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Numrering	Referens	Omslagsbild	Hitta
1.	Antti, Marta-Lena, et al. (författare) Phase reactions in a hot pressed TiC/Si powder mixture 2012 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 38:3, s. 1999-2003 Tidskriftsartikel (refereegranskat)abstract This work investigated the possibility of producing dense Ti3SiC2 by hot pressing TiC/Si powders. A hot press with graphite heating elements was used for densification and the phase reactions of some hot pressed samples were further evaluated by pressureless heating in a dilatometer. The density and phase composition of the heat treated samples were evaluated using Archimedes principle and by x-ray diffractometry respectively. Hot pressing resulted in a low Ti3SiC2 yield; the main phases were TiC and TiSi2 regardless of starting powder composition, temperature, holding time or pressure. A second heating without pressure resulted in Ti3SiC2 formation, but only in samples initially hot pressed at 1300 °C or lower. At higher hot pressing temperatures, thin oxide layers on particle surfaces were locked into the structure. Acting as diffusion barriers, they prevented the Ti3SiC2 forming reaction. In hot pressed samples the density was significantly higher than in samples sintered without pressure.
2.	Batool, S S., et al. (författare) Investigation of dielectric relaxation behavior of electrospun titanium dioxide nanofibers using temperature dependent impedance spectroscopy 2013 Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 39:2, s. 1775-1783 Tidskriftsartikel (refereegranskat)abstract The electrospinning method has been utilized in the fabrication of titanium dioxide nanofibers (TNFs) with an average diameter of similar to 50 nm and length of 100 um. Effect of temperature on the dielectric relaxation behavior of the fabricated nanofibers have been studied using AC impedance spectroscopy. The morphological, structural and compositional aspects as well as the optical properties of the TNFs have been investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX) and ultraviolet visible (UV vis) absorption spectrum. The permittivity behavior of the device at the frequency below 10(2) Hz shows the relaxation contribution along with the electrode polarization. Dielectric loss peak in loss tangent also confirms the presence of relaxing dipoles in TNFs. The AC conductance as a function of frequency confirms the semiconducting nature of TNFs and obeys Jonschers power law except a small deviation in the low frequency region. DC conductivity increases with increase in temperature.
3.	Ebin, Burcak, et al. (författare) Preparation and electrochemical properties of spinel LiFexCuyMn1.2O4 by ultrasonic spray pyrolysis 2014 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 40:1, s. 1019-1027 Tidskriftsartikel (refereegranskat)abstract 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.
4.	Imran, Z., et al. (författare) Excellent humidity sensing properties of cadmium titanate nanofibers 2013 Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 39:1, s. 457-462 Tidskriftsartikel (refereegranskat)abstract We report humidity sensing characteristics of CdTiO3 nanofibers prepared by electrospinning. The nanofibers were porous having an average diameter and length of similar to 50-200 nm and similar to 100 mu m, respectively. The nanofiber humidity sensor was fabricated by defining aluminum electrodes using photolithography on top of the nanofibers deposited on glass substrate. The performance of the CdTiO3 nanofiber humidity sensor was evaluated by AC electrical characterization from 40% to 90% relative humidity at 25 degrees C. The frequency of the AC signal was varied from 10(-1) to 10(6) Hz. Fast response time and recovery time of 4 s and 6 s were observed, respectively. The sensor was highly sensitive and exhibited a reversible response with small hysteresis of less than 7%. Long term stability of the sensor was confirmed during 30 day test. The excellent sensing characteristics prove that the CdTiO3 nanofibers are potential candidate for use in high performance humidity sensors.
5.	Imran, Z, et al. (författare) Fabrication of cadmium titanate nanofibers via electrospinning technique 2012 Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 38:4, s. 3361-3365 Tidskriftsartikel (refereegranskat)abstract Here we present an electrospinning technique for the fabrication of cadmium titanate/polyvinyl-pyrrolidone composite nanofibers. The composite nanofibers are then annealed at 600 degrees C to obtain ilmenite rhombohedral phase cadmium titanate nanofibers. The structure, composition, thermal stability and optical properties of as synthesized and annealed cadmium titanate nanofibers are characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy. The average diameter and length of the nanofibers are found to be similar to 150-200 nm and similar to 100 mu m, respectively.
