Pattayil Joy

Pattayil Joy
None · None

PhD

About

233
Publications
32,348
Reads
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9,067
Citations
Citations since 2016
43 Research Items
4383 Citations
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
Additional affiliations
November 1993 - present
CSIR-National Chemical Laboratory
Position
  • Researcher
August 1983 - December 1992
Indian Institute of Science
Position
  • Student

Publications

Publications (233)
Article
Thermal conductivity enhancement of nanofluids of oleic acid coated magnetite nanoparticles dispersed in four different base fluids (toluene, xylene, mesitylene, kerosene) is studied to understand the role of the solvent (base fluid). From the correlation of the thermophysical properties of the base fluid with the thermal conductivity of the corres...
Article
Stable magnetic nanofluids are prepared by dispersing long-chain fatty acid surfactants coated magnetite (Fe3O4) nanoparticles in toluene and investigated the effect of chain length of the surfactant molecules on the thermal conductivity of the magnetite nanofluids in a magnetic field. Superparamagnetic magnetite nanoparticles having a comparable p...
Article
The magnetic properties of sintered particulate magnetoelectric CoFe2O4−BaTiO3 composites have been studied. The particulate composites are sintered in the temperature range 1000–1300 °C, for a short duration of 10 min. The magnetic transition temperature (Tc) of CoFe2O4 is found to decrease with increasing the sintering temperature and sintering t...
Article
The effect of particle size on the thermal conductivity of nanofluids is studied by dispersing myristic acid coated magnetite (Fe3O4) nanoparticles in two different base fluids; toluene and kerosene. Magnetite nanoparticles of three different sizes 4, 7 and 10 nm dispersed in toluene and kerosene showed a linear increase in the thermal conductivity...
Article
Full-text available
Bismuth sodium titanate Bi0.5Na0.5TiO3 (BNT) is a lead‐free piezoelectric ceramic material with high Curie temperature. The effect of substitution of the smaller ion Li+ for the larger ion Na+ in Bi0.5(Na⁠1‐xLix)0.5TiO⁠3 (0 ≤ x ≤ 0.20) on the structure of BNT is studied using powder X‐ray diffraction (XRD) and Raman spectroscopy. Rietveld refinemen...
Article
We have demonstrated a simple fabrication methodology of free-standing polymer composite film firework that sparkles, provides colour display and moderate sound, yet is less polluting. The polymer composite film fireworks are composed of magnesium boride (MgB2), sodium nitrite (NaNO2) and poly(vinyl alcohol) (PVA). This study also suggested that a...
Article
Full-text available
Structural, magnetic and microstructural properties of transition metal (TM) substituted cobalt ferrite Co0.9TM0.1Fe2O4 (where TM = Ti, Cr, Mn, Ni and Cu and Zn) were investigated. The present study shows marked dependence of the magnetostriction on the concentration of the substituted transition metal ions for Cobalt in CoFe2O4. The magnetic chara...
Article
Doping of quantum spin liquid (QSL) insulators by electron or hole leads to intriguing phase transitions to metallic and superconducting states. The barlowite family with geometrically perfect S=1/2 kagome planes and tunable interkagome coupling is an emerging platform to realize spin-ordered, valence bond crystal, QSL states. Theoretical investiga...
Article
Thermal properties of nanofluids are very well investigated by the global research community for their various applications. The dispersion and stability of the nanoparticles in the base fluid are the essential requirements for the efficient utilization of the nanofluids in many applications. The interfacial layer plays the crucial role in the disp...
Article
Six coordination polymers based on Mn( ii ) and V-shaped ligand were successfully isolated and their dielectric as well as magnetic behaviours were investigated. The paper also discusses the growth of solids in terms of supramolecular aggregation.
Article
In this letter, magnetic and magnetostriction studies were performed on spinel ferrite Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1–</sub> <sub>x</sub> Ni <sub>x</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="h...
Article
Co-BDC ([Co2(OH)2BDC], H2BDC = 1,4-benzenedicarboxylic acid) is known to possess metamagnetism originating from the antiparallel spins and high magneto crystalline anisotropy of Co(II).1 Herein, we have introduced a bimetallic concept by incorporating Ni(II) along with Co(II) in the same coordination polymer to modulate the magnetocrystalline aniso...
Article
S=1/2 kagome-lattice hydroxychlorides are promising candidates for realizing the elusive quantum spin liquid (QSL) state. Herbertsmithite [Cu3Zn(OH)6Cl2], a naturally occurring hydoxochloride mineral from the class of atacamites {[Cu4-xMx(OH)6X2] where M=Zn, Cu, Co, Ni and X=Cl, Br, I}, is one of the most appealing systems to study QSL state due to...
