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  • 1.
    Ali, Amjad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. COMSATS Inst Informat Technol, Dept Phys, Lahore 54000, Pakistan.;Univ Okara, Dept Phys, Okara 56300, Pakistan.
    Raza, Rizwan
    COMSATS Inst Informat Technol, Dept Phys, Lahore 54000, Pakistan.;Royal Inst Technol KTH, Dept Energy Technol, S-10044 Stockholm, Sweden..
    Khalil, R. M. Arif
    Bahauddin Zakariya Univ, Dept Phys, Multan 60800, Pakistan..
    Ahmad, M. Ashfaq
    COMSATS Inst Informat Technol, Dept Phys, Lahore 54000, Pakistan..
    Rafique, Asia
    COMSATS Inst Informat Technol, Dept Phys, Lahore 54000, Pakistan..
    Ullah, M. Kaleem
    COMSATS Inst Informat Technol, Dept Phys, Lahore 54000, Pakistan..
    Rehman, Amin Ur
    Lahore Univ, Dept Phys, Lahore 54000, Pakistan..
    Mushtaq, M. Naveed
    COMSATS Inst Informat Technol, Dept Phys, Lahore 54000, Pakistan..
    Belova, Lyubov
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    A potential electrolyte (Ce1-x CaxO2-delta) for fuel cells:Theoretical andexperimental study2018Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 44, nr 11, s. 12676-12683Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    First-principles calculations are performed using density function theory to explore the effects of dopant Ca in ceria (Ce1-x CaxO2-delta). The impact of oxygen vacancy on band gap and density of states is examined in doped ceria using generalized gradient approximations. Vacancy association and vacancy formation energies of the doped ceria are calculated to reveal the effect of dopant on ion conduction. The experimental study of the sample Ce0.875Ca0.125O2-delta) was performed to compare with the theoretical results. The obtained results from theoretical calculation and experimental techniques show that oxygen vacancy increases the volume, lattice constant (5.47315 angstrom) but decrease the band gap (1.72 eV) and bulk modulus. The dopant radius (1.173 angstrom) and lattice constant (5.4718 angstrom) are also calculated by equations which is close to the DFT lattice parameter. The result shows that oxygen vacancy shifts the density of states to lower energy region. Band gap is decreased due to shifting of valence states to conduction band. Vacancy formation shows a significance increase in density of states near the Fermi level. Density of states at Fermi level is proportional to the conductivity, so an increase in density of states near the Fermi level increases the conductivity. The experimental measured ionic conductivity is found to 0.095 S cm(-1) at 600 degrees C. The microstructural studies is also reported in this work.

  • 2.
    Bu, Junfu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Zhao, Z.
    Transport properties of BaZr0.5Ce0.3Y0.2O3-δ proton conductor prepared by spark plasma sintering2016Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 42, nr 3, s. 4393-4399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dense BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) proton conductors were prepared by a spark plasma sintering method. Their conductivities were determined in different atmospheres: dry air, wet N2 and wet H2. Moreover, the potential electronic conductivity contribution to the total conductivity was also identified by testing their total conductivities at different oxygen partial pressures (1-10-24 atm) in combination with an XPS analysis. It is found that the prepared dense BZCY532 ceramics are good proton conductors at 600 °C. In addition, the Ce3+ concentration in the dense BZCY532 ceramics is around 3.5 atm% of the total Ce element, and the electronic contribution to the total conductivity can be neglected after a postheat treatment.

  • 3.
    Bu, Junfu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi.
    Preparation of 30 mol.% Y-doped hafnia (Hf0.7Y0.3O2-delta) using a modified solid-state reaction method2015Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, nr 2, s. 2611-2615Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A pure and well-crystallized Hf0.7Y0.3O2-delta (YSH) powder was synthesized using a modified solid-state reaction method. Water-based milling and freeze drying process were implemented to facilitate powder synthesis and final densification process. The improved powder performance, in aspects of phase development and sintering behaviour, was investigated by systematic comparison between different powder processing procedures. Dense YSH ceramic material with a relative density of 0.975 was successfully obtained using conventional sintering at 1650 degrees C for 10 h. XRD, SEM and EDS were employed to characterize the synthesized powder and dense YSH ceramics. Dense YSH ceramic possesses a fluorite cubic structure with an a value of 5.1406 angstrom, and the ionic radius of Y3+ in YSH was determined to be 0.1006 nm.

