Structural and dielectric studies of Zr and Co co-substituted Ni0.5Zn0.5Fe2O4 using sol-gel auto combustion method

Science.gov (United States)

Jalaiah, K.; Vijaya Babu, K.; Rajashekhar Babu, K.; Chandra Mouli, K.

2018-06-01

Zr and Co substituted Ni0.5Zn0.5 ZrxCuxFe2-2xO4 with x values varies from the 0.0 to 0.4 in steps of 0.08 wt% ferrites synthesized by using sol-gel auto combustion method. The XRD patterns give evidence for formation of the single phase cubic spinel. The lattice constant was initially decreased from 8.3995 Å to 8.3941 Å with dopant concentration for x = 0.00-0.08 thereafter the lattice parameter steeply increased up to 8.4129 Å fox x = 0.4 with increasing dopant concentration. The estimated crystallite size and measured particle sizes are in comparable nano size. The grain size initially increased 2.3137-3.0430 μm, later it decreased to 2.2952 μm with increasing dopant concentration. The prepared samples porosity shows the opposite trend to grain size. The FT-IR spectrum for prepared samples shows the Fd3m (O7h). The wavenumber for tetrahedral site increased from 579 cm-1 to 593 cm-1 with increasing dopant concentration and the wavenumber of octahedral site are initially decreased from 414 cm-1 to 400 cm-1 for x = 0.00 to x = 0.08 later increased to 422 cm-1 with increasing dopant concentration. The dielectric constant increased from 8.85 to 34.5127 with dopant increasing concentration. The corresponding loss factor was fallows the similar trend as dielectric constant. The AC conductivity increased with increasing dopant concentration from 3.0261 × 10-7 S/m to 4.4169 × 10-6 S/m.

An intensity map of hydrogen 21-cm emission at redshift z approximately 0.8.

Science.gov (United States)

Chang, Tzu-Ching; Pen, Ue-Li; Bandura, Kevin; Peterson, Jeffrey B

2010-07-22

Observations of 21-cm radio emission by neutral hydrogen at redshifts z approximately 0.5 to approximately 2.5 are expected to provide a sensitive probe of cosmic dark energy. This is particularly true around the onset of acceleration at z approximately 1, where traditional optical cosmology becomes very difficult because of the infrared opacity of the atmosphere. Hitherto, 21-cm emission has been detected only to z = 0.24. More distant galaxies generally are too faint for individual detections but it is possible to measure the aggregate emission from many unresolved galaxies in the 'cosmic web'. Here we report a three-dimensional 21-cm intensity field at z = 0.53 to 1.12. We then co-add neutral-hydrogen (H i) emission from the volumes surrounding about 10,000 galaxies (from the DEEP2 optical galaxy redshift survey). We detect the aggregate 21-cm glow at a significance of approximately 4sigma.

Enhancement in electrical and magnetic properties with Ti-doping in Bi0.5La0.5Fe0.5Mn0.5O3

Science.gov (United States)

Singh, Rahul; Gupta, Prince Kumar; Kumar, Shiv; Joshi, Amish G.; Ghosh, A. K.; Patil, S.; Chatterjee, Sandip

2017-04-01

In this investigation, we have synthesized Bi0.5La0.5Fe0.5Mn0.5-xTixO3 (where x = 0 and 0.05) samples. The Rietveld refinement of X-ray diffraction (XRD) patterns shows that the systems crystallize in the orthorhombic phase with the Pnma space group. The observed Raman modes support the XRD results. The appearance of prominent A1-3 and weak E-2 modes in Bi0.5La0.5Fe0.5Mn0.45Ti0.05O3 indicates the presence of chemically more active Bi-O covalent bonds. Ferromagnetism of Bi0.5La0.5Fe0.5Mn0.5O3 is enhanced by Ti doping at the Mn-site, indicating that these particular samples might be interesting for device applications.

Design and performances of the 5 cm microtron

International Nuclear Information System (INIS)

Zakharov, M.A.; Melekhin, V.N.; Sukhachev, V.Ya.

1979-01-01

Described is the 5 cm microtron with 14 orbits and the 10 MeV maximum energy of electron beam, the 10 μA pulse current and the 100 W average power. The electromagnet of the armoured type with the external diameter of 680 mm, the height of 260 mm, the pole gap of 62 mm is designed for generation of the 0.32 T magnetic field. The vacuum chamber is made of stainless steel and it is totally separated from the electromagnet. An accelerating resonator is inserted through the connection pipe. An intermetallic thermoemitter of the iridium-cerium alloy is used in the microtron. The acceleration regime of the first type with zero initial phases is used in the microtron. The prospects of utilization of the 5-cm microtron is illustrated

Microstructure optimization for high-performance PrBa0.5Sr0.5Co1.5Fe0.5O5+δ-La2NiO4+δ core-shell cathode of solid oxide fuel cells

Science.gov (United States)

Li, Jin; Qiu, Peng; Xia, Meng; Jia, Lichao; Chi, Bo; Pu, Jian; Li, Jian

2018-03-01

Four PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF)-La2NiO4+δ (LN) core-shell cathodes, designated as PL-0, PL-1, PL-3 and PL-5, are prepared by infiltrating LN solution into PBSCF scaffold, and they are investigated in terms of the effect of LN thickness on their electrochemical performance. PL-3 with a continuous LN coating of a moderate average thickness (∼9 nm) demonstrates the lowest initial polarization resistance (0.51 Ω cm2) and highest power density (0.71 W cm-2) among all the cathodes. Polarized at 400 mA cm-2 and 700 °C for up to 40 h, the polarization resistance of all the prepared cathodes increases to approach a stable level after early stage decrease due to current activation, and PL-3 exhibits a slower average rate of performance degradation (25%). The electrochemical performance improvement is mainly attributed to that LN has a relatively high oxygen surface exchange coefficient and continuous LN coating depresses Sr segregation at PBSCF/LN interface.

High energy storage property and breakdown strength of Bi{sub 0.5}(Na{sub 0.82}K{sub 0.18}){sub 0.5}TiO{sub 3} ceramics modified by (Al{sub 0.5}Nb{sub 0.5}){sup 4+} complex-ion

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yangyang [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Xu, Jiwen, E-mail: csuxjw@126.com [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Experiment Center of Information Science, Guilin 541004 (China); Yang, Ling; Zhou, Changrong [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Experiment Center of Information Science, Guilin 541004 (China); Lu, Xiaopeng; Yuan, Changlai; Li, Qingning; Chen, Guohua; Wang, Hua [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China)

2016-05-05

The influence of B-site (Al{sub 0.5}Nb{sub 0.5}){sup 4+} complex-ion substitution on the phase transition, microstructure, dielectric, ferroelectric, and energy-storage properties of Bi{sub 0.5}(Na{sub 0.82}K{sub 0.18}){sub 0.5}Ti{sub 1–x}(Al{sub 0.5}Nb{sub 0.5}){sub x}O{sub 3} (BNKT-xAN) ceramics were systematically investigated. BNKT-xAN ceramics showed single-phase perovskite structure without an obvious phase transition after adding AN. Compact and uniform microstructure with almost the same grain morphology and size was obtained. The AN doping produced slimmer P-E loops and thus improved energy storage property. Meanwhile, the energy storage density increases drastically, and a maximum value of 1.41 J/cm{sup 3} at 105 kV/cm was achieved in BNKT-0.08AN through increasing greatly its breakdown strength with more AN content. The temperature dependence of dielectric constant and dielectric loss of BNKT-xAN ceramics illustrated the obvious relaxor phase transition characteristics. Low ionic conductivity and electronic conductivity indicated the BNKT-xAN ceramics have excellent dielectric properties. These results indicated that the BNKT-AN system may be a promising lead-free material for high energy storage density capacitor. - Highlights: • The (Al{sub 0.5}Nb{sub 0.5}){sup 4+} B-site complex ions were introduced into BNT-BKT system. • The P-E loops were pinched and the P{sub r} and E{sub c} were decreased by complex ions. • Impedance spectrum revealed excellent dielectric property of complex-ion modified BNT-BNK. • Breakdown strength of BNT-BKT was enhanced by complex ions. • The energy storage density was improved to 1.41 J/cm{sup 3} by complex ions.

5cm aperture dipole studies

International Nuclear Information System (INIS)

McInturff, A.D.; Bossert, R.; Carson, J.; Fisk, H.E.; Hanft, R.; Kuchnir, M.; Lundy, R.; Mantech, P.; Strait, J.

1986-01-01

The results obtained during the evolution of the design, construction, and testing program of the design ''B'' dipole are presented here. Design ''B'' is one of the original three competing designs for the Superconducting Super Collider ''SSC'' arc dipoles. The final design parameters were as follows: air cored (less than a few percent of the magnetic field derived from any iron present), aluminum collared, two layered winding, 5.5T maximum operating field, and a 5 cm cold aperture. There have been fourteen 64 cm long 5 cm aperture model dipoles cold tested (at 4.3K and less) in this program so far. There was a half length full size (6m) mechanical analog (M-10) built and tested to check the cryostat's mechanical design under ramping and quench conditions. Several deviations from the ''Tevatron'' dipole fabrication technique were incorporated, for example the use of aluminum collars instead of stainless steel. The winding technique variations explored were ''dry welding,'' a technique with the cable covered with Kapton insulation only and ''wet winding'' where the Kapton was covered with a light coat of ''B'' stage epoxy. Test data include quench currents, field quality (Fourier multipole co-efficients), coil magnetization, conductor current performance, and coil loading. Quench current, loss per cycle, and harmonics were measured as a function of the magnitude and rate of change of the magnetic field, and helium bath temperature

Liquid praseodymium heat content by levitation calorimetry. [Sample size 0. 5 - 1. 5g; 1460 to 2289/sup 0/K

Energy Technology Data Exchange (ETDEWEB)

Stretz, L.A.; Bautista, R.G.

1976-01-01

The high-temperature heat content of liquid praseodymium was measured experimentally by the levitation calorimetry technique. The samples, ranging in size from 0.5 to 1.5 g, were simultaneously levitated and heated by a radiofrequency generator in an argon-helium mixture prior to being dropped into a conventional copper block drop calorimeter. Corrections were made for the convection and radiation losses during the fall of the sample from the levitation chamber into the calorimeter. The praseodymium data, from 1460 to 2289K, were fitted by the following equation where the indicated errors represent the average deviation of the experimental value from the value predicted by the equation: H/sub T/ - H/sub 298/./sub 15/ = (41.57 +- 0.29) (T - 1208) + (41733 +- 197) J/mol. (auth)

Band gap modification and ferroelectric properties of Bi0.5(Na,K0.5TiO3-based by Li substitution

Directory of Open Access Journals (Sweden)

Ngo Duc Quan

2014-01-01

Full Text Available We report on the reduction of band gap in Bi0.5(Na0.82-xLixK0.180.5(Ti0.95Sn0.05O3 from 2.99 eV to 2.84 eV due to the substitutions of Li+ ions to Na+ sites. In addition, the lithium substitution samples exhibit an increasing of the maximal polarizations from 21.8 to 25.7 μC/cm2. The polarization enhancement of ferroelectric and reduction of the band gaps are strongly related to the Li substitution concentration as evaluated via the electronegative between A-site and oxygen and tolerance factor. The results are promising for photovoltaic and photocatalytic applications.

Determination of Pu, Am and Cm in Environmental Samples

Energy Technology Data Exchange (ETDEWEB)

Lujaniene, G. [SRI Centre for Physical Sciences and Technology, Vilnius (Lithuania)

2013-07-15

The determination of actinides in the environmental samples at a lower detection limit is required for monitoring purposes and for environmental research. The method for Pu, Am and Cm measurements in soil and sediment samples provides high recoveries and good decontamination from interfering radionuclides. The main steps of the method involve digestion of the samples, separation of radionuclides from matrix using the TOPO /cyclohexane extraction and final purification using extraction Eichrom resins (TEVA, TRU). The accuracy and precision of Pu, Am and Cm analyses were tested using IAEA RM No 135, NIST SRM No 4350b, No 4357 and in intercomparison runs organized by the Riso National Laboratory, Denmark, and in the proficiency tests organized by National Physical Laboratory, UK. The method was applied for measurement of radionuclides in aerosol samples (ashes {approx}30 g), bottom sediments (50-80 g dr. wt) and soil (including Chernobyl soil) samples. (author)

Eu3+-doped (Y0.5La0.5)2O3: new nanophosphor with the bixbyite cubic structure

Science.gov (United States)

Đorđević, Vesna; Nikolić, Marko G.; Bartova, Barbora; Krsmanović, Radenka M.; Antić, Željka; Dramićanin, Miroslav D.

2013-01-01

New red sesquioxide phosphor, Eu3+-doped (Y0.5La0.5)2O3, was synthesized in the form of nanocrystalline powder with excellent structural ordering in cubic bixbyite-type, and with nanoparticle sizes ranging between 10 and 20 nm. Photoluminescence measurements show strong, Eu3+ characteristic, red emission ( x = 0.66 and y = 0.34 CIE color coordinates) with an average 5D0 emission lifetime of about 1.3 ms. Maximum splitting of the 7F1 manifold of the Eu3+ ion emission behaves in a way directly proportional to the crystal field strength parameter, and experimental results show perfect agreement with theoretical values for pure cubic sesquioxides. This could be used as an indicator of complete dissolution of Y2O3 and La2O3, showing that (Y0.5La0.5)2O3:Eu3+ behaves as a new bixbyite structure oxide, M2O3, where M acts as an ion having average ionic radius of constituting Y3+ and La3+. Emission properties of this new phosphor were documented with detailed assignments of Eu3+ energy levels at 10 K and at room temperature. Second order crystal field parameters were found to be B 20 = -66 cm-1 and B 22 = -665 cm-1 at 10 K and B 20 = -78 cm-1 and B 22 = -602 cm-1 at room temperature, while for the crystal field strength the value of 1495 cm-1 was calculated at 10 K and 1355 cm-1 at room temperature.

UV Light-Driven Photodegradation of Methylene Blue by Using Mn0.5Zn0.5Fe2O4/SiO2 Nanocomposites

Science.gov (United States)

Indrayana, I. P. T.; Julian, T.; Suharyadi, E.

2018-04-01

The photodegradation activity of nanocomposites for 20 ppm methylene blue solution has been investigated in this work. Nanocomposites Mn0.5Zn0.5Fe2O4/SiO2 have been synthesized using coprecipitation method. The X-ray diffraction (XRD) pattern confirmed the formation of three phases in sample Mn0.5Zn0.5Fe2O4/SiO2 i.e., Mn0.5Zn0.5Fe2O4, Zn(OH)2, and SiO2. The appearance of SiO2 phase showed that the encapsulation process has been carried out. The calculated particles size of Mn0.5Zn0.5Fe2O4/SiO2 is greater than Mn0.5Zn0.5Fe2O4. Bonding analysis via vibrational spectra for Mn0.5Zn0.5Fe2O4/SiO2 confirmed the formation of bonds Me-O-Si stretching (2854.65 cm-1) and Si-O-Si asymmetric stretching (1026.13 cm-1). The optical gap energy of Mn0.5Zn0.5Fe2O4/SiO2 was smaller (2.70 eV) than Mn0.5Zn0.5Fe2O4 (3.04 eV) due to smaller lattice dislocation and microstrain that affect their electronic structure. The Mn0.5Zn0.5Fe2O4/SiO2 showed high photodegradation ability due to smaller optical gap energy and the appearance of SiO2 ligand that can easily attract dye molecules. The Mn0.5Zn0.5Fe2O4/SiO2 also showed high degradation activity even without UV light radiation. The result showed that photodegradation reaction doesn’t follow pseudo-first order kinetics.

Clinical Features of Ground Glass Opacity-Dominant Lung Cancer Exceeding 3.0 cm in the Whole Tumor Size.

Science.gov (United States)

Suzuki, Shigeki; Sakurai, Hiroyuki; Yotsukura, Masaya; Masai, Kyohei; Asakura, Keisuke; Nakagawa, Kazuo; Motoi, Noriko; Watanabe, Shun-Ichi

2018-05-01

Ground glass opacity (GGO)-dominant lung adenocarcinoma sized 3.0 cm or less in the whole tumor size is widely known to have an excellent prognosis and is regarded as early lung cancer. However, the characteristics and prognosis of lung cancer showing GGO exceeding 3.0 cm remains unclear. From 2002 through 2012, we reviewed 3,735 lung cancers that underwent complete resection at our institution. We identified 160 lung cancers (4.3%) showing GGO exceeding 3.0 cm on thin-section computed tomography and divided them into three types by the consolidation/tumor ratio (CTR) using cutoff values of 0.25 and 0.5. We compared the characteristics and prognosis among these types. Type A (CTR, 0 to ≤0.25), type B (CTR, >0.25 to ≤0.5), and type C (CTR, >0.5 to 3.0 cm can be considered to be in a group of patients with nodal-negative disease and an excellent prognosis. Copyright © 2018 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Magnetoelectric effect of (1-x) Ba0.5Sr0.5Zr0.5Ti0.5O3+(x) Ni0.12Mg0.18Cu0.2Zn0.5Fe2O4 composites

Science.gov (United States)

Rahaman, Md. D.; Saha, S. K.; Ahmed, T. N.; Saha, D. K.; Hossain, A. K. M. Akther

2014-12-01

The magnetoelectric composites with chemical compositions (1-x) Ba0.5Sr0.5Zr0.5Ti0.5O3+(x) Ni0.12Mg0.18Cu0.2Zn0.5Fe2O4 (x=20, 40, 60 and 80 wt%) was prepared by the conventional solid state reaction method. The presence of a biphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric dispersion is observed at lower frequencies due to interfacial polarization arising from the interface of the two phases. At higher frequencies, the dielectric constant is almost constant due to the inability of electric dipoles to follow the first variation of the alternating applied electric field. The dielectric loss shows maxima which are attributed when the hopping frequency of electrons between different ionic sites becomes nearly equal to the frequency of the applied field. The linearity in the log(σAC) vs. log(ω2) plots confirmed the small polaron hopping type of conduction mechanism. The composite materials are found to exhibit an excellent frequency dependence of magnetic properties. In the high frequency range, with increasing ferrite concentration the initial permeability increases and cut-off frequency decreases. An optimal magnetoelectric coupling responding voltage of about 600 μV cm-1 Oe-1 is obtained for x=20 wt% at room temperature.

The Magnetoelectric Effect of a Ni0.3Zn0.62Cu0.08Fe2O4 - PbFe0.5Nb0.5O3 Multilayer Composite

Directory of Open Access Journals (Sweden)

Guzdek P.

2014-10-01

Full Text Available The magnetoelectric effect in multiferroic materials has been widely studied for its fundamental interest and practical applications. The magnetoelectric effect observed for single phase materials like Cr2O3, BiFeO3, and Pb(Fe0.5Nb0.5O3 is usually small. A much larger effect can be obtained in composites consisting of magnetostrictive and piezoelectric phases. This paper investigates the magnetoelectric effect of a multilayer (laminated structure consisting of 6 nickel ferrite and 7 PFN relaxor layers. It describes the synthesis and tape casting process for Ni0.3Zn0.62Cu0.08Fe2O4 ferrite and relaxor PbFe0.5Nb0.5O3 (PFN. Magnetic hysteresis, ZFC - FC curves and dependencies of magnetization versus temperature for PFN relaxor and magnetoelectric composite were measured with a vibrating sample magnetometer (VSM in an applied magnetic field up to 85 kOe at a temperature range of 10 – 400 K. Magnetoelectric effect at room temperature was investigated as a function of a static magnetic field (0.3 - 6.5 kOe and the frequency of sinusoidal magnetic field (0.01 - 6.5 kHz. At lower magnetic field, the magnetoelectric coefficient increases slightly before reaching a maximum and then decreases. The magnetoelectric coefficient aME increases continuously as the frequency is raised, although this increase is less pronounced in the 1-6.5 kHz range. Maximum values of the magnetoelectric coefficient attained for the layered composites exceed about 50 mV/(Oe cm.

High performance Bi0.5Na0.5TiO3-BiAlO3-K0.5Na0.5NbO3 lead-free pyroelectric ceramics for thermal detectors

Science.gov (United States)

Liu, Zhen; Ren, Weijun; Peng, Ping; Guo, Shaobo; Lu, Teng; Liu, Yun; Dong, Xianlin; Wang, Genshui

2018-04-01

Both high pyroelectric properties and good temperature stability of ferroelectric materials are desirable when used for applications in infrared thermal detectors. In this work, we report lead-free ternary 0.97(0.99Bi0.5Na0.5TiO3-0.01BiAlO3)-0.03K0.5Na0.5NbO3 (BNT-BA-KNN) ceramics, which not only exhibits a large pyroelectric coefficient (p ˜ 3.7 × 10-8 C cm-2 K-1) and figures of merit (Fi, Fv, and Fd) but also shows excellent thermal stable properties. At room temperature, Fi, Fv, and Fd are determined as high as 1.32 × 10-10 m/V, 2.89 × 10-2 m2/C, and 1.15 × 10-5 Pa-1/2 at 1 kHz and 1.32 × 10-10 m/V, 2.70 × 10-2 m2/C, and 1.09 × 10-5 Pa-1/2 at 20 Hz, respectively. During the temperature range of RT to 85 °C, the achieved p, Fi, Fv, and Fd do not vary too much. The high depolarization temperature and the undispersed ferroelectric-ergodic relaxor phase transition with a sharp pyroelectric coefficient peak value of ˜400 × 10-8 C cm-2 K-1 are suggested to be responsible for this thermal stability, which ensures reliable actual operation. The results reveal the BNT-BA-KNN ceramics as promising lead-free candidates for infrared thermal detector applications.

Note: Radio frequency surface impedance characterization system for superconducting samples at 7.5 GHz.

Science.gov (United States)

Xiao, B P; Reece, C E; Phillips, H L; Geng, R L; Wang, H; Marhauser, F; Kelley, M J

2011-05-01

A radio frequency (RF) surface impedance characterization (SIC) system that uses a novel sapphire-loaded niobium cavity operating at 7.5 GHz has been developed as a tool to measure the RF surface impedance of flat superconducting material samples. The SIC system can presently make direct calorimetric RF surface impedance measurements on the central 0.8 cm(2) area of 5 cm diameter disk samples from 2 to 20 K exposed to RF magnetic fields up to 14 mT. To illustrate system utility, we present first measurement results for a bulk niobium sample.

Magnetic behaviour of hydrogenated La_0_._5Ca_0_._5MnO_3

International Nuclear Information System (INIS)

Lal, Ganesh; Punia, Khushboo; Kumar, Sudhish; Jyoti; Dolia, S.N.