Preprint
Full-text available
Bismuth sodium titanate Bi0.5Na0.5TiO3 (BNT) is a lead-free piezoelectric ceramic material with high Curie temperature. The effect of substitution of the smaller ion Li⁺ for the larger ion Na⁺ in Bi0.5(Na⁠1−xLix)0.5TiO⁠3 (0 ≤ x ≤ 0.20) on the structure of BNT is studied using powder X-ray diffraction (XRD) and Raman spectroscopy. Rietveld refinemen...
Article
Study on magnetism in two-dimensional (2D) spin-lattices is advancing rapidly. In this work, phase-pure botallackite (Bo) (Cu2(OH)3Br), a quasi-2D S = 1/2 anisotropic triangular spin-lattice is stabilized over 2D reduced graphene oxide (rGO) nanosheets via simple oxidation-reduction reaction chemistry. In comparison to polycrystalline Bo, such an a...
Article
Materials that respond to multiple stimuli such as magnetic field and light are attractive for security and medical diagnostic applications. One of the major challenges in dual functional microspheres is that the presence of magnetic nanoparticles can quench fluorescence emission. Also, there is a probability of solid-state quenching due to the pro...
Article
Obtaining higher magnetic parameters is essential for high-power sintered strontium ferrite (SrFe12O19) for various applications. A novel approach has been made to improve the magnetic parameters of sintered strontium ferrite by making self-composites from nano and micron-sized powders. Powders with two different weight ratios (50 wt% nano:50 wt% m...
Article
Superparamagnetic cobalt ferrite (CFO) nanocrystals (NCs) with sizes ∼6 nm and ∼4 nm were synthesized using a facile solvothermal method using fatty acids, lauric acid and stearic acid, as the capping agents. The synthesized nanocrystals were well characterized by XRD, FT‐IR, XPS, SEM and TEM. The formation mechanism was explored and it was shown t...
Article
An elegant platform to explore frustrated magnetism is the kagome spin lattice. In this work, clinoatacamite, a naturally occurring quasi S=½ kagome-like antiferromagnetic insulator, is synthesized in water at ambient pressure for the first time from a cuprous chloride (CuCl) precursor whereby Cu(I) was spontaneously oxidized to Cu(II) in the form...
Article
The local structural changes, due to the substitution of the smaller Na+ by the larger K+ ion, in the lead-free piezoelectric ceramic compositions Bi0.5(Na1-xKx)0.5TiO3 have been studied using Raman and 23Na solid-state NMR spectroscopy. Different close compositions in the solid solution series Bi0.5(Na1-xKx)0.5TiO3 (0 ≤ x ≤ 0.36, Δx = 0.02) are st...
Article
Obtaining higher magnetic parameters is essential for high-power sintered strontium ferrite (SrFe 12 O 19 ) for various applications. A novel approach has been made to improve the magnetic parameters of sintered strontium ferrite by making self-composites from nano and micron-sized powders. Powders with two different weight ratios (50 wt% nano:50 w...
Article
A lossy dielectric with an appropriate magnetic property is one of the requirements of a stealth material. The thickness of the absorber and the corresponding bandwidth of absorption are also other deciding factors that determine the choice of the material as microwave absorbers. A stable emulsion, which is lossy as well as magnetic, is promising,...
Article
ABSTRACT: In the emergence of magnetic metal− 12 organic frameworks (MOFs), metamagnetism is desirable 13 for device applications. Herein, we have synthesized at 14 room-temperature two-dimensional nanosheets of a MOF 15 comprised of a cobalt(II) ion with a benzenedicarboxylic 16 acid (H2BDC) ligand, Co-BDC, which exhibited unusual 17 magnetic prop...
Article
Full-text available
Nanoparticles of undoped and copper-doped cobalt ferrite Co1−xCuxFe2O4 at very low dopant concentrations (x = 0; 0.02; 0.04; 0.06; 0.08) were successfully synthesized by pyrolysis of the corresponding hetero metal octanoate precursors obtained via coprecipitation using the octanoate ligand as precipitating agent. The precursors were then characteri...
Article
Oxygen evolution is the key step in the oxidation of water in electrolyzers and photoelectrochemical cells for the production of hydrogen. Developing a non-precious metal oxide catalyst with good electrocatalytic activity for the oxygen evolution reaction (OER) is very challenging. In this work, nanostructured ZnxCo3-xO4 has been shown as efficient...
