scholarly journals XAFS study on nanostructured (La;Sr)CoO and (La;Sr)(Co;Fe)O IT-SOFC cathodes

2014 ◽  
Vol 70 (a1) ◽  
pp. C1528-C1528
Author(s):  
Augusto Mejía Gómez ◽  
Joaquín Sacanell ◽  
Analía Soldati ◽  
Marcia Fantini ◽  
Aldo Craievich ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Pore Size ◽  
Reduction Reaction ◽  
Average Pore ◽  
X Ray ◽  
Rhombohedral Crystal Structure ◽  
Sem Study ◽  
Rhombohedral Crystal ◽  
Synchrotron Light ◽  
Mixed Ionic Electronic Conductors

In the last years, extensive research has been devoted to develop novel materials and structures with high electrochemical performance for intermediate-temperatures solid-oxide fuel cells (IT-SOFCs) electrodes. In recent works, we have investigated the structural and electrochemical properties of nanostructured La0.6Sr0.4CoO3(LSCO) and La0.6Sr0.4(Co;Fe)O3(LSCFO) cathodes, finding that they exhibit excellent electrocatalytic properties for the oxygen reduction reaction [1,2]. These materials were prepared by a pore-wetting technique using polycarbonate porous membranes as templates. Two average pore sizes were used: 200 nm and 800 nm. Our scanning electronic microscopy (SEM) study showed that the lower pore size yielded nanorods, while nanotubes were obtained with the bigger pore size. All the samples were calcined at 10000C in order to produce materials with the desired perovskite-type crystal structure. In this work, we analyze the oxidation states of Co and Fe and the local atomic order of LSCO and LSCFO nanotubes and nanowires for various compositions by X-ray absorption spectroscopies. For this purpose we performed XANES and EXAFS studies on both Co and Fe K edges. These measurements were carried out at the D08B-XAFS2 beamline of the Brazilian Synchrotron Light Laboratory (LNLS). XANES spectroscopy showed that Co and Fe only change slightly their oxidation state upon Fe addition. Surprisingly, XANES results indicated that the content of oxygen vacancies is low, even though it is well-known that these materials are mixed ionic-electronic conductors. EXAFS results were consistent with those expected according to the rhombohedral crystal structure determined in previous X-ray powder diffraction investigations.

Microwave-Assisted Solution Combustion Synthesis and Characterization of Thermoelectric Ca3Co2O6 Powders

2013 ◽  
Vol 802 ◽  
pp. 84-88
Author(s):  
Sagulthai Kahatta ◽  
Nopsiri Chaiyo ◽  
Chesta Ruttanapun ◽  
Wicharn Techitdheera ◽  
Wisanu Pecharapa ◽  
...  
Keyword(s):  
Combustion Synthesis ◽  
Solution Combustion Synthesis ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
X Ray ◽  
Microwave Assisted ◽  
Product Characterization ◽  
Rhombohedral Crystal Structure ◽  
Rhombohedral Crystal

The microwave-assisted solution combustion synthesis was applied to the initial synthesizing of Ca3Co2O6powder using glycine as a fuel and nitrate as an oxidant. The as-synthesized powders were calcined at 700-1,000ºC for 4h. Product characterization was performed using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Scanning electron microscope (SEM). The fuel-to-oxidizer molar ratio was found to affect the combustion reaction and character of the powder obtained. The phase composition of powder after calcination at various temperatures has shown that the formation of Ca3Co2O6occurs directly. The calcined powder possesses a rhombohedral crystal structure with an X-ray diffraction pattern that could be matched with the Ca3Co2O6JCPDS: 89-0629. This method is a simple way of synthesizing fine Ca3Co2O6powder with a low calcination temperature.

scholarly journals Fabrication of Porous Bone Scaffolds Using Alginate and Bioactive Glass

2019 ◽  
Vol 10 (1) ◽  
pp. 15 ◽  
Author(s):  
Jonathan Hatton ◽  
Graham Roy Davis ◽  
Abdel-Hamid I. Mourad ◽  
Nizamudeen Cherupurakal ◽  
Robert G. Hill ◽  
...  
Keyword(s):  
Bioactive Glass ◽  
Pore Size ◽  
Composite Scaffold ◽  
Average Pore Size ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Average Pore ◽  
X Ray ◽  
Novel Material