  • 4.
    Bu, Junfu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi. Shanghai Institute of Technology, China .
    Sintering behaviour of the protonic conductors BaZr(x)Ce(0.8-x)Ln(0.2)O(3-delta) (x=0.8, 0.5, 0.1; Ln=Y, Sm, Gd, Dy) during the solid-state reactive-sintering process2015Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, nr 2, s. 2558-2564Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The protonic conductors BaZr(x)Ce(0.8-x)Ln(0.2)O(3-delta) (x=0.8, 0.5, 0.1; Ln=Y, Sm, Gd, Dy) were successfully prepared using a solid-state reactive-sintering method. NiO (1 wt.%) was added as a sintering aid, and it was proven that NiO produced tremendous enhancement in the densification process. The morphologies of the variously doped BaZr(0.8)Ln(0.2)O(3-delta), BaZr(0.5)Ce(0.3)Ln(0.2)O(3-delta) and BaZr(0.1)Ce(0.7)Ln(0.2)O(3-delta) ceramics, as well as their sintering behaviour, were investigated. The results show that the Ce content in the BaZr(0.8)Ln(0.2)O(3-delta), BaZr(0.5)Ce(0.3)Ln(0.2)O(3-delta) and BaZr(0.1)Ce(0.7)Ln(0.2)O(3-delta) compounds influences the sintering temperature significantly, and a larger Ce content will lead to a lower sintering temperature. In addition, ionic radii of the dopants that are similar to the ionic radii of the B-site will also result in a lowered sintering temperature. Based on the present study, NiO has no influence on the lattice parameters.

  • 5.
    Bu, Junfu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Shanghai Institute of Technology, China.
    Transport properties of BaZr0.5Ce0.3Y0.2O3-delta proton conductor prepared by spark plasma sintering2016Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 42, nr 3, s. 4393-4399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dense BaZr0.5Ce0.3Y0.2O3-delta (BZCY532) proton conductors were prepared by a spark plasma sintering method. Their conductivities were determined in different atmospheres: dry air, wet N-2 and wet H-2. Moreover, the potential electronic conductivity contribution to the total conductivity was also identified by testing their total conductivities at different oxygen partial pressures (1-10(-24) atm) in combination with an XPS analysis. It is found that the prepared dense BZCY532 ceramics are good proton conductors at 600 degrees C. In addition, the Ce3+ concentration in the dense BZCY532 ceramics is around 3.5 atm% of the total Ce element, and the electronic contribution to the total conductivity can be neglected after a postheat treatment.

  • 6.
    Chen, Song
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Wang, Shihuai
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Li, Hu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap..
    Forsberg, Kerstin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Eu3+ doped monetite and its use as fluorescent agent for dental restorations2018Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 44, nr 9, s. 10510-10516Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is essential but challenging to distinguish the dental restorations from the surrounding teeth when removing filling materials from cavity. In this study, Eu3+ doped monetite was proposed as a fluorescent agent for dental restorations to meet this challenge. Eu3+ doped monetite with enhanced fluorescent property was obtained via a precipitation method. The presence of Eu3+ could prevent the phase transformation of brushite to monetite. However, all the brushite particles transformed to monetite at 300 °C and to tricalcium phosphate at 800 °C. The emission intensity increased with the addition of Eu3+ and reached the maximum when 12 mol% Eu3+ was added into the aqueous solution. With either 254 nm or 393 nm excitation, Eu3+ doped monetite showed the strongest fluorescence emission peaking at 616 nm and other two moderate bands peaking at 699 nm and 593 nm. The excitation spectra at the emission wavelength of 616 nm showed strong absorption peaks at 254 nm and 393 nm. We further investigate the fluorescence properties of Eu3+ doped monetite in one type of dental restorations. Glass ionomer cement with Eu3+ doped monetite exhibited clear fluoresce with origin color under UV irradiation at 254 nm, showing that Eu3+doped monetite is a promising fluorescent agent for dental restorations.

  • 7. Cheng, Z.
    et al.
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Tianjin University, Tianjin, China.
    Ink-jet printed BNT thin films with improved ferroelectric properties via annealing in wet air2018Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 44, nr 9, s. 10700-10707Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, an ink-jet printing process based on the sol-gel route was applied to prepare lead-free ferroelectric Na0.5Bi0.5TiO3(BNT) thin films for the first time. Dense and crack-free films with perovskite structure were obtained from a modified precursor solution through multiple printing and pyrolysis processes. The ferroelectric, dielectric and electrical properties were significantly affected by the annealing temperature and atmosphere. The film annealed at 670 °C in wet air showed a high remnant polarization of 24.7 μC/cm2 with a low coercive field of 263 kV/cm, the dielectric constant and loss were 185 and 0.1 at 10 kHz, respectively. It was found that wet air was an alternative to reduce oxygen vacancies and enhance properties of ferroelectric films, which can be explained by the defect chemical reaction between water and oxygen vacancies. X-ray photoelectron spectroscopy(XPS) confirmed the decrease of oxygen vacancies after annealing with water presence, with a formation of Ohmic conduction mechanism dominated by charged hydroxyl groups.

