@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: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:000227321500008, title = {Simple oxalate precursor route for the preparation of barium-strontium titanate: Ba1-xSrxTiO3 powders}, journal = {Materials Characterization}, volume = {54}, number = {1}, year = {2005}, month = {JAN}, pages = {63-74}, publisher = {ELSEVIER SCIENCE INC}, type = {Article}, address = {360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA}, abstract = {

A simple one-step cation-exchange reaction between the stoichiometric solutions of ammonium titanyl oxalate (ATO) and barium hydroxide+strontium nitrate at room temperature (RT) is investigated successfully for the quantitative precipitation of barium-strontium titanyl oxalate (BSTO): Ba1-xSrxTiO(C2O4)(2).4H(2)O (x=0.25) precursor powders with nearly theoretical yield (greater than or equal to99\%). The pyrolysis of BSTO at 730degreesC/4 h in air produced barium-strontium titanate (Ba1-xSrxTiO3; BST) powders. The characterization studies on BSTO and BST powders by using various physico-chemical techniques: micro- and chemical analysis, differential thermal analysis (DTA)/thermo-gavimetric analysis (TGA), XRD, FTIR, X-ray fluorescence (XRF) and scanning electron microscopy (SEM) revealed that the powders formed are cubic, highly pure, stoichiometric and sub-micron-sized with nearly uniform size and shape distribution. The ceramic compacts obtained by sintering the BST pellets at 1300degreesC/4 It showed density similar to95\%, dielectric constant epsilon(Tc)similar to9500, tan delta-0.15\% and T(C)similar to32 degreesC. (C) 2004 Elsevier Inc. All rights reserved.

}, keywords = {barium-strontium titanate, barium-strontium titanyl oxalate, permittivity, XRF}, issn = {1044-5803}, doi = {10.1016/j.matchar.2004.11.002}, author = {Khollam, Y. B. and Deshpande, S. B. and Potdar, H. S. and Bhoraskar, S. V. and Sainkar, S. R. and Date, Sadgopal K.} } @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.} } @article { ISI:000236922600018, title = {Synthesis of star shaped Ba1-xSrTiO3 (BST) powders}, journal = {Materials Chemistry and Physics}, volume = {97}, number = {2-3}, year = {2006}, month = {JUN}, pages = {295-300}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

Uniform star shaped strontium substituted barium titanyl oxalate Ba1-xSrxTiO(C2O4)(2) (BSTO)/strontium substituted barium titanate, Ba1-xSrxTiO3 (BST) powders were prepared via a simple chemical co-precipitation route with x = 0.15, 0.20, and 0.25. The process involved an addition of 0.1 M solution of titanium tetrabutoxide (BTM) in isopropanol (IPA) to 0.1 M oxalic acid in IPA containing 0.2 M of H2O to produce titanyl oxalate precipitate which was further reacted with 0.1 M solution of ammonium oxalate to obtain 0.1 M clear homogeneous solution of ammonium titanyl oxalate (ATO) with pH 4.25 containing titanium in the form of soluble anionic oxalate species [TiO(C2O4)(2)(2-)]. Stoichiometric quantities of barium hydroxide and strontium nitrate were dissolved in distilled water and its pH was adjusted nearly equal to that of ATO (similar to 4.15) by drop wise addition of dilute HNO3 solution 1:10 (v/v). The addition of this mixed cation precursor solution to ATO solution resulted in precipitation of strontium substituted barium titanyl oxalate (BSTO) having star shaped morphology. The calcination of BSTO precursors at 730 degrees C for 4 h in air produced cubic BST powders (a(o) similar to 4.001, 3.996 and 3.991 angstrom for x = 0. 15, 0.20, 0.25, respectively) having star shaped morphology. SEM, XRD and IFTIR techniques were used to characterize the BSTO/BST powders. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {barium-strontium titanate, barium-strontium titanyl oxalate, capping agent, Co-precipitation, Morphology}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2005.08.013}, author = {Khollam, Y. B. and Potdar, H. S. and Deshpande, S. B. and Gaikwad, A. B.} } @article { ISI:000254222400007, title = {Synthesis of bismuth titanate (Bi4Ti3O12)powders via calcination of microwave-hydrothermally (MH) derived precursor}, journal = {Indian Journal of Engineering and Materials Sciences}, volume = {15}, number = {1}, year = {2008}, month = {FEB}, pages = {51-54}, publisher = {NATL INST SCIENCE COMMUNICATION}, type = {Article}, address = {DR K S KRISHNAN MARG, NEW DELHI 110 012, INDIA}, abstract = {

