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  • 1. Al-Hinai, A. T.
    et al.
    Al-Hinai, M. H.
    Dutta, Joydeep
    Sultan Qaboos Univ, Water Res Ctr, Al Khoud 123, Oman.
    Application of Eh-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media2014In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 49, no 1, p. 645-650Article in journal (Refereed)
    Abstract [en]

    Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO3) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn2+ and Sn4+ was controlled for the precipitation in a one pot synthesis step at room temperature (25 degrees C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn2+ + Sn4+) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization olnano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO3.3H(2)O form.

  • 2. Baykal, A.
    et al.
    Günay, M.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Sozeri, H.
    Effect of ionic liquids on the electrical and magnetic performance of polyaniline-nickel ferrite nanocomposite2013In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 48, no 2, p. 378-382Article in journal (Refereed)
    Abstract [en]

    Polyaniline-NiFe2O4 nanofiber composites were successfully synthesized at the interface of water and ionic liquid via in situ polymerization using cetyl trimethylammonium bromide (CTAB) as surfactant. Both TG analysis and FT-IR measurements proved the presence of organic layer on the surface of NiFe2O4 nanoparticles. The influence of 1-butyl-3-methyl-imidazolium bromide [BMIM]Br as ionic liquid on the structure, conductivity and magnetic property of polyaniline-NiFe2O 4-CTAB nanocomposite were studied in detail. The results show that imidazolium-based ionic liquids BMIMBr acts as an anchor agent for the formation of morphology in polyaniline-NiFe2O4-CTAB nanocomposite. Introduction of ionic liquids obviously improves the conductivity but weakens the magnetization of polyaniline-NiFe2O4 nanocomposite.

  • 3.
    Chandar, Nagamuthu Krishna
    et al.
    Centre for Nanoscience and Technology, Anna University, Chennai 600025, India.
    Jayavel, R.
    Structural, morphological and optical properties of solvothermally synthesized Pr(OH)(3) nanoparticles and calcined Pr6O11 nanorods2014In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 50, p. 417-420Article in journal (Refereed)
    Abstract [en]

    The structural, morphological and optical properties of solvothermally synthesized Pr(OH)(3) nanoparticles and calcined Pr6O11 nanorods have been studied. Pr6O11 nanorods were grown by subsequent thermal decomposition of the synthesized Pr(OH)(3) nanoparticles at 700 degrees C for 2 h. Structural analysis showed that the synthesized Pr(OH)(3) nanoparticles possess hexagonal phase and calcined Pr6O11 nanorods have cubic fluorite phase. HRSEM images revealed that the Pr6O11 sample contains well-defined rod-like morphology. The UV-vis absorbance study of Pr6O11 nanorods showed shapedependent absorption edge toward higher wavelength as compared to Pr(OH)(3) nanoparticles. The PL spectrum of Pr6O11 nanorods reveals the enhanced near-band-edge emission in the blue region, with significant defect level green emission. The mechanism for the formation of Pr6O11 nanorods from Pr(OH)(3) nanoparticles has been proposed.

  • 4. Deligoz, H.
    et al.
    Baykal, A.
    Tanriverdi, E. E.
    Durmus, Z.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Synthesis, structural and electrical properties of triethylene glycol (TREG) stabilized Mn0.2Co0.8Fe2O4 NPs2012In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, no 3, p. 537-543Article in journal (Refereed)
    Abstract [en]

    Triethylene glycol (TREG) stabilized Mn0.2Co0.8Fe2O4 NPs was synthesized by a glycothermal reaction. XRD analysis identified the product as Mn0.2Co0.8Fe2O4 with a high phase purity. Nano-sized particles with an average size of about 6-8 nm were obtained with nearly single crystalline nature with TEM analysis. Superparamagnetic-like behavior of TREG stabilized Mn0.2Co0.8Fe2O4 NPs was observed by VSM. The binding between TREG and Mn0.2Co0.8Fe2O4 NPs was investigated with FT-IR and found to be via O on the TREG and NP surface. TG analysis indicated that the Mn0.2Co0.8Fe2O4 NP content was about 40%, with a TREG-shell content to be around 60%. Overall conductivity of the nanocomposite is in the range of 10(-10) to 10(-7) S cm(-1) with a strong dependence on temperature and frequency, indicating ionic conductivity. The nanocomposite exhibited lower epsilon' and epsilon '' compared to TREG stabilized Mn0.2Co0.8Fe2O4 NPs due to the doping of co-doping of manganese and cobalt.

