A. D. Damodaran's research while affiliated with Council of Scientific and Industrial Research (CSIR), New Delhi and other places

Publications (210)

Chapter
Fine SiC particulates of size less than 0.3 μam were coated uniformly with mullite precursor by controlled hydrolysis of a mixture of boehmite and silica sols. SiC powders dispersed in TEOS-water mixture were first coated with hydrous silica followed by flocculation in boehmite sol. Coated powders on calcination at temperatures > 1250°C produced mu...
Article
The history of metals and their shaping is as ancient as the history of civilization. Many of the artifacts excavated and preserved as well as some of the metallurgical arts still being practiced are standing examples depicting the excellent metallurgical skill possessed by mankind. The Indian subcontinent too stood at par with the rest of the worl...
Article
Studies on the membrane solvent extraction consisting of source and membrane, and membrane and receiving phases in extraction and stripping processes of praseodym- ium, samarium and yttrium in hollow fiber membrane one after the other, have been in- vestigated. Different experimental variables, such as the pH, carrier, metal ion and strip- ping age...
Article
Indian artisans and craftsmen have long been masters at extracting and shaping metals and alloys, as proven by archaeological finds from the 2nd-3rd millennia B.C. For example, two wellknown artifacts, castings of the dancing girl of Mohenjo Daro and the Mother Goddess of Adichanallur, Tamilnadu, depict a high degree of metallurgical knowledge. Tho...
Article
The effect of Fe content (0.2 to 0.6 pct) on the microstructure and mechanical properties of a cast Al-7Si-0.3Mg (LM 25/356) alloy has been investigated. Further, 1 pct mischmetal (MM) additions (a mixture of rare-earth (RE) elements) were made to these alloys, and their mechanical properties at room and at elevated temperatures (up to 200 °C) were...
Article
Fourier Transform Infrared Spectroscopic (FTIR) investigation has been carried out to study the structural changes and coordination of Al and Ti in the sol-gel derived aluminium titanate system as a function of temperature (65°–1400°C). An analysis of the FTIR spectral patterns shows that both octahedral as well as tetrahedral coordinations are pre...
Article
A new ceramic perovskite, GdBa2HfO5.5, has been synthesized and developed for use as substrate for the YBa2Cu3O7- delta superconductor. The dielectric constant and loss factor of this material are in a range suitable for its use as substrate for microwave applications. No detectable chemical reaction between YBa2Cu3O7- delta and GdBa2HfO5.5 was obs...
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The addition of Sb2O3 to YBa2Cu3O7- delta resulted in the formation of a second phase during high-temperature sintering at 950 degrees C. This phase is identified as YBa2SbO6, having a cubic structure with a lattice constant a=8.403 AA. This compound has been synthesized as a single-phase material by solid-state reaction for the first time. Sinteri...
Article
The superconducting and normal state percolation behaviour of a new ceramic insulator-superconductor composite system has been studied. A value for the percolation threshold of the superconducting state of 40 vol.% of YBCO has been obtained, whereas the normal state percolation threshold value is 30 vol.% of YBCO. The critical exponents 't' and 'u'...
Article
Multilayered Ag/Bi(Pb)-2223 tapes with high critical current densities have been fabricated using partially heat treated, textured monolayered tapes. Cut sections of the monolayered tapes have been stacked one over the other and folded together using high-purity silver foil and further rolled and heat treated to obtain multilayered tapes of differe...
Article
Density variations of the superconductor core during the powder-in-tube (PIT) fabrication of Ag/BPSCCO monolayer tapes have been studied. The PIT procedure involved steps such as filling the tubes with precursor powder, rich in 2212 phase, with packing densities in the range 20 - 55% of theoretical density, groove rolling, flat rolling and finally...
Article
Full-text available
Silver-YBCO composite powders containing up to 50% by weight of silver have been prepared from nitrate mixtures as citrate felt followed by thermal decomposition. These powders possess a bulk density of 2 g cm-3, an average particle size of 3 mu m and near spherical morphology. Consolidated pellets of these powders when sintered at 915 degrees C in...