Micrometer sized platelet-like particles of bismuth titanate (Bi4Ti3O12) ire prepared successfully by the calcination of a mixed-precursor in air. The mixed precursor is precipitated Under microwave-hydrothermal (MH) treatment via dissolution-recrystallization kinetics. The mixed precursor is precipitated in-situ by giving MH treatment (at 200 degrees C, 200 psi, and 30 min hold time) to the hydrolysed slurry containing Bi and Ti cations. The slurry was prepared by adding 20\% aqueous KOH precipitant solution to a well-mixed stoichiometric nitrate solution containing Bi and Ti cations. XRD results revealed that the as-dried precursor consisted of a homogenous mixture of non-crystalline particles of Bi2O3 and TiO2. The calcination of the as-dried precursor at 700 degrees C/2 h in air resulted ill the formation of micron sized platelet like single-phase Bi4Ti3O12 powders having orthorhombic structure.

}, keywords = {Bi4Ti3O12, MH processing, SEM, XRD}, issn = {0971-4588}, author = {Khollam, Y. B. and Deshpande, S. B. and Samuel, V. and Potdar, H. S.} } @article { ISI:000269638800052, title = {Magnetic characteristics of nanocrystalline multiferroic BiFeO3 at low temperatures}, journal = {Physical Review B}, volume = {80}, number = {6}, year = {2009}, month = {AUG}, pages = {064423}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {

The magnetic characteristics of nanocrystalline BiFeO3 with average crystallite sizes of similar to 50 and similar to 100 nm are evaluated by studying the temperature and field dependence of magnetization at low temperatures. Different properties such as magnetization, coercivity, and remanence show evidence for changes in the magnetic properties associated with the phase transitions at low temperatures, reported from Raman studies. Detailed field-cooled and zero-field-cooled magnetization measurements show that the likely origin of the changes in the magnetic characteristics is from the changes in the domain structure.

}, keywords = {bismuth compounds, coercive force, crystallites, magnetic domains, magnetic transitions, Multiferroics, Nanostructured materials, Raman spectra, remanence}, issn = {1098-0121}, doi = {10.1103/PhysRevB.80.064423}, author = {Vijayanand, S. and Mahajan, Mangesh B. and Potdar, H. S. and Joy, Pattayil Alias} } @article { ISI:000269291500035, title = {Nanocrystalline Mn-Zn-ferrite by novel oxalato-hydrazinated complex method}, journal = {Materials Chemistry and Physics}, volume = {117}, number = {1}, year = {2009}, month = {SEP}, pages = {187-191}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

We report here for the first time the synthesis of technologically important ferrite, using a metal oxalato-hydrazinate (MOH) complex method. The MOH complex of iron-manganese-zinc was synthesized at room temperature using the precursors, ferrous ammonium sulphate, manganese acetate and zinc acetate. Thermo-gravimetric studies of MOH intermediate showed complete phase formation of MnZnFe(2)O(4) at 280 degrees C. XRD data showed the formation of single phase cubic spinel MnZnFe(2)O(4). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrate the spherical shape particle morphology. TEM images indicated the particle size of ferrite powder in the range of 20-36 nm. Magnetization of synthesized nano-sized Mn(0.69)Zn(.0.19)Fe(2.12)O(4) was observed coercive force (H(c)) at 127.82 Oe with a saturation magnetization (M(s)), 34.5 emu g(-1) using vibrating sample magnetometer (VSM) at room temperature. Mossbauer study of nano-sized ferrite powder showed super-paramagnteic behavior. (c) 2009 Elsevier B.V. All rights reserved.