2016-01-01

The half doped manganite La_0_._5Ca_0_._5MnO_3 have attracted considerable attention owing to its complex electrical and magnetic properties. This work is focused on the effects of hydrogenation on the magnetic behaviour of La_0_._5Ca_0_._5MnO_3. For hydrogenation the La_0_._5Ca_0_._5MnO_3 sample was annealed in a hydrogen atmosphere at 600°C for 6 hours in a reduction furnace and for reducing hydrogen the sample was heated in air at 600°C for 6 hours in a chamber furnace. Room temperature X-ray diffraction studies confirmed that the hydrogenation and annealing of the sample in air does not affect the single phase orthorhombic structure of La_0_._5Ca_0_._5MnO_3. These observations indicate that magnetic behaviour of La_0_._5Ca_0_._5MnO_3. can be tailored by hydrogenation

EFFECT OF DIFFERENT COMPACTION PRESSURE AND DIFFERENT SINTERING ROUTE ON K0.5NA0.5NBO₃ PHYSICAL AND DIELECTRIC PROPERTIES

Directory of Open Access Journals (Sweden)

Nor Fatin Khairah Bahanurddin

2016-07-01

Full Text Available Alkaline niobate known as K0.5Na0.5NbO3 (KNN, a lead-free piezoelectric ceramic was synthesized via a solid state reaction method. The samples were compacted at different pressures (100, 200, 300 and 400 MPa and sintered using two different techniques (conventional furnace and hot isostatic pressing (HIP. The effect of compaction pressure and sintering technique on physical and dielectric properties was studied. The optimum compaction pressure (300 MPa and sintering via HIP (at 1080 °C for 30 min increased the density and grain size ( range 30 - 300 nm and improved its dielectric properties. Therefore, the combination of suitable compaction pressure and sintering technique has produced larger grain size and higher density of KNN which resulted in outstanding dielectric properties. At room temperature, excellent values of ε r (5517.35 and tan δ (0.954, recorded at 1 MHz were measured for the KNN300HIP sample with highest density (4.4885 g/cm³.

Sinterability and conductivity of barium doped aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} electrolyte of solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Cao Xiaoguo [Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China); Jiang Sanping, E-mail: s.jiang@curtin.edu.au [Fuels and Energy Technology Institute and Department of Chemical Engineering, Curtin University, Perth, WA 6102 (Australia)

2012-05-15

Highlights: Black-Right-Pointing-Pointer Ba doping enhances the sintering and densification properties of aluminium lanthanum apatite. Black-Right-Pointing-Pointer Ba doping improves the oxide conductivity of aluminium lanthanum apatite. Black-Right-Pointing-Pointer The enhancement of Ba doping is mainly due to the significantly reduced grain boundary resistance of the aluminium lanthanum apatite. - Abstract: Apatite ceramics are interesting alternative solid oxide fuel cells (SOFCs) electrolytes because of their open structure for the transportation of oxide ions and their good chemical stability. This study reports the influence of barium doping on the microstructure, sinterability and oxide conductivity properties of the aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5}. SEM results show that lanthanum substitution with barium improves the sinterability of apatite ceramics. The barium doping also enhances the conductivity of the aluminium lanthanum silicates. The oxygen ion conductivity of La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} sintered at 1600 Degree-Sign C is 2.21 Multiplication-Sign 10{sup -2} S cm{sup -1} at 800 Degree-Sign C, higher than 9.81 Multiplication-Sign 10{sup -3} S cm{sup -1} of La{sub 10}Si{sub 5}AlO{sub 26.5} sample prepared under the same conditions. The results in the present study demonstrate that doping Ba on the La site for aluminium lanthanum oxyapatite reduces the sintering temperature and improves the ion conductivity. The enhancement of Ba dopant is mainly on the improvement of the densification and thus substantially reduced grain boundary resistance of aluminium lanthanum oxyapatite particularly at low temperatures.

Properties of epitaxial ferroelectric PbZr0.56Ti0.44O3 heterostructures with La0.5Sr0.5CoO3 metallic oxide electrodes

International Nuclear Information System (INIS)

Wang, F.; Leppaevuori, S.

1997-01-01

PbZr 0.56 Ti 0.44 O 3 (PZT) epitaxial ferroelectric thin films on a LaAlO 3 (100) substrate, covered by a metallic oxide electrode La 0.5 Sr 0.5 CoO 3 (LSCO) are demonstrated in this work. The films are fabricated by the sol endash gel method and effort was focused on thermal processing to obtain the desired epitaxial heterostructure. The dielectric and ferroelectric properties of PZT thin films were measured and it was found that they are as good as in the films deposited by other thin-film methods. The dielectric constant and the dissipation factor of the PZT films are, respectively, about 500 and 0.06 below 20 kHz. The remanent polarization P r is about 27 μC/cm 2 and the coercive field E c is about 50 kV/cm. It was found that the ferroelectric properties were significantly influenced by the microstructure of the PZT layers. The present study also showed that the fatigue characteristics of the epitaxial heterostructure with LSCO electrodes under a reversed electrical field are far superior to those obtained with a polycrystalline ferroelectric layer on Pt bottom electrodes. A low leakage current, about 3 μA/cm 2 at 0.5 MV/cm, was obtained for these epitaxial films. In addition, the optical transmittance spectrum of PZT thin films was also measured and the conduction mechanism is discussed.copyright 1997 American Institute of Physics

Stable and easily sintered BaCe0.5Zr0.3Y0.2O3−δ electrolytes using ZnO and Na2CO3 additives for protonic oxide fuel cells

International Nuclear Information System (INIS)

Li, Yong; Guo, Ruisong; Wang, Chao; Liu, Yu; Shao, Zongping; An, Jing; Liu, Chongwei

2013-01-01

Highlights: ► Sintering temperature of BCZY-Z pellets was reduced by adding ZnO and Na 2 CO 3 . ► Chemical stability of BCZY-Z towards CO 2 was improved with Na 2 CO 3 addition. ► Good chemical stability against boiling water was observed for BCZY-Z-C2 sample. ► The electrical conductivity is 7.68 × 10 −3 S cm −1 for BCZY-Z-C2 sample at 700 °C. ► An anode-supported POFC delivered a peak output 302 mW cm 2 at 700 °C. -- Abstract: BaCe 0.5 Zr 0.3 Y 0.2 O 3−δ (BCZY) based composite electrolyte materials were fabricated with ZnO sintering aid (BCZY-Z). The effects of Na 2 CO 3 modification on sintering behavior, chemical stability and electrochemical performance were systematically investigated. The X-ray diffraction patterns indicate that the specimens with Na 2 CO 3 addition possessed a single perovskite structure after sintering at 1320 °C for 2 h. The linear shrinkage of 0.5 mol% Na 2 CO 3 -modified BCZY-Z sample (BCZY-Z-C2) was about 17.5%, higher than that without Na 2 CO 3 addition (14.9%). Energy dispersive spectrometer shows that Na and C elements still existed and mainly distributed along the grain boundaries. Reactivities with carbon dioxide and boiling water of BCZY-Z and Na 2 CO 3 -modified BCZY-Z samples were also evaluated and good chemical stability was observed for Na 2 CO 3 -modified BCZY-Z samples. A conductivity of 7.68 × 10 −3 S cm −1 for BCZY-Z-C2 was obtained at 700 °C in 3% wet hydrogen atmosphere. An anode-supported fuel cell with thin-film BCZY-Z-C2 as electrolyte was fabricated. The fuel cell delivered a peak power density of 302 mW cm 2 and interface resistance value of 0.08 Ω cm 2 at 700 °C

Layered perovskite PrBa0.5Sr0.5CoCuO5+δ as a cathode for intermediate-temperature solid oxide fuel cells

International Nuclear Information System (INIS)

Wang, Biao; Long, Guohui; Ji, Yuan; Pang, Mingjun; Meng, Xiangwei

2014-01-01

Highlights: • A single-phase layered-perovskite PrBa 0.5 Sr 0.5 CoCuO 5+δ (PBSCCu) is prepared by the EDTA–citrate complexing method. • PBSCCu cathode has a good chemical compatible with GDC electrolyte. • Partial substitution of Cu for Co can efficiently lower the thermal expansion coefficient. • Performances of PrBa 0.5 Sr 0.5 CoCuO 5+δ cathode based on Gd 0.1 Ce 0.9 O 1.95 electrolyte is reported firstly. - Abstract: Layered perovskite PrBa 0.5 Sr 0.5 CoCuO 5+δ (PBSCCo) oxide is synthesized by EDTA–citrate complexing method and investigated as a novel cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). X-ray diffraction results show that PBSCCo is chemical compatible with Gd 0.1 Ce 0.9 O 1.95 (GDC) electrolyte below 950 °C. The thermal expansion coefficient of PBSCCo is 17.58 × 10 −6 K −1 between 30 °C and 900 °C. The maximum electrical conductivity of PBSCCo is 483 S cm −1 at 325 °C. The polarization resistance of PBSCCo cathode on GDC electrolyte is as low as 0.06 Ω cm 2 at 800 °C. The maximum power density of the electrolyte-supported single cell with PBSCCo cathode achieves 521 mW cm −2 at 800 °C. Preliminary results indicate that PBSCCo is a potential cathode material for application in IT-SOFCs

Effect of cerium addition on the microstructure, electrical and relaxor behavior of Sr{sub 0.5}Ba{sub 0.5}Nb{sub 2}O{sub 6} ceramics

Energy Technology Data Exchange (ETDEWEB)

Velayutham, T.S., E-mail: t_selvi@um.edu.my; Salim, N.I.F.; Gan, W.C.; Abd Majid, W.H.

2016-05-05

Sr{sub 0.5}Ba{sub 0.5}Nb{sub 2}O{sub 6} (SBN50) ceramic doped with different concentrations of Cerium (Ce) according to the stoichiometry formulation of Sr{sub 0.5-3y/2}Ba{sub 0.5}Ce{sub y}Nb{sub 2}O{sub 6} (Ce-SBN) with y = 0, 0.01, 0.02, 0.03, 0.04 and 0.05 was prepared using the conventional solid state reaction method. The morphology, structure, and electrical properties of the samples were studied using field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), ferroelectric and dielectric spectroscopy, respectively. The FESEM images reveal a strong influence of cerium on the SBN microstructure. The X-ray diffraction patterns show that all compositions of SBN ceramic exhibit tetragonal tungsten bronze structure. As the dopant concentration, y increased, both unit cell volume and axial ratio c/a decreased gradually. In addition, dopant incorporation lowers the phase transition temperature, T{sub m}. As a result, all practical parameters are sufficiently increased, i.e. the dielectric constant and remnant polarization. SBN50 doped with a 3% Ce sample is most attractive for practical applications due to its high remnant polarization, P{sub r} = 58.6 μC/cm{sup 2} and dielectric constant, ε’ ≈ 8000 (10 kHz) at room temperature, respectively. - Highlights: • Sr{sub 0.5-3y/2}Ba{sub 0.5}Ce{sub y}Nb{sub 2}O{sub 6} synthesized using solid-state reaction method. • Cerium dopant improved the overall properties of SBN. • Dopant incorporation lowers the phase transition temperature, T{sub m}. • 3% Ce dopant exhibits best functional properties among the rest of the composition. • The P{sub r} of 3%Ce-doped SBN is 58.6 μC/cm{sup 2} and ε’ ≈ 8000 (10 kHz) at room temperature.

Magnetoelectric effect of (1−x) Ba{sub 0.5}Sr{sub 0.5}Zr{sub 0.5}Ti{sub 0.5}O{sub 3}+(x) Ni{sub 0.12}Mg{sub 0.18}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} composites

Energy Technology Data Exchange (ETDEWEB)

Rahaman, Md. D., E-mail: dalilurrahaman1976@gmail.com [Department of Physics, University of Dhaka, Dhaka-1000 (Bangladesh); Saha, S.K.; Ahmed, T.N. [Department of Physics, University of Dhaka, Dhaka-1000 (Bangladesh); Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh); Saha, D.K. [Materials Science Division, Atomic Energy Centre, PO Box 164, Dhaka 1000 (Bangladesh); Hossain, A.K.M. Akther [Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh)

2014-12-15

The magnetoelectric composites with chemical compositions (1−x) Ba{sub 0.5}Sr{sub 0.5}Zr{sub 0.5}Ti{sub 0.5}O{sub 3}+(x) Ni{sub 0.12}Mg{sub 0.18}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} (x=20, 40, 60 and 80 wt%) was prepared by the conventional solid state reaction method. The presence of a biphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric dispersion is observed at lower frequencies due to interfacial polarization arising from the interface of the two phases. At higher frequencies, the dielectric constant is almost constant due to the inability of electric dipoles to follow the first variation of the alternating applied electric field. The dielectric loss shows maxima which are attributed when the hopping frequency of electrons between different ionic sites becomes nearly equal to the frequency of the applied field. The linearity in the log(σ{sub AC}) vs. log(ω{sup 2}) plots confirmed the small polaron hopping type of conduction mechanism. The composite materials are found to exhibit an excellent frequency dependence of magnetic properties. In the high frequency range, with increasing ferrite concentration the initial permeability increases and cut-off frequency decreases. An optimal magnetoelectric coupling responding voltage of about 600 μV cm{sup −1} Oe{sup −1} is obtained for x=20 wt% at room temperature. - Highlights: • XRD patterns confirmed the coexistence of ferroelectric and ferrimagnetic phases. • Dielectric dispersion observed at low frequencies due to interfacial polarization. • Linearity in logσ{sub ac} vs. logω{sup 2} is due to small polaron hopping mechanism. • Maximum ME voltage coefficient 600 μV cm{sup −1} Oe{sup −1} observed for 20% of ferrite.

Band gap modification and ferroelectric properties of Bi{sub 0.5}(Na,K){sub 0.5}TiO{sub 3}-based by Li substitution

Energy Technology Data Exchange (ETDEWEB)

Quan, Ngo Duc [Department of General Physics, School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam); International Training Institute for Materials Science, Hanoi University of Science and Technology, 1 Dai Co Viet road, Hanoi (Viet Nam); Hung, Vu Ngoc [International Training Institute for Materials Science, Hanoi University of Science and Technology, 1 Dai Co Viet road, Hanoi (Viet Nam); Quyet, Nguyen Van [Hanautech Co., Ltd., 832, Tamnip-dong, Yuseong-gu, Daejeon (Korea, Republic of); Chung, Hoang Vu [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet street, Hanoi (Viet Nam); Dung, Dang Duc, E-mail: dung.dangduc@hust.edu.vn [Department of General Physics, School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam)

2014-01-15

We report on the reduction of band gap in Bi{sub 0.5}(Na{sub 0.82-x}Li{sub x}K{sub 0.18}){sub 0.5}(Ti{sub 0.95}Sn{sub 0.05})O{sub 3} from 2.99 eV to 2.84 eV due to the substitutions of Li{sup +} ions to Na{sup +} sites. In addition, the lithium substitution samples exhibit an increasing of the maximal polarizations from 21.8 to 25.7 μC/cm{sup 2}. The polarization enhancement of ferroelectric and reduction of the band gaps are strongly related to the Li substitution concentration as evaluated via the electronegative between A-site and oxygen and tolerance factor. The results are promising for photovoltaic and photocatalytic applications.

Electric Field-Induced Large Strain in Ni/Sb-co Doped (Bi0.5Na0.5) TiO3-Based Lead-Free Ceramics

Science.gov (United States)

Li, Liangliang; Hao, Jigong; Xu, Zhijun; Li, Wei; Chu, Ruiqing

2018-02-01

Lead-free piezoelectric ceramics (Bi0.5Na0.5)0.935Ba0.065Ti1- x (Ni0.5Sb0.5) x O3 (BNBT6.5- xNS) have been fabricated using conventional solid sintering technique. The effect of (Ni, Sb) doping on the phase structure and electrical properties of BNBT6.5 ceramics were systematically investigated. Results show that the addition of (Ni, Sb) destroyed the ferroelectric long-range order of BNBT6.5 and shifted the ferroelectric-relaxor transition temperature ( T F-R) down to room temperature. Thus, this process induced an ergodic relaxor phase at zero field in samples with x = 0.005. Under the electric field, the ergodic relaxor phase could reversibly transform to ferroelectric phase, which promotes the strain response with peak value of 0.38% (at 80 kV/cm, corresponding to d 33 * = 479 pm/V) at x = 0.005. Temperature-dependent measurements of both polarization and strain confirmed that the large strain originated from a reversible field-induced ergodic relaxor to ferroelectric phase transformation. The proposed material exhibits potential for nonlinear actuators.

A screen-printed Ce 0.8Sm 0.2O 1.9 film solid oxide fuel cell with a Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ cathode

Science.gov (United States)

Zhang, Yaohui; Huang, Xiqiang; Lu, Zhe; Liu, Zhiguo; Ge, Xiaodong; Xu, Jiahuan; Xin, Xianshuang; Sha, Xueqing; Su, Wenhui

Screen-printing technology was developed to fabricate Ce 0.8Sm 0.2O 1.9 (SDC) electrolyte films onto porous NiO-SDC green anode substrates. After sintering at 1400 °C for 4 h, a gas-tight SDC film with a thickness of 12 μm was obtained. A novel cathode material of Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ was subsequently applied onto the sintered SDC electrolyte film also by screen-printing and sintered at 970 °C for 3 h to get a single cell. A fuel cell of Ni-SDC/SDC (12 μm)/Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ provides the maximum power densities of 1280, 1080, 670, 370, 180 and 73 mW cm -2 at 650, 600, 555, 505, 455 and 405 °C, respectively, using hydrogen as fuel and stationary air as oxidant. When dry methane was used as fuel, the maximum power densities are 876, 568, 346 and 114 mW cm -2 at 650, 600, 555 and 505 °C, respectively. The present fuel cell shows excellent performance at lowered temperatures.

Depairing current density of Ba0.5K0.5Fe1.95Co0.05As2 microbridges with nanoscale thickness

International Nuclear Information System (INIS)

Li, Jun; Yuan, Jie; Ge, Jun-Yi; Ji, Min; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Vanacken, Johan; Yamaura, Kazunari; Wang, Hua-Bing

2014-01-01

Highlights: • The critical current density of Ba 0.5 K 0.5 Fe 1.95 Co 0.05 As 2 microbridges is 7.9 MA/cm 2 at 21 K. • The critical current is in consistence with the Ginzburg–Landau depairing limit. • The depairing current density is less than that of impurity-free crystal. - Abstract: We investigated the depairing current density of Ba 0.5 K 0.5 Fe 1.95 Co 0.05 As 2 microbridges with width of 2 μm and thickness of 150 nm. The current vs. voltage characteristics of the microbridges show a Josephson-like behavior with the obvious hysteresis. The critical current density was observed as J c = 7.9 MA/cm 2 at temperature 21 K, which is consistent with the Ginzburg–Landau depairing limit. However, the depairing current density is less than that of impurity-free crystal, although the Co ions provide additional pinning centers within the superconducting Fe 2 As 2 layers. The Co impurity also enhances the anisotropic factor of the critical current density by 1.3 (1 T) or 1.7 (3 T)

Microstructural analysis nanoferritas Mn_0_,_5Zn_0_,_5Fe_2O_4 e Mn_0_,_6_5Zn_0_,_3_5Fe_2O_4 synthesized by combustion reaction

International Nuclear Information System (INIS)

Diniz, V.C.S.; Figueiredo, A.R.; Costa Junior, A.D.S.; Diniz, H.M.; Vieira, D.A.; Costa, A.C.F.M.

2014-01-01

The MnZn ferrites are ferrimagnetic materials that have been studied and used in various technological fields. In this work investigated the microstructural characteristics of ferrites and Mn_0_,_5Zn_0_,_5Fe_2O_4 Mn_0_,_6_5Zn_0_,_3_5Fe_2O_4 synthesized by combustion reaction in 200g scale production. The samples were characterized by XRD, crystallinity, crystallite size, X-ray fluorescence and scanning electron microscopy. Given the results it was observed that for both samples the synthesis combustion reaction was efficient for the production of single-phase ferrites with high crystallinity. With respect to the analysis of X-ray fluorescence was noted that the experimental values composition were consistent with the theoretical values calculated for both samples. Regarding morphology for both samples, the formation of the porous powders with feature consisting of dense clumps in the form of irregular foam was observed. (author)

The temperature influence against conductivity of solid state electrolyte of (CuI)0,5(β-Al2O3)0,5

International Nuclear Information System (INIS)

Purwanto, -P; Kartini, -E; Purnama, Safei

2004-01-01

The solid electrolyte (CuI) 0,5 (β-Al 2 O 3 ) 0,5 has been prepared by a solid state reaction, by mixing of CuI with β-Al 2 O 3 powders. The mixture was compacted and heated at the temperature 300 o C for 3 hours. The conductivity values of (CuI) 0,5 (β-Al 2 O 3 ) 0,5 increased with the temperature and frequency. The x ray diffraction peaks of the solid electrolyte (CuI) 0,5 (β-Al 2 O 3 ) 0,5 are dominated by the peaks of CuI than the peaks of β-Al 2 O 3 . The activation energy of the solid electrolyte is relatively stable, with the range from 0.09 eV to 0.13 eV. The conductivities solid electrolyte (CuI) 0,5 (β-Al 2 O 3 ) 0,5 at room temperature and at 300 o C are 1.48 x 10 -5 S/cm and 8.33 x 10 -4 S/cm, respectively

Enhanced elevated-temperature performance of LiAl_xSi_0_._0_5Mg_0_._0_5Mn_1_._9_0_-_xO_4 (0≤x≤0.08) cathode materials for high-performance lithium-ion batteries

International Nuclear Information System (INIS)

Zhao, Hongyuan; Liu, Shanshan; Wang, Zhenwei; Cai, Yu; Tan, Ming; Liu, Xingquan

2016-01-01

In order to significantly enhance the elevated-temperature performance of LiSi_0_._0_5Mg_0_._0_5Mn_1_._9_0O_4, the LiAl_xSi_0_._0_5Mg_0_._0_5Mn_1_._9_0_-_xO_4 (0 ≤ x ≤ 0.08) samples were firstly prepared via sol-gel technique. All the obtained samples showed the intrinsic spinel structure without any other detectable impurity phases. Among these samples, the LiAl_0_._0_5Si_0_._0_5Mg_0_._0_5Mn_1_._8_5O_4 sample was found to be optimal possessing regular crystal morphology with clean surfaces and presented much better elevated-temperature cycling stability and rate capability. When carried out at 55 °C, the LiAl_0_._0_5Si_0_._0_5Mg_0_._0_5Mn_1_._8_5O_4 sample exhibited the initial discharge capacity of 123.6 mAh g"−"1 at 0.5C between 3.20 and 4.35 V. After 100 cycles, the discharge capacity could still reach up to 115.9 mAh g"−"1 with capacity retention of 93.8%, which was much higher than that of LiSi_0_._0_5Mg_0_._0_5Mn_1_._9_0O_4. At the higher discharge rate of 10C, a high discharge capacity of 82.5 mAh g"−"1 could be obtained with capacity retention of 95.6% after 50 cycles at 55 °C. By contrast, the LiSi_0_._0_5Mg_0_._0_5Mn_1_._9_0O_4 sample only exhibited 43.7 mAh g"−"1 with lower capacity retention of 61.8%. These results indicate that the introduction of appropriate amount of aluminium ions in the magnesium and silicon co-doped spinel can make up for the shortage of co-doping with magnesium and silicon ions in term of the elevated-temperature performance.

