Viswanathan S. Saji

Publications

• Corrosion protection and control using nanomaterials

  V.S. Saji, Ronald Cook

  edited by V.S. Saji, Ronald Cook, 02/2012; Woodhead Publishing.

  ISBN: ISBN 1 84569 949 1
• 4.77

  Impact points

  Molybdenum, Molybdenum oxides and their electrochemistry

  V.S. Saji, C.W. Lee

  ChemSusChem. 01/2012; DOI number: 10.1002/cssc.201100660.
• 4.12

  Impact points

  One-dimensional (1D) nanostructured and nanocomposited LiFePO4: its perspective advantages for cathode materials of lithium ion batteries.

  Viswanathan S Saji, Young-Soo Kim, Tae-Hee Kim, Jaephil Cho, Hyun-Kon Song

  Physical chemistry chemical physics : PCCP. 11/2011; 13(43):19226-37.

  Nanostructured materials have attracted recent research interest as battery materials due to their expected enhancement of properties. The characteristic nanoscale dimension and its structuring guarantees improved charge and mass transfer during charge/discharge processes. Among the potential cathod... [more] Nanostructured materials have attracted recent research interest as battery materials due to their expected enhancement of properties. The characteristic nanoscale dimension and its structuring guarantees improved charge and mass transfer during charge/discharge processes. Among the potential cathode materials investigated as a substitute to LiCoO(2), one of the most promising materials is LiFePO(4) with olivine structure (LFP). In this perspective article, the current research and development in the synthesis and electrochemical studies of nanostructured LFP are reviewed with a special emphasis on one-dimensional (1D) nanostructures and nanocompositing with 1D conductive materials. In addition to various examples of 1D LFP with detailed synthetic methods, why 1D nanostructures could be meaningful is discussed in terms of a geometric point of view and the anisotropic lithiation/de-lithiation mechanism of LFP.
• 2.89

  Impact points

  Organic-skinned inorganic nanoparticles: surface-confined polymerization of 6-(3-thienyl)hexanoic acid bound to nanocrystalline TiO2.

  Viswanathan S Saji, Yimhyun Jo, Hoi Ri Moon, Yongseok Jun, Hyun-Kon Song

  Nanoscale research letters. 09/2011; 6(1):521.

  ABSTRACT: There are many practical difficulties in direct adsorption of polymers onto nanocrystalline inorganic oxide surface such as Al2O3 and TiO2 mainly due to the insolubility of polymers in solvents or polymer agglomeration during adsorption process. As an alternative approach to the direct pol... [more] ABSTRACT: There are many practical difficulties in direct adsorption of polymers onto nanocrystalline inorganic oxide surface such as Al2O3 and TiO2 mainly due to the insolubility of polymers in solvents or polymer agglomeration during adsorption process. As an alternative approach to the direct polymer adsorption, we propose surface-bound polymerization of pre-adsorbed monomers. 6-(3-Thienyl)hexanoic acid (THA) was used as a monomer for poly[3-(5-carboxypentyl)thiophene-2,5-diyl] (PTHA). PTHA-coated nanocrystalline TiO2/FTO glass electrodes were prepared by immersing THA-adsorbed electrodes in FeCl3 oxidant solution. Characterization by ultraviolet/visible/infrared spectroscopy and thermal analysis showed that the monolayer of regiorandom-structured PTHA was successfully formed from intermolecular bonding between neighbored THA surface-bound to TiO2. The anchoring functional groups (-COOH) of the surface-crawling PTHA were completely utilized for strong bonding to the surface of TiO2.
• 2.01

  Impact points

  Progress in electrodeposited absorber layer for CuIn(1−x)GaxSe2 (CIGS) solar cells

  V.S. Saji, I.K. Choi, C.W. Lee

  Solar Energy. 01/2011; 85:2666–2678.
• 1.09

  Impact points

  The effect of post-heat treatment on the ion dissolution behavior of nanotubular titanium alloys

  V.S. Saji, H.C. Choe

  Metals and Materials International. 01/2011; 17:275-278.

• The Impact of Nanotechnology in Reducing Corrosion Cost

  V.S. Saji

  01/2011;

  ISBN: 1 84569 949 1

• Nanoscience and Biomaterials Corrosion Control

  M. Bobby Kannan, V.S. Saji

  01/2011;

  ISBN: 1 84569 949 1

• Nanotechnological Applications in Tissue and Implant Engineering

  V.S. Saji, H.C. Choe

  01/2011: pages 399-413;

  ISBN: 978-1-57808-725-9

• Contemporary Developments in Corrosion Inhibitors – Review of Patents

  V.S. Saji

  Recent patents on Corrosion Science. 01/2011; 1:63-71.