Article
Different chemical compositions in Co1+2xVxFe2-3xO4 (0 ≤ x ≤ 0.1) have been synthesized by the conventional solid-state reaction method and processed under identical conditions. The materials are investigated to assess the impact of change in the oxidation states of metal ions on structural and magnetic properties of cobalt ferrite. Rietveld refine...
Article
The effect of the length of surfactant molecules on the surface of the nanoparticles on the thermal conductivity of nanofluids is studied. Magnetite (\(\hbox {Fe}_{3}\hbox {O}_{4}\)) nanoparticles of comparable sizes are stabilized with short-chain capric acid (\(\hbox {C}_{9}\hbox {H}_{19}\hbox {COOH}\)) and long-chain stearic acid (\(\hbox {C}_{1...
Article
A new strategy to enhance the magnetostriction parameters of cobalt ferrite (CoFe2O4) is illustrated. A composite comprising of nanocrystalline CoFe2O4 and bulk CoFe1.9Ga0.1O4 powders were mixed together then compacted and sintered at 1450 °C for 10 min. For a composite of 70 wt% CoFe2O4 and 30 wt% of CoFe1.9Ga0.1O4, maximum magnetostriction coeffi...
Article
Single phase monoclinic La2Ni1−xCoxMnO6 (x = 0.2, 0.4, 0.8) compounds, henceforth, referred as LNCxMO (x = 0.2, 0.4, 0.8) have been prepared by Sol–gel technique. The structural study and redox titration suggest that the samples are both La and O deficient. The generated atomic models using Rietveld refined structural parameters show octahedral dis...
Article
A liquid dielectric based on a core-shell architecture having a superparamagnetic iron oxide core and a shell of silicon dioxide was synthesized. The frequency dependence of dielectric properties was evaluated for different concentrations of iron oxide. The dependence of magnetic field on the dielectric properties was also studied. Aqueous ferroflu...
Article
The influence of size and crystallographic site preference of three non-magnetic isovalent metal ions of larger (In³⁺), comparable (Ga³⁺) and smaller (Al³⁺) sizes, substituted for Fe³⁺ in the spinel lattice of CoFe2O4 on its magnetostrictive properties is compared. For the different compositions in CoFe2-xMxO4 (M = In³⁺, Ga³⁺, Al³⁺ and 0 x 0.3), si...
Article
We report the magnetic and magnetoelastic properties of spinel oxide system Co1−xZnxFe2O4 (CZF series) where x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5. All the composition were prepared by conventional solid state synthesis method and exhibited pure spinel phase formation. The lattice parameters showed gradual increase indicating uniform distribution Zn...
Article
Full-text available
Around 40% of high-risk prostate cancer patients who undergo radiotherapy (RT) will experience biochemical failure. Chemotherapy, such as docetaxel (DTX), can enhance the efficacy of RT. Multidrug resistance mechanisms often limit drug efficacy by decreasing intracellular concentrations of drugs in tumor cells. It is, therefore, of interest to deve...
Article
The magnetic properties of terbium substituted cobalt ferrites CoFe2-xTbxO4 (x = 0, 0.05, 0.1, 0.15 and 0.2) prepared by conventional solid state method are studied. The coercivity showed marked increase up to x = 0.1 and saturation magnetization decreased with increasing terbium content. Magnetostriction measurements did not show much decrease in...
Article
To study the role of unsaturation in the surfactant molecule on the thermal conductivity of magnetite nanofluids, four different fatty acid (stearic, oleic, linoleic, and linolenic acids with different degree of unsaturation) coated magnetite nanoparticles of comparable size are prepared and dispersed in toluene. It is found that the nanofluid with...
Article
The correlation between the magnetic and electrical properties of activated carbon with its microstructure is studied. The changes in the microstructure of activated carbon, after activation at three different temperatures (800°C, 900°C, 1000°C) using different amounts of the activating agent, KOH (KOH/C ratio of 1:1, 2:1, 3:1 and 4:1), are studied...
Article
Comparative studies have been made to understand the role of different crystallographic site preferences of the substituted non-magnetic divalent metal ions in the magnetostrictive properties of cobaltferrite, by substitution of Zn²⁺ and/or Mg²⁺ for Fe³⁺ in CoMgxFe2−xO4, CoZnxFe2−xO4, and CoMgx/2Znx/2Fe2−xO4 (0.0 ≤ x ≤ 0.2). Detailed Raman spectral...