Phase transitions and optical characterization of lead-free piezoelectric (K0.5Na0.5)0.96Li0.04(Nb 0.8Ta0.2)O3 thin films

KAUST Repository

Yao, Yingbang

2013-06-01

Lead-free piezoelectric thin films, (K0.5Na0.5) 0.96Li0.04(Nb0.8Ta0.2)O 3, were epitaxially grown on MgO(001) and Nb-doped SrTiO 3(001) substrates using pulsed laser deposition. The optimum deposition temperature was found to be 600 C. Two types of in-plane orientations were observed in the films depending on the substrates used. The transmittance and photoluminescence spectra as well as the dielectric and ferroelectric properties of the films were measured. The measured band-gap energy was found to be decreased with the deposition temperature. The dielectric constant decreased from 550 to 300 as the frequency increased from 100 Hz to 1 MHz. The measured remnant polarization and coercive field were 4 μC/cm2 and 68 kV/cm, respectively. The phase transitions of the films were studied by Raman spectroscopy. Two distinct anomalies originating from the cubic-to-tetragonal (TC-T ~ 300 C) and tetragonal-to-orthorhombic (TT-O ~ 120 C) phase transitions were observed. Our results show that Raman spectroscopy is a powerful tool in identifying the phase transitions in ferroelectric thin films. © 2013 Elsevier B.V.

Multilayer thin films with compositional PbZr0.52Ti0.48O3/Bi1.5Zn1.0Nb1.5O7 layers for tunable applications

Science.gov (United States)

Yu, Shihui; Li, Lingxia; Zhang, Weifeng; Sun, Zheng; Dong, Helei

2015-01-01

The dielectric properties and tunability of multilayer thin films with compositional PbZr0.52Ti0.48O3/Bi1.5Zn1.0Nb1.5O7 (PZT/BZN) layers (PPBLs) fabricated by pulsed laser deposition on Pt/TiO2/SiO2/Si substrate have been investigated. Dielectric measurements indicate that the PZT/BZN bilayer thin films exhibit medium dielectric constant of about 490, low loss tangent of 0.017, and superior tunable dielectric properties (tunability = 49.7% at 500 kV/cm) at a PZT/BZN thickness ratio of 3, while the largest figure of merit is obtained as 51.8. The thickness effect is discussed with a series connection model of bilayer capacitors, and the calculated dielectric constant and loss tangent are obtained. Furthermore, five kinds of thin–film samples comprising single bilayers, two, three, four and five PPBLs were also elaborated with the final same thickness. The four PPBLs show the largest dielectric constant of ~538 and tunability of 53.3% at a maximum applied bias field of 500 kV/cm and the lowest loss tangent of ~0.015, while the largest figure of merit is 65.6. The results indicate that four PPBLs are excellent candidates for applications of tunable devices. PMID:25960043

Stable, easily sintered BaCe{sub 0.5}Zr{sub 0.3}Y{sub 0.16}Zn{sub 0.04}O{sub 3-{delta}} electrolyte-based protonic ceramic membrane fuel cells with Ba{sub 0.5}Sr{sub 0.5}Zn{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} perovskite cathode

Energy Technology Data Exchange (ETDEWEB)

Lin, Bin; Hu, Mingjun; Ma, Jianjun; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), 96 Jinzhai Road, Hefei, Anhui 230026 (China); Jiang, Yinzhu [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), 96 Jinzhai Road, Hefei, Anhui 230026 (China); Department of Chemistry, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Tao, Shanwen [Department of Chemistry, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

2008-09-01

A stable, easily sintered perovskite oxide BaCe{sub 0.5}Zr{sub 0.3}Y{sub 0.16}Zn{sub 0.04}O{sub 3-{delta}} (BCZYZn) as an electrolyte for protonic ceramic membrane fuel cells (PCMFCs) with Ba{sub 0.5}Sr{sub 0.5}Zn{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (BSZF) perovskite cathode was investigated. The BCZYZn perovskite electrolyte synthesized by a modified Pechini method exhibited higher sinterability and reached 97.4% relative density at 1200 C for 5 h in air, which is about 200 C lower than that without Zn dopant. By fabricating thin membrane BCZYZn electrolyte (about 30 {mu}m in thickness) on NiO-BCZYZn anode support, PCMFCs were assembled and tested by selecting stable BSZF perovskite cathode. An open-circuit potential of 1.00 V, a maximum power density of 236 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.17 {omega} cm{sup 2} were achieved at 700 C. This investigation indicated that proton conducting electrolyte BCZYZn with BSZF perovskite cathode is a promising material system for the next generation solid oxide fuel cells. (author)

Thermally assisted interlayer magnetic coupling through Ba_0_._0_5Sr_0_._9_5TiO_3 barriers

International Nuclear Information System (INIS)

Carreira, Santiago J.; Steren, Laura B.; Avilés Félix, Luis; Alejandro, Gabriela; Sirena, Martín

2016-01-01

We report on the interlayer exchange coupling across insulating barriers observed on Ni_8_0Fe_2_0/Ba_0_._0_5Sr_0_._9_5TiO_3/La_0_._6_6Sr_0_._3_3MnO_3 (Py/BST_0_._0_5/LSMO) trilayers. The coupling mechanism has been analyzed in terms of the barrier thickness, samples' substrate, and temperature. We examined the effect of MgO (MGO) and SrTiO_3 (STO) (001) single-crystalline substrates on the magnetic coupling and also on the magnetic anisotropies of the samples in order to get a deeper understanding of the magnetism of the structures. We measured a weak coupling mediated by spin-dependent tunneling phenomena whose sign and strength depend on barrier thickness and substrate. An antiferromagnetic (AF) exchange prevails for most of the samples and smoothly increases with the barrier thicknesses as a consequence of the screening effects of the BST_0_._0_5. The coupling monotonically increases with temperature in all the samples and this behavior is attributed to thermally assisted mechanisms. The magnetic anisotropy of both magnetic components has a cubic symmetry that in the case of permalloy is added to a small uniaxial component.

DESAIN SIMULASI PEMBENTUKAN BAYANGAN PADA CERMIN CEMBUNG MENGGUNAKAN GUI BUILDER SCILAB 5.5.0

Directory of Open Access Journals (Sweden)

Erwin Randjawali

2017-12-01

Full Text Available Penelitian ini merupakan pengembangan dari makalah yang telah dipresentasikan pada Seminar Internasional namun menggunakan tipe cermin yang berbeda dan berbasis Graphical User Interface (GUI. Penelitian ini bertujuan untuk menghasilkan simulasi pembentukan bayangan pada cermin cembung sebagai media pembelajaran Fisika yang dapat digunakan secara mudah dan efektif. Penelitian ini bersifat studi literatur, dengan menggunakan metode komparatif antara hasil simulasi dan hasil analitik. Simulasi dalam penelitian ini dibuat menggunakan aplikasi Scilab 5.5.0 dengan GUI Builder versi 3.0, dengan memanfaatkan konsep Fisika dan Matematika, di mana cermin cembung disimulasikan menggunakan persamaan parametrik untuk lingkaran, sedangkan sinar-sinar istimewa disimulasikan menggunakan persamaan garis lurus dengan gradien tertentu. Dalam penelitian ini disimulasikan pembentukan bayangan dari sebuah benda dengan tinggi 7cm yang diletakkan pada jarak 15cm dari sebuah cermin cembung yang memiliki radius kelengkungan -30cm. Cermin cembung yang disimulasikan dalam penelitian ini diasumsikan sebagai sebuah permukaan datar. Simulasi yang telah dibuat dapat berjalan dengan baik pada Scilab 5.5.0. Dari hasil simulasi ini, diperoleh tinggi bayangan sebesar 3.5cm dan jarak bayangan sebesar -7.5cm. Hasil perhitungan ini dibandingkan dengan hasil perhitungan secara analitik, dan diperoleh error perhitungan sebesar 0%, dengan kata lain hasil tersebut sama dengan hasil yang diperoleh dengan cara analitik, dan sekaligus membenarkan pernyataan bahwa proses pembentukan bayangan pada cermin cembung lebih mudah untuk digambarkan apabila cermin tersebut dianggap sebagai sebuah permukaan datar. Dengan demikian, simulasi ini dapat digunakan dalam proses pembelajaran Fisika.

Synthesis of homogeneous Ca0.5Sr0.5FeO2.5+δ compound using a mirror furnace method

International Nuclear Information System (INIS)

Mahboub, M.S.; Zeroual, S.; Boudjada, A.

2012-01-01

Graphical abstract: X-ray diffraction pattern indexing of Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample obtained by mirror furnace method after thermal treatment. Highlights: ► A homogenous compound Ca 0.5 Sr 0.5 FeO 2.5+δ has been synthesized for the first time by a mirror furnace method. ► Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample is perfectly homogenous, confirmed by X-ray diffraction, Raman spectroscopy and EDS technique. ► The thermal treatment of Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample can increase their average grain sizes. -- Abstract: A new synthesis method using melting zone technique via the double mirror furnace around 1600 °C is used to obtain homogenous brownmillerite compounds Ca 1−x Sr x FeO 2.5+δ in the range 0.3 ≤ x ≤ 0.7. These compounds play important role in understanding the mystery of the oxygen diffusion in the perovskite-related oxides. We have successfully solved the miscibility gap problem by synthesizing a good quality of homogenous powder samples of Ca 0.5 Sr 0.5 FeO 2.5+δ compound. Our result was confirmed by X-rays diffraction, Raman spectroscopy and energy dispersive spectroscopy analysis. Thermal treatment was also applied until 800 °C under vacuum to confirm again the homogeneity of powder samples, improve its quality and show that no decomposition or return to form Ca- and Sr-enriched microdomains takes place as a result of phase separation.

Investigation on magnetoelectric behavior of (80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3)-CoFe2O4 particulate composites

Science.gov (United States)

Liu, Sheng; Yan, Shuoqing; Yao, Lingling; He, Jun; He, Longhui; Hu, Zhaowen; Huang, Shengxiang; Deng, Lianwen

2017-12-01

Particulate magnetoelectric (ME) ceramics constituted by (1-x)(80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3)-xCoFe2O4 [(1-x)BNKT-xCFO] (x = 0, 0.1, 0.2, 0.3, 0.4 and 1.0) were synthesized by an powder-in-sol precursor hybrid processing method and their structure, magnetic, ferroelectric, magnetodielectric (MD) and ME properties have been investigated. Results showed that the ceramics consisted of only two chemically separated phases and had homogeneous microstructure. The introduction of CFO into BNKT matrix led to the weakening of ferroelectric and dielectric properties whereas the strengthening magnetic and MD properties. The observation of the MD effect revealed the evidence of the strain-induced ME coupling and the MD value is well scaled with M2. A maximum value of ME output of 25.07 mV/cm·Oe was achieved for the 0.7BNKT-0.3CFO composite. The improved ME response together with the linear MD effect makes the ceramics promise for use in magnetic field controllable devices or magneto-electric transducers.

Preparation of thin-film (Ba(0.5),Sr(0.5))TiO3 by the laser ablation technique and electrical properties

Science.gov (United States)

Yoon, Soon-Gil; Lee, Jai-Chan; Safari, A.

1994-09-01

The chemical composition and electrical properties were investigated for epitaxially crystallized (Ba(0.5),Sr(0.5))TiO3 (BST) films deposited on Pt/MgO and YBa2Cu3O(7-x) (YBCO)/MgO substrates by the laser ablation technique. Rutherford backscattering spectroscopy analysis shows that thin films on Pt/MgO have almost the same stoichiometric composition as the target material. Films deposited at 600 C exhibited an excellent epitaxial growth, a dielectric constant of 430, and a dissipation factor of 0.02 at 10 kHz frequency. They have a charge storage density of 40 fC/sq micron at an applied electric field of 0.15 MV/cm. Leakage current density of BST thin films on Pt/MgO was smaller than on YBCO/MgO. Their leakage current density is about 0.8 microA/sq cm at an applied electric field of 0.15 MV/cm.

Low-temperature processing of sol-gel derived La0.5Sr0.5MnO3 buffer electrode and PbZr0.52Ti0.48O3 films using CO2 laser annealing

International Nuclear Information System (INIS)

Pan, H.-C.; Chou, C.-C.; Tsai, H.-L.

2003-01-01

Fabrication of well-crystallized sol-gel derived (La 0.5 Sr 0.5 )MnO 3 (LSMO) buffer electrode layers and ferroelectric Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films using a continuous wave CO 2 laser annealing technique at a relatively low temperature was studied on a Pt/Ti/SiO 2 /Si substrate. Resistivity, carrier concentration and Hall mobility of laser-annealed conducting oxide LSMO films were optimized by changing the radiation fluence and the substrate temperature. The minimum resistivity of 1.27x10 -4 Ω cm was obtained for LSMO/Pt(Si) films prepared by laser irradiating at a fluence of 533 W/cm 2 with a simultaneous substrate heating at a temperature of 300 deg. C. The laser-annealed PZT films coated on LSMO/Pt(Si) substrate shows enhancement in remanent polarization from 10.1 to 17.3 μC/cm 2 as the PZT irradiated with a laser fluence of 433-483 W/cm 2 . The PZT(483 W/cm 2 )/LSMO(533 W/cm 2 )/Pt(Si) films showed a good fatigue resistance after 1x10 10 switching cycles with a bipolar electric field of 300 kV/cm, implying the feasibility of fabricating reliable ferroelectric-oxide electrode heterostructures using CO 2 laser annealing at temperatures lower than 400 deg. C

Measurement of the intensity of the cosmic background radiation at 3.0 cm

International Nuclear Information System (INIS)

Friedman, S.D.

1984-01-01

The intensity of the cosmic background radiation (CBR) has been measured at a wavelength of 3.0 cm as part of a program to measure th Rayleigh-Jeans spectrum of the CBR at five wavelengths between 0.33 cm and 12 cm. The instrument used is a dual-antenna Dicke-switched radiometer with a double-sideband noise temperature of 490 K and a sensitivity of 46 mK/Hz/sup 1/2/. The entire radiometer is mounted on bearings. The atmospheric emission was measured by rotating the radiometer, and thus directing one antenna to zenith angles of +- 30 0 and +- 40 0 . 61 references, 24 figures, 18 tables

Representasi Persahabatan dalam Film 5 Cm

OpenAIRE

Handayani, Intan Murni; Lukmantoro, Triyono; Naryoso, Agus

2013-01-01

Representasi Persahabatan dalam Film 5 cmSkripsiDisusun untuk memenuhi persyaratan menyelesaikanPendidikan Strata-1Jurusan IlmumKomunikasi Fakultas Ilmu Sosial dan Ilmu PolitikUniversitas DiponegoroPenyusunNama: Intan Murni HandayaniNIM: D2C 009 034JURUSAN ILMU KOMUNIKASIFAKULTAS ILMU SOSIAL DAN ILMU POLITIKUNIVERSITAS DIPONEGOROSEMARANG2013ABSTRAKSIFilm merupakan salah satu media massa yang menjadi wadah bagi parapembuat film untuk menyampaikan pesan serta nilai-nilai yang dimiliki olehpara ...

Annealing dependence of magnetic properties in nanostructured Sm0.5Y0.5Co5

International Nuclear Information System (INIS)

Elizalde-Galindo, J.T.; Hidalgo, J.L.; Botez, C.E.; Matutes-Aquino, J.A.

2008-01-01

Nanocrystalline Sm 0.5 Y 0.5 Co 5 powders with high coercivity H C and enhanced remanence M r were prepared by mechanical milling and subsequent annealing. Annealing temperatures T ranging from 973 to 1173 K, and times t ranging from 1 to 5 min were used. X-ray diffraction (XRD) and DC-magnetization measurements were carried out to study the microstructure and magnetic properties of these samples. XRD patterns demonstrate that the average grain size of the nanocrystalline powders depends on the annealing temperature T and time t: ranges from 11 nm (for T=973 K and t=1 min) to 93 nm (for T=1173 K and t=5 min). Magnetic measurements performed at room temperature indicate high coercivity values (H C >955 kA/m), and enhanced remanence (M r /M max >0.5) for all samples. A strong annealing-induced grain size dependence of these magnetic properties was found

Climate Prediction Center (CPC) NCEP-Global Forecast System (GFS) 0-10cm Soil-Moisture Forecast Product

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Global Forecast System (GFS) forecast 0-10cm soil-moisture data at 37.5km resolution is created at the NOAA Climate Prediction Center for the purpose of near...

Study of Zr{sub x}Zn{sub 0.5−x}Ni{sub 0.5}Fe{sub 2}O{sub 4} 0≤x≤0.25: Synthesis, structural, magnetic and electrical properties

Energy Technology Data Exchange (ETDEWEB)

Saini, Jasmeen; Kumar, Rupesh [Nanotechnology Research Centre, DAV Institute of Engineering and Technology, Jalandhar 144008 (India); Rajput, Jaspreet Kaur [Department of Chemistry, Dr. B.R. Ambedkar National Institute of Technology, Jalandhar 144011 (India); Kumar, Arvind [Department of Electronics and Communication, UIET, Panjab University, Chandigarh 160025 (India)

2016-03-01

Zirconium substituted zinc–nickel ferrite nanoparticles with chemical composition of Zr{sub x}Zn{sub 0.5−x}Ni{sub 0.5}Fe{sub 2}O{sub 4} (0≤x≤0.25) have been synthesized successfully by solution combustion method using high purity nitrates and fueling agent urea. Powder XRD study confirms the single phase formation of composite ferrite which belongs to cubic spinel structure. TEM further reveals the morphology of well dispersed Zn–Ni ferrite nanoparticles to be spherical. Effect of change of doping concentration of Zirconium is observed using FTIR. The saturation magnetization gradually decreases with the increase in Zr substitution and reaches minimum when x=0.25 whereas the coercivity value reaches minimum when x=0.15. DC electrical resistivity has been found to vary with increasing Zr content. The good electrical resistivity (>10{sup 7} Ωcm) qualify the ceramic for high frequency transformer applications. - Graphical abstract: Zr Doped Zn–Ni Ferrite nanoparticles. - Highlights: • Zr{sub x}Zn{sub 0.5-x}Ni{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles were synthesized by solution combustion method. • Increase in doping concentration of Zirconium reduces the grain size of the nanoparticles. • Very low value of coercivity (0.73 Oe to 137.34 Oe) obtained for such particles indicates that the material is soft magnet. • High resistivity (90 MΩcm to 845 MΩcm) was obtained that qualified the material for high frequency and power supply transformers applications.

Superconductivity in REO0.5F0.5BiS2 with high-entropy-alloy-type blocking layers

Science.gov (United States)

Sogabe, Ryota; Goto, Yosuke; Mizuguchi, Yoshikazu

2018-05-01

We synthesized new REO0.5F0.5BiS2 (RE: rare earth) superconductors with high-entropy-alloy-type (HEA-type) REO blocking layers. The lattice constant a systematically changed in the HEA-type samples with the RE concentration and the RE ionic radius. A sharp superconducting transition was observed in the resistivity measurements for all the HEA-type samples, and the transition temperature of the HEA-type samples was higher than that of typical REO0.5F0.5BiS2. The sharp superconducting transition and the enhanced superconducting properties of the HEA-type samples may indicate the effectiveness of the HEA states of the REO blocking layers in the REO0.5F0.5BiS2 system.

Crystallographic structure and magnetic properties of pseudobrookite Fe2-xNixTiO5 system (x = 0, 0.1, 0.2, 0.3, 0.5 and 1)

International Nuclear Information System (INIS)

Yosef Sarwanto and Wisnu Ari Adi

2018-01-01

Crystallographic structure and magnetic properties of pseudobrookite Fe 2-x Ni x TiO 5 system (x=0, 0.1, 0.2, 0.3 ,0.5 and 1)have been performed through solid state reaction. Pseudobrookite Fe 2-x Ni x TiO 5 system was synthesized by mixing of Fe 2 O 3 , NiO, and TiO 2 with stoichiometry composition using wet mill. The mixture was milled for 5 hours and sintered in the electric chamber furnace at 1000 °C in the air at atmosphere pressure for 5 hours. The refinement against of X-ray diffraction data shows that the samples with composition of (x = 0) and (x = 0.1) have a single phase with Fe 2 TiO 5 structure. How ever the samples with composition of (x > 0.1) consist of multiple phases, namely Fe 2-x Ni x TiO 5 , FeTiO 3 , Fe 2 NiO 4 and NiO. Particle morphologies of the composition x = 0 and x =0.1 are homogenous and uniform on the sample surface with a polygonal particle shape and particle size varies. At room temperature, the sample with x =0 is paramagnetic and that with x =0.1 is ferromagnetic. Magnetic phase transformation of this study is the caused by the present of Ni substituted Fe in the system. Thus substitution Ni into Fe on the system pseudobrookite Fe 2 TiO 5 only capable of 0.1 at.% without changing the crystal structure of the material. It means that there is an interaction between the magnetic spin Fe 3+ on the 3d 5 configurations and Ni 2 + on the 3d 3 configurations through the mechanism of double exchange. Double exchange mechanism is a magnetic type of exchange that appears between the ions Fe 3+ and Ni 2+ adjacent in different oxidation states. (author)

Uranium and zirconium mass transfer testing of 5.5-cm-diam centrifugal contactors

International Nuclear Information System (INIS)

DeMuth, S.F.; Randolph, J.D.

1988-01-01

As part of the Consolidated Fuel Reprocessing Program of the Oak Ridge National Laboratory, compact centrifugal contacts were designed and prototypes build for the Breeder Reprocessing Engineering Test (BRET) facility with a throughput capacity of 0.1 t/d of heavy metals. While the construction of BRET has been put on hold indefinitely, development of the 5.5-cm-diam centrifugal contactors has advanced due to the contactor's broad applicability in other areas of fuel reprocessing and other liquid-liquid extraction. Due to the short residence time of the process fluids in a centrifugal contactor, it was necessary to measure the mass transfer efficiency for a typical process flowsheet. This was done with depleted uranium and 91 Zr. The results of mass transfer tests with uranium and zirconium are reported in this paper

Upper limits on the 21 cm power spectrum at z = 5.9 from quasar absorption line spectroscopy

Science.gov (United States)

Pober, Jonathan C.; Greig, Bradley; Mesinger, Andrei

2016-11-01

We present upper limits on the 21 cm power spectrum at z = 5.9 calculated from the model-independent limit on the neutral fraction of the intergalactic medium of x_{H I} chain Monte Carlo Epoch of Reionization analysis code, we explore the probability distribution of 21 cm power spectra consistent with this constraint on the neutral fraction. We present 99 per cent confidence upper limits of Δ2(k) limit dependent on the sampled k mode. This limit can be used as a null test for 21 cm experiments: a detection of power at z = 5.9 in excess of this value is highly suggestive of residual foreground contamination or other systematic errors affecting the analysis.

