02293nas a2200253 4500008004100000022001400041245009300055210006900148260013000217300001200347490000700359520135300366653001101719653004001730653001901770653001401789653001801803100002201821700001901843700001801862700002201880700002001902856011701922 2006 eng d a1226-086X00aDielectric properties of BaTiO3 ceramics prepared from powders with bimodal distribution0 aDielectric properties of BaTiO3 ceramics prepared from powders w aA-803 TWIN BLDG, 275-3, YANGJAE-DONG, SEOCHO-KU, SEOUL 137-130, SOUTH KOREAbKOREAN SOC INDUSTRIAL ENGINEERING CHEMISTRYcJUL a584-5880 v123 a

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.

10aBaTiO310adielectric-ferroelectric properties10aMicrostructure10aSintering10astoichiometry1 aDeshpande, S., B.1 aPotdar, H., S.1 aPatil, M., M.1 aDeshpande, V., V.1 aKhollam, Y., B. uhttps://library.ncl.res.in/content/dielectric-properties-batio3-ceramics-prepared-powders-bimodal-distribution-001543nas a2200205 4500008004100000022001400041245010300055210006900158260006900227300001200296490000800308520078200316653002001098653003301118653001401151100001801165700001301183700001701196856012401213 2008 eng d a0925-838800aVaristor property of SnO2 center dot CoO center dot Ta2O5 ceramic modified by barium and strontium0 aVaristor property of SnO2 center dot CoO center dot Ta2O5 cerami aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcOCT a483-4870 v4663 a

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.

10aOxide materials10ascanning electron microscopy10aSintering1 aDhage, S., R.1 aRavi, V.1 aYang, O., B. uhttps://library.ncl.res.in/content/varistor-property-sno2-center-dot-coo-center-dot-ta2o5-ceramic-modified-barium-and-001744nas a2200253 4500008004100000022001400041245006500055210006400120260006900184300001200253490000800265520089700273653002601170653001401196653003701210653002201247100002001269700002001289700001801309700002201327700002101349700002101370856009901391 2009 eng d a0925-838800aSynthesis and characterization of CoCrxFe2-xO4 nanoparticles0 aSynthesis and characterization of CoCrxFe2xO4 nanoparticles aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcOCT a798-8010 v4853 a

Spinel-phase nanocrystalline CoCrxFe2-xO4 powders (0.0 <= x <= 2.0) were synthesized by citrate-gel precursor method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). transmission electron microscopy (TEM) and infra-red spectroscopy (FT-IR). The XRD and selected-area electron diffraction (SAED) patterns indicated that the synthesized nanoparticles have single-phase spinet structure without the presence of any other impurities. The changes in electrical and magnetic properties of different stiochiometric compositions have also been investigated. It is seen that with increase in chromium contents, the measured magnetic hysteresis loops become narrow with decreasing trend in saturation magnetization. Electrical resistivity indicated that all the compounds are semiconducting nature. (C) 2009 Elsevier B.V. All rights reserved.

10aMagnetic measurements10aSintering10atransmission electron microscopy10aX-ray diffraction1 aHankare, P., P.1 aSankpal, U., B.1 aPatil, R., P.1 aMulla, Imtiaz, S.1 aLokhande, P., D.1 aGajbhiye, N., S. uhttps://library.ncl.res.in/content/synthesis-and-characterization-cocrxfe2-xo4-nanoparticles-002296nas a2200289 4500008004100000022001400041245011600055210006900171260006900240300001200309490000800321520129400329653001301623653002301636653001101659653001401670100001901684700001901703700002801722700001801750700002501768700001901793700002101812700002301833700001901856856013101875 2010 eng d a0254-058400aSimple chemical co-precipitation/calcination route for the synthesis of simulated synroc-B and synroc-C powders0 aSimple chemical coprecipitationcalcination route for the synthes aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcOCT a695-6990 v1233 a

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.