Article
Swift heavy ion irradiation provides unique ways to modify physical and chemical properties of materials. In ferrites, the magnetic properties can change significantly as a result of swift heavy ion irradiation. Zinc ferrite is an antiferromagnet with a Neel temperature of 10. K and exhibits anomalous magnetic properties in the nano regime. Ion irr...
Article
Structural, magnetic, dielectric and magnetodielectric properties of Ca and Mn co-substituted bismuth ferrite, Bi1−x Cax Fe1−x Mnx O3 (0 ≤ x ≤ 0.4) are reported. Structural studies by Rietveld refinement of XRD patterns revealed rhombohedral R3c structure for x ≤ 0.11 and orthorhombic Pbnm structure for x ≥ 0.2. For compositions in the range 0.11 <...
Article
Impact of substitution of the non-magnetic ion Ga³⁺ for Fe³⁺ on the magnetostriction parameters of CoFe2O4 has been investigated for samples prepared by a tartrate-gel method. All the Ga-substituted compositions in CoGaxFe2-xO4 (0 ⩽ x ⩽ 0.3) showed higher strain sensitivity (dλ/dH), at low magnetic fields, compared to that of the unsubstituted samp...
Article
Lauric (dodecanoic) acid coated magnetite nanoparticles with different amounts of primary and secondary surfactant layers on the surface of the nanoparticles have been synthesized. Two sets of the surfactant coated nanoparticles are prepared; one with comparable amount of primary surfactant and the other with comparable amount of secondary surfacta...
Article
Attaining high magnetostrictive strain sensitivity (dλ/dH) with high magnetostriction strain (λ) is desirable for sintered polycrystalline cobalt ferrite for various applications. It is shown that substitution of a small amount of Fe3+ by Mg2+ in CoMgxFe2-xO4 (x <0.1) gives comparable maximum magnetostriction coefficient as that of the unsubstitute...
Article
Full-text available
Solid solutions of the lead-free ferroelectric oxides Bi0.5Na0.5TiO3 (BNT) and Bi0.5K0.5TiO3 (BKT), represented as (1−x)BNT–xBKT, are studied for very close compositions in the range 0≤x≤0.36 to understand the correlation between the structure and the properties. Compositions are varied in steps of Δx=0.02 in the range 0≤x≤0.1 and 0.2≤x≤0.36 and Δx...
Article
Structural, magnetic and magnetostrictive properties of sintered aluminium-substituted cobalt ferrite, CoAlx Fe2−x O4 (x = 0.0, 0.1, 0.20, 0.30), derived from nanosized powders synthesized by a citrate-gel method, have been investigated. The sample with x = 0.1 is found to exhibit higher maximum magnetostriction strain at relatively lower magnetic...
Article
An efficient magnetic adsorbent nanocomposite material is prepared by simple chemical methods using coconut shell based activated carbon and iron oxide nanoparticles. The composite material shows good oil retention capacity with fast kinetics and can be recovered along with the adsorbed oil by using an external magnet. The adsorbent material can be...
Article
Decanoic acid coated magnetite (Fe3O4) nanoparticles of comparable average size (5–7 nm), but with different particle size distributions, are synthesized by varying the rate of addition of ammonium hydroxide in the co-precipitation method. The particle size distribution is obtained from TEM measurements which showed that faster rate of base additio...
Article
Nanocomposites containing magnetic nanoparticles embedded in a polymer matrix with good thermal stability (up to 200°C) are technologically important. We report an environmentally benign solid-solid approach for synthesis of cobalt sulfide and its nanocomposite using a thermally stable matrix of polyphenylene sulfide. Physicochemical characterizati...
Article
Here we show a surrogate strategy for power production, wherein light is used to actuate a discharge chemistry in the cathode of an aqueous rechargeable battery (ARB). The proposed photo battery consists of a titanium nitride photoanode, promising cathode material iron (III) hexacyanoferrate (II) as the battery active species and Na2S2O8 as the che...
Article
The changes in the electrical transport properties and mechanism of conduction in disordered carbon, with the extent of graphitization, are studied and discussed. With heat treatment induced graphitic ordering, the electrical properties are considerably modified, inducing a crossover from strong localization to weak localization behavior. According...
Article
Magnetic Fe3O4 nanoparticles (∼20 nm) were synthesized using the chemical co-precipitation method with a view of developing flexible and easily processable ferromagnetic materials with high mouldability to be used as microwave absorbers. The nanoparticles prepared were incorporated into natural rubber through latex stage processing. This novel proc...