Measurement of 0.8 and 1.5 GeV proton induced neutron production cross sections at 0deg

International Nuclear Information System (INIS)

Shigyo, Nobuhiro; Kunieda, Satoshi; Watanabe, Takehito; Ishibashi, Kenji; Satoh, Daiki; Meigo, Shin-ichiro

2004-01-01

Neutron-production double-differential cross sections at 0deg were measured for proton-induced reactions on Fe and Pb targets at 0.8 and 1.5 GeV. The experiment was performed at the π2 beam line of the 12 GeV proton synchrotron in High Energy Accelerator Research Organization (KEK). Neutrons were measured by time-of-flight technique with two different flight path lengths, i.e. 3.5 and 5.0 m at 0.8 and 1.5 GeV, respectively. NE213 liquid organic scintillators 12.7 cm in diameter and 12.7 cm in thickness were set at 0deg as neutron detector. For the improvement of the energy resolution, the scintillator was connected with three Hamamatsu H2431 photomultipliers 5.1 cm in diameter. The neutron detection efficiencies were obtained by the SCINFUL-QMD code. The experimental data were compared with the calculation results of the intranuclear-cascade-evaporation (INC/E) and the quantum-molecular-dynamics (QMD) models. (author)

Bk and Cf chromatographic separation and 249Bk/248Cm and 249Cf/248Cm elemental ratios determination by inductively coupled plasma quadrupole mass spectrometry

International Nuclear Information System (INIS)

Gourgiotis, A.; Isnard, H.; Nonell, A.; Aubert, M.; Stadelmann, G.; Dupont, E.; AlMahamid, I.; Tiang, G.; Rao, L.; Lukens, W.; Cassette, P.; Panebianco, S.; Letourneau, A.; Chartier, F.

2013-01-01

The French Atomic Energy Commission has carried out several experiments for the study of minor-actinide transmutation processes in high intensity thermal neutron flux. In this context a Cm sample enriched in 248 Cm (97%) was irradiated in a thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). The precise and accurate determination of Cf isotope ratios and of 249 Bk/ 248 Cm and 249 Cf/ 248 Cm elemental ratios in the 248 Cm irradiated sample is crucial for the calculation of actinide neutron capture cross-sections.This work describes an analytical procedure for the separation and the isotope ratio measurement of Bk and Cf in the irradiated sample.The Bk and Cf separation is based on a lanthanides separation protocol previously developed by the laboratory. Well-defined retention times for Bk and Cf were obtained by coupling the Ionic Chromatography (IC) with an ICP-QMS. All conditions of element separation by IC and the different steps of the analytical protocol in order to obtain the isotopic and elemental ratios are presented. Relative uncertainties of Cf isotopic ratios range from 0.3% to 0.5% and the uncertainty of the 249 Bk/ 248 Cm and 249 Cf/ 248 Cm elemental ratios are respectively 6.1% and 3.2%.This level of uncertainty for both isotopic and elemental ratios is in perfect agreement with the requirement for transmutation studies. (authors)

High performance protonic ceramic membrane fuel cells (PCMFCs) with Ba{sub 0.5}Sr{sub 0.5}Zn{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} perovskite cathode

Energy Technology Data Exchange (ETDEWEB)

Ding, Hanping; Lin, Bin; Liu, Xingqin; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), No. 96 Jinzhai Road, Hefei 230026 (China)

2008-09-15

Protonic ceramic membrane fuel cells (PCMFCs) based on proton-conducting electrolytes have attracted much attention because of many advantages, such as low activation energy and high energy efficiency. BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY7) electrolyte based PCMFCs with stable Ba{sub 0.5}Sr{sub 0.5}Zn{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (BSZF) perovskite cathode were investigated. Using thin membrane BZCY7 electrolyte (about 15 {mu}m in thickness) synthesized by a modified Pechini method on NiO-BZCY7 anode support, PCMFCs were assembled and tested by selecting stable BSZF perovskite cathode. An open-circuit potential of 1.015 V, a maximum power density of 486 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.08 {omega} cm{sup 2} was achieved at 700 C. The results have indicated that BZCY7 proton-conducting electrolyte with BSZF cathode is a promising material system for the next generation solid oxide fuel cells. (author)

Effect of Al2O3 on the sintering of garnet-type Li6.5La3Zr1.5Ta0.5O12

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuxing; Yan, Pengfei; Xiao, Jie; Lu, Xiaochuan; Zhang, Ji-Guang; Sprenkle, Vincent L.

2016-10-01

It is widely recognized that Al plays a dual role in the fabrication of garnet-type solid electrolytes, i.e., as a dopant that stabilizes the cubic structure and a sintering aid that facilitates the densification. However, the sintering effect of Al2O3 has not been well understood so far because Al is typically “unintentionally” introduced into the sample from the crucible during the fabrication process. In this study, we have investigated the sintering effect of Al on the phase composition, microstructure, and ionic conductivity of Li6.5La3Zr1.5Ta0.5O12 by using an Al-free crucible and intentionally adding various amounts of γ-Al2O3. It was found that the densification of Li6.5La3Zr1.5Ta0.5O12 occurred via liquid-phase sintering, with evidence of morphology change among different compositions. Among all of the compositions, samples with 0.05 mol of Al per unit formula of garnet oxide (i.e., 0.3 wt% Al2O3) exhibited the optimal microstructure and the highest total ionic conductivity of 5 10-4 S cm-1 at room temperature.

Evaporation Rates of Chemical Warfare Agents Using 5 cm Wind Tunnels, IV. VX From Glass

Science.gov (United States)

2010-06-01

J »- o 3? a? j5 d £ * fi SC s? s? s s CO 00 ^ StSRRKf 8 tD Irt « 6 « « »§ ooopooooo WWUJfjJUJUJLULJJlJJ i-0)rtNO)NNT-(p OT...go? * • 8. E • g T5 ti w 5> w 3 ’ flj £ g> A. ft. ft. 3 *° ro (U (U « IB t_> < < < I 8...SCOCOCOCpCOeOCiCDCOCO OOlOOi-rWWnO ! K f^-" r^ I--• K r^ i^ • tD OJ CO S o> c O OJ CM CM (%) 6uiu!etuou juo6v

Growth, spectral properties, and laser demonstration of Nd:(Lu0.5Gd0.5)2SiO5 crystal

International Nuclear Information System (INIS)

Li, D Z; Xu, X D; Wu, F; Xia, C T; Zhang, J; Ma, J; Cong, Z H; Tang, D Y; Zhu, H M; Chen, X Y; Xu, J

2011-01-01

A Nd:(Lu 0.5 Gd 0.5 ) 2 SiO 5 (Nd:LGSO) crystal has been grown by the Czochralski method. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intensity parameters Ω 2,4,6 were obtained to be 5.37, 1.63, and 5.57×10 -20 cm 2 , respectively. The absorption and emission cross sections and branching ratios were calculated. The Nd:LGSO crystal reveals a broadband emission feature (FWHM = 9.8 nm), which shows potential as gain medium for ultrashort pulse lasers. The radiative and fluorescence lifetimes are 299 and 230 μs, respectively, resulting in a quantum efficiency of 77%. Pumped by a laser diode, the maximum continuous wave (CW) output power of 444 mW and a slope efficiency of 17.7% have been obtained

Growth, spectral properties, and laser demonstration of Nd:(Lu0.5Gd0.5)2SiO5 crystal

Science.gov (United States)

Li, D. Z.; Xu, X. D.; Zhang, J.; Cong, Z. H.; Tang, D. Y.; Ma, J.; Zhu, H. M.; Chen, X. Y.; Wu, F.; Xia, C. T.; Xu, J.

2011-09-01

A Nd:(Lu0.5Gd0.5)2SiO5 (Nd:LGSO) crystal has been grown by the Czochralski method. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intensity parameters Ω2,4,6 were obtained to be 5.37, 1.63, and 5.57×10-20 cm2, respectively. The absorption and emission cross sections and branching ratios were calculated. The Nd:LGSO crystal reveals a broadband emission feature (FWHM = 9.8 nm), which shows potential as gain medium for ultrashort pulse lasers. The radiative and fluorescence lifetimes are 299 and 230 μs, respectively, resulting in a quantum efficiency of 77%. Pumped by a laser diode, the maximum continuous wave (CW) output power of 444 mW and a slope efficiency of 17.7% have been obtained.

A TV camera system for digitizing single shot oscillograms at sweep rate of 0.1 ns/cm

International Nuclear Information System (INIS)

Kienlen, M.; Knispel, G.; Miehe, J.A.; Sipp, B.

1976-01-01

A TV camera digitizing system associated with a 5 GHz photocell-oscilloscope apparatus allows the digitizing of single shot oscillograms; with an oscilloscope sweep rate of 0.1 ns/cm an accuracy on time measurements of 4 ps is obtained [fr

Liver acquisition with volume acceleration flex on 70-cm wide-bore and 60-cm conventional-bore 3.0-T MRI.

Science.gov (United States)

Saito, Shigeyoshi; Tanaka, Keiko; Hashido, Takashi

2016-07-01

This study aimed to compare the uniformity of fat suppression and image quality between liver acquisition with volume acceleration flex (LAVA-Flex) and LAVA on 60-cm conventional-bore and 70-cm wide-bore 3.0-T magnetic resonance imaging (MRI). The uniformity of fat suppression by LAVA-Flex and LAVA was assessed as the efficiency of suppression of superficial fat at the levels of the liver dome, porta, and renal hilum. Percentage standard deviation (%SD) was calculated using the following equation: %SD (%) = 100 × SD of the regions of interest (ROIs)/mean value of the signal intensity (SI) in the ROIs. Signal-to-noise ratio (SNR) and contrast ratio (CR) were calculated. In the LAVA sequence, the %SD in all slices on wide-bore 3.0-T MRI was significantly higher than that on conventional-bore 3.0-T MRI (P 3.0-T MRI.

Effect of oxygen incorporation on the vibrational properties of Al0.2Ga0.3In0.5P:Be films

International Nuclear Information System (INIS)

Soubervielle-Montalvo, C.; Vital-Ochoa, O.; Anda, F. de; Vazquez-Cortes, D.; Rodriguez, A.G.; Melendez-Lira, M.; Mendez-Garcia, V.H.

2011-01-01

The vibrational properties of Al 0.2 Ga 0.3 In 0.5 P:Be films grown on (100) GaAs substrates by solid source molecular beam epitaxy varying the phosphorous cracking-zone temperature (PCT) were studied by Raman spectroscopy. The Raman-intensity ratio between the allowed longitudinal optical and the forbidden transverse optical (TO) phonons, and the full width at half maximum of their Lorentzian fits were used to characterize the crystalline quality of the films. The Raman spectra from the samples show changes in the shape and intensity of phonon resonances depending on the PCT variation, indicating that the disorder in the lattice increases with PCT. The increasing disorder is related to the inclusion of oxygen, which act as a non-intentional perturbing impurity in the lattice. In addition, a vibrational mode located at 598 cm -1 related to a forbidden InP-like TO phonon resonance was correlated with oxygen-induced disorder. Photoluminescence at room temperature shows that the high inclusion of oxygen also deteriorates the optical properties of the samples, by introducing non-radiative recombination centers.

The BRIDGE HadCM3 family of climate models: HadCM3@Bristol v1.0

Science.gov (United States)

Valdes, Paul J.; Armstrong, Edward; Badger, Marcus P. S.; Bradshaw, Catherine D.; Bragg, Fran; Crucifix, Michel; Davies-Barnard, Taraka; Day, Jonathan J.; Farnsworth, Alex; Gordon, Chris; Hopcroft, Peter O.; Kennedy, Alan T.; Lord, Natalie S.; Lunt, Dan J.; Marzocchi, Alice; Parry, Louise M.; Pope, Vicky; Roberts, William H. G.; Stone, Emma J.; Tourte, Gregory J. L.; Williams, Jonny H. T.

2017-10-01

Understanding natural and anthropogenic climate change processes involves using computational models that represent the main components of the Earth system: the atmosphere, ocean, sea ice, and land surface. These models have become increasingly computationally expensive as resolution is increased and more complex process representations are included. However, to gain robust insight into how climate may respond to a given forcing, and to meaningfully quantify the associated uncertainty, it is often required to use either or both ensemble approaches and very long integrations. For this reason, more computationally efficient models can be very valuable tools. Here we provide a comprehensive overview of the suite of climate models based around the HadCM3 coupled general circulation model. This model was developed at the UK Met Office and has been heavily used during the last 15 years for a range of future (and past) climate change studies, but has now been largely superseded for many scientific studies by more recently developed models. However, it continues to be extensively used by various institutions, including the BRIDGE (Bristol Research Initiative for the Dynamic Global Environment) research group at the University of Bristol, who have made modest adaptations to the base HadCM3 model over time. These adaptations mean that the original documentation is not entirely representative, and several other relatively undocumented configurations are in use. We therefore describe the key features of a number of configurations of the HadCM3 climate model family, which together make up HadCM3@Bristol version 1.0. In order to differentiate variants that have undergone development at BRIDGE, we have introduced the letter B into the model nomenclature. We include descriptions of the atmosphere-only model (HadAM3B), the coupled model with a low-resolution ocean (HadCM3BL), the high-resolution atmosphere-only model (HadAM3BH), and the regional model (HadRM3B). These also include

Magnetic properties of screen-printed (Y0.5Sm0.5)Co5 magnet arrays

International Nuclear Information System (INIS)

Bueno-Baques, D.; Maldonado-Chavez, L.; Hidalgo-Gonzalez, J.L.; Matutes-Aquino, J.A.; Corral-Flores, V.

2007-01-01

(Y 0.5 Sm 0.5 )Co 5 magnet arrays of square μdots of 300 μm were prepared by screen printing. A well controlled paste like ink prepared with the (Y 0.5 Sm 0.5 )Co 5 nanoparticles and a mixture of organic solvent and polymer was used to print different pattern arrays. (Y 0.5 Sm 0.5 )Co 5 nanoparticles were obtained by mechanical milling starting from arc melted ingots and heat treated in Ar atmosphere. Two different heat treatment were considered, resulting in powders with different magnetic properties. The microstructure of the magnet arrays was studied by scanning electron microscopy (SEM). An isotropic homogeneous distribution of the nanoparticles inside the μdots was observed. The final shape of the μdots in the array was found to be highly dependent on the squeeze pressure and speed over the mesh. Magnetic properties were studied by pulsed field magnetometry and vibrating sample magnetometry at room temperature. The micro size arrays showed lower saturation magnetization and a slightly increase in the coercive field. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Morphologically well-defined Gd0.1Ce0.9O1.95 embedded Ba0.5Sr0.5Co0.8Fe0.2O3-δ nanofiber with an enhanced triple phase boundary as cathode for low-temperature solid oxide fuel cells

Science.gov (United States)

Kim, Chanho; Park, Hyunjung; Jang, Inyoung; Kim, Sungmin; Kim, Kijung; Yoon, Heesung; Paik, Ungyu

2018-02-01

Controlling triple phase boundary (TPB), an intersection of the ionic conductor, electronic conductor and gas phase as a major reaction site, is a key to improve cell performances for low-temperature solid oxide fuel cells. We report a synthesis of morphologically well-defined Gd0.1Ce0.9O1.95 (GDC) embedded Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) nanofibers and their electrochemical performances as a cathode. Electrospun fibers prepared with a polymeric solution that contains crystalline Ba0.5Sr0.5Co0.8Fe0.2O3-δ particles in ∼200 nm size and Gd(NO3)3/Ce(NO3)3 precursors in an optimized weight ratio of 3 to 2 result in one dimensional structure without severe agglomeration and morphological collapse even after a high calcination at 1000 °C. As-prepared nanofibers have fast electron pathways along the axial direction of fibers, a higher surface area of 7.5 m2 g-1, and more oxygen reaction sites at TPBs than those of GDC/BSCF composite particles and core-shell nanofibers. As a result, the Gd0.1Ce0.9O1.95 embedded Ba0.5Sr0.5Co0.8Fe0.2O3-δ nanofiber cell shows excellent performances of the maximum power density of 0.65 W cm-2 at 550 °C and 1.02 W cm-2 at 600 °C, respectively.

High dielectric constant observed in (1 − x)Ba(Zr0.07Ti0.93)O3–xBa(Fe0.5Nb0.5)O3 binary solid-solution

International Nuclear Information System (INIS)

Kruea-In, Chatchai; Eitssayeam, Sukum; Pengpat, Kamonpan; Rujijanagul, Gobwute

2012-01-01

Binary solid-solutions of the (1 − x)Ba(Zr 0.07 Ti 0.93 )O 3 –xBa(Fe 0.5 Nb 0.5 O 3 ) system, with 0.1 ≤ x ≤ 0.9,were fabricated via a solid-state processing technique. X-ray diffraction analysis revealed that all samples exhibited a single perovskite phase. The BaFe 0.5 Nb 0.5 O 3 also promoted densification and grain growth of the system. Dielectric measurements showed that all samples displayed a relaxor like behavior. The x = 0.1 sample presented a dielectric-frequency and temperature with low loss tangent ( 0.2 samples, the dielectric data showed a broad dielectric constant–temperature curve with a giant dielectric characteristic. In addition, a high dielectric constant > 50,000 (at 10 kHz and temperature > 150 °C) was observed for the x = 0.9 sample.

Enhanced piezoelectric properties in vanadium-modified lead-free (K{sub 0.485}Na{sub 0.5}Li{sub 0.015})(Nb{sub 0.88}Ta{sub 0.1}V{sub 0.02})O{sub 3} ceramics prepared from nanopowders

Energy Technology Data Exchange (ETDEWEB)

Gaur, Roopam; Dhingra, Apurva; Pal, Soham; Chandramani Singh, K., E-mail: kongbam@gmail.com

2015-03-15

Highlights: • (K{sub 0.485}Na{sub 0.5}Li{sub 0.015})(Nb{sub 0.9−x}Ta{sub 0.1}V{sub x}) O{sub 3}(x = 0, 0.01, 0.02, 0.03) ceramics were prepared. • These ceramics were synthesized from 35-nm powders. • Density, microstrain, crystallite size, tetragonality were high at x = 0.02. • Dielectric, ferroelectric and piezoelectric properties were enhanced at x = 0.02. • The increased properties are attributed to crystal structure and microstructure. - Abstract: Enhancing the piezoelectric properties of lead-free piezoceramics like alkaline niobate system has been an important research topic in our search for an alternative to widely used but highly toxic lead-based PZT piezoceramics system. In the present study, lead-free alkaline niobate-based compositions (K{sub 0.485}Na{sub 0.5}Li{sub 0.015})(Nb{sub 0.9−x}Ta{sub 0.1}V{sub x})O{sub 3} (x = 0, 0.01, 0.02 and 0.03) were synthesized using conventional solid state reaction method. Nanocrystalline powders of these compositions, produced by high energy ball milling, were sintered at 1050 °C for 4 h to produce corresponding ceramics. Increasing V{sup 5+} content in the ceramics from x = 0 to 0.02 results in a gradual increase in the room temperature dielectric constant (ε{sub r}) from 1185 to 1336, remnant polarization (P{sub r}) from 13.4 μC/cm{sup 2} to 17.1 μC/cm{sup 2}, electromechanical coupling factor (k{sub p}) from 0.37 to 0.40, and piezoelectric charge constant (d{sub 33}) from 156 pC/N to 185 pC/N. Further increase in x to 0.03 lowers these values to 1082, 13.4 μC/cm{sup 2}, 0.36 and 128 pC/N respectively. Correspondingly, the coercive field (E{sub c}) first shows a gradual decline from 8.5 kV/cm to 7.9 kV/cm and then a rise to 9.2 kV/cm, as x increases from 0 to 0.02 and then to 0.03. The enhancement of piezoelectric properties in (K{sub 0.485}Na{sub 0.5}Li{sub 0.015})(Nb{sub 0.88}Ta{sub 0.1}V{sub 0.02})O{sub 3} ceramics is attributed to the associated higher values of density, tetragonality and

Mass spectrometic isotope dilution analysis of Am and Cm in spent fuels

International Nuclear Information System (INIS)

Wantschik, M.; Koch, L.; Commission of the European Communities, Karlsruhe; Ganser, B.

1983-01-01

Spent nuclear fuels contain Am and Cm in the 10 ppb to 100 ppm range. Because of this low abundance and the necessity of handling small samples of the highly toxic fuel material only a mass-spectrometric isotope dilution analysis can give sufficiently accurate results. Since suitable spikes and/or standards have been lacking, this method has not been applied. Using known masses (+- 0.1%) of Am-241 and Cm-244 metal, Am-243 and Cm-248 spikes were calibrated to an accuracy of better than 0.2%. The standards were reanalysed by chemical titration and several radiometric techniques. The chemical conditioning is based on ionexchange chromatography with alpha-hydroxyisobutyric acid. A sample size of 10 -7 g is sufficient. For the mass-spectrometric measurement 10 -9 g of the elements are required. The accuracy for the determination of the main isotope is 0.5%. (orig./BRB)

Organic matter evolution throughout a 100-cm ombrotrophic profile from an Italian floating mire

Science.gov (United States)

Zaccone, Claudio; D'Orazio, Valeria; Lobianco, Daniela; Miano, Teodoro M.

2015-04-01

The curious sight of an island floating and moving on a lake naturally, already described by Pliny the Elder in his Naturalis historia (AD 77-79), fascinated people from time immemorial. Floating mires are defined by the occurrence of emergent vegetation rooted in highly organic buoyant mats that rise and fall with changes in water level. Peat-forming floating mires could provide an exceptional tool for environmental studies, since much of their evolution, as well as the changes of the surrounding areas, is recorded in their peat deposits. A complete, 4-m deep peat core was collected in July 2012 from the floating island of Posta Fibreno, a relic mire in the Central Italy. This floating island has a diameter of ca. 30 m, a submerged thickness of about 3 m, and the vegetation is organized in concentric belts, from the Carex paniculata palisade to the Sphagnum centre. Here, some of the southernmost Italian populations of Sphagnum palustre occur. The 14C age dating of macrofossils removed from the sample at 360 cm of depth revealed that the island probably formed more than 500 yrs ago (435±20 yr BP). In the present work, we show preliminary results regarding the evolution of the organic matter along the first, ombrotrophic 100 cm of depth, hoping also to provide some insight into the possible mechanism of the evolution of this floating island. The 100 cm monolith was collected using a Wardenaar corer and cut frozen in 1-cm layers. It consists almost exclusively of Sphagnum mosses, often spaced out, in the top 20-30 cm, by leaves of Populus tremula that annually fell off. This section shows a very low bulk density, ranging from 0.017 and 0.059 g cm-3 (avg. value, 0.03±0.01 g cm-3), an average water content of 96.1±1.1%, and a gravimetric water content ranging between 14.3 and 41.5 gwater gdrypeat-1. The pH of porewaters was in the range 5-5.5. The C content along the profile ranged between 35 and 47% (avg., 41±1%), whereas the N between 0.3 and 0.9% (avg., 0.6±0

Effect of ZnO Nanoparticles on the Sintering Behavior and Physical Properties of Bi0.5(Na0.8K0.2)0.5TiO3 Lead-Free Ceramics

Science.gov (United States)

Vuong, Le Dai; Truong-Tho, Nguyen

2017-11-01

Sintered Bi0.5(Na0.8K0.2)0.5TiO3 + x wt.% ZnO nanoparticle (BNKT- xZnOn) ceramics have been fabricated by conventional annealing with the aid of ultrasound waves for preliminary milling. Because of the presence of the liquid Bi2O3-ZnO phase at the eutectic point of 738°C, the sintering temperature decreased from 1150°C to 1000°C, and the morphology phase boundary of BNKT- xZnOn ceramics can be clarified by two separated peaks at (002)T and (200)T of 2 θ in the x-ray diffraction (XRD) patterns. The improvement of ferroelectric properties has been obtained for BNZT-0.2 wt.% ZnOn ceramics by the increase of remanent polarization up to 20.4 μC/cm2 and a decrease of electric coercive field down to 14.2 kV/cm. The piezoelectric parameters of the ceramic included a piezoelectric charge constant of d 31 = 78 pC/N; electromechanical coupling factors k p = 0.31 and k t = 0.34, larger than the values of 42 pC/N, 0.12 and 0.13, respectively, were obtained for the BNKT ceramics.

