@article { ISI:000232801900001, title = {Characterization of barium titanate: BaTiO3 (BT) ceramics prepared from sol-gel derived BT powders}, journal = {Journal of Electroceramics}, volume = {15}, number = {2}, year = {2005}, month = {NOV}, pages = {103-108}, publisher = {SPRINGER}, type = {Article}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

Sol-gel synthesis was attempted at room temperature by adding drop wise a clear solution (made by reacting BaCO3 with glacial acetic acid) to an equi-molar solution of titanium tetrabutoxide in isopropanol (IPA) and acetic acid. The gelation occurred within 30 minutes. The as-dried gel was calcined at 750 degrees C/6 h in air to obtain carbon free BaTiO3 powders. The resulting BT powders were further pressed into pellets and sintered at 1280 degrees C/4 h in air to get dense ceramics (density similar to 94\%). XRD and SEM techniques were used for phase and microstructure analysis respectively. The room temperature relative permittivity (e) of 1280 increased to 7200 (at Curie temperature of 127 degrees C) at 1 kHz frequency. The dissipation factor (tan delta) similar to 1.6\% was observed in these samples. Also, the ferroelectric properties such as spontaneous polarization (Ps similar to 13 mu C/cm(2)), coercive field (E-c similar to 4.0 kV/cm) and dielectric strength (similar to 34 kV/cm) are estimated for these samples. These performance parameters are compared with the available standard data from the literature.

}, keywords = {barium titanate, ferroelectricity, Microstructure, relative permittivity, sol-gel processing}, issn = {1385-3449}, doi = {10.1007/s10832-005-1460-7}, author = {Deshpande, S. B. and Godbole, P. D. and Khollam, Y. B. and Potdar, H. S.} } @article { ISI:000225497800035, title = {Synthesis and characterization of microwave-hydrothermally derived Ba1-xSrxTiO3 powders}, journal = {Materials Letters}, volume = {59}, number = {2-3}, year = {2005}, month = {JAN}, pages = {293-296}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Submicron-sized, spherical, stoichiometric strontium substituted barium titanate: Ba0.75Sr0.25TiO3 (BST) powders are prepared by microwave-hydrothermal (MH) route under the MH conditions of 200 degreesC, 200 psi, and 30 min in strongly alkaline conditions (pH\>12) using potassium titanyl oxalate (KTO) and nitrates of Ba and Sr as the starting precursors and KOH as the mineralizer. The characterization studies by XRD, XRF and SEM indicated that stoichiometric cubic BST powders (a(0)=3.992 A) were obtained by adjusting MH conditions mentioned earlier and keeping the (Ba+Sr)/Ti ratio in starting solution slightly in excess (similar to1.06). (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {barium-strontium titanate, dissolution-recrystallization, Microstructure, microwave-hydrothermal synthesis, mineralizer, SEM, XRD, XRF}, issn = {0167-577X}, doi = {10.1016/j.matlet.2004.10.006}, author = {Deshpande, S. B. and Khollam, Y. B. and Bhoraskar, Y. B. and Date, Sadgopal K. and Sainkara, S. R. and Potdar, H. S.} } @article { ISI:000239359100012, title = {Dielectric properties of BaTiO3 ceramics prepared from powders with bimodal distribution}, journal = {Journal of Industrial and Engineering Chemistry}, volume = {12}, number = {4}, year = {2006}, month = {JUL}, pages = {584-588}, publisher = {KOREAN SOC INDUSTRIAL ENGINEERING CHEMISTRY}, type = {Article}, address = {A-803 TWIN BLDG, 275-3, YANGJAE-DONG, SEOCHO-KU, SEOUL 137-130, SOUTH KOREA}, abstract = {

BaTiO3 (BT) powders having bimodal distribution were synthesized successfully through a simple classical solid-state reaction route using cheap BaCO3 and TiO2 as starting materials. These powders were further processed in the form of green pellets to obtain dense BT ceramics having densities of similar to 94 similar to 96 \% after sintering in air at 1350 and 1400 degrees C/4 h in air. The room temperature dielectric constant (epsilon(RT)) of similar to 1500 at 1 KHz frequency was increased to : 10000 at a Curie temperature (T-C) similar to 126 degrees C, showing a very sharp transition from a polar tetragonal to a non-polar cubic structure. The dielectric loss factor (tan 6) was similar to 1.5 \%. SEM studies revealed the presence of dense microstructures having a distribution of smaller grains (size: 2 similar to 3 gm) surrounded by larger grains (\>= 35 mu m). The ferroelectric hysteresis loop measurements on these samples gave values of spontaneous polarization (P-s) of similar to 12.0 mu C/cm(2), a coercive field (E-C) of similar to 2 similar to 2.5 kV/cm, and a dielectric strength (E-b) of similar to 48.0 kV/cm. DC-resistivity as high as 1.5 x 10(9) Omega-cm was obtained in these samples. All these results are quite comparable with reported ferroelectric/dielectric data and are discussed elaborately in this paper.

}, keywords = {BaTiO3, dielectric-ferroelectric properties, Microstructure, Sintering, stoichiometry}, issn = {1226-086X}, author = {Deshpande, S. B. and Potdar, H. S. and Patil, M. M. and Deshpande, V. V. and Khollam, Y. B.} } @article { ISI:000236922600002, title = {Room temperature synthesis of mesoporous aggregates of anatase TiO2 nanoparticles}, journal = {Materials Chemistry and Physics}, volume = {97}, number = {2-3}, year = {2006}, month = {JUN}, pages = {207-212}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The controlled hydrolysis reaction of titanium tetrabutoxide in presence of acetic acid in isopropanol, i.e. in non-aqueous media was adopted in the present work for the synthesis of nanocrystalline titania followed by aging at ambient conditions for longer duration. The powder XRD shows that the as-dried precursor (without any aging) is non-crystalline in nature. However, room temperature aging for longer duration \> 120 days not only helped to develop crystallinity in TiO2 nanoparticles but also led to the formation of their self-assembly towards mesoporous aggregates creating sponge like TiO2 nano-structure having high surface area similar to 250m (2) g(-1)and narrow pore size distribution of 4-5 nm. TEM observations revealed the generation of spherical TiO2 nanoparticles (4-5 nm) assembled to form stable spongy scaffold having porous network structure with pore size 5-6 nm. Also, presence of a pronounced hysteresis loop in BET isotherm is indicative of a 3D-intersection network of the pores of size 4-5 nm. Further heat-treatment to the aged precursor at 400 degrees C/2 h in air modify pore network structure due to sintering of TiO2 particles as is observed in TEM studies and lowering thereby the surface area to 125 m(2) g(-1) (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Microstructure, porous materials, sol-gel processing, titania}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2005.02.014}, author = {Deshpande, S. B. and Potdar, H. S. and Khollam, Y. B. and Patil, K. R. and Pasricha, R. and Jacob, Nalini E.} }