Porous composite scaffold using an alginate and bioactive glass ICIE16M was synthesized by a simple freeze-drying technique. The scaffold was characterized using compression testing, Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), X-ray microtomography (XMT) and scanning electron microscopy (SEM). The bioactivity of the scaffold was evaluated by its ability to form apatite on its surface in simulated body fluid (SBF). The data collected showed evidence that the novel material produced had an appropriate pore size for osteoconduction, with an average pore size of 110 µm and maximum pore size of 309 µm. Statistical analysis confirmed that the glass filler significantly (P < 0.05) increased the collapse yield of the scaffolds compared with pure alginate scaffolds. The ICIE16M glass had an amorphous structure, favorable for bioactivity.

scholarly journals CELL-FREE TRANSMISSION IN ADULT SWISS MICE OF A DISEASE HAVING THE CHARACTER OF A LEUKEMIA

1957 ◽  
Vol 105 (4) ◽  
pp. 307-318 ◽  
Author(s):  
Charlotte Friend
Keyword(s):  
Pore Size ◽  
Average Pore Size ◽  
Splenic Tissue ◽  
Cell Suspensions ◽  
Average Pore ◽  
X Ray ◽  
Membrane Filters ◽  
Swiss Mice ◽  
Intramuscular Injections

A disease with the characteristics of a leukemia has been found to be serially transmissible in adult Swiss mice by means of cell-free filtrates. Thus far, the disease has been transmitted through twenty-six serial passages with filtrates as well as cell suspensions. The agent readily passes through Selas 03, Berkefeld N, and gradocol membrane filters—these last having an average pore size of 220 mµ. Filtrates remain stable when stored for long periods at –70°C. or when lyophilized. Splenic tissue containing the agent, which was subjected to massive doses of x-ray (50,000 r),—far more than sufficient to kill the cells,—show undiminished infectivity. The agent is inactivated by heating to 56°C. for 30 minutes and by exposure to ether or formalin. The disease can be transmitted to adult Swiss mice or DBA/2 mice, but not to adult PRI, C3H, A, C57B1/6, or F1(C58 x BALB) mice. Intraperitoneal, subcutaneous, intracerebral, and intramuscular injections are all effective.

scholarly journals Analysis Crystal Structure of La0.7Ba(1-xSrx)0.3MnO3 by Sol-Gel Method

2020 ◽  
Vol 3 (1) ◽  
pp. 35-41
Author(s):  
Juli Hartati ◽  
Sitti Ahmiatri Saptari ◽  
Arif Tjahjono
Keyword(s):  
Crystal Structure ◽  
Sol Gel ◽  
Ammonia Solution ◽  
Hot Plate ◽  
Ionic Radii ◽  
Xrd Pattern ◽  
Gel Method ◽  
Sol Gel Method ◽  
Rhombohedral Crystal Structure ◽  
Rhombohedral Crystal

Abstrak.Penelitian tentang struktur kristal  bahan La0.7(Ba1-xSrx)MnO3  menggunakan metode sol-gel telah berhasil dilakukan. Bahan-bahan dasar yang digunakan dicampur di atas hot plate diaduk sambil ditetesi ammonia solution sehingga mencapai pH 7, selanjutnya didiamkan sampai diperoleh bentuk gel. Gel dikeringkan pada suhu 120°C, selanjutnya dilakukan pra-kalsinasi dengan suhu 650°C selama 6 jam, dilanjutkan dengan kalsinasi  pada suhu 1000°C selama 12 jam, dan kemudian disinter pada temperatur 1200°C selama 12 jam. Hasil refinement data  XRD memberikan informasi bahwa struktur kristal  La0.7(Ba1-xSrx)MnO3 adalah rombohedral dengan space grup R-3c. Penambahan substitusi ion Sr2+ mengakibatkan terjadinya penurunan intensitas dan pergeseran puncak ke arah sudut yang lebih besar. Hal ini disebabkan karena pengaruh jari-jari ion Sr2+ yang lebih kecil dibandingkan dengan jari-jari ion Ba2+ . Abstract.In this research,  La0.7(Ba1-xSrx)0.3MnO3  compound (x = 0; 0.2; 0.3; and 0.5) by sol-gel method has been investigated.  The compound used is mixed on a hot plate until reached a pH 7 when dropped ammonia solution, then let stand until turn into a gel. Dehydrated gel at 120°C, pra-calcination at 650°C for 6 hours, calcination t 1000°C for 12 hours, and sintering at 1200°C for 12 hours. The result of refinement XRD pattern shown that samples are single phase with rhombohedral crystal structure with R-3c space group. The intensity decrease and peak list shift to larger angle when Sr-substitution increased, it’s caused  ionic radii of Sr2+ is smaller than Ba2+ .