6.	Israr Qadir, Muhammad, et al. (författare) Fabrication of ZnO nanodisks from structural transformation of ZnO nanorods through natural oxidation and their emission characteristics 2014 Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 40:1, s. 2435-2439 Tidskriftsartikel (refereegranskat)abstract An environmentally benign natural oxidation based synthetic technique has been developed to grow and transform the ZnO nanorods into nanodisks at a very mild temperature of 55 degrees C with excellent features of its novelty and reproducibility. Metallic zinc foil and formamide solution have been utilized as substrate and reacting solution, respectively, for the growth of ZnO nanostructures. The optimized values of temperature, concentration of formamide and the reaction time are achieved to obtain the controlled and desired nanoscale morphologies. Detailed mechanism of the structural transformation of the nanorods into nanodisks has been discussed. Strong ultraviolet emission peak along with the much weaker deep level defects related emission has been realized in the microphotoluminescence spectrum. A visible red-shift and decrease in the intensity of ultraviolet peak are observed with increasing range of temperature from 20 to 300 K.
7.	Jamil, Hira, et al. (författare) Electrospun titanium dioxide nanofiber humidity sensors with high sensitivity 2012 Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 38:3, s. 2437-2441 Tidskriftsartikel (refereegranskat)abstract Titanium dioxide nanofibers were synthesized using electrospinning technique. The nanofibers were porous with an average diameter and length of similar to 150 nm and 200 p,m, respectively. Humidity-sensing devices were fabricated by lithographically defined aluminum electrodes on top of the nanofibers deposited on silicon dioxide grown thermally on a silicon substrate. The performance of a TiO2 nanofiber humidity sensor was tested by AC and DC electrical measurements at 40-90% relative humidity. The response and the recovery time were 1 s and 4 s, respectively, between 40% and 90% relative humidity. The sensitivity of the TiO2 humidity sensor in the range of 40-90% RH was 150 M Omega/%RH and 20 M Omega/%RH at 10 Hz and 100 Hz, respectively. The excellent sensing characteristics are attributed to the porous nature and the small diameter of the nanofibers.
8.	Jamil-Rana, Sadaf, et al. (författare) Naturally oxidized synthesis of ZnO dahlia-flower nanoarchitecture 2014 Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 40:8, s. 13667-13671 Tidskriftsartikel (refereegranskat)abstract Three dimensional ZnO dahlia-flowers have been engineered at room temperature relying on natural oxidation based aqueous chemical synthetic approach. Glycine abetted multicomponent isotropic morphology has been synthesized through the conglomeration of thin nanopetals as building blocks with highly large surface area to volume ratio. Highly controllable morphology of thin nanopetals is achieved by stabilizing their polar faces through the adsorption of reactive hydroxyl and amide functions of glycine. Fourier transform infrared conclusions also exemplify good corroboration towards the use of organic additives. Moreover, the synthesized ZnO flowers have been utilized to fabricate cholesterol biosensor and biosensing measurements which have been performed over the cholesterol concentration range of 1 x 10(-6) M to 1 x 10(-3) M.
9.	Jurkow, Dominik, et al. (författare) Investigation of High Temperature Co-fired Ceramics sintering conditions using Taguchi Design of the experiment 2014 Ingår i: Ceramics International. - : Elsevier Ltd. - 0272-8842 .- 1873-3956. ; 40:7 PART B, s. 10447-10455 Tidskriftsartikel (refereegranskat)abstract Influence of sintering conditions of High Temperature Co-fired Ceramics on surface roughness, density and shrinkage of the sintered samples is presented in this paper. The investigations were conducted using Taguchi Design of the experiment. Mathematical statistics was applied in the estimation of the optimal process conditions. The estimation accuracy was verified by real measurements.