Article
Water-dispersible magnetite nanoparticles functionalized with citric acid (CIT) modified β-cyclodextrin (CD) are prepared and curcumin (CUR) is loaded inside the cavity of CD. The CUR loading capacity of CD-CIT functionalized magnetite nanoparticles is found to be much larger than that of CD alone as well as the CD-CIT conjugate. The release profil...
Article
From the studies on the magnetostriction characteristics of two-stage sintered polycrystalline CoFe2O4 made from nanocrystalline powders, it is found that two-stage sintering at low temperatures is very effective for enhancing the density and for attaining higher magnetostriction coefficient. Magnetostriction coefficient and strain derivative are f...
Article
Full-text available
Flexile single layer electromagnetic wave absorbers were designed by incorporating appropriate amounts of carbon black in a nitrile butadiene rubber matrix along with an optimized amount of magnetic counterpart, namely, barium hexaferrite for applications in S, C, and X-bands. Effective dielectric permittivity and magnetic permeability were measure...
Article
Full-text available
Superparamagnetic iron oxide nanoparticles of size ~5 nm surface functionalized with ascorbic acid (vitamin C) form a stable dispersion in water with a hydrodynamic size of ~30 nm. The anti-oxidant property of ascorbic acid is retained after capping, as evidenced from the capability of converting methylene blue to its reduced leuco form. NMR relaxi...
Article
The La–Zn substituted hexagonal strontium aluminate, Sr1−xLaxAl12−xZnxO19, with the magnetoplumbite structure and having five different coordination environments for Al with different symmetries, is investigated using 27Al solid-state NMR to get detailed information on the sites of substitution of Zn and the associated changes in the local coordina...
Article
High room temperature ferromagnetic moment with high Curie temperature (>>700 K) for graphene oxide (GO) is obtained by a simple chemical activation using phosphoric acid followed by heat treatment at 800 °C. The field and temperature variations of the magnetization data indicate ferromagnetic, paramagnetic and diamagnetic contributions in the acid...
Article
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 corre...
Article
Curcumin is known for its excellent anti-oxidant, anti-cancer, anti-inflammatory, and anti-microbial activities, which makes it a promising candidate for coating on iron oxide nanoparticles for biomedical applications. Curcumin coated ultra-small superparamagnetic iron oxide nanoparticles (USPIONs) of 3 nm size have been synthesized and characteriz...
Article
Core–shell bimetallic Au@Ni nanoparticles, with gold cores and thin nickel shells with overall size less than 10 nm, are synthesized and stabilized in pure cubic (fcc) and hexagonal (hcp) phase. Due to their unique crystal, electronic, and geometric structure, they show interesting magnetic and chemical properties. The Au@Ni fcc is magnetic, wherea...
Article
Magnetic properties of disordered carbon have been investigated as a function of the extent of graphitization. It is found that the magnetization of the disordered carbon decreases with increasing degree of graphitization. Treatment with acid modifies the magnetic characteristics considerably and the original magnetic characteristics are retained u...
Article
The evolution and magnetic behaviour of NiO-Ni(OH)2 core-shell nanostructures with different thicknesses of the hydroxide shell have been studied. The nickel hydroxide shell is found to alter the magnetic characteristics of nickel oxide at low temperatures and explains the origin of the exchange bias effect due to the antiferromagnetic NiO core and...
Article
The role of initial particle size on the magnetostriction coefficient of sintered cobalt ferrite derived from nanocrystalline powders is studied. Nanoparticles of cobalt ferrite with different sizes in the range 3-80 nm are synthesized by an autocombustion method using metal nitrates and glycine. It has been observed that the initial particle size...
Article
Magnetostriction characteristics of Mn substituted cobalt ferrite, CoFe2-xMnxO4 (0 <= x <= 0.3), sintered from nanocrystalline powders of average particle size of similar to 4 nm have been studied. Larger value of magnetostriction at lower magnetic field is achieved after substitution of Mn for Fe. The maximum value of magnetostriction coefficient...
Article
Porous aggregated nanorods of Co3O4 with a surface area of ~100 m2 g−1 synthesized without using any templates or surfactants give very high specific capacitance of ~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 achie...
Article
Full-text available
The present work derives motivation from the so called surface/interfacial magnetism in core shell structures and commercial samples of Fe3O4 and g-Fe2O3with sizes ranging from 20 to 30 nm were coated with polyaniline using plasma polymerization and studied. The High Resolution Transmission Electron Microscopy images indicate a core shell structure...
Article
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....