Article
The effect of ZrO2 addition on the superconducting properties of YBa2Cu3O7- delta superconductors has been investigated by temperature-resistance measurements and X-ray diffraction studies. The results revealed that ZrO2 additions up to 2.0 wt.% do not have any detrimental effect on the superconducting properties of YBa2Cu3O7- delta . It is also fo...
Article
The chemical reactivity and percolation in a rapidly quenched superconducting YBa2Cu3O7- delta -YBa2SbO6 composite system have been studied by X-ray diffraction and temperature-resistivity measurements. No chemical reaction between Y1Ba2Cu3O7- delta and YBa2SbO6 was observed, even under severe heat treatment, and the system behaved as an ideal cond...
Article
Alumina–20 vol% zirconia (12 mol% ceria) composite powder has been extruded using boehmite (AlOOH) as an extrusion aid. A higher order of homogeneity of the constituent phases has been achieved in this work by controlling the pH of flocculation at 8.5. Sintering was carried out at 1600°C. The microstructural evaluation confirms uniform distribution...
Article
The effect of Mg (up to 0.5%) and Fe content (up to 0.6%), melt holding time, hydrogen content, modification (by Sr and mischmetal (MM)), pouring temperature, grain refinement (by Zr and TiB) and cooling rate on the mechanical properties and microstructure of cast Al-7Si-0.3Mg (LM 25/ 356) alloy has been investigated. Structure property correlation...
Article
High temperature densification and associated microstructural features of alumina derived through sintering of microwave dehydroxylated boehmite are presented. α-alumina has been obtained through a series of transitional alumina phases within 60 min of exposure of boehmite gel to microwaves of 2.45 GHz and 600 W power. The phase formation has been...
Article
The phase evolution and transport properties of Ag/(Bi,Pb)-2223 tapes prepared by PIT process using `conventional' precursors of six different phase assemblages are studied. The precursors with an initial stoichiometry of Bi1.8Pb0.4Ca2.2Cu3Oy are prepared by a sol–gel method and samples having different phase assemblages are obtained by changing th...
Article
An alumina-30 vol.-% silicon carbide particulate gel composite was prepared by uniformly dispersing ultra fine SiC particles (<0.5 μm) in an aqueous boehmite sol, at pH 7.5, followed by drying, at varied power levels, in a domestic microwave oven. Comparison experiments were also carried out with identical samples prepared by humidity drying. These...
Article
Solid complexes of lanthanide ions with l-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and diphenylsulphoxide (DPSO), dioctyl sulphoxide (DOSO) and tributyl phosphate (TBP) have been isolated by solvent extraction. Analytical data and H NMR spectra establish their stoichiometry as [Ln(PMBP)2NO3X2] where X is the oxo donor. The IR spectra of these...
Article
Mullite has been synthesised from gels formed from mixtures of tetraethoxysilane (TEOS) and boehmite (AlOOH) sol at various values of pH (3-8) and the effect on phase formation characteristics and microstructural features of calcined gels has been studied. Powders obtained from gels calcined at 400 and 900°C for 3 h respectively showed an increasin...
Article
Al-pillared montmorillonite has been prepared by the intercalation of boehmite (A1OOH) sol by a novel method involving refluxing the montmorillonite-boehmite mixtures. Al/g montmorillonite ratio in the range 0.25 to 20 has been used for the preparation of a variety of pillared compounds. Results indicate that a minimum amount of A1 is required (> 5...
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Full-text available
Mullite precursor gels have been prepared from a mixture of particulate boehmite sol and tetraethoxysilane at a pH of 4. The sol has been seeded with submicron size α-Al2O3, γ-Al2O3 and mullite limited to two percent by weight of the mullite phase. These gels have been invesitgated with respect to phase formation, densification and microstructural...