  • 8. Choopani, S.
    et al.
    Samavat, F.
    Kolobova, E. N.
    Grishin, Alexander M.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektronik och inbyggda system.
    Ferromagnetic resonance and magnetic anisotropy in biocompatible Y3Fe5O12@Na0.5K0.5NbO3 core-shell nanofibers2019Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 46, nr 2, s. 2072-2078Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Y3Fe5O12@Na0.5K0.5NbO3 (YIG@NKN) core-shell nanofibers were synthesized by the coaxial electrospinning technique. For comparison, samples of YIG and NKN nanofibers were prepared. Scanning Electron Microscopy (SEM) and 3D laser-scanning confocal microscopy (TDLM) of YIG@NKN nanofibers revealed long uniform size distributed fibers with the average diameter of 100–150 nm. X-Ray diffraction (XRD) examination shows the existence of the distinct peaks of orthorhombic NKN and cubic YIG. Magnetic force microscopy (MFM) of individual YIG@NKN nanofiber demonstrates a magnetic core that is extended in one half of the diameter of the fiber. These nanofibers show obvious Ferromagnetic resonance (FMR) with resonance near 2 KOe similar to YIG fibers but in such a way that it starts to increase linearly with applying magnetic field from zero up to near resonance field. Also they show a soft magnetic behavior with saturation magnetization of 10 emu/gr. Furthermore, we propose a model to explain line shape of randomly oriented fibers and extract all the magnetic anisotropy parameters from FMR data. The results rely the shape anisotropy as dominant effect, however the dipolar field among fibers should be considered. The highest degree of asymmetry observed in the case of core-shell fibers in hard direction that it can be originated from magneto electric effects. By taking into account the observed FMR, the ability of adequate control of microwave absorption by applying magnetic field and biocompatibility, the synthesized core-shell nanofibers are the most promising candidate for clinical application such as microwave cancer thermotherapy and adjustable microwave absorbers.

  • 9. Dahl, P.
    et al.
    Kaus, I.
    Zhao, Zhe
    Department of Physical Inorganic and Structural Chemistry, Stockholm University.
    Johnsson, M.
    Nygren, M.
    Wiik, K.
    Grande, T.
    Einarsrud, M. A.
    Densification and properties of zirconia prepared by three different sintering techniques2007Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 33, nr 8, s. 1603-1610Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Densification of nanocrystalline yttria stabilized zirconia (YSZ) powder with 8 mol% Y2O3, prepared by a glycine/nitrate smoldering combustion method, was investigated by spark plasma sintering, hot pressing and conventional sintering. The spark plasma sintering technique was shown to be superior to the other methods giving dense materials (>= 96%) with uniform morphology at lower temperatures and shorter sintering time. The grain size of the materials was 0.21, 0.37 and 12 mu m after spark plasma sintering, hot pressing and conventional sintering, respectively. Total electrical conductivity of the materials showed no clear correlation with the grain size, but the activation energy for spark plasma sintered materials was slightly higher than for materials prepared by the two other densification methods. The hardness, measured by the Vickers indentation method, was found to be independent on grain size while fracture toughness, derived by the indentation method, was slightly decreasing with increasing grain size.

  • 10. Ebin, Burcak
    et al.
    Gürmen, Sebahattin
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Preparation and electrochemical properties of spinel LiFexCuyMn1.2O4 by ultrasonic spray pyrolysis2014Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 40, nr 1, s. 1019-1027Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanocrystalline LiFexCuyMn1.2O4 (x and y=0.2, 0.4 and 0.6) particles were prepared by the ultrasonic spray pyrolysis method using nitrate salts at 800 degrees C in air atmosphere. Particle properties were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Also, cyclic voltammetry and galvanostatic tests were performed to investigate the effects of the double substituent and doping amounts on electrochemical behavior. Results show that the aggregation of nanocrystallites around 90 nm size formed submicron spherical cathode particles. Transition metal ratios in particles exhibited a perfect fit with desired amounts. Although the change of iron and copper amounts do not show significant differences in the particle size and shape morphology, they modify the 4 V and 3 V potential plateaus of spinel LiMn2O4. The discharge capacities of LiFe0.2Cu0.6Mn1.2O4 particles are 39 and 23 mAh g(-1) for 4 and 2.6 V potential regions, respectively. 4 V discharge capacity disappeared with increasing of iron and decreasing of copper contents due to random occupation of iron and copper ions in the spinel lattice.