  • 5. Deligöz, H.
    et al.
    Baykal, A.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Tanriverdi, E. E.
    Durmus, Z.
    Sözeri, H.
    Synthesis, structural, magnetic and electrical properties of Co 1-xZnxFe2O4 (x = 0.0, 0.2) nanoparticles2013In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 48, no 2, p. 646-654Article in journal (Refereed)
    Abstract [en]

    Co1-xZnxFe2O4 spinel nanoparticles with Zn concentrations of x = 0.0, 0.2 were prepared by a hydrothermal route in the presence of triethylene glycol (TEG). The structural, magnetic, electrical and dielectric properties of the prepared nanoparticles were studied. The XRD results confirmed the formation of single spinel ferrite structure with crystallite size 9 and 10 nm for x = 0.0 and 0.2 compositions respectively. The lattice parameter (a) increased with increasing Zn concentration. Temperature and frequency dependent electrical and dielectric properties of the prepared ferrites have also been investigated. Our findings show that overall conductivity of Co0.8Zn0.2Fe 2O4 nanoparticle is lower than that of CoFe 2O4 and roughly in the range of 10-11-10 -7 S cm-1 depending strongly temperature and frequency owing to the formation of stable electric bonds between the Zn2+ and Fe2+ ions, which localizes Fe2+ charge carriers. The ac conductivity showed a temperature dependent behavior at low frequencies and temperature independent behavior at high frequencies, which is an indication of ionic conductivity. dc conductivity of Co0.8Zn0.2Fe 2O4 nanoparticle are found to obey the Arrhenius plot and can be classified into two regions over with activation energy of 0.113 and 0.163 eV in the ranges of 20-40 °C and 70-120 °C, respectively when CoFe2O4 has an activation energy of 0.245 eV.

  • 6. Erdemi, H.
    et al.
    Baykal, A.
    Karaoglu, E.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Synthesis and conductivity studies of piperidine-4-carboxylic acid functionalized Fe 3O 4 nanoparticles2012In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, no 9, p. 2193-2199Article in journal (Refereed)
    Abstract [en]

    Piperidine-4-carboxylic acid (PPCA) functionalized Fe 3O 4 nanoparticles as a novel organic-inorganic hybrid was fabricated and characterized by XRD, FT-IR, VSM, and TEM techniques. Its detailed electrical properties are also presented. Composition was determined as Fe 3O 4, while particles were observed to have spherical morphology. VSM measurement proved the super-paramagnetic property of the as synthesized nanocomposite. ac and dc conductivity measurements indicated semiconductor characteristics and changing trends with temperature because of reorganization of the nanocomposite. dc conductivity is strongly temperature dependent and is classified into three regions. Analysis of the real and imaginary parts of the permittivity of nanocomposite showed the ionic polarization mechanism consisting of ionic conductivity and interfacial polarization.

  • 7. Günay, M.
    et al.
    Erdemi, H.
    Baykal, A.
    Sözeri, H.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Triethylene glycol stabilized MnFe2O4 nanoparticle: Synthesis, magnetic and electrical characterization2013In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 48, no 3, p. 1057-1064Article in journal (Refereed)
    Abstract [en]

    In this study, triethylene glycol (TEG) stabilized superparamagnetic MnFe2O4 nanoparticle (TEG@Mn-Fe2O4) was synthesized via a simple polyol route. Composition of nanoparticle was confirmed as MnFe2O4 and surface conjugation of TEG was confirmed by Fourier transform infrared spectroscopy to be via oxygens on TEG covalently attached to metal centers on the NPs: Vibrating sample magnetometer measurements confirmed the superparamagnetic character of these nanoparticles without reaching to a saturation, and has no coercivity. The TEG@MnFe2O4 nanocomposite showed thermally activated conductivity, significant interfacial polarization effect also in the dielectric permittivity evaluations. Temperature dependency of conductivity is a strong evidence for thermally activated polarization mechanism. dc conductivity is classified into two regions over a limited temperature range and shows maximum conductivity of about 4 x 10(-7) S cm(-1) at 120 degrees C. Temperature and frequency dependence of dielectric permittivity indicated interfacial polarization and temperature-assisted-reorganization effects.