Article
Monohydroxy aluminium oxide (Boehmite, AlOOH) has been used as an extrusion aid along with α-alumina and γ-alumina particulates. Extended ball milling of the mixture using alumina grinding media imparts nucleating seeds to boehmite for an early conversion to α-alumina. The boehmite-γ-alumina mixture appears to result in a denser alumina ceramic acc...
Article
Mullite precursor gel of stoichiometric composition 3Al2O3 · 2SiO2 has been prepared by reacting boehmite sol and tetraethyl orthosilicate (TEOS) in a stoichiometric ratio. The pH of the preparation medium was varied from pH 3.5–8. The sol to gel transformation of the precursor was studied using optical microscopy. Phase formation characteristics o...
Article
Aluminium titanate has been prepared by thermal decomposition of a precursor gel formed by the controlled flocculation of a homogeneous mixture of boehmite and titanium isopropoxide sols. The effect of aluminium titanate seed nuclei, with average size less than 0.25 mm, on the phase formation, densification and microstructure development is reporte...
Article
A FTIR spectrum is used to study the formation characteristics of aluminium titanate precursor gel under the influence of temperature. From an analysis of the spectra of the gel heated at different temperatures in the 30–1400°C range, it is found that both octahedral and tetrahedral Al–O coordinations are present up to 800°C. At temperatures above...
Article
Coexistence of pyrochlore phase is one of the major problems in the preparation of lead magnesium niobate (PMN) based perovskites as it leads to deterioration of the dielectric and piezoelectric properties. Although the columbite precursor method substantially reduces the formation of pyrochlore phase, the success of this process depends on various...
Article
Intercalation of boehmite species has been carried out in different media for the preparation of alumina pillared montmorillonite (PILC — pillared clays). The effect of different media such as water, water-isopropanol and water-butanol on the intercalation and thermal stability of the resulting pillared montmorillonite is discussed. Montmorillonite...
Article
A luminescence spectrometric method was developed for the determination of ultra trace amounts of europium (down to 1 x 10(-13) M) in high purity lanthanum, praseodymium and dysprosium oxides. This is based on the enhanced luminescence of europium-thenoyltrifluoroacetone (TTA)-dibenzo-18-crown-6 (DBC)-Triton X-100 in the presence of terbium. The fl...
Article
A group of complex perovskites, Ba2−xSrxEuSbO6 (where x=0, 1 and 2) was synthesized and sintered as single-phase materials for their use as substrates for YBCO superconductor films. These compounds have a complex cubic perovskite (A2BB′O6) crystal structure with lattice constant in the range 0.85–0.83 nm. The values of dielectric constant and loss...
Article
The studies on ion transport of terbium and dysprosium through a porous supported liquid membrane (SLM) containing TOPO (trioctyl phosphine oxide) and TBP (tributyl phosphate) as immobilised carriers have been carried out. The effect of stirring of bulk solutions on permeability coefficient has been investigated. The permeability coefficient increa...
Article
Kinetic studies of yttrium recovery, consisting of extraction and stripping processes have made using 2-ethylhexyl-phosphonic acid mono-2-ethylhexyl ester (PC-88A, EHPNA) as an acidic extractant. The experimental variables affecting the ion transport flux of yttrium have been explored; that is, pH, carrier and stripping agent concentrations. Kineti...
Article
Full-text available
Mixed-ligand chelate extraction of trivalent lanthanides such as Nd(III), Eu(III) and Lu(III) into benzene with mixtures of 4,4,4-trifluoro-1-phenyl-1,3-butanedione (HBFA) and bis-2-ethylhexyl sulphoxide (B2EHSO) or triphenylphosphine oxide (TPhPO) from thiocyanate solutions was investigated. The results demonstrate that these metal ions are extrac...