Carbothermic synthesis of (Cm,Pu)N

International Nuclear Information System (INIS)

Takano, Masahide; Itoh, Akinori; Akabori, Mitsuo; Ogawa, Toru; Numata, Masami; Okamoto, Hisato

2001-01-01

Nitrides are being considered as fuel candidates for the transmutation of minor actinides. Carbothermic reduction of oxides is an effective method to fabricate nitride fuels. In this study, (Cm 0.40 ,Pu 0.60 )N was synthesized by the carbothermic reduction of the mixed oxide in N 2 . By applying excess carbon, an oxide-free nitride was obtained at 1773 K. The lattice parameter of the oxide-free sample was 0.4948 nm, and that of the nitride with oxides was 0.4974 nm. The former value agreed well with that estimated from the literature values for CmN and PuN. The larger lattice parameter of the latter sample is considered to be due to the oxygen dissolved in the nitride. (authors)

High performance Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3}-La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3} composite cathodes

Energy Technology Data Exchange (ETDEWEB)

Wang, Shizhong; Zou, Yuman [College of Chemistry and Chemical Engineering, Department of Chemistry, Xiamen University, Xiamen 361005, Fujian (China)

2006-06-15

High performance Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3}(SSC)-La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3} (LSGMC5) composite cathodes for intermediate temperature solid oxide fuel cells (ITSOFC) were prepared and characterized. The SSC powders were synthesized using the glycine-nitrate method and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3}(LSGMC5) powders were synthesized using the citrate method. The calcining temperature for the SSC and LSGMC5 powders had strong effect on the microstructure of the composite electrode and electrode/electrolyte interface, which affected the performance of the SSC-LSGMC5 electrode strongly. The electrode based on SSC calcined at 1223K and LSGMC5 calcined at 1273K exhibited the highest performance among the electrodes studied. The electrode resistance was about 0.07{omega}cm{sup 2}, and the overpotential under 1Acm{sup -2} current density was as low as 0.077V at 973K in oxygen, which could be an ideal cathode for ITSOFC based on lanthanum gallate electrolytes. (author)

Proton conducting solid oxide fuel cells with layered PrBa{sub 0.5}Sr{sub 0.5}Co{sub 2}O{sub 5+{delta}} perovskite cathode

Energy Technology Data Exchange (ETDEWEB)

Ding, Hanping; Xue, Xingjian [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

2010-03-15

BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY7) exhibits adequate protonic conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered perovskite PrBa{sub 0.5}Sr{sub 0.5}Co{sub 2}O{sub 5+{delta}} (PBSC) has advanced electrochemical properties. This research fully takes advantage of these advanced properties and develops a novel protonic ceramic membrane fuel cell (PCMFC) of Ni-BZCY7 vertical stroke BZCY7 vertical stroke PBSC. Experimental results show that the cell may achieve the open-circuit potential of 1.005 V, the maximal power density of 520 mW cm{sup -2}, and a low electrode polarization resistance of 0.12 {omega}cm{sup 2} at 700 C. Increasing operating temperature leads to the decrease of total cell resistance, among which electrolyte resistance becomes increasingly dominant over polarization resistance. The results also indicate that PBSC perovskite cathode is a good candidate for intermediate temperature PCMFC development, while the developed Ni-BZCY7 vertical stroke BZCY7 vertical stroke PBSC cell is a promising functional material system for SOFCs. (author)

Properties of La0.5Sr0.5CoO3 thin films grown by laser ablation

International Nuclear Information System (INIS)

Drozdov, Yu.N.; Klyuenkov, E.B.; Salashenko, N.N.; Suslov, L.A.

1997-01-01

The epitaxial films of lanthanum-strontium cobaltate La 0.5 Sr 0.5 CoO 3 (LSCO) are obtained on the neodium gallate and strontium titanate substrates. It is established that the LSCO layer lattice has tetragonal distortion, the degree where of depends on the oxygen deficit. The LSCO specific resistance at room temperature is approximately equal to 200 μOhm cm. The resistance dependence on temperature is of metal character. The possibility is shown of utilizing the LSCO as electrode material by fabrication of condenser structures on the basis of DbZr 1-x Ti x O 3 ferroelectric films

Density determination in Pino Radiata (D.Don) samples using 59.5 keV gamma radiation attenuation

International Nuclear Information System (INIS)

Dinator, Maria I.; Morales, Jose R.; Aliaga, Nelson; Karsulovic, Jose T.; Sanchez, Jaime; Leon, Adolfo

1996-01-01

A non destructive method to determine wood samples density is presented. The photon mass attenuation coefficient in samples of Pino radiata (D.Don) was measured at 59.5 keV with a radioactive source of Am-241. The value of 0.192 ± 0.002 cm 2 /g was obtained with a gamma spectroscopy system and later used on the determination of the mass density in sixteen samples of the same species. Comparison of these results with those of gravimetric method through a linear regression showed a slope of 1.001 and a correlation factor of 0.94. (author)

Crystal and magnetic study of the disordered perovskites Ca(Mn0.5Sb0.5)O3 and Ca(Fe0.5Sb0.5)O3

International Nuclear Information System (INIS)

Retuerto, M.; Martinez-Lope, M.J.; Garcia-Hernandez, M.; Munoz, A.; Fernandez-Diaz, M.T.; Alonso, J.A.

2010-01-01

We have investigated the double perovskites Ca 2 MSbO 6 (M = Mn, Fe) that have been prepared by solid-state reaction (M = Fe) and wet chemistry procedures (M = Mn). The crystal and magnetic structures have been studied from X-ray (XRD) and neutron powder diffraction (NPD) data. Rietveld refinements show that the crystal structures are orthorhombic (space group Pbnm) with complete disorder of M and Sb cations, so the formula should be rewritten as Ca(M 0.5 Sb 0.5 )O 3 . Due to this disorder no evidences of Jahn-Teller distortion can be observed in the MnO 6 octahedra of Ca(Mn 0.5 Sb 0.5 )O 3 , in contrast with the ordered double perovskite Sr 2 MnSbO 6 . Ca(Fe 0.5 Sb 0.5 )O 3 behaves as an antiferromagnet with an ordered magnetic moment for Fe 3+ of 1.53(4)μ B and a propagation vector k = 0, as investigated by low-temperature NPD. The antiferromagnetic ordering is a result of the high degree of Fe/Sb anti-site disorder of the sample, which originates the spontaneous formation of Fe-rich islands, characterized by the presence of strong Fe-O-Fe antiferromagnetic couplings with enough long-range coherence to produce a magnetic contribution perceptible by NPD. By contrast, the magnetic structure of Ca(Mn 0.5 Sb 0.5 )O 3 cannot be observed by low-temperature NPD because the magnitude of the ordered magnetic moments is below the detection threshold for neutrons.

C-axial oriented (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 thin film grown on Nb doped SrTiO3 substrate by pulsed laser deposition

International Nuclear Information System (INIS)

Cao, L Z; Fu, W Y; Wang, S F; Wang, Q; Sun, Z H; Yang, H; Cheng, B L; Wang, H; Zhou, Y L

2007-01-01

A c-axial oriented (Bi 1.5 Zn 0.5 )(Zn 0.5 Nb 1.5 )O 7 thin film has been grown on a (0 0 1) Nb doped SrTiO 3 substrate by pulsed laser deposition. The permittivity, dielectric loss and tunability of the c-axial oriented film are 187, 0.002 and 6% (at 750 kV cm -1 biasing), respectively, indicating a figure of merit of 30. Moreover, an asymmetry behaviour is observed in the dc electric field dependence of permittivity, which could be attributed to the asymmetry of top and bottom electrodes

Dependence of magnetic and structural properties of Ni 0.5 M 0.5 Fe ...

African Journals Online (AJOL)

Ni0.5M0.5Fe2O4 (M = Co, Cu) ferrite nanoparticles were synthesized using citrate precursor method. The citrate precursor was annealed at temperatures 400oC, 450oC, 500oC and 550oC. The annealed powders were characterized using X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM). Observed ...

Phase formation, structure and dielectric properties of ceramics (Na0.5Bi0.5TiO3–(K0.5Na0.5NbO3–BiFeO3

Directory of Open Access Journals (Sweden)

G. M. Kaleva

2016-03-01

Full Text Available Influence of BiFeO3 (BF on phase formation, unit cell parameters, microstructure, dielectric and ferroelectric properties of solid solutions close to the morphotropic phase boundary in the (Na0.5Bi0.5TiO3–(K0.5Na0.5NbO3 system additionally modified by the low-melting KCl additives has been studied. The formation of pure perovskite structure samples decrease in the unit cell parameters and increase in the TC value stimulated by the BF addition have been revealed. It was proved that modification of compositions by small amounts of the BF and KCl additives leads to improvement of dielectric parameters.

Low cycle fatigue behaviour of Ti-6Al-5Zr-0.5Mo-0.25Si alloy at room temperature

International Nuclear Information System (INIS)

Nag, Anil Kumar; Praveen, K.V.U.; Singh, Vakil

2006-01-01

Low cycle fatigue (LCF) behaviour of the near α titanium alloy, Ti-6Al-5Zr-0.5Mo-0.25Si (LT26A), was investigated in the (α+ β) as well as β treated conditions at room temperature. LCF tests were carried out under total strain controlled mode in the range of Δε t /2: from ± 0.60% to ± 1.40%. The alloy shows cyclic softening in both the conditions. Also it exhibits dual slope Coffin-Manson (C-M) relationship in both the treated conditions. (author)

Oxygen permeation and stability of La 0.4Ca 0.6Fe 1-xCo xO 3-δ ( x = 0, 0.25, 0.5) membranes

Science.gov (United States)

Diethelm, S.; Van herle, J.; Middleton, P. H.; Favrat, D.

Three perovskite-type compounds of composition La 0.4Ca 0.6Fe 1- xCo xO 3- δ ( x=0, 0.25 and 0.5) were investigated for use as oxygen separation membranes for the partial oxidation (POX) of methane to syngas. Special attention was given to the question of their stability in real operating conditions. A permeation set-up was specially designed to measure oxygen fluxes through these materials when placed in a strong pO 2 gradient. It also facilitated testing the long-term stability of the specimen. Permeation measurements performed in an air/argon gradient between 800 and 1000 °C showed that the highest fluxes were obtained with the highest content of cobalt (La 0.4Ca 0.6Fe 0.5Co 0.5O 3- δ ≅ La 0.4Ca 0.6Fe 0.75Co 0.25O 3- δ > La 0.4Ca 0.6FeO 3- δ). In addition, comparison between the fluxes of samples of different thickness gave clear evidence of surface limitations in the oxygen transport. The long-term stability test showed opposite trends: only the two lowest Co containing compounds ( x=0 and 0.25) sustained an air/(Ar+H 2) gradient over more than 600 h. The other ( x=0.5) broke shortly after the introduction of H 2. In the presence of H 2, the oxygen flux was increased by a factor 10 compared to Ar and reached 0.83 μmol/cm 2 s for La 0.4Ca 0.6Fe 0.75Co 0.25O 3- δ at 900 °C. Post-operation SEM examination of the cross-section and both surfaces revealed that the surface exposed to H 2 had started to decompose resulting in the formation of a thin porous layer but the bulk of the material remained unchanged.

Room temperature multiferroic properties of Pb(Fe{sub 0.5}Nb{sub 0.5})O{sub 3}–Co{sub 0.65}Zn{sub 0.35}Fe{sub 2}O{sub 4} composites

Energy Technology Data Exchange (ETDEWEB)

Pradhan, Dhiren K., E-mail: dhirenkumarp@gmail.com, E-mail: rkatiyar@hpcf.upr.edu; Katiyar, Ram S., E-mail: dhirenkumarp@gmail.com, E-mail: rkatiyar@hpcf.upr.edu [Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00936 (United States); Puli, Venkata S. [Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118 (United States); Narayan Tripathy, Satya; Pradhan, Dillip K. [Department of Physics, National Institute of Technology, Rourkela 769008 (India); Scott, J. F. [Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00936 (United States); Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom)

2013-12-21

We report the crystal structure, magnetic, ferroelectric, dielectric, and magneto-dielectric properties of [Pb(Fe{sub 0.5}Nb{sub 0.5})O{sub 3}]{sub (1−x)}[Co{sub 0.65}Zn{sub 0.35}Fe{sub 2}O{sub 4}]{sub x}: (x = 0.1, 0.2, 0.3, and 0.4) composites. Rietveld refinement results of X-ray diffraction patterns confirm the formation of these composites for all x values. All the composites show well-saturated ferroelectric and ferromagnetic hysteresis (multiferroic-composite behavior) at room temperature. With increase in Co{sub 0.65}Zn{sub 0.35}Fe{sub 2}O{sub 4} (CZFO) content an increase in saturation magnetization, and decrease in saturation polarization, remanent polarization, and dielectric constant are observed. The ferroelectric phase transition temperature increases with increase in CZFO content. All of the compositions undergo second-order ferroelectric phase transitions, which can be explained by Landau-Devonshire theory. The recoverable energy density (∼0.20 to 0.04 J/cm{sup 3}) and charge-curve energy density (∼0.84 to 0.11 J/cm{sup 3}) decrease with increase in the CZFO content. The room-temperature magneto-dielectric measurements provide direct evidence of magneto-electric coupling via strain at room temperature.

Testing And Performance Analysis Of NASA 5 CM BY 5 CM Bi-Supported Solid Oxide Electrolysis Cells Operated In Both Fuel Cell And Steam Electrolysis Modes

International Nuclear Information System (INIS)

O'Brien, R.C.; O'Brien, J.E.; Stoots, C.M.; Zhang, X.; Farmer, S.C.; Cable, T.L.; Setlock, J.A.

2011-01-01

A series of 5 cm by 5 cm bi-supported Solid Oxide Electrolysis Cells (SOEC) were produced by NASA for the Idaho National Laboratory (INL) and tested under the INL High Temperature Steam Electrolysis program. The results from the experimental demonstration of cell operation for both hydrogen production and operation as fuel cells is presented. An overview of the cell technology, test apparatus and performance analysis is also provided. The INL High Temperature Steam Electrolysis laboratory has developed significant test infrastructure in support of single cell and stack performance analyses. An overview of the single cell test apparatus is presented. The test data presented in this paper is representative of a first batch of NASA's prototypic 5 cm by 5 cm SOEC single cells. Clearly a significant relationship between the operational current density and cell degradation rate is evident. While the performance of these cells was lower than anticipated, in-house testing at NASA Glenn has yielded significantly higher performance and lower degradation rates with subsequent production batches of cells. Current post-test microstructure analyses of the cells tested at INL will be published in a future paper. Modification to cell compositions and cell reduction techniques will be altered in the next series of cells to be delivered to INL with the aim to decrease the cell degradation rate while allowing for higher operational current densities to be sustained. Results from the testing of new batches of single cells will be presented in a future paper.

An ultrasonic therapeutic transducers using lead-free Na0.5K0.5NbO3-CuNb2O6 ceramics

International Nuclear Information System (INIS)

Yang, Ming-Ru; Chu, Sheng-Yuan; Tsai, Cheng-Che

2010-01-01

Research highlights: → In this paper, CN was added to NKN ceramics to decrease the sintering temperature and to improve the density and piezoelectric characteristics. The influence of CuNb 2 O 6 (CN) content on the microstructure, electrical properties, temperature stability, and mechanical properties of the synthesized samples was investigated. Results show that the samples synthesized with CN-doped not only improved the density but also exhibited superior piezoelectric characteristic, temperature stability of resonance frequency (TCF), and elastic stiffness coefficient than those of pure NKN piezoelectric ceramics. → The bulk density (4.47 g/cm 3 ), k p (40%), k t (45%), Q m (1642), C 33 D (19.64 x 10 10 N/m 2 ), TCF (-0.011%/ o C) and TCC (0.135%/ o C) values for NKN-01CN ceramics obtained from experiments show excellent 'hard' piezoelectric properties. Furthermore, a lead-free NKN-01CN ultrasonic therapeutic transducer was successfully driven by a self-tuning circuit. - Abstract: In this work, we reports on the CuNb 2 O 6 (CN) modified lead-free Na 0.5 K 0.5 NbO 3 (NKN) based piezoelectric ceramics were synthesized by solid-state reaction methods and sintered at 1075 o C for 3 h. A secondary phase of K 4 CuNb 8 O 23 was found in the XRD pattern of NKN-based ceramics as the CN dopants is 1 mol%. Microstructural analyses of un-doped and CN-doped ceramics were performed in a scanning electron microscope. The influence of CN content on the microstructure, electrical properties, temperature stability, and mechanical properties of the synthesized ceramics was investigated. The results show that the synthesized ceramics with CN-doped not only had improved density but also exhibited superior piezoelectric characteristics, temperature stability of resonance frequency (TCF), and a better elastic stiffness coefficient than those of pure NKN piezoelectric ceramics. The bulk density (4.47 g/cm 3 ), k p (40%), k t (45%), Q m (1642), C 33 D (19.64 x 10 10 N/m 2 ), TCF (-0

Effect of oxygen stoichiometry on the electrical properties of La0.5Sr0.5CoO3 electrodes

International Nuclear Information System (INIS)

Madhukar, S.; Aggarwal, S.; Dhote, A.M.; Ramesh, R.; Krishnan, A.; Keeble, D.; Poindexter, E.

1997-01-01

We report on the metal-insulator transition of La 0.5 Sr 0.5 CoO 3 thin films deposited by pulsed laser ablation on LaAlO 3 substrates. The films were cooled in oxygen partial pressures between 760 and 10 -5 Torr and electrical resistivity of the films was measured as a function of cooling oxygen pressure. La 0.5 Sr 0.5 CoO 3 films changed from metallic to insulating behavior depending on their oxygen content. A defect model has been proposed to explain this transition and the change in conductivity is related to the change in the oxidation state of the cobalt ions. The model explains the relationship between oxygen partial pressure and electrical conductivity in La 0.5 Sr 0.5 CoO 3 , which describes the experimental dependence reasonably well. Positron annihilation studies were also done on the same set of samples and the S parameter was seen to increase by 8% from a fully oxygenated sample to a sample cooled in 10 -5 Torr. copyright 1997 American Institute of Physics

High performance protonic ceramic membrane fuel cells (PCMFCs) with Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}} perovskite cathode

Energy Technology Data Exchange (ETDEWEB)

Ding Hanping [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei 230026 (China); Xue Xingjian, E-mail: Xue@cec.sc.ed [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Liu Xingqin; Meng Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei 230026 (China)

2010-04-02

Protonic ceramic membrane fuel cells (PCMFCs) based on proton-conducting electrolytes have attracted much attention because of many advantages, such as low activation energy and high energy efficiency. A stable, easily sintered perovskite oxide BaCe{sub 0.5}Zr{sub 0.3}Y{sub 0.16}Zn{sub 0.04}O{sub 3-{delta}} (BCZYZ) as electrolyte for proton-conducting solid oxide fuel cells (SOFCs) with Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}} (SSC) composite cathode is investigated. By fabricating thin membrane BCZYZ electrolyte ({approx}20 {mu}m) synthesized by a modified Pechini method on NiO-BCZYZ anode support, PCMFCs are assembled and tested by selecting SSC perovskite cathode with high mixed ionic and electronic conductivities. An open-circuit potential of 1.015 V, a maximal power density of 528 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.15 {Omega} cm{sup 2} is achieved at 700 {sup o}C. The results indicate that BCZYZ proton-conducting electrolyte with SSC cathode is a promising material system for SOFCs.

A method to determine density in wood samples using attenuation of 59.5 KeV gamma radiation

International Nuclear Information System (INIS)

Dinator, M.I.; Morales, J.R.; Aliaga, N.; Karsulovic, J.T.; Sanchez, J.; Leon, L.A.

1996-01-01

A nondestructive method to determine the density of wood samples is presented. The photon mass attenuation coefficient in samples of Pino Radiata was measured at 59.5 KeV with a radioactive source of Am-241. The value of 0.192 ± 0.002 cm 2 /g was obtained with a gamma spectroscopy system and later used on the determination of the mass density in sixteen samples of the same species. Comparison of these results with those of gravimetric method through a linear regression showed a slope of 1.001 and correlation factor of 0.94. (author)

Studies of N{sub 2}0 adsorption and decomposition on Fe-ZSM-5

Energy Technology Data Exchange (ETDEWEB)

Wood, Benjamin R.; Reimer, Jeffrey A.; Bell, Alexis T.

2002-03-08

The interactions of N2O with H-ZSM-5 and Fe-ZSM-5 have been investigated using infrared spectroscopy and temperature-programmed reaction. Fe-ZSM-5 samples with Fe/Al ratios of 0.17 and 0.33 were prepared by solid-state exchange. It was determined that most of the iron in the samples of Fe-ZSM-5 is in the form of isolated cations, which have exchanged with Bronsted acid H+ in H-ZSM-5. The infrared spectrum of N2O adsorbed on H-ZSM-5 at 298 K exhibits bands at 2226 and 1308 cm-1 associated with vibrations of the N-N and N-O bonds, respectively. The positions of these bands relative to those seen in the gas phase suggest that N2O adsorbs through the nitrogen end of the molecule. The heat of N2O adsorption in H-ZSM-5 is estimated to be 5 kcal/mol. In the case of Fe-ZSM-5, additional infrared bands are observed at 2282 and 1344 cm-1 due to the interactions of N2O with the iron cations. Here too, the directions of the shifts in the vibrational features relative to those for gas-phase N2O suggest that the molecule adsorbs through its nitrogen end. The heat of adsorption of N2O on the Fe sites is estimated to be 16 kcal/mol. The extent of N2O adsorption on Fe depends on the oxidation state of Fe. The degree of N2O adsorption is higher following pretreatment of the sample in He or CO at 773 K, than following pretreatment in O2 or N2O at the same temperature. Temperature-programmed decomposition of N2O was performed on the Fe-ZSM-5 samples and revealed that N2O decomposes stoichiometrically to N2 and O2. A higher activity was observed if the catalysts were pretreated in He than if they were pretreated in N2O. For the He-pretreated samples, the activation energy for N2O decomposition was estimated to be 42 kcal/mol and the preexponential factor of the rate coefficient for this process was found to increase with Fe/Al ratio. This trend was attributed to the increasing auto reducibility of Fe3+ cations to Fe2+ cations with increasing Fe/Al ratio.

