279 research outputs found
Sheykh ül-islam Feyzullah Efendi and the Armenian Patriarch Awetik‘: a case of entangled confessional disciplining?
No full textAmong the Sheyk ül-islams, the chief religious authority of the Ottoman Empire, Feyzullah Efendi is one of the best known and most studied. This is certainly due to the incredible amount of power and wealth he was able to obtain during his tenure, as well as to his sudden and tragic end during the Rebellion of 1703. What is less known is that he played a central role in the religious and social turmoil which affected the Eastern Christian communities of the Empire at the turn of the eighteenth century, interfering directly in the ecclesiastical organization of the Syriac and especially Armenian Church. Already in 1692, when he was still a qadi in Erzurum, he meddled in the disputes between Catholic missionaries and Armenian Apostolic prelates, supporting the latter against the former and provoking the intervention of the French Ambassador, who obtained the exile of the local Armenian bishop. Few years later, once reached the summit of power, he resumed his fight against Catholic propaganda by appointing as Armenian Patriarch of Constantinople (and later of Jerusalem too) the very same bishop he had sided with in Erzurum, Awetik' Ewdokac’i. The condition behind these appointments was that Awetik‘ would have directed his efforts to stop the work of Catholic missionaries among the Armenians, punishing those who had been converted to the «Frank» religion. But why a high-ranking Ottoman officer should have been concerned by the doctrinal quarrels going on within the Eastern Christian communities? By cross-checking Ottoman, Western and Armenian sources, my chapter addresses this question, highlighting the political and entangled dimension of the Ottoman Confessionalization
Detailed survey on minimum activation energy for penetration of Ni nanoparticles into Bi-2223 crystal structure and temperature-dependent Ni diffusivity
No full textThe primary contributions of this study are not only to explore the role of diffusion annealing temperature interval 650 to 850 A degrees C on the formation of effective electron-phonon coupling or cooper-pair probabilities (percentage of clusters in the superconducting path), densities of active and dynamic electronic states at Fermi energy level, stabilization of superconductivity in the homogeneous regions, overlapping of Cu-3d and O-2p wave functions and bond strengths in the crystal matrix of Ni surface-layered Bi-2223 polycrystalline ceramics, but also to determine the temperature-dependent diffusion fast-rate and required minimum activation energy for the diffusion of Ni foreign impurities into the bulk Bi-2223 superconducting crystal structure for the first time. The dc electrical measurement results obtained show that the optimum diffusion annealing temperature is found to be 700 A degrees C for the penetration of optimum Ni concentration into the Bi-2223 crystal lattice so that the ceramic compound exposed to 700 A degrees C annealing temperature exhibits the highest electrical and superconducting properties. In this respect, the material with the minimum electrical resistivity parameters of Delta rho, rho (115K) , rho (res) and rho (norm) obtains the maximum superconducting characteristics of , and RRR. Accordingly, the annealing temperature of 700 A degrees C promotes the Bi-2223 ceramics for usage in the engineering, electro-optic, industrial and large scale applications. At the same time, the diffusion coefficients [D = D(o)exp(E/k(B)T)] determined at annealing temperature ranging from 650 to 850 A degrees C are observed to be much more significant at rather higher temperatures as compared to lower temperatures. The temperature-dependent Ni diffusion coefficient is determined to be D = 3.9707 x 10(- 7)exp[- 1.132 eV/k(B)T] for the Bi-2223 particulate solid material. Namely, the diffusion coefficient is calculated to be about 3.9707 x 10(- 7)cm(2) s(- 1) when the required minimum activation energy for the introduction of heavy metal Ni ions to the bulk Bi-2223 crystal structure is computed to be about 1.132 eV, being one of the most striking points deduced form this work
SYNTHESIS OF MAGNESIUM SILICATE FROM WHEAT HUSK ASH: EFFECTS OF PARAMETERS ON STRUCTURAL AND SURFACE PROPERTIES
No full textTERZIOGLU, Pinar/0000-0003-4114-7044WOS: 000311336800077In the present study, magnesium silicate was produced by using wheat husk ash. Wheat husk was burned at 600 degrees C to obtain an amorphous ash structure, and the ash was processed with sodium hydroxide solution with heat to extract silica. Sodium silicate solution and magnesium salts were used to synthesize magnesium silicate. The present study investigates effects of the feeding rate on magnesium silicate production (0.6 mL/min, 35 mL/min, 70 mL/min), the type of magnesium salt (MgSO4 center dot 7H(2)O or MgCl2 center dot 6H(2)O), temperature (25 degrees C or 50 degrees C), and the washing agent ( water and acetone) on the chemical composition and surface characteristics of magnesium silicate. The results demonstrated that all of the variables affected the surface characteristics of magnesium silicate, such as surface area, particle size, and pore volume. However, it was also observed that the studied parameters did not affect the chemical composition of magnesium silicate. The wheat husk ash-based magnesium silicates obtained in the experimental study had a BET surface area ranging from 79 to 91 m(2)/g and a particle size varying from 42 to 63 mu m.Yildiz Technical University, Coordination of Scientific Research Projects (BAP)Yildiz Technical University [29-07-04-YL05]This study was funded by Yildiz Technical University, Coordination of Scientific Research Projects (BAP) with project number 29-07-04-YL05
