Maghemite (γ-Fe 2 O 3 ) nanoparticles have been synthesized using co-precipitation method followed by chemically induced transition process. As prepared nanoparticles have been analyzed by X-ray diffraction, Raman and FTIR spectroscopies which reveal the γ-Fe 2 O 3 phase. These γ-Fe 2 O 3 nanoparticles have been used to modify the glassy carbon electrode (GCE) to form nano γ-Fe 2 O 3 modified GC electrode for electrochemical sensing of acetaminophen (C 6 H 9 NO 2 ) using potential controlled cyclic voltammetric (CV) technique. The obtained modified electrode shows an excellent electrocatalytic ability to sense acetaminophen in 0.1 M KCl supporting electrolyte. In addition, a significant enhancement in anodic peak current has been observed using nano γ-Fe 2 O 3 modified GC electrode than the bare electrode. The CV plots reveal that redox peaks have been linearly co-related to the acetaminophen concentration in the range of 0.031 mM to 1 mM with sensitivity ~30.78 µA/mM.

Magnetite (Fe3O4) and hematite (α-Fe2O3) iron oxide nanoparticles were synthesized using the co-precipitation method via subsequent heat treatment using ferrous chloride (FeCl2.4H2O) as a source of iron. The synthesized powder was annealed at high temperature in an air atmosphere to promote the formation of the hematite (α-Fe2O3) phase. Both oxide phases of iron oxide were characterized using x-ray diffraction, thermogravimetric, and differential scanning calorimetric analysis, and Raman spectroscopy. The phases of as-synthesized nanoparticles were confirmed by XRD and Raman studies. The thermal behavior and weight loss of the initial powdered Fe3O4 to α-Fe2O3 was studied using TG-DSC analysis. In the present case, the Fe3O4 and α-Fe2O3 nanoparticles were used for the electrochemical sensing of acetaminophen (C6H9NO2). The sensing of acetaminophen was performed by Fe3O4 and α-Fe2O3 modified glassy carbon electrode, using a potential controlled cyclic voltammetric technique. The Fe3O4 and α-Fe2O3 nanoparticles exhibited electrocatalytic ability for sensing acetaminophen. Detailed results are included.

In this project, multifunctional nanostructured spintronic and magnetoelectric materials were investigated by experimental and computational efforts for applications in energy efficient electronic systems that integrate functionalities and thus have the potential to enable a new generation of faster responding devices and increased integration densities. The team systematically investigated transition metal (TM)-doped ZnO nanostructures, silicide nanorods, magnetoelectric oxides, and ferroelectric/ferromagnetic heterostructures. In what follows, we report the progress made by researchers during the above period in developing and understanding of 1) Spintronics nanostructures; 2) Resistive switching phenomenon in oxides for memory devices; 3) Magnetoelectric multiferroics; 4) Novel high-k gate oxides for logic devices; 5) Two dimensional (2D) materials; and 6) Theoretical studies in the above fields.

Bi3.4Nd0.6Ti3O12 and CoFe2O4 were synthesized by chemical solution route. Multilayer structures (two, four, and ten alternate layers) of CoFe2O4/Bi3.4Nd0.6Ti3O12 were deposited on Pt substrate (Pt/TiO2/SiO2/Si) by spin coating. X- ray diffraction of multilayer structures reveals composite-like polycrystalline film. Leakage current of the composite ten multilayers was less than 10-6 A and Ohmic-like bulk response up to electric field 120kV/cm, showed the co-existence of ferroelectric polarization (Pr) > 47μC/cm2 and ferromagnetic memory (Mr) > 400 emu/cm3 at room temperature. FE and FM coupling in the same material can be attributed to stress different permeability and permittivity of the materials involved.

Pristine and MgO-coated 0.5Li(2)MnO(3)-0.5LiNi(0.5)Mn(0.5)O(2) (LLNMO) composites were synthesized by carbonate based co-precipitation method for cathode material in Li-ion battery. Xray diffraction confirmed the layered structure of pure material and no major change in crystal structure with MgO-coating. Raman spectroscopy revealed ionic arrangement corresponding to space group of C2/m and R-3m for Li2MnO3 and LiNi0.5Mn0.5O2, respectively. Scanning electron microscopy shows the primary particle size to be less than 0.5 mu m. The observed increase in charge/discharge capacity with number of cycles can be attributed to more activation of Li2MnO3. However, MgO-coated 0.5Li(2)MnO(3)-0.5LiNi(0.5)Mn(0.5)O(2) composite cathode showed good cyclability and columbic efficiency, where lower surface layer resistance may contribute to better performance with MgO-coated LLNMO. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Bi3.4La0.6Ti3O12 and CoFe2O4 were synthesized by chemical solution route, and Bi3.4La0.6Ti3O12/CoFe2O4 multilayers were deposited by spin coating on Pt substrate. X-ray diffraction of multilayer structures reveals composite-like polycrystalline film. Leakage current is less than 10−5 A at electric field < 90 KV/cm and follows the Ohmic behavior. Dielectric response shows relaxation and the loss (tan δ) is below 3% at 106 Hz. Room temperature ferrroelectric polarization (Pr) = 20.2 μC/cm2 and ferromagnetic memory (Mr) = 46.5 emu/cm3 has been obtained. Co-existence of FE and FM response can be attributed to stress and different permeability and permittivity involved in multilayer structures.