Surface resistances of 5-cm-diameter YBCO films prepared by MOD for microwave applications

International Nuclear Information System (INIS)

Manabe, T.; Sohma, M.; Yamaguchi, I.; Tsukada, K.; Kondo, W.; Kamiya, K.; Tsuchiya, T.; Mizuta, S.; Kumagai, T.

2006-01-01

Large-area high-T c superconducting films with low surface resistances R s are required for use in microwave applications such as band pass filters. In this paper, preparation of 5-cm-diameter YBCO films on LaAlO 3 (LAO) and CeO 2 -buffered sapphire (CbS) substrates by metalorganic deposition (MOD) using a fluorine-free coating solution and their superconducting properties are described. The optimum firing conditions for YBCO films greatly depend on the substrate materials; a heating rate at ramp as high as 200 deg. C /min is necessary for films on LAO whereas a lower heating rate, e.g., 20 deg. C /min, is required for films on CbS. Accordingly, the suitable furnace systems for these substrates have been varied. As a result, a YBCO film with high J c (77 K) of 2.7 MA/cm 2 and a low R s (12 GHz, 77 K) of 0.54 mΩ was prepared on LAO by using an infrared image furnace. On the other hand, a YBCO film with a higher J c (77 K) of 4.0 MA/cm 2 and the same R s (12 GHz, 77 K) of 0.54 mΩ was prepared on CbS by using a tube furnace

Elastic Properties of Ho0.5Er0.5 Single Crystal

DEFF Research Database (Denmark)

Spichkin, Yu.I.; Bohr, Jakob; Tishin, A.M.

1996-01-01

The results of an investigation of the Young's modulus E and the interval friction Q-1 of a Ho0.5Er0.5 single crystal in the basal plane in the temperature range 4.2-400 K are reported. The measurements were carried out by the method of flexural autovibrations of a thin sample with sound frequency...... (3 kHz). The Young's modulus at 4.2 K was measured to be 154 GPa. From the obtained data the magnetic part of the Young's modulus and the Debye temperature theta-D=375 K were calculated. The anomalies on the Young's modulus and the interval friction temperature dependencies corresponding to magnetic...

Structural and magnetic properties of Fe76P5(Si0.3B0.5C0.2)19 amorphous alloy

International Nuclear Information System (INIS)

Lavorato, G.C.; Fiore, G.; Tiberto, P.; Baricco, M.; Sirkin, H.; Moya, J.A.

2012-01-01

Highlights: ► Fe 76 P 5 (Si 0.3 B 0.5 C 0.2 ) 19 amorphous alloy in ribbons and 1 mm and 2 mm rod samples. ► Good glass forming ability with ΔT = 50 K and γ = 0.37 and off-eutectic composition. ► Good soft magnetic properties with magnetization saturation of 1.44 T. ► Geometrical factors are the primary causes of magnetic losses in frequencies above 10 Hz. - Abstract: Recently, bulk amorphous alloys were produced in the Fe–B–Si–P–C system with high glass forming ability, excellent magnetic properties and the advantage of containing no expensive glass-forming elements, such as Ga, Y, Cr or Nb, having, therefore, a good perspective of commercial applications. In the present work, the Fe 76 P 5 (Si 0.3 B 0.5 C 0.2 ) 19 amorphous alloy prepared by two quenching techniques has been studied. Amorphous ribbons of about 40 μm thick were obtained by planar-flow casting together with cylinders having 1 and 2 mm diameter produced by copper mold injection casting. All the samples appear fully amorphous after X-ray diffraction analysis. A comprehensive set of thermal data (glass, crystallization, melting and liquidus temperatures) were obtained as well as a description of the melting and solidification processes. Mechanical microhardness tests showed that the samples have a hardness of 9.7 ± 0.3 GPa. Good soft-magnetic properties were obtained, including a high magnetization of 1.44 T and a low coercivity (4.5 A/m for ribbons and 7.5 A/m in the case of 1 mm rod samples, both in as-cast state). Thermomagnetic studies showed a Curie temperature around 665 K and the precipitation of new magnetic phases upon temperatures of 1000 K. Furthermore, the frequency dependence of magnetic losses at a fixed peak induction was studied. The results suggest the occurrence of a fine magnetic domain structure in bulk samples. The good soft magnetic properties of the bulk metallic glass obtained by copper mold casting for this particular Fe-based composition suggests possible

Study on Dy0.45Ba0.05Sr0.5Co0.8Fe0.2O3-δ-Ce0.85Gd0.15O1.95 composite cathode material for intermediate temperature solid oxide fuel cell

Science.gov (United States)

Kautkar, Pranay R.; Acharya, Smita A.

2018-05-01

xDy0.45Ba0.05Sr0.5Co0.8Fe0.2O3-δ - xCe0.85Gd0.15O1.95 (x = 50 %) composite cathode supported on Ce0.85Gd0.15O1.95 (GDC15) electrolyte are studied for applications in IT-SOFCs. Results attribute that Dy0.45Ba0.05Sr0.5Co0.8Fe0.2O3-δ material is chemically compatible with Ce0.85Gd0.15O1.95 (GDC15). Rietveld refined X-ray diffraction patterns notify orthorhombic (space group:Pbnm) symmetry for Dy0.45 Ba0.05Sr0.5Co0.8Fe0.2O3-δ and fluorite type structure (space group: Fm-3m) symmetry for GDC15. The polarization resistance (Rp) of composite cathode reduces to the minimum value of 1.35 Ω cm2 at 650 °C in air. Area specific resistance (ASR) of composite cathode has found 0.67 Ω.cm2 at 650°C respectively. Result shows that the surface diffusion of the dissociative adsorbed oxygen at electrode/electrolyte interface on the composite cathode.

Oxygen isotope systematics of chondrules in the Murchison CM2 chondrite and implications for the CO-CM relationship

Science.gov (United States)

Chaumard, Noël; Defouilloy, Céline; Kita, Noriko T.

2018-05-01

High-precision oxygen three-isotope measurements of olivine and pyroxene were performed on 29 chondrules in the Murchison CM2 chondrite by secondary ion mass spectrometry (SIMS). The oxygen isotope ratios of analyzed chondrules all plot very close to the primitive chondrule minerals (PCM) line. In each of 24 chondrules, the olivine and/or pyroxene grains analyzed show indistinguishable oxygen isotope ratios. Exceptions are minor occurrences of isotopically distinguished relict olivine grains, which were found in nine chondrules. The isotope homogeneity of these phenocrysts is consistent with a co-magmatic crystallization of olivine and pyroxene from the final chondrule melts and a significant oxygen isotope exchange between the ambient gas and the melts. Homogeneous type I chondrules with Mg#'s of 98.9-99.5 have host chondrule Δ17O values ranging from -6.0‰ to -4.1‰, with one exception (Δ17O: -1.2‰; Mg#: 99.6). Homogeneous chondrules with Mg#'s poor H2O ice (∼0.3-0.4× the CI dust; Δ17O > 0‰) and at dust enrichments of ∼300-2000×. Regarding the Mg# and oxygen isotope ratios, the chondrule populations sampled by CM and CO chondrites are similar and indistinguishable. The similarity of these 16O-rich components in CO and CM chondrites is also supported by the common Fe/Mn ratio of olivine in type II chondrules. Although they accreted similar high-temperature silicates, CO chondrites are anhydrous compared to CM chondrites, suggesting they derived from different parent bodies formed inside and outside the snow line, respectively. If chondrules in CO and CM chondrites formed at the same disk locations but the CM parent body accreted later than the CO parent body, the snow line might have crossed the common chondrule-forming region towards the Sun between the time of the CO and CM parent bodies accretion.

Gene expression analysis supports tumor threshold over 2.0 cm for T-category breast cancer.

Science.gov (United States)

Solvang, Hiroko K; Frigessi, Arnoldo; Kaveh, Fateme; Riis, Margit L H; Lüders, Torben; Bukholm, Ida R K; Kristensen, Vessela N; Andreassen, Bettina K

2016-12-01

Tumor size, as indicated by the T-category, is known as a strong prognostic indicator for breast cancer. It is common practice to distinguish the T1 and T2 groups at a tumor size of 2.0 cm. We investigated the 2.0-cm rule from a new point of view. Here, we try to find the optimal threshold based on the differences between the gene expression profiles of the T1 and T2 groups (as defined by the threshold). We developed a numerical algorithm to measure the overall differential gene expression between patients with smaller tumors and those with larger tumors among multiple expression datasets from different studies. We confirmed the performance of the proposed algorithm by a simulation study and then applied it to three different studies conducted at two Norwegian hospitals. We found that the maximum difference in gene expression is obtained at a threshold of 2.2-2.4 cm, and we confirmed that the optimum threshold was over 2.0 cm, as indicated by a validation study using five publicly available expression datasets. Furthermore, we observed a significant differentiation between the two threshold groups in terms of time to local recurrence for the Norwegian datasets. In addition, we performed an associated network and canonical pathway analyses for the genes differentially expressed between tumors below and above the given thresholds, 2.0 and 2.4 cm, using the Norwegian datasets. The associated network function illustrated a cellular assembly of the genes for the 2.0-cm threshold: an energy production for the 2.4-cm threshold and an enrichment in lipid metabolism based on the genes in the intersection for the 2.0- and 2.4-cm thresholds.

GdBa{sub 0.5}Sr{sub 0.5}Co{sub 2}O{sub 5+{delta}} layered perovskite as promising cathode for proton conducting solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Ding, Hanping [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Xue, Xingjian, E-mail: Xue@cec.sc.ed [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

2010-04-30

BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY7) exhibits adequate proton conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered GdBa{sub 0.5}Sr{sub 0.5}Co{sub 2}O{sub 5+{delta}} (GBSC) perovskite deposited on a doped ceria electrolyte demonstrates advanced electrochemical properties. This research fully takes advantage of these advanced properties and develops novel protonic ceramic membrane fuel cells (PCMFCs) of Ni-BZCY7|BZCY7|GBSC. The results show that the open-circuit potential of 1.003 V, maximum power density of 430 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.08 {Omega} cm{sup 2} are achieved at 700 {sup o}C. With temperature increases, the total cell resistance decreases, among which electrolyte resistance becomes increasingly dominant over polarization resistance. The results also indicate that GBSC perovskite cathode is a good candidate for intermediate temperature PCMFC development, while the developed Ni-BZCY7|BZCY7|GBSC cell is a promising functional material system for next generation SOFCs.

Performance of La 0.75Sr 0.25Cr 0.5Mn 0.5O 3- δ perovskite-structure anode material at lanthanum gallate electrolyte for IT-SOFC running on ethanol fuel

Science.gov (United States)

Huang, Bo; Wang, S. R.; Liu, R. Z.; Ye, X. F.; Nie, H. W.; Sun, X. F.; Wen, T. L.

Perovskite-structure La 0.75Sr 0.25Cr 0.5Mn 0.5O 3- δ (LSCM) powders were prepared using a simple combustion process. Thermal analysis was carried out on the perovskite precursor to investigate the oxide-phase formation. The structural phase of the powders was determined by X-ray diffraction. These results showed that the decomposition of the precursors occurs in a two-step reaction and temperatures higher than 1100 °C are required for these decomposition reactions. For the electrochemical characterization, LSCM anode materials and (Pr 0.7Ca 0.3) 0.9MnO 3 (PCM) cathode materials were screen-printed on two sides of dense La 0.8Sr 0.2Ga 0.8Mg 0.2O 3 (LSGM) electrolyte layers prepared by tape casting with a thickness of about 600 μm, respectively. The morphology of the screen-printed La 0.75Sr 0.25Cr 0.5Mn 0.5O 3- δ perovskite thick films (65 μm) was investigated by field emission scanning electron microscope and showed a porous microstructure. In addition, fuel cell tests were carried out using humidified hydrogen or ethanol stream as fuel and oxygen as oxidant. The performance of the conventional electrolyte-supported cell LSCM/LSGM/PCM while operating on humidified hydrogen was modest with a maximum power density of 165, 99 and 62 mW cm -2 at 850, 800 and 750 °C, respectively, the corresponding values for the cell while operating on ethanol stream was 160, 101 and 58 mW cm -2, respectively. Cell stability tests indicate no significant degradation in performance has been observed after 60 h of cell testing when LSCM anode was exposed to ethanol steam at 750 °C, suggesting that carbon deposition was limited during cell operation.

Excitation functions of inelastic and transfer channels in {sup 12} C+{sup 12} C around E{sub c.m.} = 32.5 MeV

Energy Technology Data Exchange (ETDEWEB)

Szilner, S.; Basrak, Z.; Freeman, R.M.; Haas, F.; Beck, C. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires]|[Strasbourg-1 Univ., 67 (France); Morsad, A. [Universite Hassan II, Casablanca (Morocco). Faculte des Sciences

1996-12-31

A prominent and wide resonance centered at E{sub c.m.} = 32.5 MeV has recently been found in the (0{sub 2}{sup +}, 0{sub 2}{sup +}) inelastic channel of the {sup 12}C+{sup 12}C reaction. It has been suggested that it corresponds to a 6{alpha}-particle-chain state in {sup 24}Mg. In the present work we study {sup 12}C+{sup 12}C excitation functions between center-of-mass energies of 30 and 35 MeV in steps of 250 keV for weakly populated outgoing channels. We present the inelastic channels to the states above the {alpha}-particle decay threshold, (0{sub 1}{sup +},0{sub 2}{sup +}), (0{sub 1}{sup +},3{sub 1}{sup -}), and (0{sub 1}{sup +},4{sub 1}{sup 4}), and the one- and two-nucleon transfer channels. In the inelastic and the transfer channels we observe correlated intermediate-width structures at E{sub c.m.} = 31, 32.5, and 33.5 MeV, whose widths are appreciably smaller than the width measured in the (0{sub 2}{sup +},0{sub 2}{sup +}) channel. Our E{sub c.m.} = 31, 32.5, and 33.5 MeV, whose widths are appreciably smaller than the width measured in the (0{sub 2}{sup +},0{sub 2}{sup +}) channel. Our E{sub c.m.} = 32.5 MeV angular distribution of the (0{sub 1}{sup +},0{sub 2}{sup +})channel exhibits oscillatory behavior and, unlike that of the (0{sup +}{sub 2}, 0{sup +}{sub 2}) channel, does not display enhancement around {Theta}{sub c.m.} = 90 deg. Data were collected via the kinematic coincidence technique. For data reduction we use a novel approach allowing for the extraction of results on non-binary channels. (authors). 39 refs.

A sensitive method for electrochemical determination of molybdenum (VI in plant foodstuff samples using Ni0.5Zn0.5Fe2O4 nanocomposite modified carbon paste electrode

Directory of Open Access Journals (Sweden)

Abbas Afkhami

2016-07-01

Full Text Available In the present study, a new chemically modified carbon paste electrode (CPE is constructed for rapid, accurate, simple, highly sensitive, and selective determination of Mo (VI using differential pulse voltammetry. The electrode was prepared using magnetic nickel zinc ferrite nanocomposite (Ni0.5Zn0.5Fe2O4, as the modifier in CPE (Ni0.5Zn0.5Fe2O4/CPE. Mo (VI was determined after preconcentration at the surface of the modified electrode at -0.7 V vs. Ag/AgCl. Under the optimal conditions, the linear dynamic range and limit of detection were 0.005-1.00 and 0.003 µgmL-1, respectively. Ten successive measurements of 0.06 and 0.70 µg mL-1 of Mo (VI ions showed the relative standard deviation of 3.20 and 1.98 %, respectively. The reproducibility and stability of the electrode response were also studied. Investigation of the effects of different cations and anions on the determination of Mo (VI indicated that the electrode is highly selective. Furthermore, the present method was applied to the determination of Mo (VI in several plant foodstuff samples with satisfactory results.

ROV seafloor surveys combining 5-cm lateral resolution multibeam bathymetry with color stereo photographic imagery

Science.gov (United States)

Caress, D. W.; Hobson, B.; Thomas, H. J.; Henthorn, R.; Martin, E. J.; Bird, L.; Rock, S. M.; Risi, M.; Padial, J. A.

2013-12-01

The Monterey Bay Aquarium Research Institute is developing a low altitude, high-resolution seafloor mapping capability that combines multibeam sonar with stereo photographic imagery. The goal is to obtain spatially quantitative, repeatable renderings of the seafloor with fidelity at scales of 5 cm or better from altitudes of 2-3 m. The initial test surveys using this sensor system are being conducted from a remotely operated vehicle (ROV). Ultimately we intend to field this survey system from an autonomous underwater vehicle (AUV). This presentation focuses on the current sensor configuration, methods for data processing, and results from recent test surveys. Bathymetry data are collected using a 400-kHz Reson 7125 multibeam sonar. This configuration produces 512 beams across a 135° wide swath; each beam has a 0.5° acrosstrack by 1.0° alongtrack angular width. At a 2-m altitude, the nadir beams have a 1.7-cm acrosstrack and 3.5 cm alongtrack footprint. Dual Allied Vision Technology GX1920 2.8 Mpixel color cameras provide color stereo photography of the seafloor. The camera housings have been fitted with corrective optics achieving a 90° field of view through a dome port. Illumination is provided by dual 100J xenon strobes. Position, depth, and attitude data are provided by a Kearfott SeaDevil Inertial Navigation System (INS) integrated with a 300 kHz RDI Doppler velocity log (DVL). A separate Paroscientific pressure sensor is mounted adjacent to the INS. The INS Kalman filter is aided by the DVL velocity and pressure data, achieving navigational drift rates less than 0.05% of the distance traveled during surveys. The sensors are mounted onto a toolsled fitted below MBARI's ROV Doc Ricketts with the sonars, cameras and strobes all pointed vertically down. During surveys the ROV flies at a 2-m altitude at speeds of 0.1-0.2 m/s. During a four-day R/V Western Flyer cruise in June 2013, we successfully collected multibeam and camera survey data from a 2-m altitude

Nanopowders Y1−yNdyV1−xCrxO4 with y=0 and 1; x=0, 0.1, 0.2 and 0.5 synthesized by a sol–gel process. Relationship between morphological characteristics and optical properties

International Nuclear Information System (INIS)

Alcaraz, L.; Isasi, J.; Caballero, A.C.; Izquierdo, J.G.; Bañares, L.

2015-01-01

Y 1−y Nd y V 1−x Cr x O 4 nanopowders with y=0 and 0.1; x=0, 0.1, 0.2 and 0.5, have been synthetized by a sol–gel process followed by heating in an oxygen flow. This second treatment was done only in the case of samples containing chromium. The samples have been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structural analysis revealed that when chromium was inserted at vanadium-sites in Y 0.9 Nd 0.1 VO 4 , the host retained the tetragonal symmetry corresponding to a zircon-type structure, attributed to the space group I4 1 /amd. In addition, a loss of crystallinity was observed when chromium substitutes vanadium into the Y 0.9 Nd 0.1 VO 4 host. The morphological studies revealed agglomerates of spherical particles whose size is increased with the Cr content and confirmed the composition of all synthetized samples. FTIR spectra of these samples exhibit a broadening and a slight shift of the bands around 830 cm −1 towards higher values of frequency when the chromium content increases. The effect of vanadium substitution by chromium on the optical properties was also evaluated by UV–vis absorption and photoluminescence (PL) spectroscopies. The broad UV band absorption is due to the presence of Cr 5+ . A decrease of PL emission is found when chromium substitutes vanadium in the YVO 4 host. - Highlights: • Nanophosphors Y 1−y Nd y V 1−x Cr x O 4 with y=0, 0.1 and x=0, 0.1, 0.2 and 0.5 have been synthesized. • Structural analysis reveals structural distortions associated to chromium insertion. • Morphological studies confirm the nanocristalline size and the stoichiometry of synthesized samples. • Chromium insertion causes a decrease of the PL emission intensity

Synthesis and growth mechanism of Zn0.5Cd0.5S nanohexagon dendrite

Science.gov (United States)

Yu, Wen; Fang, Pengfei; Wang, Shaojie

2014-12-01

Hierarchical Zn0.5Cd0.5S nanohexagon dendrites were synthesized by a one-step hydrothermal method. The Zn0.5Cd0.5S nanohexagon dendrites were made up of nanohexagons with a side length of about 90 nm. The nanohexagons were regularly arranged forming as embranchments which were parallel to each other along certain hexagonal directions. Furthermore, these embranchments made up primary trunks shaping as dendrites. The growth mechanism of Zn0.5Cd0.5S nanohexagon dendrites was proposed in which molecular soft template and lowest energy principle played key roles. By adjusting the composition of the reactants, a series of ZnxCd1-xS solid solutions could be obtained. The morphology of the synthesized ZnxCd1-xS depended much on the x value. The UV-vis spectra absorb edges of the ZnxCd1-xS samples continuously shifted indicating the changes of the band gap.

TESTING AND PERFORMANCE ANALYSIS OF NASA 5 CM BY 5 CM BI-SUPPORTED SOLID OXIDE ELECTROLYSIS CELLS OPERATED IN BOTH FUEL CELL AND STEAM ELECTROLYSIS MODES

Energy Technology Data Exchange (ETDEWEB)

R. C. O' Brien; J. E. O' Brien; C. M. Stoots; X. Zhang; S. C. Farmer; T. L. Cable; J. A. Setlock

2011-11-01

A series of 5 cm by 5 cm bi-supported Solid Oxide Electrolysis Cells (SOEC) were produced by NASA for the Idaho National Laboratory (INL) and tested under the INL High Temperature Steam Electrolysis program. The results from the experimental demonstration of cell operation for both hydrogen production and operation as fuel cells is presented. An overview of the cell technology, test apparatus and performance analysis is also provided. The INL High Temperature Steam Electrolysis laboratory has developed significant test infrastructure in support of single cell and stack performance analyses. An overview of the single cell test apparatus is presented. The test data presented in this paper is representative of a first batch of NASA's prototypic 5 cm by 5 cm SOEC single cells. Clearly a significant relationship between the operational current density and cell degradation rate is evident. While the performance of these cells was lower than anticipated, in-house testing at NASA Glenn has yielded significantly higher performance and lower degradation rates with subsequent production batches of cells. Current post-test microstructure analyses of the cells tested at INL will be published in a future paper. Modification to cell compositions and cell reduction techniques will be altered in the next series of cells to be delivered to INL with the aim to decrease the cell degradation rate while allowing for higher operational current densities to be sustained. Results from the testing of new batches of single cells will be presented in a future paper.