  • 11.
    Hussain, Fida
    et al.
    COMSATS Univ Islamabad, Dept Elect Engn, Islamabad 44000, Pakistan..
    Abbas, Ghazanfar
    COMSATS Univ Islamabad, Dept Phys, Lahore Campus, Lahore 54000, Pakistan..
    Ahmad, M. Ashfaq
    COMSATS Univ Islamabad, Dept Phys, Lahore Campus, Lahore 54000, Pakistan..
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. COMSATS Univ Islamabad, Dept Phys, Lahore Campus, Lahore 54000, Pakistan.
    Rehman, Zohaib Ur
    COMSATS Univ Islamabad, Dept Phys, Lahore Campus, Lahore 54000, Pakistan..
    Mumtaz, Saleem
    Bahauddin Zakariya Univ, Inst Chem Sci, Multan 60800, Pakistan..
    Akbar, M.
    COMSATS Univ Islamabad, Dept Phys, Lahore Campus, Lahore 54000, Pakistan..
    Riaz, Raja Ali
    COMSATS Univ Islamabad, Dept Elect Engn, Islamabad 44000, Pakistan..
    Dilshad, Saad
    COMSATS Univ Islamabad, Dept Elect Engn, Islamabad 44000, Pakistan..
    Comparative electrochemical investigation of zinc based nano-composite anode materials for solid oxide fuel cell2019Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 45, nr 1, s. 1077-1083Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structural and electrochemical properties of zinc based nano-composites anode materials with a composition of X0.25Ti0.5Zn0.70 (where X = Cu, Mn, Ag) have been investigated in this present study. The proposed Xo.zsTiousZno.70 oxide materials have been synthesized through sol-gel method. The doping effect of Cu, Mn, and Ag on TiZn oxides were analyzed in terms of electronic conduction and power density in hydrogen atmosphere at comparatively low temperature in the range of 650 degrees C. The crystal structure and surface morphology were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis techniques. The XRD patterns of composites depict that the average crystalline sizes lie in the range of 20-100 nm. Four -probe DC conductivity technique was used to measure the conductivity of the materials and maximum electrical conductivity of Ag0.25Ti0.05Zn0.70 oxide was found to be 7.81 S/cm at 650 degrees C. The band gap and absorption spectra were determined by ultra-violet visible (UV-Vis) and Fourier Transform Infrared spectroscopy (FTIR) techniques respectively. The maximum power density was achieved to be 354 mW/cm(2) at 650 degrees C by Ag0.25Ti0.05Zn0.70 oxide anode with SDC (electrolyte) and BSCF (conventional cathode) materials.

  • 12. Kese, K. O.
    et al.
    Li, Z. C.
    Bergman, Bill
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi.
    Effect of ageing on the electrical resistivities of (Ba0.69Pb0.31)Ti-3 PTCR ceramic thermistors2005Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 31, nr 3, s. 375-378Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electrical resistivity of (Ba0.69Pb0.31)TiO3 PTCR ceramic thermistors aged at temperatures of 175, 200, 250 and 300 degrees C, respectively, were measured. When the samples were aged at temperatures of 175 and 200 degrees C, room-temperature resistivity decreased at the initial ageing stage, and then increased with the ageing time. The samples displayed a monotonous rise of the room-temperature resistivity when the ageing treatments were performed at 250 and 300 degrees C. PTCR effects showed different characteristics after different ageing treatments. These ageing characteristics were analyzed by considering interior oxidation and reduction reactions.

  • 13. Khan, M. Ajmal
    et al.
    Raza, Rizwan
    Bohn Lima, Raquel
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Chaudhry, M. Asharf
    Ahmed, E.
    Khalid, N. R.
    Abbas, Ghazanfar
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Nasir, Nadeem
    Effect of titania concentration on the grain boundary conductivity of calcium-doped ceria electrolyte2014Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 40, nr 7, s. 9775-9781Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A solid-state technique was used to synthesize ceria-based (CDC-xT, in which x=0-1 mol%) solid electrolyte ceramics. The effects of doping the ceramic solid electrolyte (CDC) with titanium oxide were studied with regard to densification, crystal structure, morphology, electro-impedance spectroscopy and fuel cell performance. TiO2 doping afforded materials a 95% relative density at 940 degrees C, approximately 200 degrees C lower than the temperature required without titanium oxide. The addition of titanium oxide (TiO2) reduced the CDC sintering temperature and significantly improved the grain boundary conduction. The minimum grain boundary resistivity was obtained at 0.8 mol% TiO2. X-ray diffraction (XRD) results showed that the lattice parameters enhanced with increased titanium oxide concentrations up to 0.8 mol%, revealing the solubility limit for Caria's fluorite structure. The optimum doping level (0.8 mol%) is provided maximum conductivity. Conductivities were measured using EIS (Electrochemical Impedance Spectroscopy) with a two-probe method, and the activation energies were calculated using the Arrhenius plots. The maximum power density (660 mW/cm(2)) was achieved with CDC 0.8T electrolyte at 650 degrees C using LiCuZnNi oxide electrodes.