Bi3.4La0.6Ti3O12/CoFe2O4 bilayer films were synthesized by chemical solution method and deposited by spin coating on Pt (Pt/TiO2/SiO2/Si) substrate. X-ray diffraction of the bilayer system revealed the composite-like structure. The leakage current is less than 10−7 A at electric field below100 kV/cm, and it shows the ohmic behavior. Dielectric constant decreases with increasing frequency and reaches to 140 at 10−6 Hz. Bi3.4La0.6Ti3O12/CoFe2O4 system shows the co-existence of ferroelectric polarization (Pr) = 51 μC/cm2 and magnetization (Mr) = 206 emu/cm3 at room temperature. Observed ferromagnetic and ferroelectric responses in bilayer system may be useful for bi-functional devices.

Superior battery materials LiAl x Co 1− x O 2 ( x = 0.0, 0.1, 0.3, 0.5, and 0.7) were synthesized using a solution-based route at various sintering temperatures (450–800 °C). In this communication, we report on the use of Raman spectroscopy to study effect of composition and sintering temperature on the resulting material. The phase evolutions in LiAl x Co 1− x O 2 compositions were studied using micro-Raman spectroscopy and a phase diagram is proposed based on the observations. For less Al content, the low-temperature phases of LiAl x Co 1− x O 2 showed Raman spectra corresponding to a monoclinic (space group C2/m) structure, while a low-temperature spinel (space group Fd3m) phase was observed for 50% or more Al in these compounds. All these compositions exhibited a layered hexagonal (space group R3m) structure when sintered above 700 °C. Raman spectra also revealed residual Co 3 O 4 in the low-temperature forms of LiCoO 2 and LiA1 0.01 Co 0.9 O 2 .

Bi(Fe1-xCox)O-3 (BFCO) material and the composite based on doped Bi4Ti3O12/CoFe2O4 was synthesized by solution route for various compositions and films were deposited by spin coating on Pt substrate (Pt/Ti/SiO2/Si). Structural, ferroelectric, and ferromagnetic properties were investigated, respectively, using x-ray diffraction, Raman spectroscopy, VSM, and ferroelectric probe. X-ray diffraction patterns shows intense (110) peak of BFO in Bi(Fe1-xCox)O-3 with space group R3c and distorted rhombohedral perovskite structure without impure phase. The ferromagnetic response (M - H) showed room temperature magnetization of similar to 3 emu/cm(3) and coercive field Hc similar to 200 Oe for Bi(Fe0.98Co0.02)O-3 films. The ferroelectrics response shows week remnant polarizations (P-r) = 0.4 mu C cm(-2) for Bi(Fe0.98Co0.02)O-3 at room temperature, but saturation was not observed. The composite film of multilayer structures Bi3.5Nd0.5Ti3O12/CoFe2O4 shows composite phase, with considerable ferroelectric and ferromagnetic responses at room temperature.

Bismuth-layered-structure materials with (Bi2O2)(2+) layers intervening with pseudo perovskite blocks (Mn-1RnO3n+1)(2-) , where n = 1,2,3,4,5, M is mono, di, or trivalent ions such as Ba, Sr, Bi, Pb; R is tetra, penta-, or hexavalent ions such as Ti, Ta, Nb, show interesting ferroelectric and dielectric properties. Aurivillius phase [(1-x) SrBi2Nb2O9 - (x) Bi3TiNbO9] family of material has been synthesized by a chemical solution method, and thin films were deposited by spin coating. The samples were characterized by x-ray diffraction, Raman spectroscopy and scanning electron microscopy. The study reveals that a complete solid solution is formed for all compositions. Thin films deposited on ITO coated polished stainless steel substrate showed ferroelectric response.

Materials which possess electrical and magnetic coupling are of great interest for novel devices. Bi(Fe1-xCox)O3 (BFCO) material system was synthesized by solution route for various compositions and thin films were prepared by spin coating on Pt (Pt/Ti/SiO2/Si) substrates. Structural properties of the films were investigated by x-ray diffraction and Raman spectroscopy. X-ray diffraction patterns confirms intense (110) in BiFeO3 and Bi(Fe1-xCox)O3 with rhombohedra distorted perovskite structure without impure phase. Bi(Fe1-xCox)O3 films show week ferroelectric polarization and ferromagnetism at room temperature. Ferroelectric and ferromagnetic coupling could be attributed to the elimination of oxygen vacancies and increased stress in the crystal structure by partial replacement of Fe2+ ion by Co2+ ion.