  • 8. Jeon, So-Hyoun
    et al.
    Hwang, Ki-Hwan
    Seo, Hyun-Jin
    Lee, Jin-Soo
    Yu, Jung-Hoon
    Jung, Won-Suk
    Boo, Jin-Hyo
    Yun, Sang Ho
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Selective control of wetting on various substrates2014In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 58, p. 32-34Article in journal (Refereed)
    Abstract [en]

    Selective control of wetting is highly demanded for a broad window of applications. To selectively control wetting a surface should be locally modified by structuring surfaces or modulating surface chemistry. However, the local modifications are still challenging due to their complex and expensive processes. In this report we demonstrate the development of a facile approach for selective control of wetting on various substrates. Taking superhydrophobic polypropylene particles and hydrophilic silica nanoparticles, we here show that the locally controlled wetting can be achieved by coating the particles on a wide range of substrates including metal and paper and be applied to microfluidic channels. Furthermore, we represent that the coating method can be applied to any surfaces regardless of compositions and geometries.

  • 9. Karaoglu, E.
    et al.
    Baykal, A.
    Şenel, M.
    Sözeri, H.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Synthesis and characterization of Piperidine-4-carboxylic acid functionalized Fe 3O 4 nanoparticles as a magnetic catalyst for Knoevenagel reaction2012In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, no 9, p. 2480-2486Article in journal (Refereed)
    Abstract [en]

    Piperidine-4-carboxylic acid (PPCA) functionalized Fe 3O 4 nanoparticles as a novel organic-inorganic hybrid heterogeneous catalyst was fabricated and characterized by XRD, FT-IR, TGA, TEM and VSM techniques. Composition was determined as Fe 3O 4, while particles were observed to have spherical morphology. Size estimations using X-ray line profile fitting (10 nm), TEM (11 nm) and magnetization fitting (9 nm) agree well, revealing nearly single crystalline character of Fe 3O 4 nanoparticles. Magnetization measurements reveal that PPCA functionalized Fe 3O 4 NPs have superparamagnetic features, namely immeasurable coercivity and absence of saturation. Small coercivity is established at low temperatures. The catalytic activity of Fe 3O 4-PPCA was probed through one-pot synthesis of nitro alkenes through Knoevenagel reaction in CH 2Cl 2 at room temperature. The heterogeneous catalyst showed very high conversion rates (97%) and could be recovered easily and reused many times without significant loss of its catalytic activity.

  • 10. Nissinen, T.
    et al.
    Kiros, Yohannes
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Gasik, M.
    Lampinen, M.
    Comparison of preparation routes of spinel catalyst for alkaline fuel cells2004In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 39, no 9, p. 1195-1208Article in journal (Refereed)
    Abstract [en]

    MnCo2O4 has been used as a catalyst for oxygen reduction reaction (ORR) in alkaline fuel cells due to easier production and lower costs compared to noble metals. A novel method using a microwave-assisted route of synthesis in the presence of amorphous carbon was developed resulting in MnCo2O4 with particle sizes

  • 11. Saoud, K.
    et al.
    Alsoubaihi, R.
    Bensalah, N.
    Bora, T.
    Bertino, M.
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Synthesis of supported silver nano-spheres on zinc oxide nanorods for visible light photocatalytic applications2015In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 63, p. 134-140Article in journal (Refereed)
    Abstract [en]