Article
This paper describes a sensitive spectrophotometric method for the determination of mercury, based on the flotation of a mercury iodide-brilliant green complex with cyclohexane at pH 5 and dissolution of the complex in acetone. The absorbance of the complex is measured at 625 nm. Beer's law is obeyed from 4–500 g/l of mercury. The method is highly...
Article
Synergistic solvent extraction of trivalent lanthanides such as Nd, Eu and Tm has been studied using mixtures of 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and 18-crown-6; 15-crown-5, benzo-15-crown-5, or dibenzo-18-crown-6. The results demonstrate that these trivalent metal ions are extracted into chloroform as Ln(PBI)3 with HPBI alone and as Ln(PBI)...
Article
The extraction of zinc(II), cadmium(II) and mercury(II) from thiocyanate solutions has been investigated by tracer techniques with triisobutylphosphine sulfide (= TIBPS, commercially known as CYANEX 471X) in benzene as an extractant. The extraction data have been analyzed by both graphical and theoretical methods taking into account aqueous phase s...
Article
An alumina-silicon carbide nanocomposite precursor was prepared by a sol-gel method using a boehmite sol and a kinetically stable colloidal suspension of ultrafine (<0-3 urn) silicon carbide particleS. Flocculation of the boehmite sol containing uniformly dispersed silicon carbide particles using ammonia, immobilised the dispersed particles resulti...
Article
A highly selective and sensitive spectrophotometric procedure for the determination of lead is developed. This is based on the interaction of iodide complex of lead with Rhodamine 6G to form a pink product which absorbs maximally at 575 nm that is stable for 24 h when stabilized with gelatin. The Pb-I--Rhodamine 6G ternary complex was fully formed...
Article
Fine grained , alumina and mullite matrix -silicon carbide nanocomposites have indicated excellent mechanical properties. Further in order to achieve superplasticity in oxide ceramics fine grained microstructures, introduction of grain boundary engineered liquid phases as well as particle pinning centres have shown positive effects. For any of the...
Article
Coexistence of pyrochlore phase is one of the major problems in the preparation of lead magnesium niobate (PMN) based perovskites as it leads to deterioration of the dielectric and piezoelectric properties. Although the columbite precursor method substantially reduces the formation of pyrochlore phase, the success of this process depends on various...
Article
A rapid microwave decomposition method has been reported for the preparation of ZnO varistor precursors which on subsequent heat treatment for short period results in non-ohmic properties. Thus a mixture of nitrates of zinc and praseodymium along with minor additives such as cobalt, chromium and potassium when subjected to microwaves of 2.45 GHz in...
Article
The extraction of Zn(II) and Cd(II) from thiocyanate solutions with bis-2-ethylhexyl sulphoxide (B2EHSO) in benzene as an extractant has been studied by tracer techniques. For comparison, extraction has also been carried out with tributylphosphate (TBP). The extraction data have been analysed by both graphical and theoretical methods by taking into...
Article
A DPCSV procedure for the determination of selenium (IV) with a prior preconcentrative coprecipitation on iron (III) hydroxide has been developed. The experimental conditions for coprecipitation of selenium (IV) onto iron (III) hydroxide, viz. pH, iron (III) concentration, volume of aqueous phase and selenium concentration, were optimized. The copr...
Article
Synergistic extraction of trivalent lanthanides such as Nd, Eu and Tm with mixtures of 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5 (HPMTFP) and 18-crown-6 or dibenzo-18-crown-6 or 15-crown-5 or monobenzo-15-crown-5 (CE) in chloroform has been investigated. Lanthanides are found to be extracted as Ln(PMTFP)3 with HPMTFP alone and in the presenc...
Article
The extraction behavior of selected trivalent lanthanides, actinides and yttrium was studied from thiocyanate and nitrate solutions using octyl(phenyl)N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) in xylene as an extractant. It was found that these trivalent metal ions were extracted as MX{sub 3}.3CMPO (where X = SCN{sup -} or NO{sub 3}{sup -...