  Selection of an appropriate corrosion inhibitor, inhibitor combination or package is an exceptionally cost effective and materials saving measure in various industries. The article reviews recent (2008-2010) patents reported on corrosion inhibitors. Up-to-date developments in the inhibition technolo... [more] Selection of an appropriate corrosion inhibitor, inhibitor combination or package is an exceptionally cost effective and materials saving measure in various industries. The article reviews recent (2008-2010) patents reported on corrosion inhibitors. Up-to-date developments in the inhibition technology are presented in accordance with the areas of application of inhibitors - industrial cooling water systems, oil and gas fields, coatings, acid pickling, lubricants, vapor phase inhibition, concrete corrosion etc. Nanotechnological advancements in inhibitor technology (in coatings) and novel products employing vapor phase corrosion inhibitors were discussed.

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• CIGS solar cells by electrodeposition

  V.S. Saji, S.M. Lee, C.W. Lee

  Journal of Korean Electrocehmical Society. 01/2011; 14:61-70.

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• 1.44

  Impact points

  Nanotube morphology and corrosion resistance of a low rigidity quaternary titanium alloy for biomedical applications.

  Viswanathan S Saji, Han-Cheol Choe, Yeong Mu Ko, Hoon Ahn

  Journal of nanoscience and nanotechnology. 07/2010; 10(7):4635-9.

  Highly ordered nanotube oxide layers were developed on low rigidity quaternary beta-type Ti-35Nb-5Ta-7Zr alloy by controlled anodic oxidation in electrolyte containing 1 M H3PO4 and 0.5 wt% NaF at room temperature. The diameters of the nanotubes formed were in the range of 30 to 80 nm. Electrochemic... [more] Highly ordered nanotube oxide layers were developed on low rigidity quaternary beta-type Ti-35Nb-5Ta-7Zr alloy by controlled anodic oxidation in electrolyte containing 1 M H3PO4 and 0.5 wt% NaF at room temperature. The diameters of the nanotubes formed were in the range of 30 to 80 nm. Electrochemical corrosion behavior of the nanotubular alloy was studied in Ringer's solution at 37 +/- 1 degrees C using potentiodynamic polarization and AC Impedance. The result of the study showed that nanotube formation on the surface affect the passivation behavior of the quaternary alloy significantly. However the corrosion current density was considerably higher for the nanotubular alloy.
• 0.78

  Impact points

  Thermal expansion of doped lanthanum gallates

  K.T.Jacob, S.Jain, V.S.Saji, P.V.K.Srikanth

  Bulletin of Materials Science. 01/2010; 33:407-411.

  Thermal expansion of several compositions of Sr and Mg-doped LaGaO3 including an A-site deficient composition (La0⋅9Sr0⋅1)0⋅98(Ga0⋅8Mg0⋅2)O2⋅821 were measured in the temperature range from 298 to 1273 K. The effect of doping on thermal expansion was studied by varying the composition at one site of ... [more] Thermal expansion of several compositions of Sr and Mg-doped LaGaO3 including an A-site deficient composition (La0⋅9Sr0⋅1)0⋅98(Ga0⋅8Mg0⋅2)O2⋅821 were measured in the temperature range from 298 to 1273 K. The effect of doping on thermal expansion was studied by varying the composition at one site of the perovskite structure (either A or B), while keeping the composition at the other site invariant. Thermal expansion varied nonlinearly with temperature and exhibited an inflexion between 550 and 620 K, probably related to the change in crystal structure from orthorhombic to rhombohedral. The dependence of average thermal expansion coefficient (αav) on the dopant concentration on either A or B site of the perovskite structure was found to be linear, when the composition at the other site was kept constant. Mg doping on the B-site had a greater effect on the average thermal expansion coefficient than Sr doping on the A-site. Cation deficiency at the A-site decreases thermal expansion when compositions at both sites are held constant.

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• Nanotechnology in biomedical applications-A Review

  V.S. Saji, H.C. Choe, K.W.K. Young

  International Journal of Nano and Biomaterials. 01/2010; 3:119-139.

