@article { ISI:000243821700012, title = {Structural evolutions of hydrothermally prepared mesostructured MCM-48 silica using differently manufactured amorphous silica powders}, journal = {Journal of Non-Crystalline Solids}, volume = {353}, number = {2}, year = {2007}, month = {FEB}, pages = {194-199}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The hydrothermal synthesis of Si-MCM-48 mesoporous molecular sieves was carried out using a ternary SiO2:CTAOH:H2O System wherein differently manufactured amorphous silica powders such as fumed silica (FMDS), spray dried precipitated silica (SDPS) and flash dried precipitated silica (FDPS) were used as silica source materials. The changes in structural/textural properties were evaluated using powder XRD, N-2 adsorption-desorption and scanning electron microscopy techniques. Studies on the progressive development of MCM-48 mesophases revealed that, the reactivity of the silica source follow the trend: FMDS \> SDPS \> FDPS. MCM-48 synthesized using low cost FDPS has exhibited thicker pore walls but poorer orderness, while MCM-48 prepared from relatively expensive FMDS has thinner pore walls and more ordered structure. Moreover, the extent of contraction caused by calcinations, agglomerate size and structural stability were found to depend on the reactivity of the silica source used. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {long-range order, micelles, scanning electron microscopy, silica, silicates, sol-gels (xerogels), X-ray diffraction}, issn = {0022-3093}, doi = {10.1016/j.jnoncrysol.2006.10.005}, author = {Taralkar, U. S. and Jha, Ratnesh Kumar and Joshi, P. N.} } @article { ISI:000257367100016, title = {Low temperature synthesis and characterization of BiNbO4 powders}, journal = {Materials Characterization}, volume = {59}, number = {8}, year = {2008}, month = {AUG}, pages = {1083-1087}, publisher = {ELSEVIER SCIENCE INC}, address = {360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA}, abstract = {

BiNbO4 powders, a potential microwave dielectric ceramic were prepared by both coprecipitation and solid state techniques. In the former method, an aqueous ammonium hydroxide was used to precipitate Bi3+ and Ta5+ cations as hydroxides simultaneously under basic conditions. It is observed that the co-precipitation produces BiNbO4 phase on heating at 600 degrees C, whereas complete phase formation occurs only at 800 degrees C in the case of solid state method. The phase contents and lattice parameters were studied by powder X-ray diffraction. The sequence of the reaction and phase evolution of BiNbO4 were also studied by the X-ray diffraction. The samples were characterized by the differential-thermal/thermo-gravimetric analyses and scanning electron microscopy techniques. (C) 2007 Elsevier Inc. All rights reserved.

}, keywords = {BiNbO4, Ceramics, Chemical synthesis, Electron microscopy, Oxides, X-ray diffraction}, issn = {1044-5803}, doi = {10.1016/j.matchar.2007.08.026}, author = {Radha, R. and Muthurajan, H. and Rao, N. Koteswara and Pradhan, Sivaram and Gupta, U. N. and Jha, Ratnesh Kumar and Mirji, S. A. and Ravi, V.} } @article { ISI:000253106100026, title = {Low temperature synthesis of SrNb2O6 and SrTa2O6 using hydroxide precursor}, journal = {Materials Letters}, volume = {62}, number = {6-7}, year = {2008}, month = {MAR}, pages = {892-894}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

SrNb2O6 (SN) or SrTA(2)O(6) (ST) compounds were prepared at low temperatures for the first time from hydroxide precursors. A simple procedure of mixing commercially purchased strontium hydroxide and niobium (or tantalum) hydroxide thoroughly together and heating at a low temperature (\<400 degrees C) produced SrNb2O6 (SN) or SrTa2O6 (ST) powders. This is the lowest temperature so far reported for the formation of these phases. These materials are potential candidates for ferroelectric and electro-optic applications. The reaction sequence and evolution of the phase formation were investigated by X-ray diffraction (XRD) studies. The average particle size and morphology of these powders were studied by scanning electron microscopy (SEM). (C) 2007 Elsevier B.V. All rights reserved.

}, keywords = {Chemical synthesis, Electron microscopy, electronic materials, X-ray diffraction}, issn = {0167-577X}, doi = {10.1016/j.matlet.2007.07.006}, author = {Muthurajan, H. and Kumar, H. H. and Koteswara Rao, N. and Pradhan, Sivaram and Jha, Ratnesh Kumar and Ravi, V.} } @article { ISI:000257365900027, title = {Novel hydroxide precursors for low temperature synthesis of selected ternary oxides}, journal = {Materials Research Bulletin}, volume = {43}, number = {7}, year = {2008}, month = {JUL}, pages = {1842-1849}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

A novel method of using hydroxide precursors to reduce the synthesis temperature for few selected ternary oxides has been presented here. This technique is very useful and advantageous when the ternary oxides contain an alkaline earth element. The selected compositions for this method are BaCeO3 (BC), BaBiO3 (BB), La0.7Sr0.3CoO3 (LSCO) and BaBi2Nb2O9 (BBN). Commercially purchased strontium (or barium) hydroxide and freshly prepared lanthanum, cobalt, bismuth and niobium hydroxides were mixed thoroughly in stoichiometric ratio and heated at different temperatures ranging from 100 to 700 degrees C for 10 h for corresponding compositions. The sequence of the reaction and evolution of the product phase were studied by the X-ray diffraction (XRD) studies. The phase purity and lattice parameters were also determined by XRD investigations. All the product phases in each case were formed at relatively low temperature than when they were prepared by co-precipitation or solid state method. The morphology and average particle size of these powders were investigated by scanning electron microscopy (SEM). (C) 2007 Elsevier Ltd. All rights reserved.

}, keywords = {Ceramics, Chemical synthesis, Electron microscopy, Oxides, X-ray diffraction}, issn = {0025-5408}, doi = {10.1016/j.materresbull.2007.07.006}, author = {Muthurajan, H. and Rao, N. Koteswara and Gupta, U. N. and Pradhan, Sivaram and Jha, Ratnesh Kumar and Kumar, H. H. and Mirji, S. A. and Ravi, V.} }