10.	Kero, Ida, et al. (författare) Carbon atmosphere effect on on Ti3SiC2 based composites made from TiC/Si powders 2010 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 36:4, s. 1259-1263 Tidskriftsartikel (refereegranskat)abstract The previous termeffect of carbonnext term activity and CO pressure in the furnace previous termatmospherenext term is investigated with respect to the phase reactions during heat treatment of TiC/Si powders. Special attention is given to the production and decomposition of Ti3SiC2. Samples were heated in graphite and alumina furnaces, connected to a dilatometer which enabled the in-situ analysis of the phase reactions. The phase compositions of the heat treated samples were determined by x-ray diffraction. The reducing previous termatmospherenext term of the graphite furnace enhanced the reactivity of the starting powder and enabled phase reactions to take place at a lower temperature than in the alumina furnace. TiSi2 and SiC phases formed at temperatures below the melting point of Si and were continuously consumed at higher temperatures. Ti3SiC2 formed at the melting point of Si regardless of furnace previous termatmosphere.next term No decomposition of the Ti3SiC2 was observed in either furnace.
11.	Kero, Ida, et al. (författare) Effect of the amounts of silicon on the in situ synthesis of Ti3SiC2 based composites made from TiC/Si powder mixtures 2010 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 36:1, s. 375-379 Tidskriftsartikel (refereegranskat)abstract This paper describes how variations in silicon content and heat treatment influence on the phase composition of TiC/Si powder mixtures during heat treatment. The sintering procedure is investigated with respect to the phases produced with a particular emphasis on maximisation of the Ti3SiC2 content. The heat treated products have been analysed using scanning electron microscopy, energy dispersive spectroscopy and x-ray diffractometry. In the heat treated products Ti3SiC2 and TiC are the dominant phases and SiC and TiSi2 are found in smaller (0-30vol%) amounts. The composition was found to depend on both Si content and heat treatment temperature and time. The silicon content can be optimised with respect to maximum Ti3SiC2 production, but its value changes with different temperature programs. The highest amount (56 vol%) of Ti3SiC2 is achieved by heat treating powder mixtures of initial composition 3TiC/2.2Si at 1350° for 1 h. Heat treatment at lower temperatures (1250-1300 °C) results in an incomplete reaction and production of TiSi2.
12.	Kero, Ida, et al. (författare) Phase reactions associated with the formation of Ti3SiC2 from TiC/Si powders 2011 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 37:7, s. 2615-2619 Tidskriftsartikel (refereegranskat)abstract The objective of this paper was to investigate the high temperature phase reactions that take place in a 3TiC/2Si powder mixture during heating. Special attention was paid to the formation of Ti3SiC2 and to the evaporation of gases. Differential scanning calorimetry and thermogravimetry were used for in situ analysis of the phase reactions. Samples were heated at a rate of 5 K/min to various temperatures between 890 and 1450 °C and then cooled at a rate of 20 K/min. Heat treated samples were analysed by X-ray diffractometry. The first phase to form was TiSi2, which was consumed in the Ti3SiC2 forming reactions. No decomposition of Ti3SiC2 was observed at temperatures below 1450 °C. Evaporation of CO(g) and small amounts of Si(g) were detected at 1430 °C.
13.	Khan, M. Ajmal, et al. (författare) Effect of titania concentration on the grain boundary conductivity of calcium-doped ceria electrolyte 2014 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 40:7, s. 9775-9781 Tidskriftsartikel (refereegranskat)abstract 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. (författare) Temperature dependent magnetic properties of CoFe2O4/CTAB nanocomposite synthesized by sol gel auto-combustion technique 2013 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:6, s. 6551-6558 Tidskriftsartikel (refereegranskat)abstract 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.
15.	Najam Khan, M., et al. (författare) Visible light photocatalysis of mixed phase zinc stannate/zinc oxide nanostructures precipitated at room temperature in aqueous media 2014 Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 40:6, s. 8743-8752 Tidskriftsartikel (refereegranskat)abstract 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.