Structural and physical properties of Sm-doped Bi1.6Pb0.4Sr2Ca2-xSmxCu3Oy superconductors
No full textOzturk, Ozgur/0000-0002-0391-5551; Terzioglu, Cabir/0000-0002-3944-0367The superconducting Bi1.6Pb0.4Sr2Ca2-xSMxCu3Oy (X = 0.0, 0.0005, 0.001, 0.005, 0.01, 0.1, 0.5, 1.0, and 1.5) system was investigated for different concentrations of Sm. The structural analysis was carried out by XRD. XRD results show that the samples with substitution of various amounts of Sm for Ca transform from the major high-T-c phase (Bi-2223) to the low-T-c phase (Bi-2212). The lattice parameter data extracted from XRD showed that with increasing Sm concentration (x), the lattice parameter a increases slightly while the lattice parameter c decreases significantly. DC resistivity measurements were carried out by the standard four-probe technique in the temperature range between 25 K and 130 K. With increasing Sm substitution up to x = 0.1, the values of T-e(offset) vary between 107 K and 70 K. The samples with x > 0.1 did not show any superconducting transition down to 25 K. The critical current density measurements were performed in liquid nitrogen. Critical current density decreases with increasing Sm substitution, and it was measured to be 43 A/cm(2) for the sample with x = 0.0 at zero field. Microstructure examinations were carried out by SEM. All the reported data were discussed, and compared with earlier results on Sm and other substituted Bi-Sr-Ca-Cu-O system. (c) 2005 Elsevier B.V. All rights reserved
Investigation of some physical properties of Gd added Bi-2223 superconductors
No full textX-ray powder diffraction (XRD), scanning electron microscopy (SEM), dc electrical resistivity, critical current density and static microindentation measurements are performed to investigate some physical properties of Bi(1.8)Pb(0.35)Sr(1.9)Ca(2.1)Cu(3)Gd(x)O(y) superconducting samples with x = 0.0, 0.1, 0.3 and 0.5. We observe from the transport measurements that, for the Gd added sample, the critical transition temperature (T(c)) and the critical current density (J(c)) are decreased in comparison with that of undoped sample. In addition, surface morphology and grain connectivity of the samples are degraded and the high-T(c) phase of the samples decreases with increasing Gd addition. The indentation load versus diagonal length of the samples under different indentation loads in the range of 0.245-2.940 N are measured. The microindentation measurements showed that, for the Gd added sample, the load dependent (apparent) microhardness value (H(v)) is lower in comparison with that of the pure sample (x = 0). The values of H(v) are found to be load dependent. In addition, we extract the load independent (true) microhardness using the Kick's law, proportional specimen resistance (PSR), modified proportional specimen resistance (MPSR) and the Hays-Kendall (HK) approach and compare the true hardness with the apparent hardness. The possible reasons for the observed degradation in microstructure, superconducting and mechanical properties due to Gd addition are discussed. (C) 2010 Elsevier B.V. All rights reserved
Investigation of Cr addition effect on structural, morphological, electrical and magnetic properties of Bi(Pb)-2212 superconductors
No full textThe main purpose of this research work will assess the effect of Cr addition on the properties of Bi1.8Pb0.4Sr2CaCu2O8+d superconducting ceramics. The samples are produced from industrial powders with different amounts of Cr (0, 1, 2, 3, 4, 5, 6 and 7 wt %) by sol–gel synthesis route. The influence of doping element has been determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrical resistivity and magnetic characterizations. In particular, the eventual presence of secondary phases as a result of Cr doping on the undoped sample was investigated by using XRD. By means of SEM analysis, the Cr doping influence on the grain morphology of the samples was explored. Contrarily, the Tc,on and the Tc,off of the samples have been obtained by using electrical resistivity measurements and their behavior as a function of the Cr doping has been discussed. Finally, by performing magnetization analysis versus temperature and magnetic field, the behavior of the critical temperature Tc and of the critical current density Jc as a proportion of the Cr concentration has been discussed
Journal of Physics Conference Series
No full textWe investigated the effect of cooling rates on the microstructure and mechanical properties of Bi(1,6)Pb(0,4)Sr(2)Ca(2)Cu(3)Oy superconductors prepared by standard solid state reaction methods. The samples were annealed under identical condition and cooled with different cooling rates. The investigations consisted of Vickers microhardness, SEM and XRD measurements. XRD examination of the samples showed that high percentage of Bi-2212 phase was observed and low-T(c) phase increased with increasing the cooling rates. From SEM analysis, flake-like grains were more pronounced with increasing cooling rates. The indentation load versus diagonal length of the samples under different indentation loads in the range of 0.245-2.940 N were presented. We calculated Vickers hardness, Young's modulus, yield strength, fracture toughness values. These mechanical properties of the samples were found to be load and cooling rate dependent. In addition, we calculated the load independent microhardness, Young's modulus, and yield strength and fracture toughness of the samples using different models. The possible reasons for the observed changes in microstructure and mechanical properties of the samples due to cooling rates were discussed