scholarly journals CH3NH3PbI3: precise structural consequences of water absorption at ambient conditions

2016 ◽  
Vol 72 (5) ◽  
pp. 716-722 ◽  
Author(s):  
Alla Arakcheeva ◽  
Dmitry Chernyshov ◽  
Massimo Spina ◽  
László Forró ◽  
Endre Horváth
Keyword(s):  
Crystal Structure ◽  
Direct Consequence ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
X Ray ◽  
Space Groups ◽  
Tetragonal Unit Cell ◽  
Synchrotron Light ◽  
The Difference

The crystal structure of the pristine (I) and aged (II) crystals of CH3NH3PbI3(hereafter MAPbI3) hybrid organic–inorganic lead iodide has been studied at 293 K with high-precision single-crystal X-ray diffraction using a synchrotron light source. We show that (I) and (II) are characterized by an identical tetragonal unit cell but different space groups:I422 for (I) andP42212 for (II). Both space groups are subgroups ofI4/mcm, which is widely used for MAPbI3. The main difference between (I) and (II) comes from the difference in hydrogen bonds between the MA+cation and the PbI3framework which is the direct consequence of H2O insertion in the aged crystal (II).

Synthesis of Ternary Semiconductor Silver Bismuth Telluride by Chemical Bath Deposition

2017 ◽  
Vol 751 ◽  
pp. 489-493 ◽  
Author(s):  
Patamaporn Termsaithong ◽  
Aphichart Rodchanarowan
Keyword(s):  
Chemical Bath Deposition ◽  
Bismuth Telluride ◽  
X Ray Diffraction ◽  
Solar Cell Application ◽  
X Ray ◽  
Rhombohedral Crystal Structure ◽  
Rhombohedral Crystal ◽  
Ternary Semiconductor ◽  
Cbd Method ◽  
Scanning Electron

In this study, the synthesis of the ternary semiconductor sensitized silver bismuth telluride (AgBiTe2: SBT) particles was produced in the solution of AgNO3, Bi (NO3)3×5H2O and Na2O3Te by using a chemical bath deposition (CBD) method and annealing at 200°C for 1 h. According to scanning electron microscopy (SEM), the particle size of SBT after annealing was bigger than before annealing. Based on X-ray diffraction, the SBT after annealing for 1h became more crystalline. In addition, the XRF data also demonstrated that the SBT powder consists of Ag, Bi, and Te as dominant elements. The XRD result confirms a successful growth of the SBT particles with rhombohedral crystal structure. Based on the obtaining results, the SBT particles were successfully synthesized and potentially applied for solar cell application.

Obtaining Ceramic Filter from Rice Husk and Kaolinitic Clay

2014 ◽  
Vol 802 ◽  
pp. 232-238 ◽  
Author(s):  
R.P.A. Souza ◽  
F.V. Motta ◽  
R.G. Carvalho ◽  
W. Acchar ◽  
E. Harima ◽  
...  
Keyword(s):  
Pore Size ◽  
Rice Husk ◽  
Average Pore Size ◽  
Mercury Porosimetry ◽  
Standard Technique ◽  
Ceramic Filter ◽  
X Ray Diffraction ◽  
Average Pore ◽  
X Ray ◽  
Kaolinitic Clay

In this study, different compositions based on rice husk carbon and kaolinitic clay aimed at obtaining ceramic filter were studied. Three compositions of 40, 60 and 80% rice husk of the total mass were prepared. The specimens were uniaxially compressed in rectangular shape at pressure of 28 MPa and were sintered at temperatures of 1100oC, 1150oC and 1200oC for 1 h. The sintered samples were characterized according to standard technique for linear shrinkage, water absorption, apparent porosity and flexural strength. Scanning Electron Microscopy (SEM) was also performed to check the average pore size, and X-Ray Diffraction (XRD) to verify existing crystalline phases, chemical analysis and mercury porosimetry. The X-ray diffraction results showed mostly alpha quartz peaks and mullite after sintering. Mercury porosimetry showed porosity of 44.33% and average pore size of approximately 8.33 μm for sample with 60% rice husk sintered at 1200°C.

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