Article
Multimodal imaging agents that combine magnetic and fluorescent imaging capabilities are desirable for the high spatial and temporal resolution. In the present work, we report the synthesis of multifunctional fluorescent ferrofluids using iron oxide as the magnetic core and rhodamine B as fluorochrome shell. The core-shell structure was designed in...
Article
High magnetostriction (lambda) and coupling coefficient (d lambda/dH) of 315 ppm and 1.97 x 10(-9) A(-1) m, respectively, are obtained at room temperature for sintered cobalt ferrite derived from nanocrystalline powders. Also, the powder was compacted at a low pressure of 8 MPa and sintered for a short duration of 10 min at 1450 degrees C. Magnetic...
Article
Antiferromagnetic multiferroic BiFeO3 shows ferromagnetic characteristics by simultaneous substitution of Bi by La and decrease in the particle size to nanometer dimensions. Large changes in saturation and remnant magnetization, magnetic susceptibility at low and high fields, along with some anomalous changes in the magnetic transition temperature...
Article
Full-text available
Cobalt-ferrite (CoFe2O4) based materials are suitable candidates for magnetomechanical sensor applications owing to a strong sensitivity of their magnetostriction to an applied magnetic field. Zn-doped cobalt-ferrites, with nominal compositions CoFe2−xZnxO4 (x = 0–0.3), were synthesized by auto-combustion technique using Co- , Fe- , and Zn-nitrate...
Article
Cobalt-ferrite (CoFe2O4) based materials are suitable candidates for magnetomechanical sensor applications owing to a strong sensitivity of their magnetostriction to an applied magnetic field. Zn-doped cobalt-ferrites, with nominal compositions CoFe2−xZnxO4 (x=0–0.3), were synthesized by auto-combustion technique using Co- , Fe- , and Zn-nitrate as...
Article
Full-text available
The magnetic behaviour of two ferromagnetic oxides and two ferrimagnetic oxides (ferrites) are compared to study the effect of magnetocrystalline anisotropy on thermal-history-dependence of magnetization of these ordered magnetic systems. All four compounds show thermomagnetic irreversibility (M FC >M ZFC) below a certain temperature,T irr. The hig...
Article
Full-text available
Nanoparticles of magnetite (Fe3O4) are synthesised by a coprecipitation method and coated with the biocompatible polymer, dextran. The uncoated and dextran coated magnetite nanoparticles are characterised by powder X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and magnetic measurements. The magnetic properties of the u...
Article
The present work involves the development of hydrogel magnetic nanocomposites for protein purification and heavy metal extraction applications. The magnetic nanoparticles (MNPs) were prepared in situ in poly(acrylamide)-gum acacia (PAM-GA) hydrogels. The formation of magnetic nanoparticles in the hydrogel networks was confirmed by Fourier transform...
Article
Magnetic and electrically responsive hydrogel networks were developed for drug-delivery applications. The hydrogel matrices were synthesized by the polymerization of acrylamide monomer in the presence of carboxymethylcellulose (CMC) or methylcellulose (MC) with N,N-methylenebisacrylamide, a crosslinker with the redox initiating system ammonium pers...
Article
Nanocrystalline Ni0.5Zn0.5Fe2O4 powders, synthesized by a combustion method are investigated by X-ray diffraction, vibrating sample magnetometry and Mössbauer spectroscopic techniques. We adopt a strategy to systematically control the particle sizes between 4 and 45nm simply by changing the elemental stoichiometric coefficient, Φe, of the combustio...
Article
Nanostrucutred spinel ZnCo2O4 (∼26–30nm) was synthesized by calcining the mixed precursor (consisting of cobalt hydroxyl carbonate and zinc hydroxyl carbonate) in air at 600°C for 5h. The mixed precursor was prepared through a low cost and simple co-precipitation/digestion method. The transformation of the mixed precursor into nanostructured spinel...
Article
Tetrabutylammonium salt of [PW12O40](3-) and its transition metal (Mn2+, Fe2+, Co2+ and Cu2+) substituted compounds are characterized by elemental analysis, thermogravimetric and spectroscopic techniques. Thermal stability of these compounds decreases after metal ion substitution, but the cobalt substituted compound is relatively more stable. The c...
Article
Full-text available
Magnetic properties of trivalent rare-earth ion substituted nanocrystalline BiFeO3 have been studied for the compositions Bi0.875R0.125FeO3 (R = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb). All compositions show ferromagnetic characteristics at room temperature, with enhanced magnetization after substitution. Very high magnetization (at 6 T...