  • 14. Kurtan, U.
    et al.
    Dursun, D.
    Aydin, H.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Baykal, A.
    Bozkurt, A.
    Influence of calcination rate on morphologies and magnetic properties of MnFe2O4 nanofibers2016Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 42, nr 16, s. 18189-18195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, we succesfully synthesized electrospun MnFe2O4 nanofibers (NFs) from poly(N-vinylpyrrolidone)/manganese(II) nitrate composite by electrospinning and then as-spun NFs were calcined 450 degrees C for 2 h in air atmosphere to remove the polymer matrix and fabricate inorganic MnFe2O4 nanofibers. In order to investigate the sintering behavior of MnFe2O4 nanofibers in air atmosphere, the synthesized as-spun nanofibers were calcined with different calcination rates. Thus the effect of calcination rate on structure and morphology of nanofibers were discussed clearly. The structural, magnetic, morphological, spectroscopic and thermal characterizations were also done by XRD, VSM, TEM, SEM, FTIR and TG analysis. In the presence of slow calcination rate, only peaks of MnFe2O4 could be observed on other hand in the presence of rapid calcination rate, formation of an impurity was observed. Scanning electron microscope images revealed that MnFe2O4 nanorods possess a broader range size distribution with higher particle size. Also, magnetic properties were both size and shape dependent.

  • 15. Kurtan, U.
    et al.
    Topkaya, R.
    Baykal, A.
    Toprak, M. S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Temperature dependent magnetic properties of CoFe2O4/CTAB nanocomposite synthesized by sol gel auto-combustion technique2013Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 39, nr 6, s. 6551-6558Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A CoFe2O4/cetyl trimethylammonium bromide (CTAB) nanocomposite has been fabricated by a sol gel auto-combustion method. Characterization of the material revealed the composition of the crystalline phase as CoFe2O4 while FT-IR confirmed the presence of CTAB on the nanoparticles. From X-ray line profile fitting, average crystallite size was estimated to be 22 +/- 6 nm. SEM analysis showed a porous sheet-like morphology with internal nanosize grains of about 30 nm. The room temperature coercive field (He) of the CoFe2O4/CTAB nanocomposite was found to be 1045 Oe which is close to the previously reported room temperature values for bulk CoFe2O4. The H-c, was observed to decrease almost linearly with the square root of the temperature (root T) according to Kneller's law. From the linear fit of H-c versus root T, the zero-temperature coercivity (H-c0) and superparamagnetic blocking temperature (T-B) of the CoFe2O4/CTAB nanocomposite were found to be similar to 9.1 kOe and similar to 425 K, respectively. The remanence magnetization (M-r), the reduced remanent magnetization (M-r/M-s), and the effective magnetic anisotropy (K-eff) decrease with increasing temperature. The M-r/M-s value of 0.6 at 10 K higher than the theoretical value of 0.5 for non-interacting single domain particles with the easy axis randomly oriented suggests the CoFe2O4/CTAB nanocomposite to have cubic magnetocrystalline anisotropy according to the Stoner Wohlfarth model.

  • 16. Li, Z. C.
    et al.
    Zhang, H.
    Bergman, Bill
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi.
    Synthesis and characterization of nanostructured Bi2O3-doped cerium oxides fabricated by PVA polymerization process2008Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 34, nr 8, s. 1949-1953Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bi2O3-doped ceria oxygen-ion conductors were prepared by a wet chemical synthesis method, which is per-formed by polymerization of polyvinyl-alcohol (PVA). The experiments showed that Bi2O3-CeO2 solid solution with 9.2 nm grains and pure fluorite type phase can be synthesized at a calcination temperature of 500 degrees C by PVA polymerization process. X-ray analysis revealed that high density narrostructured bulks could be prepared at a sintering temperature of 900 degrees C, and these bulk samples with an average grain size less than 70 nm could effectively be obtained at various heating rates during sintering. Oxygen-ion conductivity increased with the increase of dopant concentrations between 5 mol% and 15 mol% in present study.

  • 17.
    Lyu, Yezhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi. School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, PR China .
    Sun, Yufu
    School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, PR China .
    Jing, Fengyu
    School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, PR China .
    On the Microstructure and Wear Resistance of Fe-based Composite Coatings Processed by Plasma Cladding with B4C Injection2015Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, nr 9, s. 10934-10939Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fe-based composite coatings were fabricated on Q235 steel substrate by plasma cladding. B4C particles were injected at the center and edge of the melting pool as strengthening phase. Scanning electron microscopy and pin-on-disc tribometer were applied to study the microstructure and wear resistance of the coatings. The results showed that the central injected B4C particles dissolved during plasma cladding and cementite generated. Edge injected B4C particles remained and performed metallurgical bonding with the metal matrix. With Fe-based coating containing edge injected B4C particles, wear resistance increased largely and the wear rate became 1/8 of the Q235 substrate. Afterwards, Fe-based coatings with edge injected B4C particles were prepared on real pieces of 50 picks and 12 chutes, which were taken into field probations. Average service lives of the coated picks and chutes increased 3.4 times and 5.6 times, respectively, compared with the conventional 16Mn and 42CrMo pick and chute components.