    We report the synthesis of silver (Ag) nano-spheres (NS) supported on zinc oxide (ZnO) nanorods through two step mechanism, using open vessel microwave reactor. Direct reduction of ZnO from zinc nitrates was followed by deposition precipitation of the silver on the ZnO nanorods. The supported Ag/ZnO nanoparticles were then characterized by electron microscopy, X-ray diffraction, FTIR, photoluminescence and UV-vis spectroscopy. The visible light photocatalytic activity of Ag/ZnO system was investigated using a test contaminant, methylene blue (MB). Almost complete removal of MB in about 60 min for doses higher than 0.5 g/L of the Ag/ZnO photocatalyst was achieved. This significant improvement in the photocatalytic efficiency of Ag/ZnO photocatalyst under visible light irradiation can be attributed to the presence of Ag nanoparticles on the ZnO nanoparticles which greatly enhances absorption in the visible range of solar spectrum enabled by surface plasmon resonance effect from Ag nanoparticles.

  • 12. Shafiu, S.
    et al.
    Topkaya, R.
    Baykal, A.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Facile synthesis of PVA-MnFe2O4 nanocomposite: Its magnetic investigation2013In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 48, no 10, p. 4066-4071Article in journal (Refereed)
    Abstract [en]

    Manganese ferrite (MnFe2O4)-polyvinyl alcohol (PVA) nanocomposite was prepared by a PVA assisted sot-gel auto-combustion method. The magnetic core of the carriers was manganese ferrite (MnFe2O4), with average crystallite size of 9.1 +/- 2.1 nm. The PVA-MnFe2O4 nanocomposite exhibited superparamagnetic behavior at room temperature and ferromagnetic behavior at low temperatures. Zero-field-cooled and field-cooled measurements further confirm the superparamagnetic behavior with a blocking temperature of 160 K. The lower reduced remanent magnetization values than theoretical value of 0.5 indicate that the PVA/MnFe2O4 nanocomposite used in this study has uniaxial anisotropy rather than the expected cubic anisotropy according to the Stoner-Wohlfarth model. The calculated magnetic anisotropy constant of the sample is similar to 1.45 x 10(6) erg/cm(3) which is significantly higher than that of the bulk MnFe2O4 due to the strong magnetic coupling between magnetic core and surface spins.

  • 13.
    Wang, Cao
    et al.
    Department of Materials and Environmental Chemistry,Stockholm University.
    Zhao, Zhe
    Department of Materials and Environmental Chemistry, Stockholm University.
    Transparent polycrystalline ruby ceramic by spark plasma sintering2010In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 45, no 9, p. 1127-1131Article in journal (Refereed)
    Abstract [en]

    Fine-grained and transparent polycrystalline ruby ceramics (Cr(2)O(3)-doped Al(2)O(3)) were successfully prepared by spark plasma sintering (SPS). The effect of Cr(2)O(3) concentration on the grain size, hardness, fracture toughness and thermal conductivity of ruby ceramics was investigated systematically. For 0.05 wt.% Cr(2)O(3), high in-line transmittance of 85% at 2000 nm can be reached, further increase of Cr(2)O(3) concentration leads to the decrease in transmittance. High hardness of 23.95-25.05 GPa can be achieved due to the fine grain size in all ruby ceramics. The fracture toughness of 1.9-2.29 MPa m(1/2) indicates that no improvement in fracture toughness over pure Al(2)O(3) can be obtained by Cr(2)O(3) doping in these submicron grained ruby ceramics. High thermal conductivity of 28-29.8 W/(m K) at room temperature, close to that of single crystal sapphire, can be achieved. The change in grain size for different Cr(2)O(3) concentrations is the major reason for the change in mechanical and thermal properties, but not for the change in optical properties.

  • 14.
    Zhu, Bin
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Proton and oxygen ion conduction in nonoxide ceramics2000In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 35, no 1, p. 47-52Article in journal (Refereed)
    Abstract [en]

    By directly examining fuel cell performances, it was discovered that nonoxide containing materials such as chlorides and fluorides exhibit significant proton and oxygen ion conduction. Ionic transport measurements showed that both proton and oxygen ion conduction are present, with proton conduction predominant in most cases. Steady-state current output under fuel-cell operation indicates that the transport process in both chloride and fluoride electrolytes is dominated by the source ions, protons, and oxygen ions. These new materials have significant importance for both fundamental and applied research.

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