Article
Full-text available
The extraction behaviour of selected trivalent lanthanides, actinides and yttrium was studied from thiocyanate and nitrate solutions using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide(CMPO) in xylene as an extractant. It was found that these trivalent metal ions were extracted as MX3.3CMPO (where X - SCN - or N03-). The equilibrium co...
Article
This article deals with the effect of 0.25-1.5 wt pct mischmetal (MM) addition on the mechanical properties, microstructure, electrical conductivity, and fracture behavior of cast Al-7Si-0.3Mg (LM 25/356) alloy. Modification of eutectic silicon by MM is compared with strontium modification in terms of microstructure, mechanical properties, and fadi...
Article
The transport of europium through a porous supported liquid membrane (SLM) containing PC-88A (EHPNA) and Versatic 10 (VA 10) as Immobilised carriers has been carried out. The results demonstrated that transport increases with increasing stirring speed, and reaches a constant value beyond a certain rotation speed. The permeability coefficient increa...
Article
SmBa2SbO6 has been synthesized and sintered as a single phase material for its use as a subtrate for YBa2Cu3O7−δ superconducting thick films. Superconducting YBa2Cu3O7 −δ and YBa2Cu3O7−δ-Ag thick films were fabricated by dip coating on SmBa2SbO6 and a zero resistivity superconducting transition Tc(0) = 92 K was obtained for both thick films. The YB...
Article
Rare earths (RE) form a large number of intermetallic compounds with aluminum e.g. RE{sub 3}Al, REAl, REAl{sub 2}, REAl{sub 3} and RE{sub 3}Al{sub 11}. Among these REAl{sub 2} a Laves phase, have normally the highest melting point and depending on the rare earth metal selected the density can vary. In the present investigation LaAl{sub 2} Laves pha...
Article
Full-text available
A d.c. polarographic technique has been used previously for the determination of the pesticide, ziram, in aqueous samples, this paper reports differential pulse anodic stripping voltammetric determination of ziram zinc in rice samples using a static mercury drop electrode. The procedure developed distinguishes inorganic zinc and ziram zinc in sodiu...
Article
High purity individual rare earth oxides are increasingly used as major components in lasers (Y2O3), phosphors (YVO3, Eu2O3), magnetic bubble memory films (Gd2O3) and refractive-index lenses and fibre optics (La2O3). The determination of individual lanthanides in high purity rare earth oxides is a more important and difficult task. This paper repor...
Article
Kinetic study on two phase extraction and stripping processes of holmium have been carried out by using 2-ethylhexyl-phosphonic acid mono-2-ethylhexyl ester(PC-88 A, EHPNA) as an acidic extractant. The different experimental variables such as pH,carrier, metal ion and stripping agent concentrations have been explored. Forward extraction of holmium...
Article
This chapter discusses trace determination of lanthanides in high-purity rare-earth oxides. The determination requires judicious selection of an analytical technique for the specified determination of traces of lanthanides in high-purity rare-earth oxides. Various analytical procedures have been developed for this purpose. All lanthanides have simi...
Article
Boehmite intercalated alumina pillared montmorillonite has been prepared from a 10% aqueous suspension of the sodium exchanged montmorillonite in as short a period as 20 min through ultrasonication at 32 °C. This technique has resulted in Al-PILC having specific surface area 165 m2/g and d-spacing 17 Å, stable up to 700 °C. The delamination of the...
Article
Studies on the kinetics of neodymium transport through a bulk liquid membrane, in apparatus consisting of a source, membrane and receiving phases, have been carried out. Different experimental variables, such as the pH, carrier, metal ion and stripping agent concentrations, have been explored. However, the kinetic and solvent extraction methods wer...
Article
Mixed-ligand chelate extraction of trivalent lanthanides such as La, Eu and Lu and a trivalent actinide, Am into xylene with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and dihexyl-N,N-diethylcarbamoylmethylphosphonate (CMP) has been studied by tracertechniques. These trivalent metal ions are found to be extracted from 0.01 mol/dm3...