  • 18.
    Malek Khachatourian, Adrine
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM. Iran University of Science and Technology, Iran .
    Golestani-Fard, Farhad
    Sarpoolaky, Hossein
    Vogt, Carmen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Microwave assisted synthesis of monodispersed Y2O3 and Y2O3:Eu3+ particles2015Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, nr 2, s. 2006-2014Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Monodisperse spherical Y2O3 and Y2O3:Eu3+ nanocrystalline particles with particle size between 100 nm and 350 nm were successfully prepared by microwave assisted urea precipitation method followed by a thermochemical treatment. Fast microwave heating, controlled decomposition of urea and burst nucleation of metal ions in aqueous solution led to the formation of non-aggregated spherical particles with narrow size dispersion. The particle size and size dispersion was controlled by adjusting the urea/metal ions ratio, the metal ions concentration, the reaction time and the temperature. X-ray diffraction (XRD) analysis indicated that the as prepared particles have Y(OH)CO3 composition, which converted to highly crystalline cubic Y2O3 after calcination at temperatures above 600 degrees C. The calcined Y2O3 particles preserved the spherical morphology of the as prepared particles and exhibited polycrystalline structure. The size of the crystallites increased from similar to 8 nm to similar to 37 nm with the increase of the calcination temperature from 500 degrees C to 900 degrees C. In order to transform these nanostructures to luminescent composition, Eu3+ doping has been performed. Y2O3:Eu3+ particles inherited the morphology and polycrystalline structure of the host Y2O3 particles. Photoluminescence (PL) analysis of Y2O3:Eu3+ particles showed a strong red emission peak at 613 nm corresponding to D-5(0)-F-7(2) forced electric dipole transition of Eu3+ ions under UV excitation. All these critical characteristics, and being heavy-metal free, make these particles useful for bioimaging, and display devices.

  • 19. Mushtaq, N.
    et al.
    Xia, Chen
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Dong, W.
    Abbas, G.
    Raza, R.
    Ali, A.
    Rauf, S.
    Wang, B.
    Kim, J. -S
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. Hubei University, Wuhan, Hubei, China.
    Perovskite SrFe1-xTixO3-δ (x < = 0.1) cathode for low temperature solid oxide fuel cell2018Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 44, nr 9, s. 10266-10272Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stable and compatible cathode materials are a key factor for realizing the low-temperature (LT, ≤600 °C) operation and practical implementations of solid oxide fuel cells (SOFCs). In this study, perovskite oxides SrFe1-xTixO3-δ (x &lt; = 0.1), with various ratios of Ti doping, are prepared by a sol-gel method for cathode material for LT-SOFCs. The structure, morphology and thermo-gravimetric characteristics of the resultant SFT powders are investigated. It is found that the Ti is successfully doped into SrFeO3-δ to form a single phase cubic perovskite structure and crystal structure of SFT shows better stability than SrFeO3-δ. The dc electrical conductivity and electrochemical properties of SFT are measured and analysed by four-probe and electrochemical impedance spectra (EIS) measurements, respectively. The obtained SFT exhibits a very low polarization resistance (Rp),.01 Ωcm2 at 600◦C. The SFT powders using as cathode in fuel cell devices, exhibit maximum power density of 551 mW cm−2 with open circuit voltage (OCV) of 1.15 V at 600◦C. The good performance of the SFT cathode indicates a high rate of oxygen diffusion through the material at cathode. By enabling operation at low temperatures, SFT cathodes may result in a practical implementation of SOFCs.

  • 20. Najam Khan, M.
    et al.
    Al-Hinai, M.
    Al-Hinai, A.
    Dutta, Joydeep
    School of Engineering and Technology, Asian Institute of Technology, Thailand.
    Visible light photocatalysis of mixed phase zinc stannate/zinc oxide nanostructures precipitated at room temperature in aqueous media2014Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 40, nr 6, s. 8743-8752Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aqueous synthesis was used to obtain zinc stannate (ZTO) nanoparticles by precipitation at room temperature. Pourbaix diagrams were employed to formulate the precipitation reactions and synthesis process. Solution pH was controlled during the synthesis process as a major variable. The synthesized ZTO particles showed good photocatalytic activity under UV light irradiation. In order to improve visible light photocatalytic activity of ZTO nanoparticles, mixed phase zinc stannate/zinc oxide (ZnO) composites were prepared by co-precipitation at room temperature. Effects of precursor concentrations on the size and morphology of the obtained particles are reported. The composite ZTO/ZnO showed better photodegradation under visible light irradiation compared to ZTO and ZnO nanoparticles with methylene blue (MB) as a test chemical contaminant. Experiments were designed to elaborate on the active species for photocatalytic degradation of the dye and are reported here. Benzoquinone (BQ) was found to be the most effective scavenger, reducing the photodegradation considerably, indicating that O2-• plays a major role in MB degradation since 50% reduction in photocatalytic activity was observed.