10aCeramics10aChemical synthesis10aOxides10aSintering1 aPotdar, H., S.1 aVijayanand, S.1 aMohaideen, Kamal, Khaja1 aPatil, K., R.1 aJoy, Pattayil, Alias1 aMadhavan, Raja1 aKutty, K., V. G.1 aAmbashta, Ritu, D.1 aWattal, P., K. uhttps://library.ncl.res.in/content/simple-chemical-co-precipitationcalcination-route-synthesis-simulated-synroc-b-and-synroc-001812nas a2200265 4500008004100000022001400041245008700055210006900142260006900211300001200280490000800292520091300300653002401213653001301237653001401250653002201264100002001286700002001306700001801326700002201344700001701366700002101383700002101404856012101425 2010 eng d a0925-838800aSynthesis and characterization of nanocrystalline zinc substituted nickel ferrites0 aSynthesis and characterization of nanocrystalline zinc substitut aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcAPR a256-2600 v4963 a

Nanocrystalline zinc substituted nickel ferrites, Ni(1-x)Zn(x)Fe(2)O(4) (0.0 <= x <= 1.0) have been prepared by citrate gel auto-combustion method. The effect of zinc ion content on structural, electrical transport and magnetic properties has been studied. The X-ray diffraction (XRD) pattern revealed that, all the compositions possess single-phase spinel structure. The nano-sized grain structure formation was confirmed by transmission electron microscopy (TEM). The dc electrical resistivity shows the samples are semiconducting in nature. The magnetic measurements showed that the composition Ni(0.6)Zn(0.4)Fe(2)O(4) has maximum saturation magnetization (M(s)) while high coersivity (Hc) for ZnFe(2)O(4). Thermoelectric power measurement study showed that the compounds, with x <= 0.4 are p-type and for x > 0.4 behaves n-type conduction mechanism. (C) 2010 Published by Elsevier B.V.

10aElectron microscopy10aMagnetic10aSintering10aX-ray diffraction1 aHankare, P., P.1 aSankpal, U., B.1 aPatil, R., P.1 aMulla, Imtiaz, S.1 aSasikala, R.1 aTripathi, A., K.1 aGaradkar, K., M. uhttps://library.ncl.res.in/content/synthesis-and-characterization-nanocrystalline-zinc-substituted-nickel-ferrites-001755nas a2200217 4500008004100000022001400041245013100055210006900186260007100255300001400326490000600340520092800346653001901274653002101293653002001314653001901334653001401353100002801367700002501395856011701420 2012 eng d a1944-824400aEnhancement in the magnetostriction of sintered cobalt ferrite by making self-composites from nanocrystalline and bulk powders0 aEnhancement in the magnetostriction of sintered cobalt ferrite b a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcDEC a6421-64250 v43 a

Sintered polycrystalline cobalt ferrite is a potential magnetostrictive smart material for applications as sensors and actuators. A novel concept of enhancing the magnetostrictive strain of sintered cobalt ferrite by making self-composites from nanosized and bulk powders with different particle sizes of the same material as components is reported. The self-composites give higher magnetostriction coefficient and strain derivative when compared to the sintered products obtained from the individual powders. The individual components give a maximum magnetostriction up to similar to 310 ppm, whereas up to similar to 370 ppm is obtained for a two-component system consisting of powders of two different sizes. On the other hand, a three-component self-composite made from starting powders of 3 nm, 40 nm and >1 mu m give very high magnetostriction of similar to 400 ppm at 800 kA/m, suitable for making devices.

10aCobalt ferrite10aMagnetostriction10aNanocrystalline10aself-composite10aSintering1 aMohaideen, Kamal, Khaja1 aJoy, Pattayil, Alias uhttps://library.ncl.res.in/content/enhancement-magnetostriction-sintered-cobalt-ferrite-making-self-composites-002009nas a2200217 4500008004100000022001400041245014500055210006900200260009900269300001200368490000700380520113300387653001901520653002101539653001901560653002001579653001401599100002801613700002501641856012501666 2014 eng d a0955-221900aStudies on the effect of sintering conditions on the magnetostriction characteristics of cobalt ferrite derived from nanocrystalline powders0 aStudies on the effect of sintering conditions on the magnetostri aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcMAR a677-6860 v343 a

The effect of sintering conditions on the magnetostriction characteristics of sintered cobalt ferrite derived from nanocrystalline powders is studied. It is observed that the magnetostriction coefficient as well as the slope of the magnetostriction as a function of field depends on the microstructure of the sintered product. There is a direct correlation between the magnetostriction characteristics and density as well as porosity of the sintered products. Intragranular pores are found to be strongly influencing the magnetostriction characteristics. Similarly, correlation is found between the magnetostriction parameters and the Curie temperature, indicating the role of cation distribution which affects the magnetic anisotropy. Sintering the compacts made from nanocrystalline powders at 1450 degrees C for a very short duration is found to give high values of magnetostriction coefficient. However, higher values of magnetostriction at low magnetic fields are obtained for samples sintered at lower temperatures for longer duration and having relatively lower density. (C) 2013 Elsevier Ltd. All rights reserved.