  Incorporation of functionalised and modified nanostructures in various biomedical applications has generated considerable research interest in recent years. The applications of nanotechnology in medicine and biomedical engineering are vast and spans areas such as implant and tissue engineering, diag... [more] Incorporation of functionalised and modified nanostructures in various biomedical applications has generated considerable research interest in recent years. The applications of nanotechnology in medicine and biomedical engineering are vast and spans areas such as implant and tissue engineering, diagnosis and therapy. The present scenario demands designing of nanotools which can respond to the needs of biological problems and prepare more efficient biomedical approaches. This article reviews recent developments in nanobiotechnology with special emphasis on load bearing implants and novel tissue engineered scaffolds. Novel research approaches in nanomedicine and major challenges to practical applications are also highlighted.

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• 1.59

  Impact points

  Effect of coadsorbents on dye sensitised solarcell sensitized by NIR absorbing poly(ethyl thieno[3,4-b]thiophene-2-carboxylate

  V.S. Saji, M. Pyo

  Current Applied Physics. 01/2010; 10:S410-S413.

  Poly(ethyl thieno[3,4-b]thiophene-2-carboxylate) (PTTEt), showing near infrared (NIR) absorption was employed as a polymer sensitizer in dye-sensitized solar cell (DSSC). The photovoltaic performance of DSSC was investigated with PTTEt of different molecular weights. Low molecular weight aliphatic d... [more] Poly(ethyl thieno[3,4-b]thiophene-2-carboxylate) (PTTEt), showing near infrared (NIR) absorption was employed as a polymer sensitizer in dye-sensitized solar cell (DSSC). The photovoltaic performance of DSSC was investigated with PTTEt of different molecular weights. Low molecular weight aliphatic diacids were also employed as coadsorbents along with PTTEt. It was revealed that the reduction of polymer molecular weights caused only a slight enhancement in overall power conversion efficiency (g). The species and concentration of coadsorbents, on the other hand, greatly affects g. The best performance with g of ca. 1.5% was obtained when 3,30-dithiodipropionic acid was adsorbed along with PTTEt, indicative of significant improvement of g (ca. 50% increase).

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• 0.78

  Impact points

  Preferential dissolution behavior in Ni-Cr dental cast alloy

  V.S. Saji, H.C.Choe

  Bulletin of Materials Science. 01/2010; 33:463-468.

  A Ni–Cr–Mo dental alloy was fabricated by three different casting methods, viz. centrifugal casting, high frequency induction casting and vacuum pressure casting. The dependence of cast microstructure on the electrochemical corrosion behaviour was investigated using potentiodynamic cyclic and potent... [more] A Ni–Cr–Mo dental alloy was fabricated by three different casting methods, viz. centrifugal casting, high frequency induction casting and vacuum pressure casting. The dependence of cast microstructure on the electrochemical corrosion behaviour was investigated using potentiodynamic cyclic and potentiostatic polarization techniques, impedance spectroscopy and scanning electron microscopy. The experimental results were compared and discussed with those obtained for a Co–Cr–Mo counterpart. The results of the study showed that the variation in casting morphologies with casting methods has only marginal influence in the overall corrosion resistance of Ni–Cr and Co–Cr dental alloys. There was severe preferential dissolution of Ni rich, Cr and Mo depleted zones from the Ni–Cr–Mo alloy. The overall corrosion resistance property of the Co–Cr base alloy was better than that of the Ni–Cr base alloy.

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• 1.67

  Impact points

  Electrochemical impedance behavior graphite dispersed electricallyconducting acrylic coating on AZ 31 magnesium alloy in 3.5 wt% NaCl solution

  V.S. Raja, A. Venugopal, V.S. Saji, K. Sreekumar, S. Nair, M.C. Mittal

  Progress in Organic Coatings. 01/2010; 67:12-19.

  The paper deals with understanding the electrochemical impedance behavior of (a) chromate coating (b) electrically conducting polymer coating and (c) polyurethane coating under different combinations applied over AZ31 magnesium alloy in an effort to develop a conducting organic coating that can offe... [more] The paper deals with understanding the electrochemical impedance behavior of (a) chromate coating (b) electrically conducting polymer coating and (c) polyurethane coating under different combinations applied over AZ31 magnesium alloy in an effort to develop a conducting organic coating that can offer corrosion protection as well as electrical conductivity. The study indicates that dispersion of graphite in acrylic coating though significantly brings down the electrical resistance; application of such a coating on the magnesium alloy does not offer good resistance against corrosion. In order to gain both the corrosion resistance as well as electrical conductivity an intermediate coating such as polyurethane needs to be provided. The paper discusses the electrochemical impedance behavior of the above coatings.