  • 21.
    Najmoddin, Najmeh
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Beitollahi, Ali
    Kavas, Huseyin
    Mohseni, Seyed Majid
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Rezaie, Hamidreza
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    XRD cation distribution and magnetic properties of mesoporous Zn-substituted CuFe2O42014Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 40, nr 2, s. 3619-3625Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of Zn doping on magnetic properties of mesoporous CuFe2O4 has been investigated. The cation distribution amongst tetrahedral (A) and octahedral (B) sites of the lattice has been calculated analytically by X-ray diffraction (XRD), using the Bertaut method. The results reveal that these ferrites belong to the family of mixed or partially inverse spinels and Zn2+ ions occupy mainly the A site while Cu2+ ions have more tendency for the B-site. The magnetic moments estimated from cation distribution do not coincide with the magnetization data obtained from the SQUID-VSM technique. This is attributed to the core shell structure of nanoparticles and non-collinearity of spins at the surface or spin canting in the sublattices of Zn-substituted CuFe2O4 nanoparticles. The temperature dependence of the zero field cooled (ZFC) and field cooled (PC) magnetization curves of mesoporous Cu0.75Zn0.25Fe2O4 confirms the presence of superparamagnetic phase at room temperature.

  • 22.
    Olupot, Peter Wilberforce
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    Jonsson, Stefan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi.
    Byaruhanga, Joseph K.
    Development and characterisation of triaxial electrical porcelains from Ugandan ceramic minerals2010Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 36, nr 4, s. 1455-1461Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ten formulations of triaxial porcelain composed from 30-60% clay, 20-45% feldspar and 20-25% sand, were prepared from raw materials sourced from Ugandan deposits. Specimens were made using the plastic extrusion method and characterized in terms of constituent oxide composition, flexural strength, fracture toughness, dielectric strength, microstructure and phase properties using ICP-AES analyses, 4-point load strength test, Vicker's indentation, FEG-SEM and powder-XRD analyses, respectively. XRD studies revealed that the crystalline phases are mullite and quartz and their intensity is almost identical for all samples fired at 1250 degrees C but there is a decrease in quartz content as temperature is increased. Samples with 20% sand content resulted in higher density, modulus of rupture and fracture toughness compared to those containing 25% sand. The major factor influencing bending strength was found lobe porosity in samples as opposed to crystallinity. A sample with 67.3% SiO2, 20.2% Al2O3, 3.4% K2O and 6.3% others exhibited best properties. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

  • 23. Sozeri, H.
    et al.
    Kurtan, U.
    Topkaya, R.
    Baykal, A.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Polyaniline (PANI)-Co0.5Mn0.5Fe2O4 nanocomposite: Synthesis, characterization and magnetic properties evaluation2013Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 39, nr 5, s. 5137-5143Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polyaniline (PANI)/Cobalt-manganese ferrite, (PANI)/Co0.5Mn0.5Fe2O4, nanocomposite was synthesized by oxidative chemical polymerization of aniline in the presence of ammonium peroxydisulfate (APS). Microwave assisted synthesis method was used for the fabrication of core CoFe2O4 nanoparticles. The structural, morphological, thermal and magnetic properties of the nanocomposite were investigated in detail by X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The average crystallite size of (PANI)/Co0.5Mn0.5Fe2O4 nanocomposite by the line profile method was 20 +/- 9 nm. The magnetization measurements revealed that (PANI)/Co0.5Mn0.5Fe2O4 nanocomposite has superparamagnetic behavior with blocking temperature higher than 300 K. The saturation magnetization of the composite is considerably low compared to that of CoFe2O4 nanoparticles due to the partial replacement of Co2+ ions and surface spin disorder. As temperature decreases, both coercivity and strength of antiferromagnetic interactions increase which results in unsaturated magnetization of the nanocomposite.

  • 24.
    Tafti, Mohsen Yakhshi
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Saleemi, Mohsin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. Stockholm University, Sweden.
    Han, Li
    Nong, Ngo V.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    On the chemical synthesis route to bulk-scale skutterudite materials2016Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 42, nr 4, s. 5312-5318Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article an alternative high yield route for the synthesis of CoSb3-based unfilled skutterudites is presented. Using low-melting temperature salts of the constituents, melting and mixing them homogeneously in a hydrophobic liquid with postprocessing of the powders we achieve a more intimately mixed alloy compared to the conventional melting and metallurgical processes. The proposed method consists of a fast and low-temperature processing step followed by a thermochemical post-processing step, compared to the conventional methods of fabricating skutterudites, which require high temperatures and long processing times. Several structural characterization techniques were used to assess the mechanism of synthesis, verify the purity of the material as well as the reproducibility of the process. Detailed analysis and results are presented in support of the proposed process. Additionally, compaction of the powders with SPS technique provided a safe route to maintaining the nanopowder size and achieving low thermal conductivity (3 W/mK). The proposed method can easily be scaled up and adopted by the industry.