10aCobalt ferrite10aMagnetostriction10aMicrostructure10aNanocrystalline10aSintering1 aMohaideen, Kamal, Khaja1 aJoy, Pattayil, Alias uhttps://library.ncl.res.in/content/studies-effect-sintering-conditions-magnetostriction-characteristics-cobalt-ferrite-002354nas a2200241 4500008004100000022001400041245014200055210006900197260007300266300001200339490000800351520144600359653001601805653001801821653002101839653001401860653002901874100001901903700002001922700002001942700001801962856013201980 2015 eng d a0920-586100aEncapsulation of ultra small metal clusters in silica: evolution of the concept of nanoreactors and the case of Ag-Pd@SiO2 alloy catalyst0 aEncapsulation of ultra small metal clusters in silica evolution  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG a114-1200 v2513 a

The concept of encapsulation of ultra small clusters within silica evolved as a means to address the sintering of active metal nanoparticles and subsequent deactivation observed in supported noble metal catalysts. It is hypothesised that sintering, which mainly occurs due to mobility of metal species on the support surfaces, can be minimised if the growth and movement of metal nanoparticles are constrained. First, nanoparticles are isolated inside 1D channels in 2D mesoporous compounds and the idea develops to complete encapsulation of thiol protected ultra small nanoclusters in silica spheres. Sintering is better controlled in the latter due to the confined space for growth of nanoparticles. Access of reactant molecules to the active metal surfaces also is ensured by porosity created in the silica matrix forming the basis of the concept of nanoreactors. In this paper, we elaborate on the evolution of this concept from our earlier work on highly sinter resistant silica encapsulated Au, Pd and Au-Pd alloys to the present system of Ag-Pd alloy encapsulated in silica. Silver, with the lowest Tammann temperature among noble metals, is highly prone to sintering which is adequately controlled by alloying with Pd as well as encapsulation in silica. Its enhanced activity in paranitrophenol reduction in comparison with pure metals indicates the advantageous effect of alloying. (C) 2014 Elsevier B.V. All rights reserved.

10aAg-Pd alloy10aEncapsulation10aSinter resistant10aSintering10aUltra small nanoclusters1 aMondal, Sourik1 aSamanta, Anupam1 aDhar, Basab, B.1 aDevi, Nandini uhttps://library.ncl.res.in/content/encapsulation-ultra-small-metal-clusters-silica-evolution-concept-nanoreactors-and-case-ag-001623nas a2200193 4500008004100000022001400041245009000055210006900145260000800214300001600222490000700238520097900245653001501224653002401239653001401263100001401277700001601291856012201307 2019 eng d a0272-884200aMagnetic properties of sintered CoFe2O4-BaTiO3 particulate magnetoelectric composites0 aMagnetic properties of sintered CoFe2O4BaTiO3 particulate magnet cJUN a12307-123110 v453 a

The magnetic properties of sintered particulate magnetoelectric CoFe2O4 - BaTiO3 composites have been studied. The particulate composites are sintered in the temperature range 1000-1300 degrees C, for a short duration of 10 min. The magnetic transition temperature (T-c) of CoFe2O4 is found to decrease with increasing the sintering temperature and sintering time, as well as on increasing the BaTiO3 content in the composites. Similarly, a reduced saturation magnetization at room temperature, compared to that expected for the CoFe2O4 content, is also observed. Powder X-ray diffraction studies showed the presence of the impurity phase related to the hexagonal ferrite BaFe12O19 in all the composites. Ba2Fe2Ti4O13 is observed as a second impurity phase in the BaTiO3 - rich composites. The present studies suggest that the composition of the piezomagnetic (CoFe2O4) phase in the CoFe2O4 - BaTiO3 magnetoelectric composite is affected during the sintering process.

10acomposites10amagnetic properties10aSintering1 aMohan, S.1 aJoy, P., A. uhttps://library.ncl.res.in/content/magnetic-properties-sintered-cofe2o4-batio3-particulate-magnetoelectric-composites