16.	Najmoddin, Najmeh, et al. (författare) XRD cation distribution and magnetic properties of mesoporous Zn-substituted CuFe2O4 2014 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 40:2, s. 3619-3625 Tidskriftsartikel (refereegranskat)abstract 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.
17.	Nunez-Gonzalez, Beatriz, et al. (författare) Spark-plasma-sintering kinetics of ZrC-SiC powder mixtures subjected to high-energy co-ball-milling 2013 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:8, s. 9691-9697 Tidskriftsartikel (refereegranskat)abstract The effect of SiC addition (5, 17.5, or 30 vol%) on the spark-plasma sinterability of ZrC ultra-high-temperature ceramics (UHTC) was investigated as a function of the intensity of high-energy co-ball-miffing. It was found that the spark-plasma-sintering (SPS) kinetics of the ZrC- SiC powder mixtures is enhanced progressively with increasing co-milling time, which is due to the progressive refinement of the crystallite sizes. It was also found that in practice the SiC addition is beneficial for the SPS kinetics of ZrC if the co-milling time is short enough so as to refine the SiC crystallite size only to the submicrometre range, although the improvement in sinterability does not correlate with the SiC content. On the contrary, the SiC addition is increasingly detrimental for those co-milling times that promote SiC refinement to the nanoscale. This unexpected trend is due to slower ZrC crystallite size refinement in the presence of SiC and, especially, to the complex role played during SPS by the passivating SiO2 films formed on the SiC particles, and is different from what has been observed in ZrB2-SiC. Finally, implications of interest for the UHTC community are discussed.
18.	Olupot, Peter Wilberforce, et al. (författare) Development and characterisation of triaxial electrical porcelains from Ugandan ceramic minerals 2010 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 36:4, s. 1455-1461 Tidskriftsartikel (refereegranskat)abstract 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.
19.	Sadollahkhani, Azar, et al. (författare) Photocatalytic properties of different morphologies of CuO for the degradation of Congo red organic dye 2014 Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 40:7, s. 11311-11317 Tidskriftsartikel (refereegranskat)abstract In this study, Congo red organic dye was degraded by different morphologies of CuO and it was found that CuO nanorods are more favorable for the degradation of Congo red due to their more specific surface area and sensitive surface for the Congo red. All the CuO nanostructures were prepared by low temperature aqueous growth method. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques were used for the morphological and structural characterization of CuO nanostructures. The relative degradation of Congo red for nanorods, nanoleaves and nanosheets was in order 67%, 48% and 12% respectively.
20.	Sozeri, H., et al. (författare) Polyaniline (PANI)-Co0.5Mn0.5Fe2O4 nanocomposite : Synthesis, characterization and magnetic properties evaluation 2013 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:5, s. 5137-5143 Tidskriftsartikel (refereegranskat)abstract 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.
21.	Stjernberg, Jesper, et al. (författare) Laboratory scale study of the degradation of mullite/corundum refractories by reaction with alkali-doped deposit materials 2013 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:1, s. 791-800 Tidskriftsartikel (refereegranskat)abstract Refractory bricks based on mullite and corundum, commonly used in rotary kilns for iron ore pellet production, and depositmaterial from an iron ore pellet production kiln, were used in laboratoryscale tests to investigate refractory/depositreactions and the infiltration of deposit components into the refractory bricks. The materials tested were in both monolithic form and in the form of powder. Alkali metal carbonates (containing sodium and potassium) were used as corrosive agents, to increase reaction kinetics. The morphological changes and active chemical reactions at the refractory/deposit interface in the samples were characterized by scanning electron microscopy. X-ray diffraction showed that alkali metals react with the mullite in the bricks, this being more pronounced in the case of sodium than potassium. Phases such as nepheline (Na2O·Al2O3·2SiO2), kalsilite and kaliophilite (both K2O·Al2O3·2SiO2), and leucite (K2O·Al2O3·4SiO2) were formed as a consequence of reactions between alkali metals and the refractory bricks. The formation of these phases causes volume expansions of between 20% and 25% in the brick materials, which accelerate degradation.
