, year = {2008}, month = {OCT}, pages = {483-487}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The influence of an alkali earth (Ba/Sr) element in small quantities (\< 1 at.\%) on non-linear electrical properties of 98.5\% SnO2 + 1\% CoO + 0.5\% Ta2O5 (all in at.\%) varistor system has been investigated. The non-linear coefficient increases from 33 to 52 whereas breakdown field strength varies 5025-6050 V cm(-1) for the barium-doped samples. In case of strontium-doped specimens moderate increase in non-linear coefficient but significant increase in breakdown field is observed. It is proposed that due to ionic size misfit, Ba and Sr segregates to grain boundaries thereby modifying their barrier properties. The contribution from grain boundary phase to the electrical property is confirmed by the impedance analysis. (C) 2007 Elsevier B.V. All rights reserved.

}, keywords = {Oxide materials, scanning electron microscopy, Sintering}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2007.11.062}, author = {Dhage, S. R. and Ravi, V. and Yang, O. B.} }