01465nas a2200229   4500008004100000022001400041245004900055210004900104260007300153300001400226490000700240520077000247653001301017653002401030653002401054653001101078653002201089100001501111700001401126700001201140856008301152       2005                        eng d  a0167-577X00aLow temperature synthesis of MgTa2O6 powders0 aLow temperature synthesis of MgTa2O6 powders  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC  a3926-39280 v593 a<p>A combination of digestion and further low temperature calcination to crystallize the product is employed to prepare MgTa2O6 (MT) ceramics. Freshly prepared niobium hydroxide gel is mixed with magnesium hydroxide thoroughly and allowed to react at 100 degrees C under refluxing and stirring conditions for 6-12 h. The X-ray amorphous product so formed is heated at 550 degrees C to form crystalline MgTa2O6. This is the lowest temperature so far reported for the formation of MgTa2O6. For comparison, MT powders were also prepared by the traditional solid state method. Transmission electron microscope (TEM) investigations revealed that the average particle size is 40 nm for the low temperature calcined powders. (C) 2005 Elsevier B.V. All rights reserved.</p>10aCeramics10aElectron microscopy10amagnesium tantalate10aOxides10aX-ray diffraction1 aNavale, SC1 aSamuel, V1 aRavi, V  uhttps://library.ncl.res.in/content/low-temperature-synthesis-mgta2o6-powders-001524nas a2200193   4500008004100000022001400041245007300055210006900128260006900197300001200266490000800278520083800286653002401124653003301148653001801181100001501199700001201214856010401226       2005                        eng d  a0921-510700aPreparation of fine MgTa2O6 and Mg4Ta2O9 powders by chemical methods0 aPreparation of fine MgTa2O6 and Mg4Ta2O9 powders by chemical met  aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcMAY  a189-1910 v1193 a<p>Two different chemical methods are applied to prepare MgTa2O6 (MT2) and Mg4Ta2O9 (M4T2) powders. A gel was formed when a aqueous solution of Mg(NO3)(2), TAF(5) and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 750 degrees C produced the fine crystallites of ternary oxide, M4T2. A simple co-precipitation technique had been successfully applied for the preparation of pure ultrafine single phase MT2. Ammonium hydroxide was used to precipitate Mg2+ and Ta5+ cations as hydroxides simultaneously. This precursor on heating at 750 degrees produces MT2 powders. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron microscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.</p>10aElectron microscopy10apowders-chemical preparation10aX-ray methods1 aNavale, SC1 aRavi, V  uhttps://library.ncl.res.in/content/preparation-fine-mgta2o6-and-mg4ta2o9-powders-chemical-methods-001229nas a2200229   4500008004100000022001400041245006400055210006400119260007300183300001400256490000700270520048200277653001300759653002400772653002500796653002000821653002200841100001500863700001400878700001200892856009500904       2005                        eng d  a0167-577X00aPreparation of nanocrystalline LiNbO3 by citrate gel method0 aPreparation of nanocrystalline LiNbO3 by citrate gel method  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG  a2476-24780 v593 a<p>A gel was formed when an aqueous solution of Li(NO3) NbF5 and citric acid in stoichiometric ratio is heated in a water bath at 100 degrees C. This gel on decomposition at 700 degrees C produced the fine crystallites of ternary oxide, LiNbO3 (LN). The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.</p>10aCeramics10aElectron microscopy10aelectronic materials10alithium niobate10aX-ray diffraction1 aNavale, SC1 aSamuel, V1 aRavi, V  uhttps://library.ncl.res.in/content/preparation-nanocrystalline-linbo3-citrate-gel-method-001166nas a2200217   4500008004100000022001400041245006600055210006600121260010500187300001200292490000700304520041500311653001300726653002400739653002500763653002200788100001500810700001400825700001200839856009700851       2005                        eng d  a0250-470700aPreparation of ultrafine LiTaO3 powders by citrate gel method0 aPreparation of ultrafine LiTaO3 powders by citrate gel method  aC V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIAbINDIAN ACADEMY SCIENCEScAUG  a391-3930 v283 a<p>A gel was formed when a aqueous solution of Li(NO3), TaF5 and citric acid in stoichiometric ratio was heated in a water bath. This gel on decomposition at 700 degrees C produced fine crystallites of ternary oxide, LiTaO3 (LT). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM).</p>10aCeramics10aElectron microscopy10aelectronic materials10aX-ray diffraction1 aNavale, SC1 aSamuel, V1 aRavi, V  uhttps://library.ncl.res.in/content/preparation-ultrafine-litao3-powders-citrate-gel-method-001503nas a2200229   4500008004100000022001400041245006000055210006000115260006900175300001000244490000800254520080400262653001301066653001101079653000901090653001301099653002201112100002001134700001501154700001201169856009201181       2005                        eng d  a0921-510700aTiO2 ceramic varistor modified with tantalum and barium0 aTiO2 ceramic varistor modified with tantalum and barium  aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcNOV  a50-520 v1233 a<p>The non-linear current (I)-voltage (V) characteristics of titanium dioxide doped with small quantities of tantalum and barium (99.9 TiO2 + 0.1 Ta and 99.4 TiO2 + 0.1 Ta + 0.5 Ba, all are in at.%) were investigated. These samples have the non-linear coefficient (alpha) values of (20-30) with high breakdown voltages (E-B similar to 400-700 V mm(-1)). The pentavalent tantalum acts as donor and increases the electronic conductivity. The higher electrical conductivity and decrease in the breakdown field strength with barium addition is attributed to higher density. The acceptor like surface states formed by barium ions segregate to grain boundaries due size misfit to thereby modifying the electrical barrier characteristics of grain boundaries. (c) 2005 Elsevier B.V. All rights reserved.</p>10aCeramics10aOxides10aTiO210avaristor10aX-ray diffraction1 aGaikwad, A., B.1 aNavale, SC1 aRavi, V  uhttps://library.ncl.res.in/content/tio2-ceramic-varistor-modified-tantalum-and-barium-001365nas a2200217   4500008004100000022001400041245005600055210005600111260007300167300001400240490000700254520066500261653001300926653002400939653002500963653002200988100001501010700002001025700001201045856009001057       2006                        eng d  a0167-577X00aCoprecipitation technique to prepare LiTaO3 powders0 aCoprecipitation technique to prepare LiTaO3 powders  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR  a1047-10480 v603 a<p>A simple coprecipitation technique had been successfully applied for the preparation of pure ultrafine single phase LiTaO3 (LT). An aqueous mixture of ammonium carbonate and ammonium hydroxide was used to precipitate Li+ and Ta5+ cations as carbonate and hydroxide respectively. This precursor oil heating at 750 degrees C produces LT powders. For comparison, LT powders were also prepared by the traditional solid state method. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.</p>10aCeramics10aElectron microscopy10aelectronic materials10aX-ray diffraction1 aNavale, SC1 aGaikwad, A., B.1 aRavi, V  uhttps://library.ncl.res.in/content/coprecipitation-technique-prepare-litao3-powders-0