22.	Stjernberg, Jesper, et al. (författare) Microstructural characterization of alkali metal mediated high temperature reactions in mullite based refractories 2010 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 36:2, s. 733-740 Tidskriftsartikel (refereegranskat)abstract Two types of refractory bricks were used in reaction tests with slag from a production kiln for iron ore pellet production. Electron microscopy was used to characterize morphological changes at the slag/brick interface and active chemical reactions. Phases such as kalsilite, nepheline and potassium β-alumina form, in a layered structure, as a consequence of alkali metals migration in the brick. Larger hematite grains (50-100 μm) in the slag remain at the original slag/brick interface, while smaller grains dissolve and move through the partly dissolved brick bulk, and forms micrometer sized needle shaped crystals deeper in the lining material. Thermodynamic simulations predict the formation of a solid solution between hematite and corundum which is also observed in the reaction zone after extended time periods.
23.	Suarez, M., et al. (författare) Analysis of the upconversion processes of Nd3+ ions in transparent YAG ceramics 2014 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 40:10, s. 15951-15956 Tidskriftsartikel (refereegranskat)abstract Optical properties of Nd3+ ions in YAG transparent ceramics have been analysed. The samples were prepared by a high temperature (1650 and 1680 degrees C) sintering followed by hot isostatic pressing (HIP) at 1650 or 1700 degrees C in order to obtain a well-homogeneous diffusion of the ions and functional transparency. The emission and luminescence decay curves from the F-4(3/2) metastable laser level of these samples are very similar to the ones obtained on crystal samples grown with the Czochralski method. However, excitation upconversion spectra obtained detecting at 590 nm for the transparent ceramic samples present important differences compared to the bulk YAG crystal, which can be explained by a change in the upconversion mechanism involved and the different arrangements of the Nd3+ ions in the YAG matrix. The analysis of the upconversion excitation spectra is shown to be a good method to detect the differences between the positions occupied by the Nd3+ ions in different matrices.
24.	Suarez, M., et al. (författare) Effect of freeze-drying treatment on the optical properties of SPS-sintered alumina 2013 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:6, s. 6669-6672 Tidskriftsartikel (refereegranskat)abstract This study looks at the influence of alumina powder processing on the preparation of transparent alumina by Spark Plasma Sintering (SPS). Zeta potential measurements were carried out on alumina suspensions in order to determine the best dispersion conditions. Stable slurries were submitted to a spray freeze drying process and their sintering behavior was compared with the corresponding non spray freeze dried powders. Transparent alumina samples were successfully prepared from alumina powders by Spark Plasma Sintering. An optical model considering pore and grain size distributions has been developed to obtain information about porosity in dense materials. It was found that the final density and, accordingly, the optical properties were improved when spray freeze dried starting powder was used.
25.	Taheri, Mahdiar, et al. (författare) High/room temperature mechanical properties of 3Y-TZP/CNTs composites 2014 Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 40:2, s. 3347-3352 Tidskriftsartikel (refereegranskat)abstract Spark Plasma Sintering (SPS) method was practiced, in the current investigation, to obtain fully dense materials with an excellent dispersion of MWCNTs (Multi-walled Carbon Nanotubes) within the matrix. Scanning and transmission electron microscopy micrographs as well as Raman Spectroscopy revealed no conspicuous signs of damages on the nanotubes' structure, as a result of applying appropriate processing measures. Measurements of mechanical properties' revealed the value of 15.2 +/- 0.4 MPa m(1/2) for indentation fracture toughness, impling our success to align transformation toughening (while the zirconia has the grain size around 1 mu m) with the effects of MWCNTs addition (5 wt%). High temperature mechanical properties of the composites have been investigated using Mechanical Spectroscopy (MS) up to 1600 K at frequency equal to 1 Hz. The MS results proved that CNTs could hinder grain-boundary sliding and subsequently lead to an enhanced creep resitance at high temperatures.

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