A study of (Ba0.5Sr0.5)1-xSm xCo0.8Fe0.2O3-δ as a cathode material for IT-SOFCs

International Nuclear Information System (INIS)

Li Shuyan; Lue Zhe; Wei Bo; Huang Xiqiang; Miao Jipeng; Cao Gang; Zhu Ruibin; Su Wenhui

2006-01-01

(Ba 0.5 Sr 0.5 ) 1-x Sm x Co 0.8 Fe 0.2 O 3-δ (BSSCF; x = 0.05-0.15) compounds were synthesized with EDTA-Pechini method and characterized by powder X-ray diffraction (XRD), electrical conductivity and thermal expansion coefficient (TEC) measurements, as well as the electrochemical impedance spectra measurement. According to the XRD results, the main phase of the material belongs to the cubic perovskite-type, and the lattice contracting with the increasing contents of Sm 3+ . The TEC of the compounds is 19.1-20.3 x 10 -6 K -1 from 30 to 800 deg. C, which close to the values of Co-based materials, such as Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF). And the conductivity of BSSCF is higher than that of BSCF; e.g., about 212% higher at 500 deg. C for the x = 0.15 compound. Electrochemical impedance spectra at intermediate temperature revealed the better electrochemical performance of BSSCF than BSCF; e.g., the total resistance values of BSSCF electrode is 2.98 Ω cm 2 at 500 deg. C, nearly 50% lower than that of BSCF

The BRIDGE HadCM3 family of climate models: HadCM3@Bristol v1.0

Directory of Open Access Journals (Sweden)

P. J. Valdes

2017-10-01

Full Text Available Understanding natural and anthropogenic climate change processes involves using computational models that represent the main components of the Earth system: the atmosphere, ocean, sea ice, and land surface. These models have become increasingly computationally expensive as resolution is increased and more complex process representations are included. However, to gain robust insight into how climate may respond to a given forcing, and to meaningfully quantify the associated uncertainty, it is often required to use either or both ensemble approaches and very long integrations. For this reason, more computationally efficient models can be very valuable tools. Here we provide a comprehensive overview of the suite of climate models based around the HadCM3 coupled general circulation model. This model was developed at the UK Met Office and has been heavily used during the last 15 years for a range of future (and past climate change studies, but has now been largely superseded for many scientific studies by more recently developed models. However, it continues to be extensively used by various institutions, including the BRIDGE (Bristol Research Initiative for the Dynamic Global Environment research group at the University of Bristol, who have made modest adaptations to the base HadCM3 model over time. These adaptations mean that the original documentation is not entirely representative, and several other relatively undocumented configurations are in use. We therefore describe the key features of a number of configurations of the HadCM3 climate model family, which together make up HadCM3@Bristol version 1.0. In order to differentiate variants that have undergone development at BRIDGE, we have introduced the letter B into the model nomenclature. We include descriptions of the atmosphere-only model (HadAM3B, the coupled model with a low-resolution ocean (HadCM3BL, the high-resolution atmosphere-only model (HadAM3BH, and the regional model (HadRM3B

MEASUREMENT OF 21 cm BRIGHTNESS FLUCTUATIONS AT z ∼ 0.8 IN CROSS-CORRELATION

International Nuclear Information System (INIS)

Masui, K. W.; Switzer, E. R.; Calin, L.-M.; Pen, U.-L.; Shaw, J. R.; Banavar, N.; Bandura, K.; Blake, C.; Chang, T.-C.; Liao, Y.-W.; Chen, X.; Li, Y.-C.; Natarajan, A.; Peterson, J. B.; Voytek, T. C.

2013-01-01

In this Letter, 21 cm intensity maps acquired at the Green Bank Telescope are cross-correlated with large-scale structure traced by galaxies in the WiggleZ Dark Energy Survey. The data span the redshift range 0.6 HI b HI r = [0.43 ± 0.07(stat.) ± 0.04(sys.)] × 10 –3 , where Ω HI is the neutral hydrogen (H I) fraction, r is the galaxy-hydrogen correlation coefficient, and b HI is the H I bias parameter. This is the most precise constraint on neutral hydrogen density fluctuations in a challenging redshift range. Our measurement improves the previous 21 cm cross-correlation at z ∼ 0.8 both in its precision and in the range of scales probed.

Evaluation of a new tear osmometer for repeatability and accuracy, using 0.5-microL (500-Nanoliter) samples.

Science.gov (United States)

Yildiz, Elvin H; Fan, Vincent C; Banday, Hina; Ramanathan, Lakshmi V; Bitra, Ratna K; Garry, Eileen; Asbell, Penny A

2009-07-01

To evaluate the repeatability and accuracy of a new tear osmometer that measures the osmolality of 0.5-microL (500-nanoliter) samples. Four standardized solutions were tested with 0.5-microL (500-nanoliter) samples for repeatability of measurements and comparability to standardized technique. Two known standard salt solutions (290 mOsm/kg H2O, 304 mOsm/kg H2O), a normal artificial tear matrix sample (306 mOsm/kg H2O), and an abnormal artificial tear matrix sample (336 mOsm/kg H2O) were repeatedly tested (n = 20 each) for osmolality with use of the Advanced Instruments Model 3100 Tear Osmometer (0.5-microL [500-nanoliter] sample size) and the FDA-approved Advanced Instruments Model 3D2 Clinical Osmometer (250-microL sample size). Four standard solutions were used, with osmolality values of 290, 304, 306, and 336 mOsm/kg H2O. The respective precision data, including the mean and standard deviation, were: 291.8 +/- 4.4, 305.6 +/- 2.4, 305.1 +/- 2.3, and 336.4 +/- 2.2 mOsm/kg H2O. The percent recoveries for the 290 mOsm/kg H2O standard solution, the 304 mOsm/kg H2O reference solution, the normal value-assigned 306 mOsm/kg H2O sample, and the abnormal value-assigned 336 mOsm/kg H2O sample were 100.3, 100.2, 99.8, and 100.3 mOsm/kg H2O, respectively. The repeatability data are in accordance with data obtained on clinical osmometers with use of larger sample sizes. All 4 samples tested on the tear osmometer have osmolality values that correlate well to the clinical instrument method. The tear osmometer is a suitable instrument for testing the osmolality of microliter-sized samples, such as tears, and therefore may be useful in diagnosing, monitoring, and classifying tear abnormalities such as the severity of dry eye disease.

Microstructure and electrical properties of (1−x)[0.8Bi_0_._5Na_0_._5TiO_3-0.2Bi_0_._5K_0_._5TiO_3]-xBiCoO_3 lead-free ceramics

International Nuclear Information System (INIS)

Wang, Ting; Chen, Xiao-ming; Qiu, Yan-zi; Lian, Han-li; Chen, Wei-ting

2017-01-01

The (1−x)[0.8Bi_0_._5Na_0_._5TiO_3-0.2Bi_0_._5K_0_._5TiO_3]-xBiCoO_3 (x = 0, 0.02, 0.05, abbreviated as BNKT, BNKT-002Co, BNKT-005Co, respectively) lead-free ferroelectric ceramics were prepared via the solid state reaction method. The phase structure, microstructure, dielectric, ferroelectric, pyroelectric, and piezoelectric properties of the ceramics were investigated comparatively by using a combination of characterization techniques. All the samples exhibit typical X-ray diffraction peaks of ABO_3 perovskite structure. The doping of BiCoO_3 causes a decrease in lattice parameters and an increase in grain size of the ceramics. The Raman spectroscopy results suggest a lattice distortion due to the doping. It is found that BNKT-002Co and BNKT-005Co have higher depolarization temperatures compared with BNKT. The Curie-Weiss law and modified Curie-Weiss law explored a diffuse phase transition character for all the samples. The results of ultraviolet–visible diffuse reflectance suggests that BiCoO_3-doped ceramics possess higher defect concentration. The impedance analysis shows a temperature dependent relaxation behavior, and the activation energy for the electrical responses varies with the change of BiCoO_3 amount. The ferroelectric and piezoelectric properties of the ceramics decrease due to the doping of BiCoO_3. Based on the results of the Rayleigh analysis, it was suggested that the differences in the electrical properties among the ceramics are closely related to the change in oxygen vacancy concentration. - Highlights: • BNKT-xCo ceramics were prepared by solid-state reaction method. • Electrical properties of BNKT ceramics are changed by the doping of BiCoO_3. • The doping causes a decrease in lattice parameters and an increase in grain size. • T_d of the ceramics increases with increasing x. • Oxygen vacancies play key role in determining electrical properties of the ceramics.

Conducting, magnetic polyaniline/Ba0.25Sr0.75 Fe11(Ni0.5Mn0.5)O19 nanocomposite: Fabrication, characterization and application

International Nuclear Information System (INIS)

Ezzati, S. Noushin; Rabbani, Mahboubeh; Leblanc, Roger M.; Asadi, Ebadullah; Ezzati, S. Mohammad H.; Rahimi, Rahmatollah; Azodi-Deilami, Saman

2015-01-01

In this contribution, Ni/Mn doped Barium Strontium Ferrite nanoparticles (Ba 0.25 Sr 0.75 Fe 11 (Ni 0.5 Mn 0.5 )O 19 ) and conducting polyaniline/Ba 0.25 Sr 0.75 Fe 11 (Ni 0.5 Mn 0.5 )O 19 nanocomposite were fabricated successfully through sol–gel method and in-situ polymerization technique, respectively. Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy analysis (EDX), X-ray powder diffraction (XRD), Mössbauer spectroscopic measurements and Fourier transform infrared spectroscope (FT-IR) analyses were adopted to confirm the composition, morphology and structure of materials. The obtained results revealed the formation of hexagonal M-type rod-shape ferrite with average particle size of about 45 nm (according to XRD data, using Debye–Scherre formula). The saturation magnetization of ferrite nanoparticles and PANI/Ferrite nanocomposite reported 44.03 and 9.85 emu/g, respectively, using vibrant sample magnetometer (VSM). Standard four-point-probe technique was employed to measure the conductivity of samples. Also optical characteristic of samples was examined by means of UV–Vis and Diffuse Reflectance Spectra (DRS) techniques which proved the formation of conducting coating of emeraldine on the surface of magnetic nanoparticles. Also the UV–vis studies indicated that the ferrite nanoparticles have an optical band gap of 1.8 eV while the values of 1.65 and 2.66 eV obtained for PANI/Ferrite nanocomposite. Finally, the microwave absorption properties of prepared nanoferrite and nanocomposite at different thicknesses (2, 3 and 4 mm) were determined at the X-band (8–12 GHz) using vector network analyzer (VNA). In this study, minimum reflection loss of −21.68 dB and maximum available bandwidth of 4.8 GHz were obtained for PANI/Ferrite (20 wt% ferrite) at the frequency of 10.6 GHz. The results suggested the fabricated nanocomposite could be a suitable candidate for decreasing radar signature. - Highlights: • Polyaniline

Annealing-induced near-surface ordering in disordered Ga0.5In0.5P

International Nuclear Information System (INIS)

Luo, J.S.; Olson, J.M.; Wu, M.

1995-01-01

Most samples of Ga 0.5 In 0.5 P grown by metalorganic chemical vapor deposition (MOCVD) on (001)-like surfaces are partially ordered and exhibit distinctive reflectance difference spectral (RDS) features associated with the anisotropic properties of the ordered bulk structure. It is known that the ordering is not a ground-state property of the bulk but is surface-induced during growth. On the other hand, Ga 0.5 In 0.5 P grown by liquid-phase epitaxy (LPE) is completely disordered, and it has been shown that its RD spectrum is essentially featureless. In this article, we present a study of the effects of annealing (in a PH 3 /H 2 atmosphere) on LPE-grown Ga 0.5 In 0.5 P using ex situ and in situ RDS. The annealing temperatures and times used in this study (650 degree C and tens of minutes) have virtually no effect on the bulk optical or structural properties of MOCVD-grown Ga 0.5 In 0.5 P. For LPE-grown Ga 0.5 In 0.5 P, we find that annealing induces bulk-like RDS features at both E 0 and E 1 with line shapes similar to those observed for MOCVD-grown ordered Ga 0.5 In 0.5 P. These bulk-like spectral features are, however, due to near-surface reconstruction of Ga and In because they are effectively quenched by exposure to air. Also, the E 0 feature becomes sharper and both the E 0 and the E 1 features red-shift as the annealing process is prolonged. This indicates that this reconstruction is kinetically limited, presumably by the slow interdiffusion of Ga and In necessary to achieve the ordered bulk-like structure. copyright 1995 American Vacuum SocietyGa 0.5 In 0.5 P

Effect of 120 MeV 28Si9+ ion irradiation on structural and magnetic properties of NiFe2O4 and Ni0.5Zn0.5Fe2O4

Science.gov (United States)

Sharma, R.; Raghuvanshi, S.; Satalkar, M.; Kane, S. N.; Tatarchuk, T. R.; Mazaleyrat, F.

2018-05-01

NiFe2O4, Ni0.5Zn0.5Fe2O4 samples were synthesized using sol-gel auto combustion method, and irradiated by using 120 MeV 28Si9+ ion with ion fluence of 1×1012 ions/cm2. Characterization of pristine, irradiated samples were done using X-Ray Diffraction (XRD), Field Emission Scanning Microscopy (FE-SEM), Energy Dispersive X-ray Analysis (EDAX) and Vibrating Sample Magnetometer (VSM). XRD validates the single phase nature of pristine, irradiated Ni- Zn nano ferrite except for Ni ferrite (pristine, irradiated) where secondary phases of α-Fe2O3 and Ni is observed. FE- SEM images of pristine Ni, Ni-Zn ferrite show inhomogeneous nano-range particle size distribution. Presence of diamagnetic ion (Zn2+) in NiFe2O4 increases oxygen positional parameter (u 4¯3m ), experimental, theoretical saturation magnetization (Msexp., Msth.), while decreases the grain size (Ds) and coercivity (Hc). With irradiation Msexp., Msth. increases but not much change are observed in Hc. New antistructure modeling for the pristine, irradiated Ni and Ni-Zn ferrite samples was used for describing the surface active centers.

Structure and superconductivity of double-doped Mg1-x(Al0.5Li0.5)xB2

DEFF Research Database (Denmark)

Xu, G.J.; Grivel, Jean-Claude; Abrahamsen, A.B.

2003-01-01

A series of polycrystalline samples of Mg1-x(Al0.5Li0.5)(x)B-2 (0less than or equal toxless than or equal to0.6) were prepared by a solid state reaction method and their structure, superconducting transition temperature and magneto-transport properties were investigated by means of X-ray diffract......A series of polycrystalline samples of Mg1-x(Al0.5Li0.5)(x)B-2 (0less than or equal toxless than or equal to0.6) were prepared by a solid state reaction method and their structure, superconducting transition temperature and magneto-transport properties were investigated by means of X......-ray diffraction (XRD), ac-susceptibility and resistance in varied magnetic fields. The double doping leads to decreases in both the lattice parameters a and c. The superconducting transition temperature (T-c) decreases with double doping, but the T-c is systematically higher than that of the single Al......-doped samples. It is suggested that the hole band filling has little effect on T-c at high doping level, while the disorder induced by doping plays an important role in suppressing T-c. A systematic comparison with Al-doped MgB2 of the structure, superconducting transition and irreversibility field is made. (C...

Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3}+Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} composite cathode for cermet supported thin Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} electrolyte SOFC operating below 600{sup o}C

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xinge; Robertson, Mark; Yick, Sing; Deces-Petit, Cyrille; Styles, Edward; Qu, Wei; Xie, Yongsong; Hui, Rob; Roller, Justin; Kesler, Olivera; Maric, Radenka; Ghosh, Dave [Institute for Fuel Cell Innovation, National Research Council Canada, 3250 East Mall, Vancouver, BC (Canada V6T 1W5)

2006-10-06

The cathode is a key component in low temperature solid oxide fuel cells. In this study, composite cathode, 75wt.% Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3} (SSC)+25wt.% Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} (SDC), was applied on the cermet supported thin SDC electrolyte cell which was fabricated by tape casting, screen-printing, and co-firing. Single cells with the composite cathodes sintered at different temperatures were tested from 400 to 650{sup o}C. The best cell performance, 0.75Wcm{sup -2} peak power operating at 600{sup o}C, was obtained from the 1050{sup o}C sintered cathode. The measured thin SDC electrolyte resistance R{sub s} was 0.128{omega}cm{sup 2} and total electrode polarization R{sub p}(a+c) was only 0.102{omega}cm{sup 2} at 600{sup o}C. (author)

Investigation of spectroscopic properties and energy transfer between Ce and Dy in (Lu0.2Gd0.8−x−yCexDyy)2SiO5 single crystals

International Nuclear Information System (INIS)

Strzęp, A.; Martin, I.R.; Głowacki, M.; Ryba-Romanowski, W.; Berkowski, M.; Pérez-Rodríguez, C.

2015-01-01

In this paper we present results of spectroscopic investigations of single crystals with general formula (Lu 0.2 Gd 0.8−x−y ) 2 SiO 5 codoped with x% of Ce 3+ and y% of Dy 3+ ions. Investigated materials exhibit strong optical anisotropy what can be easily observed in polarized absorption and emission spectra. Based on room temperature polarized absorption spectra calculations in framework of phenomenological Judd–Ofelt model was carried out. Intensity parameters Ω t were evaluated to be Ω 2 =7.08 (±0.39), Ω 4 =2.76 (±0.44), and Ω 6 =3.36 (±0.21) [10 −20 cm 2 ] for sample doped with 1% of cerium and Ω 2 =10.72 (±0.33), Ω 4 =1.98 (±0.37), and Ω 6 =2.11 (±0.18) [10 −20 cm 2 ] for sample doped with 3% of cerium. Influence of cerium admixture on Judd Ofelt intensity parameters is discussed. Value of experimental lifetime of 4 F 9/2 multiplet of Dy 3+ ion in sample doped with 1 at% Ce is 0.5 ms (τ rad =0.45 ms), while for sample doped with 3 at% of Ce, experimental lifetime is 0.45 ms (τ rad =0.43 ms). Absorption bands located between 440 and 460 nm, can be utilized for optical pumping of material by GaN laser diodes. Intense and broad emission bands at 465–495 and 560–590 nm, with experimental branching ratio strongly depending on polarization, give high chance for obtaining white luminophore, due to appropiate mixing of blue and yellow luminescence. By means of a pump and probe experiment optical amplification was demonstrated in the codoped sample with 1 at% of Ce and 1 at% Dy at 575 nm corresponding to the emission of Dy 3+ with a high net gain coefficient of 34 cm −1 . Such high amplification was obtained under 359 nm excitation (at the maximum of intense absorption band of Ce 3+ ions). - Highlights: • Influence of anisotropy on properties of LGSO: Ce, Dy crystals was investigated. • ET between Ce 3+ and Dy 3+ ions enhanced luminous properties of material investigated. • High optical amplification net gain in yellow�

Chemically stable perovskites as cathode materials for solid oxide fuel cells: La-doped Ba0.5Sr0.5Co0.8Fe0.2O(3-δ).

Science.gov (United States)

Kim, Junyoung; Choi, Sihyuk; Jun, Areum; Jeong, Hu Young; Shin, Jeeyoung; Kim, Guntae

2014-06-01

Ba0.5Sr0.5Co0.8Fe0.2O(3-δ) (BSCF) has won tremendous attention as a cathode material for intermediate-temperature solid-oxide fuel cells (IT-SOFC) on the basis of its fast oxygen-ion transport properties. Nevertheless, wide application of BSCF is impeded by its phase instabilities at intermediate temperature. Here we report on a chemically stable SOFC cathode material, La0.5Ba0.25Sr0.25Co0.8Fe0.2O(3-δ) (LBSCF), prepared by strategic approaches using the Goldschmidt tolerance factor. The tolerance factors of LBSCF and BSCF indicate that the structure of the former has a smaller deformation of cubic symmetry than that of the latter. The electrical property and electrochemical performance of LBSCF are improved compared with those of BSCF. LBSCF also shows excellent chemical stability under air, a CO2-containg atmosphere, and low oxygen partial pressure while BSCF decomposed under the same conditions. Together with this excellent stability, LBSCF shows a power density of 0.81 W cm(-2) after 100 h, whereas 25 % degradation for BSCF is observed after 100 h. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A new silver metaniobate semiconductor of Ag0.5La0.5Nb2O6 with defect-perovskite structure

Science.gov (United States)

Mi, Longqing; Feng, Yongyi; Cao, Lei; Xue, Mingqiang; Huang, Yanlin; Qin, Lin; Seo, Hyo Jin

2018-03-01

Silver-containing lanthanum metaniobate Ag0.5La0.5Nb2O6 nanoparticles were synthesized by sol-gel polymerized complex method. A typical defect-perovskite structure was confirmed by XRD Rietveld refinements. The surface characteristics of the sample were tested by SEM, TEM and EDS measurements. SEM and TEM show that the sample presents ball-like particles with the diameters of 100 nm to 400 nm. The sample shows both self-activated luminescence and photocatalytic activities. Ag0.5La0.5Nb2O6 has a direct transition with band energy of 2.85 eV. The Ag4d-O2p hybridization in the valence band contributes to the narrowed band gap. The luminescence properties of Ag0.5La0.5Nb2O6 have been investigated for the first time. The luminescence is characterized by two emission centers with maximum wavelength near 460 and 530 nm. The emission and excitation spectra, decay curves and the thermal quenching mechanism were discussed. Ag0.5La0.5Nb2O6 shows the efficient photocatalytic activities and the photodegradation rate for methylene blue dye (MB) can reach about 95% under visible light (> 420 nm) irradiation in 5 h. The trapped experiments for the active species were tested and discussed, which verified that rad OH radicals could be the major active species in photocatalysis.

Europium substitution effects on structural, magnetic and magnetocaloric properties in La0.5Ca0.5MnO3

Directory of Open Access Journals (Sweden)

Boujelben W.

2012-06-01

Full Text Available We have investigated structural, magnetic and magnetocaloric properties of polycrystalline samples La0.5-xEuxCa0.5MnO3 (x=0 and 0.1. Rietveld refinement of the X-ray diffraction patterns show that our samples are single phase and crystallize in the orthorhombic structure with Pnma space group. Magnetization measurements versus temperature at a magnetic applied field of 500 Oe indicate that La0.4Eu0.1Ca0.5MnO3 sample exhibits a paramagnetic to ferromagnetic transition with decreasing temperature. Magnetic measurements reveal strong magnetocaloric effect in the vicinity of the Curie temperature TC. The parent compound shows a negative magnetic entropy change of ∆SM=−1.13Jkg−1K−1 at 220K and a positive magnetocaloric effects ∆SM=1Jkg−1K−1 at 150K under a magnetic applied field of 2T. La0.4Eu0.1Ca0.5MnO3 exhibits a maximum value of magnetic entropy change ∆SM=−1.15Jkg−1K−1 at 130K under an applied field of 2T and a large relative cooling power RCP with a maximum value of 72 J/kg.