}, keywords = {crystal structure, Magnetic materials, Mn-Zn-ferrite, Nanostructures, Optical properties}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2009.05.036}, author = {Kanade, K. G. and Amalnerkar, Dinesh P. and Potdar, H. S. and Kale, B. B.} } @article { ISI:000265933700042, title = {Origin of high room temperature ferromagnetic moment of nanocrystalline multiferroic BiFeO3}, journal = {Applied Physics Letters}, volume = {94}, number = {18}, year = {2009}, month = {MAY}, pages = {182507}, publisher = {AMER INST PHYSICS}, address = {CIRCULATION \& FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA}, abstract = {

Single phase nanocrystalline BiFeO3 of average crystallite size similar to 25 nm with very high magnetization at room temperature is synthesized by an autocombustion method. Magnetic measurements above room temperature show deviation between field cooled and zero field cooled magnetization below 645 K, the Neel temperature (T-N) of the bulk material, indicating intrinsic nature of ferromagnetism. However, observation of a broad magnetic transition above T-N of BiFeO3 and extended up to 800 K suggests the presence of Fe3O4 as a possible magnetic impurity phase. Evidence for the presence of Fe3O4 is obtained from detailed analysis of the powder x-ray diffraction pattern.

}, keywords = {bismuth compounds, Combustion synthesis, crystallites, ferromagnetic materials, high-temperature effects, magnetic impurities, Magnetic moments, Magnetisation, Multiferroics, Nanostructured materials, Neel temperature, X-ray diffraction}, issn = {0003-6951}, doi = {10.1063/1.3132586}, author = {Vijayanand, S. and Potdar, H. S. and Joy, Pattayil Alias} } @article { ISI:000281175500059, title = {Simple chemical co-precipitation/calcination route for the synthesis of simulated synroc-B and synroc-C powders}, journal = {Materials Chemistry and Physics}, volume = {123}, number = {2-3}, year = {2010}, month = {OCT}, pages = {695-699}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

A simple chemical co-precipitation/calcination route was developed for the synthesis of simulated synroc-B and synroc-C powders using mostly nitrate salts as starting chemicals and 20\% ammonia solution as precipitant. In this route, a mixed solution containing Al-nitrate, Ca-nitrate, Ba-nitrate, zirconyl nitrate and titanyl nitrate in the molar proportion required for synroc-B is added to dilute ammonia solution to precipitate these cations in the form of their hydroxides at room temperature by maintaining pH approximate to 10.5 during precipitation. Formation of a major fluorite phase with minor amounts of anatase, rutile and hollandite phases is observed in the powder obtained after calcination in air at 750 degrees C. Multiphase crystalline synroc-B matrix containing hollandite, perovskite, zirconolite, and rutile phases is obtained after sintering the heat treated powder in the form of pellets at 1230 degrees C for 4h in air. Similarly, pure synroc-C phases with 14 and 20\% simulated waste loadings were synthesized following the same synthesis protocol. These pre-treated powders with a high surface area of similar to 25 m(2) g(-1) gave sintered ceramics having density of similar to 90\% for 14 and 20\% waste loadings. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Chemical synthesis, Oxides, Sintering}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2010.05.039}, author = {Potdar, H. S. and Vijayanand, S. and Mohaideen, Kamal Khaja and Patil, K. R. and Joy, Pattayil Alias and Madhavan, R. Raja and Kutty, K. V. G. and Ambashta, Ritu D. and Wattal, P. K.} } @article { ISI:000299031600049, title = {Ferroelectric and electrical characterization of multiferroic BiFeO3 at the single nanoparticle level}, journal = {Applied Physics Letters}, volume = {99}, number = {25}, year = {2011}, month = {DEC}, pages = {Article No. 252905}, publisher = {AMER INST PHYSICS}, type = {Article}, address = {CIRCULATION \& FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA}, abstract = {

Ferroelectric BiFeO3 (BFO) nanoparticles deposited on epitaxial substrates of SrRuO3 (SRO) and La1-xSrxMnO3 (LSMO) were studied using band excitation piezoresponse spectroscopy (BEPS), piezoresponse force microscopy (PFM), and ferromagnetic resonance (FMR). BEPS confirms that the nanoparticles are ferroelectric in nature. Switching behavior of nanoparticle clusters were studied and showed evidence for inhomogeneous switching. The dimensionality of domains within nanoparticles was found to be fractal in nature, with a dimensionality constant of similar to 1.4, on par with ferroelectric BFO thin-films under 100 nm in thickness. Ferromagnetic resonance studies indicate BFO nanoparticles only weakly affect the magnetic response of LSMO. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3671392]