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• 2.55

  Impact points

  NIR-absorbing poly(thieno[3,4-b]thiophene-2-carboxylic acid) as a polymer dye for dye-sensitized solar cells

  V.S. Saji, K.K. Zhong, M. Pyo

  Journal of Photochemistry and Photobiology A Chemistry. 01/2010; 212:81-87.

  Thieno[3,4-b]thiophene-2-carboxylic acid (TTHC) was newly synthesized and poly(thieno[3,4-b]thiophene-2-carboxylic acid) (PTTHC), showing NIR absorption with a low band gap of 1.0 eV, was prepared by chemical or electrochemical polymerization. Vis–NIR spectroscopic studies on PTTHC adsorption reveal... [more] Thieno[3,4-b]thiophene-2-carboxylic acid (TTHC) was newly synthesized and poly(thieno[3,4-b]thiophene-2-carboxylic acid) (PTTHC), showing NIR absorption with a low band gap of 1.0 eV, was prepared by chemical or electrochemical polymerization. Vis–NIR spectroscopic studies on PTTHC adsorption revealed that the presence of pendant carboxylic groups on a polymer chain is important to obtain highly sensitized TiO2. The extent of PTTHC adsorption showed proportional increases as raising the adsorption temperatures, reaching saturation at the amount equivalent to a monolayer formation (this does not mean PTTHC monolayer coverage on TiO2). Sequential treatments of TiO2 revealed that the polymer can be adsorbed on N3-adsorbed TiO2 without desorbing N3. The amounts of PTTHC adsorbed on N3-adsorbed TiO2 with increasing adsorption temperatures implied that only a small fraction of polymer chains is involved in anchoring with most chain segments remaining unbound to TiO2. The dye adsorption behaviors were further studied by FTIR, EDX, and TGA. Finally, PTTHC was applied for the preparation of panchromatic dye-sensitized solar cells. The power conversion efficiency ( ) of 1.2% for PTTHC-adsorbed TiO2 was increased to 4.3% after N3 adsorption on PTTHC-adsorbed TiO2. Similar enhancement of was observed after PTTHC treatment on N3-adsorbed TiO2.

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• 1.73

  Impact points

  Dye sensitized solar cell of TiO2 nanoparticle/nanorod composites prepared via low-temperature synthesis in oleic acid

  V.S. Saji, M. Pyo

  Thin Solid Films. 01/2010; 518:6542-6546.

  Titania (TiO2) nanorods (NRs) and nanoparticles (NPs) were synthesized using oleic acid as a surfactant and employed as photoanodes for dye sensitized solar cell (DSSC) fabrication. The synthesized NRs and NPs were characterized using transmission electron microscopy and X-ray diffraction. The photo... [more] Titania (TiO2) nanorods (NRs) and nanoparticles (NPs) were synthesized using oleic acid as a surfactant and employed as photoanodes for dye sensitized solar cell (DSSC) fabrication. The synthesized NRs and NPs were characterized using transmission electron microscopy and X-ray diffraction. The photovoltaic performances were compared between NRs, NPs, and their composites. The results showed that the power conversion efficiencies (η) of the composites depend on the relative compositions of NRs and NPs in photoanodes, reaching the greatest at 10% NR content. η of the pure NRs DSSC was lower than that of the NPs DSSC. Electrochemical impedance spectroscopy revealed that the highest η at 10% NRs is mainly due to reduced charge transport resistance at the TiO2/dye/electrolyte interface and electrolyte diffusion resistance, overcoming the reduction of the number of adsorbed dye molecules.

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• 0.78

  Impact points

  Chemical Solution deposition of CCTO thin film

  V.S.Saji, H.C. Choe

  Bulletin of Materials Science. 01/2010; 33:203-207.

  CaCu3Ti4O12 (CCTO) thin film was successfully deposited on boron doped silica substrate by chemical solution deposition and rapid thermal processing. The phase and microstructure of the deposited films were studied as a function of sintering temperature, employing X-ray diffractometry and scanning e... [more] CaCu3Ti4O12 (CCTO) thin film was successfully deposited on boron doped silica substrate by chemical solution deposition and rapid thermal processing. The phase and microstructure of the deposited films were studied as a function of sintering temperature, employing X-ray diffractometry and scanning electron microscopy. Dielectric properties of the films were measured at room temperature using impedance spectroscopy. Polycrystalline pure phase CCTO thin films with (220) preferential orientation was obtained at a sintering temperature of 750°C. There was a bimodal size distribution of grains. The dielectric constant and loss factor at 1 kHz obtained for a film sintered at 750°C was k ~ 2000 and tan δ ~ 0⋅05.

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