Article
A new class of complex perovskite oxides BaâREZrO{sub 6-x} (RE = Pr, Nd, Sm and Gd) have been synthesized and sintered as single phase materials with high sintered density and stability by solid state reaction method. The structure of BaâREZrO{sub 6-x} was studied by X-ray diffraction technique and all of them were found to be isostructural and hav...
Article
A new group of complex perovskites, REBa{sub 2}SnO{sub 5.5} (where RE = Pr, Sm, Eu, and Gd) have been synthesized and sintered as single-phase materials with high sintered density and stability by the solid-state reaction method. The structure of REBa{sub 2}SnO{sub 5.5} was studied by the X-ray diffraction technique, and all of them were found to b...
Article
A first-order derivative spectrophotometric method has been developed for the simultaneous determination of copper, mercury and lead at g/L levels using dithizone as reagent. The procedure involves the simultaneous extraction of these elements by dithizone in chloroform from weakly alkaline solutions. Linear calibration curves were obtained in the...
Article
Silver clad Bi-2223 tapes with consistently high critical current densities of over 30,000 A/cm2 at 77 K and zero field were prepared by powder-in-tube (PIT) technique. Powder XRD, electron microscopy, a.c. susceptibility and critical current measurements were used to study the phase assemblage, microstructure and transport properties of these tape...
Article
The carrier-mediated transport of europium through a supported liquid membrane by immobilizing PC-88A (EHPNA) and Versatic 10 on a porous support has been investigated in order to explore its efficiency, effectiveness and utility. Europium from the source solution was transported in the pH range from 1 to 5.75 for EHPNA and 3 to 5.75 for Versatic 1...
Article
Bi-based superconducting shapes were fabricated by extrusion of ceramic-polymer mixture involving a solgel derived superconductor and in situ polymerized polymethylmethacrylate as binder. The powder was intimately mixed with methylmethacrylate monomer and polymerized in the presence of other organic additives such as butylbenzyl phthalate, phosphat...
Article
The extraction of cadmium(II) and mercury(II) from iodide solutions has been investigated by tracer techniques with bis-2-ethylhexyl sulphoxide (B2EHSO) in benzene as an extractant. For comparison, extraction studies also have been carried out with a well-known neutral organophosphorus extractant, trioctyl-phosphine oxide (TOPO). The extraction dat...
Article
Post-sintering treatments, such as zone melting under a thermal gradient, have been conducted on sintered YBCO tape cast films. YBCO precursor powder was derived through decomposition of a mixture of nitrates of cations in a microwave oven for ~ 4 min. The resulting powder was characterized and made into thin sheets by tape casting and then sintere...
Article
A simple, spectrophotometric method for the determination of carbaryl in soils and insecticide formulations is described. The method is based on the coupling of carbaryl with diazotized 2-aminonaphthalenesulfonic acid in an alkaline medium, to form an azo-dye which has a maximum absorbance at 490 nm, and is extractable into n-butanol. Beer's law is...
Article
Mixed-ligand chelate extraction of trivalent lanthanides such as La, Eu and Lu and a trivalent actinide, Am, into xylene with mixtures of 3-phenyl-4-benzoy1-5-isoxazolone (HPBI) and bis-2-ethylhexyl sulphoxide (B2EHSO) or tributylphosphate (TBP) from perchlorate solutions has been investigated. The results demonstrate that these trivalent metal ion...
Article
Percolation behavior of normal state resistivity and superconductivity of SmBa2SbO6-YBa2Cu3O7-delta have been studied. The normal state and superconducting percolation threshold values of the composite are both found to be around 22% of YBa2Cu3O7-delta in the system. The X-ray diffraction and resistivity measurements on the above percolation system...