Solubility limit of tetravalent Zr nanoparticles in Bi-2223 crystal lattice and evaluation of fundamental characteristic properties of new system
No full textIn this comprehensive work, we focus sensitively on the changes of microstructural, electrical, superconducting and mechanical properties belonging to the bulk Bi1.7Pb0.4Sr2.0Ca2.0ZrxCu3.1Oy materials with the different Zr nanoparticles (0 a currency sign x a currency sign 1.0) inserted in the superconducting matrix. The characterizations of the materials prepared are experimentally performed by bulk density, dc resistivity (rho-T), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-ray (EDX) and Vickers microhardness (H (v) ) investigations. It is found that all the characteristics given above (especially superconducting properties) degrade considerably with the increment in the Zr addition level, and in fact they reach to the global minimum points in case of the maximum dopant level. The main reason of the rapid decrement in the electrical and superconducting properties stems from the presence of the localization problem in the Cu-O-2 consecutively stacked layers. Likewise, the Zr foreign addition increases the artificial random defects, dislocations and grain boundary weak-links in the superconducting system, even being favored by the SEM examinations. At the same time, the EDX surveys indicate that the Zr nanoparticles in the tetravalent state prefer to substitute for the divalent states of the Cu inclusions through the crystal structure as a result of their close ionic radius values (86 pm for Zr4+ ion and 87 pm for Cu2+ ion). Thus, the differentiation of the electronegativity reduces the mobile hole concentration in the Cu-O-2 slabs. Additionally, the XRD experimental findings show that there is a systematic decrement in the Bi-2223 (high) phase up to the Zr concentration level of x = 0.70 beyond which new characteristics peaks of ZrO2 appear immediately. This is in relation to the fact that the solubility limit corresponding to the Zr foreign impurity in the Bi-2223 system is about x = 0.70. Similarly, the regular decrement in both the c-axis length and crystallite size with the dopant confirms the deterioration of the superconducting properties. Furthermore, the dramatic reduction of the H (v) values stems from the suppression of the crystallinity and connection quality in the intergrain coupling of the superconducting samples exhibiting typical Indentation Size Effect behavior due to the existence of both elastic and plastic deformations in the system
Characterization of Wheat Hull and Wheat Hull Ash as a Potential Source of SiO2
No full textTERZIOGLU, Pinar/0000-0003-4114-7044;WOS: 000323370400097Wheat is a very important agricultural product, and is among the grains that has the highest sustenance value in the world. Every year large amounts of wheat hull is produced which has a low economic value. The present study aimed to characterize the structure of wheat hull and wheat hull ash obtained after burning wheat hull at 400 to 1000 degrees C for 5 h. This study also investigated the potential of wheat hull as a source for the production of silica xerogel. X-ray diffraction patterns, scanning electron microscope micrographs, the chemical properties, the particle morphology, particle size, surface chemistry of wheat hull, wheat hull ash, and its silica xerogels were determined by the use of various instruments and analysis techniques. A temperature of 700 degrees C was found to be the optimum ashing temperature with maximum amorphous silica content. The BET surface area of ashes ranged from 7.21 to 0.11 m(2)/g. The study demonstrated that silica xerogel powder with 93.9% silica content was obtained by the use of wheat hull after heat treating at 700 degrees C for 5 h.Yildiz Technical University, Coordination of Scientific Research Projects (BAP)Yildiz Technical University [29-07-04-YL05]This study was funded by Yildiz Technical University, Coordination of Scientific Research Projects (BAP) with the project number 29-07-04-YL05
Investigation of Sm → Ca substitution in Bi(Pb)SrCaCuO high temperature superconductor by low field AC magnetic susceptibility
No full textYegen, Dincer/0000-0003-3180-600X; Terzioglu, Cabir/0000-0002-3944-0367We have investigated the effect of Sm substitution in Bi(Pb)SrCaCuO system by performing AC susceptibility (chi = chi' + i chi ''), XRD (X Ray Diffraction) and SEM (Scanning Electron Microscopy) measurements. The Sm -> Ca substitution (Bi(1.)6Pb(0.4)Sr(2)Ca(2-x)Sm(x)Cu(3)O(y)) was carried out by conventional solid-state reaction method. The susceptibility measurements were carried out at different values of the AC field amplitudes. The imaginary part of susceptibility is used to estimate the intergranular critical current density by means of the Bean's model. The intergranular critical current density (J(c)) of pure sample is found to be about 68 A/cm(2) at 95 K. The intergranular J(c) is seen to decrease with increasing Sm substitution. XRD pattern and SEM micrographs are given to provide information about Bi-2223 phase and grain size respectively
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