The use of a ferromagnetic fluid for cooling applications represents an encouraging alternative to traditional methods; the fact that the fluid can be pumped with no moving mechanical parts, using the magnetocaloric effect, can be a great advantage for many applications where high maintenance costs and power consumption are undesirable. The nanocrystalline material suitable for this specific application must exhibit certain specific properties, such as tunable Curie temperature (TC) and high saturation magnetization (Ms). The present work is focused on the aqueous synthesis and characterization of Mn–Zn ferrite nanocrystals and their subsequent doping with rare-earth elements (Gd and Eu ions), as an attempt to modify the TC. Magnetic characterization of ferrite nanocrystals showed that room temperature Ms and the corresponding TC values were strongly dependent on the type and amount of the dopant species.

Since its introduction in the consumer market at the beginning of 1990s by Sony Corporation 'Li-ion rechargeable battery' and 'LiCoO 2 cathode' is an inseparable couple for highly reliable practical applications.However, a separation is inevitable as Li-ion rechargeable battery industry demand more and more from this well serving cathode.Spinel-type lithium manganate (e.g., LiMn 2 O 4 ), lithium-based layered oxide materials (e.g., LiNiO 2 ) and lithiumbased olivine-type compounds (e.g., LiFePO 4 ) are nowadays being extensively studied for application as alternate cathode materials in Li-ion rechargeable batteries. 1-7 Primary goal of this project was the advancement of Li-ion rechargeable battery to meet the future demands of the energy sector.Major part of the research emphasized on the investigation of electrodes and solid electrolyte materials for improving the charge transport properties in Li-ion rechargeable batteries.Theoretical computational methods were used to select electrodes and electrolyte material with enhanced structural and physical properties.The effect of nano-particles on enhancing the battery performance was also examined.Satisfactory progress has been made in the bulk form and our efforts on realizing micro-battery based on thin films is close to give dividend and work is progressing well in this direction. Recent ProgressIn some cathode materials e.g LiMn 2-x N x O 4 (x= Ni, Nd, Cr, Rh), we have optimized the process parameters to improve structural stability and electrochemical properties.We have successfully synthesized nanostructured Carbon-LiFePO4 composite cathode materials with conventional solid-state route to address the electronic conductivity and Li-diffusion.Further steps are still going towards finding the new cathode materials for high energy density Li ion rechargeable batteries.We have investigated ion transport and electrochemical behavior of some polyethylene oxide (PEO) based nano-composite solid polymer electrolytes.In relation to Li ion rechargeable batteries, the recent results of our group are describe below First-principles computationsFirst-principles computations are considered to be an important theoretical tool to predict the properties of materials.Computational modeling has been used to investigate rechargeable battery materials and prescreen their compositions when designing new cathode materials for battery applications.In an attempt to design and prescreen new cathode materials, we have computed the average intercalation voltages, lattice parameters, and density of states of a number of promising spinel cathode materials by inserting lithium ions into 2nd-row transition-metal oxides.These type cathode materials have the problem of capacity fading and limited cycleability in the 4V as well as 3V regions.

Pure lithium iron phosphate (LiFePO4) and carbon-coatedLiFePO4(C-LiFePO4) cathode materials were synthesized for Li-ion batteries. Structural and electrochemical properties of these materials were compared. X-ray diffraction revealed orthorhombic olivine structure. Micro-Raman scattering analysis indicates amorphous carbon, and TEM micrographs show carbon coating onLiFePO4particles. Ex situ Raman spectrum of C-LiFePO4at various stages of charging and discharging showed reversibility upon electrochemical cycling. The cyclic voltammograms ofLiFePO4and C-LiFePO4showed only a pair of peaks corresponding to the anodic and cathodic reactions. The first discharge capacities were 63, 43, and 13 mAh/g for C/5, C/3, and C/2, respectively forLiFePO4where as in case of C-LiFePO4that were 163, 144, 118, and 70 mAh/g for C/5, C/3, C/2, and 1C, respectively. The capacity retention of pureLiFePO4was 69% after 25 cycles where as that of C-LiFePO4was around 97% after 50 cycles. These results indicate that the capacity and the rate capability improved significantly upon carbon coating.

The present work addresses the synthesis and characterization of red emitting Gd2-xEuxO3 nanocrystalline phosphors by a modified sol-gel based method. The effects of the annealing temperature and atomic fraction of Eu3+ ions, ‘x’, on the structural and luminescence properties of the produced oxides have been systematically investigated. X-ray diffraction analyses revealed that crystalline cubic-Gd2O3 host structure was obtained when the intermediates (x=0.01-0.30) were annealed at different temperatures in air. Photoluminescence spectra of doped Gd2O3 powders showed all transitions of Eu3+ species, being the5D0→7F2 transition the most intense. On a common sample-weight basis, the highest photoluminescence intensity was obtained at ‘x’ = 0.15. The energy transfer from host to dopant was verified for all evaluated ‘x’ values, which suggest the actual incorporation of Eu species into the Gd-oxide lattice. It was also found that the photoluminescence intensity was strongly dependent on the annealing temperature and dopant concentration.