Article
Electrical transport properties and percolation behavior of superconducting Bi2Sr2Ca2Cu3O10-DyBa2SnO5.5, a superconductor-insulator composite system, have been studied by x-ray diffraction and temperature-resistivity measurements. Normal-state and superconducting percolation threshold values are found to be ∼20 vol % of Bi(2223) in the composite. T...
Article
A new group of complex perovskites, REBaâSbOâ (where RE = Pr, Sm, and Gd), have been synthesized and sintered as single phase materials by the solid state reaction method. These materials are found to be isostructural and to have a complex cubic perovskite structure. X-ray diffraction and resistivity measurements have shown that there is no detecta...
Article
The extraction of mercury(II) from chloride and thiocyanate solutions has been studied by tracer techniques using bis(2-ethylhexyl) sulphoxide (B2EHSO) in benzene as an extractant. These extraction data have been analyzed theoretically by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexat...
Article
Fracture toughness values of pressure die-cast Al-7Si-3 Mg-5 graphite composites were measured and found to be in the range 8–10 MPa m1/2. Detailed microstructure of the composite and the fractured surfaces were examined. Defects such as clusters, agglomerations and segregation of graphite particles, play a dominant role in accelerating the fractur...
Article
A sensitive spectrophotometric method has been developed for the determination of ziram in water, vegetables and grains. The method is based on the dissociation of dithiocarbamate complex of zinc with thiocyanate and rhodamine 6G at pH 4 to form a pink coloured complex that is stabilized by gelatin. The method is simple and Beer's law is obeyed ove...
Article
A review of the literature on liquid-liquid extraction processes for the separation and purification of rare earths is presented. This review also discusses computer simulation programs used for the design and optimization of processes for the separation of rare earths. The lacunae in the computer simulation programs are highlighted and suggestions...
Article
A new group of complex perovskites, REBaâSnO{sub 5.5} (where RE = Pr, Sm, Eu, and Gd) have been synthesized and sintered as single-phase materials with high sintered density and stability by the solid-state reaction method. The structure of REBaâSnO{sub 5.5} was studied by the X-ray diffraction technique, and all of them were found to be isostructu...
Article
Mono ion exchanged montmorillonite has been intercalated with monohydroxy aluminium oxide (Boehmite, AlOOH) by refluxing a mixture of the montmorillonite and boehmite in an aqueous medium. The alumina pillared montmorillonite has been prepared by further dehydroxylation of the intercalated material. Characteristics of the pillared smectite with r...
Article
High-density 10 mol% ceria-zirconia ceramic has been fabricated by extrusion of ceramic-polymer mixtures. The basic composite powder mixture has an average particle size of 3·5 μm and a tap density of 1976 kg/m3. The torque rheological features of various ceramic-polymer (polyethylene base) combinations were examined using a Brabender Plasticorder....
Article
A zone melting-refining technique, with a horizontal sample-holding pattern for incorporating grain orientation in sintered bismuth-based superconductor (BPSCCO) is presented. Acrylate precursor-derived BPSCCO powder was uniaxially compacted into strips of 60 mm10 mm 2mm and sintered at 845C for 20 h to obtain 90% density. These strips were zone me...
Article
A new ceramic material, DyBa2SnO5.5, has been synthesised and sintered as single-phase material for its use as a substrate for both YBCO and BiSCCO superconductors, for the first time. DyBa2SnO5.5 has a complex cubic perovskite (A2BB'O6) structure with the lattice constant a = 8.520 Å. The dielectric constant and loss factor of DyBa2SnO5.5 are in a...
Article
A new ceramic perovskite DyBa2SnO5.5 has been synthesized and developed for its use as a substrate for Bi(Pb)–Sr–Ca–CuO superconductors. The dielectric constant and loss factor of this material are in a range suitable for its use as a substrate for microwave applications. DyBa2SnO5.5 is found to be chemically compatible with Bi(Pb)–Sr–Ca–CuO superc...
Article
This paper describes a third-order derivative Spectrophotometric procedure for the determination of traces of phosphate, based on the for