}, issn = {0003-6951}, doi = {10.1063/1.3671392}, author = {Vasudevan, R. K. and Bogle, Kashinath A. and Kumar, A. and Jesse, S. and Magaraggia, R. and Stamps, R. and Ogale, Satishchandra B. and Potdar, H. S. and Nagarajan, V.} } @article { ISI:000234250400007, title = {Microwave-hydrothermal (MH) synthesis of Ba1-xSrxTiO3 (BST)}, journal = {Ferroelectrics}, volume = {327}, year = {2011}, note = {4th Asian Meeting on Ferroelectricity (AMF-4), Indian Inst Sci, Bangalore, INDIA, DEC 12-15, 2003}, month = {MAR}, pages = {39-43}, publisher = {Dept Sci \& Technol; Defense R\& D Org; Council Sci \& Ind Res; Mat Res Soc India; Indian Inst Sci; IEEE UFFC; Taylor \& Francis Sci Publ; Int Journal FERROELECT}, address = {4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}, abstract = {

The barium-strontium titanate (BST) powders are used in fabrication of various microelectronic devices (because of their field- \& composition dependent dielectric properties), integrated capacitors \& as thin dielectric layer in DRAM (dynamic random access memories). The utility of MH synthesis route in deriving the BST powders was explored in the present studies under strongly alkaline conditions (pH \> 12). Potassium titanyl oxalate (KTO) and nitrates of Ba \& Sr were used as the starting precursors and KOH as a mineralizer. The typical BST composition, namely, BST with Sr = 0.25 was chosen for the experimentation. All the MH experiments were carried out in the MARS-5 microwave accelerated digestion system (CEM Corpn., USA). The stoichiometric BST powders were obtained under the MH conditions of 200 degrees C, 200 psi, and 30 min when the Ba/Sr ratio (greater than or similar to 3.25) was kept slightly in excess. The acetic acid treated and water washed MH derived powders showed formation of exclusively cubic BST phase (a(0) = 3.992 A degrees) as confirmed by XRD. These powders were further processed in the form of disks and sintered at high temperature (1350 degrees C/4 h) in air to obtain dense (rho \>= 92\%) ceramic bodies. Electrical measurements on the lapped and electroded samples (sintered at 1350 degrees C/4h) revealed epsilon(T-c) = 6800, tan delta = 0.1\% and T-c = 32 degrees C. These properties are comparable to the reported standard data in the literature.

}, issn = {0015-0193}, doi = {10.1080/00150190500316226}, author = {Deshpande, S. B. and Khollam, Y. B. and Potdar, H. S.} } @article { ISI:000324098200003, title = {Porous Co3O4 nanorods as superior electrode material for supercapacitors and rechargeable Li-ion batteries}, journal = {Journal of Applied Electrochemistry}, volume = {43}, number = {10}, year = {2013}, month = {OCT}, pages = {995-1003}, publisher = {SPRINGER}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

Porous aggregated nanorods of Co3O4 with a surface area of similar to 100 m(2) g(-1) synthesized without using any templates or surfactants give very high specific capacitance of similar to 780 F g(-1) when used as electrode in a faradaic supercapacitor, with a cycle life of more than 1,000 cycles. Further, in Li-ion batteries when used as an anode, the Co3O4 nanorods achieved a capacity of 1155 mA h g(-1) in the first cycle and upon further cycling it is stabilized at 820 mA h g(-1) for more than 25 cycles. Detailed characterization indicated the stability of the material and the improved performance is attributed to the shorter Li-insertion/desertion pathways offered by the highly porous nanostructures. The environmentally benign and easily scalable method of synthesis of the porous Co3O4 nanorods coupled with the superior electrode characteristics in supercapacitors and Li-ion batteries provide efficient energy storage capabilities with promising applications.

}, keywords = {Cobalt oxide, Electrode materials, Li-ion battery, Porous nanostructures, supercapacitor}, issn = {0021-891X}, doi = {10.1007/s10800-013-0593-7}, author = {Vijayanand, S. and Kannan, Ramaiyan and Potdar, H. S. and Pillai, V. K. and Joy, Pattayil Alias} }