  • 25. Topkaya, R.
    et al.
    Kurtan, U.
    Baykal, A.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Polyvinylpyrrolidone (PVP)/MnFe2O4 nanocomposite: Sol-Gel autocombustion synthesis and its magnetic characterization2013Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 39, nr 5, s. 5651-5658Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A polyvinylpyrrolidone (PVP)/MnFe2O4 nanocomposite was prepared by the sol-gel autocombustion method and its structural, thermal, spectroscoppic, morphological and magnetic characterizations were done by XRD, FT-IR, TGA, SEM and VSM techniques. The presence of MnFe2O4 was confirmed by XRD and the size of crystallites was estimated to be 11 +/- 3 nm. Morphology analysis by SEM revealed spherical agglomerates of 15 nm. The magnetization curves confirm a superparamagnetic behavior with a blocking temperature of 287 K. The M-r/M-s value suggests the presence of uniaxial anisotropy in MnFe2O4 nanoparticles, instead of the expected cubic anisotropy according to the Stoner-Wohlfarth model. The effective magnetic anisotropy constant K-eff has been determined to be about 1.42 x 10(6) erg/cm(3) which is significantly higher than that of the bulk MnFe2O4. This suggests a strong magnetic coupling between magnetically ordered core spins and disordered surface spins of the nanoparticles in the nanocomposite.

  • 26. Yilmaz, S.
    et al.
    Nisar, J.
    Atasoy, Y.
    McGlynn, E.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Parlak, M.
    Bacaksiz, E.
    Defect-induced room temperature ferromagnetism in B-doped ZnO2013Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 39, nr 4, s. 4609-4617Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    ZnO microrods were grown on glass substrates by the spray pyrolysis method and boron was doped into the ZnO microrods by diffusion. X-ray diffraction results confirmed that the incorporation of B leads to a slight reduction in the deposit texture. Scanning electron microscopy measurements showed that the morphology of the ZnO samples changed from a microrod to nanocrystalline structure with B-doping. Photoluminescence data indicate that B-doping leads to a relative increase of the unstructured green band intensity. Magnetic measurements revealed that B-doped ZnO samples exhibited room temperature ferromagnetism related to defects, in agreement with first principles theoretical calculations.

  • 27. Zhao, Yan
    et al.
    Chen, Dengfu
    Bi, Yanyan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Long, Mujun
    Preparation of low cost glass-ceramics from molten blast furnace slag2012Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 38, nr 3, s. 2495-2500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the current paper, a low-cost technology was used to prepare glass ceramics through directly heat-treating with molten glass containing blast furnace slag and silica sand. By making use of the sensible heat of the molten slag, the energy cost was much lower than that in conventional method. The utilized ratio of slag was about 90% and the optimum heat treatment schedule for glass ceramics was confirmed by an L-9(3(4)) orthogonal test. The effect of CaF2 on the microstructure of the glass ceramics was studied by DSC, XRD and SEM, the bending strength of the glass ceramics was tested by three points bending tester. The results showed that, after the optimum heat treatment schedule of nucleation at 780 degrees C for 0.5 h and crystallization at 960 degrees C for 1.5 h, the crystalline phases were akermanite and diopside, the bending strength of the glass-ceramics was about 45.8 MPa. If CaF2 was added, a remarkable reduction of crystal size was observed, the crystallization of diopside and Ca2SiO2F2 was promoted while that of akermanite was inhibited, the bending strength of glass ceramics samples could be greatly improved to 120 MPa.

  • 28. Zhu, Jing
    et al.
    Deng, Hui
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Dong, Wenjing
    Zhang, Wei
    Li, Junjiao
    Bao, Xujin
    Polymer-assistant ceramic nanocomposite materials for advanced fuel cell technologies2017Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 43, nr 7, s. 5484-5489Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, nanocomposites of LaCePr-oxide (LCP) and Ni0.8Co0.15Al0 05LIO2-delta (NCAL) with different contents of polyvinylidene fluoride (PVDF) were prepared and applied to solid oxide fuel cells. The composite materials were characterized by X-ray diffraction analysis (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and electrochemical impedance spectrum (EIS). The effect of PVDF concentration on the conductivity and performance of the fuel cells was investigated. It was found that PVDF plays a template role of pore forming in the nanocomposites, and the changed microstructure by as-formed pores greatly influences the electrochemical property of the nanocomposites. The cell with 3 wt% PVDF heat-treated at 210 C-omicron achieved the highest power density of 982 mW cm(-2) at 520 C-omicron, which enhanced performance by more than 57% than when no heat-treatment was implemented. It is 66% higher than the cell with no PVDF and no heat-treatment. Pores formed by PVDF after heat-treatment enlarged the triple phase boundary (TPB), which results in improved fuel cell performance.

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