MEASUREMENT OF 21 cm BRIGHTNESS FLUCTUATIONS AT z {approx} 0.8 IN CROSS-CORRELATION

Energy Technology Data Exchange (ETDEWEB)

Masui, K. W.; Switzer, E. R.; Calin, L.-M.; Pen, U.-L.; Shaw, J. R. [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George St., Toronto, Ontario, M5S 3H8 (Canada); Banavar, N. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario, M5S 3H4 (Canada); Bandura, K. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, H3A 2T8 (Canada); Blake, C. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Chang, T.-C.; Liao, Y.-W. [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei, 10617, Taiwan (China); Chen, X.; Li, Y.-C. [National Astronomical Observatories, Chinese Academy of Science, 20A Datun Road, Beijing 100012 (China); Natarajan, A.; Peterson, J. B.; Voytek, T. C. [McWilliams Center for Cosmology, Carnegie Mellon University, Department of Physics, 5000 Forbes Ave., Pittsburgh, PA 15213 (United States)

2013-01-20

In this Letter, 21 cm intensity maps acquired at the Green Bank Telescope are cross-correlated with large-scale structure traced by galaxies in the WiggleZ Dark Energy Survey. The data span the redshift range 0.6 < z < 1 over two fields totaling {approx}41 deg. sq. and 190 hr of radio integration time. The cross-correlation constrains {Omega}{sub HI} b{sub HI} r = [0.43 {+-} 0.07(stat.) {+-} 0.04(sys.)] Multiplication-Sign 10{sup -3}, where {Omega}{sub HI} is the neutral hydrogen (H I) fraction, r is the galaxy-hydrogen correlation coefficient, and b{sub HI} is the H I bias parameter. This is the most precise constraint on neutral hydrogen density fluctuations in a challenging redshift range. Our measurement improves the previous 21 cm cross-correlation at z {approx} 0.8 both in its precision and in the range of scales probed.

High dielectric constant observed in (1 − x)Ba(Zr{sub 0.07}Ti{sub 0.93})O{sub 3}–xBa(Fe{sub 0.5}Nb{sub 0.5})O{sub 3} binary solid-solution

Energy Technology Data Exchange (ETDEWEB)

Kruea-In, Chatchai [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Eitssayeam, Sukum; Pengpat, Kamonpan [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Rujijanagul, Gobwute, E-mail: rujijanagul@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2012-10-15

Binary solid-solutions of the (1 − x)Ba(Zr{sub 0.07}Ti{sub 0.93})O{sub 3}–xBa(Fe{sub 0.5}Nb{sub 0.5}O{sub 3}) system, with 0.1 ≤ x ≤ 0.9,were fabricated via a solid-state processing technique. X-ray diffraction analysis revealed that all samples exhibited a single perovskite phase. The BaFe{sub 0.5}Nb{sub 0.5}O{sub 3} also promoted densification and grain growth of the system. Dielectric measurements showed that all samples displayed a relaxor like behavior. The x = 0.1 sample presented a dielectric-frequency and temperature with low loss tangent (<0.07 at 10 kHz). For x > 0.2 samples, the dielectric data showed a broad dielectric constant–temperature curve with a giant dielectric characteristic. In addition, a high dielectric constant > 50,000 (at 10 kHz and temperature > 150 °C) was observed for the x = 0.9 sample.

Effect of oxygen incorporation on the vibrational properties of Al{sub 0.2}Ga{sub 0.3}In{sub 0.5}P:Be films

Energy Technology Data Exchange (ETDEWEB)

Soubervielle-Montalvo, C., E-mail: csober22@gmail.com [Area de Computacion e Informatica, Facultad de Ingenieria, Universidad Autonoma de San Luis Potosi, Av. Dr. Manuel Nava 8, Zona Universitaria, C.P. 78290, San Luis Potosi, S.L.P (Mexico); Vital-Ochoa, O. [Area de Computacion e Informatica, Facultad de Ingenieria, Universidad Autonoma de San Luis Potosi, Av. Dr. Manuel Nava 8, Zona Universitaria, C.P. 78290, San Luis Potosi, S.L.P (Mexico); Anda, F. de [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Secc., C.P. 78210, San Luis Potosi, S.L.P. (Mexico); Vazquez-Cortes, D.; Rodriguez, A.G. [Coordinacion para la Innovacion y Aplicacion de la Ciencia y Tecnologia, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Secc., C.P. 78210, San Luis Potosi, S.L.P. (Mexico); Melendez-Lira, M. [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Av. Instituto Politecnico Nacional 2508, San Pedro Zacatenco, C.P. 07360, Mexico, D.F. (Mexico); Mendez-Garcia, V.H. [Coordinacion para la Innovacion y Aplicacion de la Ciencia y Tecnologia, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Secc., C.P. 78210, San Luis Potosi, S.L.P. (Mexico)

2011-10-31

The vibrational properties of Al{sub 0.2}Ga{sub 0.3}In{sub 0.5}P:Be films grown on (100) GaAs substrates by solid source molecular beam epitaxy varying the phosphorous cracking-zone temperature (PCT) were studied by Raman spectroscopy. The Raman-intensity ratio between the allowed longitudinal optical and the forbidden transverse optical (TO) phonons, and the full width at half maximum of their Lorentzian fits were used to characterize the crystalline quality of the films. The Raman spectra from the samples show changes in the shape and intensity of phonon resonances depending on the PCT variation, indicating that the disorder in the lattice increases with PCT. The increasing disorder is related to the inclusion of oxygen, which act as a non-intentional perturbing impurity in the lattice. In addition, a vibrational mode located at 598 cm{sup -1} related to a forbidden InP-like TO phonon resonance was correlated with oxygen-induced disorder. Photoluminescence at room temperature shows that the high inclusion of oxygen also deteriorates the optical properties of the samples, by introducing non-radiative recombination centers.

Gleeble Testing of Tungsten Samples

Science.gov (United States)

2013-02-01

temperature on an Instron load frame with a 222.41 kN (50 kip) load cell . The samples were compressed at the same strain rate as on the Gleeble...ID % RE Initial Density (cm 3 ) Density after Compression (cm 3 ) % Change in Density Test Temperature NT1 0 18.08 18.27 1.06 1000 NT3 0...4.1 Nano-Tungsten The results for the compression of the nano-tungsten samples are shown in tables 2 and 3 and figure 5. During testing, sample NT1

Structure and electrical properties of (1 − x) (Na0.5Bi0.5)0.94Ba0.06TiO3–x BiAlO3 lead-free piezoelectric ceramics

International Nuclear Information System (INIS)

Fu, Peng; Xu, Zhijun; Chu, Ruiqing; Wu, Xueyan; Li, Wei; Li, Xiaodong

2013-01-01

Highlights: ► (1 − x) BNBT6–x BA ceramics were prepared by solid-state reaction method. ► Electrical properties of BNBT6 ceramics are improved by the addition of BA. ► (1 − x) BNBT6 - x BA ceramics at x = 0.0225 have the best electrical properties. - Abstract: (1 − x) (Na 0.5 Bi 0.5 ) 0.94 Ba 0.06 TiO 3 –x BiAlO 3 ((1 − x) BNBT6–x BA) lead-free piezoelectric ceramics were synthesized by conventional solid-state processes. Effects of BiAlO 3 (BA) on the structure and electrical properties of (Na 0.5 Bi 0.5 ) 0.94 Ba 0.06 TiO 3 (BNBT6) ceramics were investigated. X-ray diffraction (XRD) data shows that (1 − x) BNBT6–x BA ceramics form the pure perovskite phases, and the ceramics have the morphotropic phase boundary (MPB) when x r = 42.5 μC/cm 2 ), the highest piezoelectric coefficient (d 33 = 204 pC/N), the highest planar coupling factor (k p = 0.3292), the highest dielectric constant (ε r = 1687) and higher mechanical quality factor (Q m = 112)

Effects of electron irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

Science.gov (United States)

Nicoletta, C. A.

1973-01-01

One OHM-cm and 10 OHM-cm silicon solar cells were exposed to 1.0 MeV electrons at a fixed flux of 10 to the 11th power e/sq cm/sec and fluences of 10 to the 13th power, 10 to the 14th power and 10 to the 15th power e/sq.cm. 1-V curves of the cells were made at room temperature, - 63 C and + or - 143 C after each irradiation. A value of 139.5 mw/sq cm was used as AMO incident energy rate per unit area. The 10 OHM-cm cells appear more efficient than 1 OHM-cm cells after exposure to a fluence greater than 10 to the 14th power e/sq cm. The 1.0 MeV electron damage coefficients for both 1 OHM-cm and 10 OHM-cm cells are somewhat less than those for previously irradiated cells at room temperature. The values of the damage coefficients increase as the cell temperatures decrease. Efficiencies pertaining to maximum power output are about the same as those of n on p silicon cells evaluated previously.

Electric-field-induced local structural phenomena in relaxor ferroelectric PbSc0.5Nb0.5O3 near the intermediate temperature T* studied by Raman spectroscopy

International Nuclear Information System (INIS)

Steilmann, T; Maier, B J; Bismayer, U; Mihailova, B; Gospodinov, M

2014-01-01

Raman spectroscopy at different temperatures and under an external electric field E was applied to PbSc 0.5 Nb 0.5 O 3 single crystals in order to gain further insights into the mesoscopic-scale coupling processes in perovskite-type (ABO 3 ) relaxor ferroelectrics. Parallel and cross-polarized Raman spectra were collected between 800–80 K with E applied along the cubic [1 0 0], [1 1 0] or [1 1 1] crystallographic directions. The analysis was focused on the field-induced changes in the temperature evolution of three low-energy phonon modes: the Pb-localized mode near 50 cm −1 , the Pb-BO 3 translation mode near 150 cm −1 , and the B-cation-localized mode near 250 cm −1 . The results show that competitive ferroelectric (FE) and antiferroelectric (AFE) coupling exists within the system of off-centred Pb 2+ cations, within the system of off-centred B-site cations as well as between off-centred Pb 2+ and B-site cations. The strong AFE-type coupling between Pb 2+ cations along the cubic body diagonal significantly influences the coupling between the B-site cations via the Pb-BO 3 mode and results in AFE-type behaviour of the ‘microscopic’ T* determined from the B-cation-localized mode near 250 cm −1 , which explains the previously reported non-trivial field dependence of the ‘macroscopic’ characteristic temperatures: the temperature of the dielectric-permittivity maximum T m , T*, and the Burns temperature T B . The comparative analysis between PbSc 0.5 Nb 0.5 O 3 and PbSc 0.5 Ta 0.5 O 3 indicates that two major displacive order parameters couple to form a relaxor state in B-site complex perovskites: the FE order associated with polar shifts of B-site cations and the AFE order associated with polar shifts of A-site cations. The latter penetrates through both polar and non-polar regions, but it is highly frustrated due to the high density of translation-symmetry faults in the chemical NaCl-type B-site order. The frustrated AFE order

Capsule, septum, and T2 hyperintense foci for differentiation between large hepatocellular carcinoma (≥5 cm) and intrahepatic cholangiocarcinoma on gadoxetic acid MRI

Energy Technology Data Exchange (ETDEWEB)

Hwang, Jiyoung; Hong, Seong Sook; Kim, Hyun-joo [Soonchunhyang University College of Medicine, Department of Radiology, Seoul Hospital, Seoul (Korea, Republic of); Kim, Young Kon; Min, Ji Hye; Jeong, Woo Kyung [Sungkyunkwan University School of Medicine, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Seoul (Korea, Republic of); Choi, Seo-Youn [Soonchunhyang University College of Medicine, Department of Radiology, Bucheon Hospital, Bucheon (Korea, Republic of); Ahn, Soohyun; Ahn, Hyeon Seon [Research Institute for Future Medicine, Biostatistics and Clinical Epidemiology Center, Samsung Medical Center, Seoul (Korea, Republic of)

2017-11-15

To determine the added value of capsule, septum, and T2 hyperintense foci for differentiating large hepatocellular carcinoma (HCC; ≥ 5 cm) from intrahepatic cholangiocarcinoma (ICC) using gadoxetic acid MRI. The study included 116 patients (94 men, 22 women; mean age, 56.8 years) with surgically confirmed HCCs (n = 87, 5.0-18.0 cm) or ICCs (n = 29, 5.0-14.0 cm) who underwent gadoxetic acid MRI. Three observers independently reviewed MRIs in two sessions, examining enhancement patterns only and then adding capsule, septum, and T2 hyperintense foci. Reviewers used a five-point scale to score accuracy, sensitivity, and specificity. A significant increase was observed in accuracy when ancillary features (96.1-98.3%) were added compared to enhancement pattern only (83.6-88.4%; p ≤ 0.02). Sensitivity was significantly increased with combined reading (97.1-98.3%) compared to enhancement features only (81.6-88.5%; p ≤ 0.006) for two observers, with no difference in specificity (84.5-89.7% vs. 86.2-98.3%; p > 0.05). We found substantial to excellent interobserver agreement for ancillary features (0.598-0.976). Adding capsule, septum, and T2 hyperintense foci to enhancement patterns for gadoxetic acid MRI increased diagnostic performance for characterizing large HCC by differentiating it from ICC. (orig.)

Nanopowders Y{sub 1−y}Nd{sub y}V{sub 1−x}Cr{sub x}O{sub 4} with y=0 and 1; x=0, 0.1, 0.2 and 0.5 synthesized by a sol–gel process. Relationship between morphological characteristics and optical properties

Energy Technology Data Exchange (ETDEWEB)

Alcaraz, L. [Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Isasi, J., E-mail: isasi@quim.ucm.es [Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Caballero, A.C. [Departamento de Electrocerámica, Instituto de Cerámica y Vidrio (CSIC), Kelsen, 5, 28049 Madrid (Spain); Izquierdo, J.G.; Bañares, L. [Departamento de Química Física I and Centro de Láseres Ultrarrápidos, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

2015-05-15

Y{sub 1−y}Nd{sub y}V{sub 1−x}Cr{sub x}O{sub 4} nanopowders with y=0 and 0.1; x=0, 0.1, 0.2 and 0.5, have been synthetized by a sol–gel process followed by heating in an oxygen flow. This second treatment was done only in the case of samples containing chromium. The samples have been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structural analysis revealed that when chromium was inserted at vanadium-sites in Y{sub 0.9}Nd{sub 0.1}VO{sub 4}, the host retained the tetragonal symmetry corresponding to a zircon-type structure, attributed to the space group I4{sub 1}/amd. In addition, a loss of crystallinity was observed when chromium substitutes vanadium into the Y{sub 0.9}Nd{sub 0.1}VO{sub 4} host. The morphological studies revealed agglomerates of spherical particles whose size is increased with the Cr content and confirmed the composition of all synthetized samples. FTIR spectra of these samples exhibit a broadening and a slight shift of the bands around 830 cm{sup −1} towards higher values of frequency when the chromium content increases. The effect of vanadium substitution by chromium on the optical properties was also evaluated by UV–vis absorption and photoluminescence (PL) spectroscopies. The broad UV band absorption is due to the presence of Cr{sup 5+}. A decrease of PL emission is found when chromium substitutes vanadium in the YVO{sub 4} host. - Highlights: • Nanophosphors Y{sub 1−y}Nd{sub y}V{sub 1−x}Cr{sub x}O{sub 4} with y=0, 0.1 and x=0, 0.1, 0.2 and 0.5 have been synthesized. • Structural analysis reveals structural distortions associated to chromium insertion. • Morphological studies confirm the nanocristalline size and the stoichiometry of synthesized samples. • Chromium insertion causes a decrease of the PL emission intensity.

Effect of Co substitution on magnetic ground state in Sm0.5Ca0.5MnO3

International Nuclear Information System (INIS)

Xu, Xiaolong; Li, Yu; Hou, Feifei; Cheng, Qian; Su, Runzhou

2015-01-01

Highlights: • Polycrystalline Sm 0.5 Ca 0.5 Mn 1−x Co x O 3 were prepared by standard solid-state reaction. • The orthorhombic deformation and normalized slope were calculated for each sample. • Critical slowing down model and dynamic scaling equation are applied in some samples. • Canted antiferromagnetic state via spin glass state, changes to ferrimagnetic state. - Abstract: The effect of cobalt doping on the structural and magnetic properties of polycrystalline Sm 0.5 Ca 0.5 Mn 1−x Co x O 3 (0 ⩽ x ⩽ 0.20) has been studied. Powder X-ray diffraction (XRD), dc magnetization and ac susceptibility measurements have been performed. The orthorhombic deformation caused by the Jahn–Teller (JT) effect can be counterbalanced by Co 3+ doping. Meanwhile, antiferromagnetic (AFM), spin glass (SG) and phase separation (PS) ferrimagnetic states appear, successively, with the increase of x. The critical slowing down model and the dynamic scaling equation were applied in some samples. The existence of two distinct length scales for SG and finite FM (ferromagnetic) order is the source of the progressive deviation which exists in the dynamic scaling fitting for x = 0.05. Moreover, the small peaks at ∼8 K in χ″(T) curves are believed to be induced by the canted moments of Mn ions as observed in Nd 2/3 Ca 1/3 MnO 3

A bottom-up building process of nanostructured La0.75Sr0.25Cr0.5Mn0.5O3-δ electrodes for symmetrical-solid oxide fuel cell: Synthesis, characterization and electrocatalytic testing

Science.gov (United States)

Chanquía, Corina M.; Montenegro-Hernández, Alejandra; Troiani, Horacio E.; Caneiro, Alberto

2014-01-01

Pure-phase La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM) nanocrystallites have been successfully synthesized by the combustion method, employing glycine as fuel and complexing agent, and ammonium nitrate as combustion trigger. A detailed morphological and structural characterization is performed, by using of X-ray diffraction, N2 physisorption and electron microscopy. The LSCM material consists in interconnected nanocrystallites (∼30 nm) forming a sponge-like structure with meso and macropores, being its specific surface area around 10 m2 g-1. Crystalline structural analyses show that the LSCM nanopowder has trigonal/rhombohedral symmetry in the R-3c space group. By employing the spin coating technique and quick-stuck thermal treatments of the ink-electrolyte, electrodes with different crystallite size (95, 160 and 325 nm) are built onto both sides of the La0.8Sr0.2Ga0.8Mg0.2O3-δ-disk electrolyte. To test the influence of the electrode crystallite size on the electrocatalytic behavior of the symmetrical cells, electrochemical impedance spectroscopy measurements at 800 °C were performed. When the electrode crystallite size becomes smaller, the area specific resistance decreases from 3.6 to 1.31 Ω cm2 under 0.2O2-0.8Ar atmosphere, possibly due to the enlarging of the triple-phase boundary, while this value increases from 7.04 to 13.78 Ω cm2 under 0.17H2-0.03H2O-0.8Ar atmosphere, probably due to thermodynamic instability of the LSCM nanocrystallites.

Preparation and electrical properties of Bi0.5Na0.5TiO3-BaTiO3-KNbO3 lead-free piezoelectric ceramics

International Nuclear Information System (INIS)

Ni Haimin; Luo Laihui; Li Weiping; Zhu Yuejin; Luo Haosu

2011-01-01

Research highlights: → Bi 0.47 Na 0.47 Ba 0.06 TiO 3 -KNbO 3 ceramics exhibit excellent piezoelectric properties. → The optimized properties of the ceramics: d 33 = 195 pC/N; k t = 58.9; Q m = 113; E c = 19.5 kV/cm. → KNbO 3 has diffused into the Bi 0.47 Na 0.47 Ba 0.06 TiO 3 lattices to form a new solid solution. → Macro-micro domain switching occurs at depolarization temperature T d . - Abstract: Lead-free (1 - x)Bi 0.47 Na 0.47 Ba 0.06 TiO 3 -xKNbO 3 (BNBT-xKN, x = 0-0.08) ceramics were prepared by ordinary ceramic sintering technique. The piezoelectric, dielectric and ferroelectric properties of the ceramics are investigated and discussed. The results of X-ray diffraction (XRD) indicate that KNbO 3 (KN) has diffused into Bi 0.47 Na 0.47 Ba 0.06 TiO 3 (BNBT) lattices to form a solid solution with a pure perovskite structure. Moderate additive of KN (x ≤ 0.02) in BNBT-xKN ceramics enhance their piezoelectric and ferroelectric properties. Three dielectric anomaly peaks are observed in BNBT-0.00KN, BNBT-0.01KN and BNBT-0.02KN ceramics. With the increment of KN in BNBT-xKN ceramics, the dielectric anomaly peaks shift to lower temperature. BNBT-0.01KN ceramic exhibits excellent piezoelectric properties and strong ferroelectricity: piezoelectric coefficient, d 33 = 195 pC/N; electromechanical coupling factor, k t = 58.9 and k p = 29.3%; mechanical quality factor, Q m = 113; remnant polarization, P r = 41.8 μC/cm 2 ; coercive field, E c = 19.5 kV/cm.

AC conductivity, magnetic and shielding effectiveness studies on polyaniline embedded Co0.5Mn0.5Fe2O4 nanoparticles for electromagnetic interference suppression

Science.gov (United States)

Gurusiddesh, M.; Madhu, B. J.; Shankaramurthy, G. J.

2018-05-01

Electrically conducting Polyaniline (PANI)/Co0.5Mn0.5Fe2O4 nanocomposites are synthesized by in situ polymerization of aniline monomer in the presence of Co0.5Mn0.5Fe2O4 nanoparticles. Structural studies on the synthesized samples have been carried out using X-ray diffraction technique, Field emission scanning electron microscopy and Energy dispersive X-ray spectroscopy. Frequency dependent ac conductivity studies on the prepared samples revealed that conductivity of the composite is high compared to Co0.5Mn0.5Fe2O4 nanoparticles. Further, both the samples exhibited hysteresis behavior under the applied magnetic field. Electromagnetic interference (EMI) shielding effectiveness of both the samples decreases with increase in the applied frequency in the studied frequency range. Maximum shielding effectiveness (SE) of 31.49 dB and 62.84 dB were obtained for Co0.5Mn0.5Fe2O4 nanoparticles and PANI/Co0.5Mn0.5Fe2O4 nanocomposites respectively in the studied frequency range. Observed higher EMI shielding in the composites was attributed to its high electrical conductivity.

Microdosimetry of 0.5 to 2.0 MeV electron beams

International Nuclear Information System (INIS)

Braby, L.A.; Roesch, W.C.

1980-08-01

The energy imparted in microscopic volumes by electron beams with initial energies from 0.5 to 2.0 MeV has been measured at various depths in plastic. The problems associated with measuring energy deposition spectra of low LET radiations are serious, but the potential importance of these measurements in radiation biophysics justifies the effort required to obtain them. Recent results obtained by Goodhead et al. indicate an RBE greater than 2 for 0.3 keV x-rays compared to 250 kV x-rays, and our results with Chlamydomonas reinhardi indicate an RBE of 1.6 for a 1.5 MeV electron beam at a depth of 400 gm/cm 2 in lucite compared to the same beam at the surface. Development of a theory which appears to explain these results in terms of the microscopic distribution of energy deposition has motivated a detailed study of energy deposition spectra for an electron beam attenuated by various thicknesses of lucite. Simulated sites from 0.5 to 1.9 μm in diameter were studied. The values of anti y determined in these single event measurements compare favorably with those calculated from direct measurements of z reported previously. As expected, the means of the distributions increase significantly with increasing depth in an absorber

Effects of A-site nonstoichiometry on oxide ion conduction in 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 ceramics

Directory of Open Access Journals (Sweden)

Sasiporn Prasertpalichat

2016-06-01

Full Text Available Lead free 0.94(Bi0.5Na0.5TiO3–0.06BaTiO3 ceramics were prepared by conventional solid-state mixed oxide route with the A-site stoichiometry modified to incorporate donor-doping (through Bi-excess and acceptor-doping (through Na-excess. Both stoichiometric and nonstoichiometric ceramics exhibited a single perovskite phase with pseudo-cubic symmetry. A significant improvement in the dielectric properties was observed in Bi-excess compositions and a deterioration in the dielectric properties was observed in Na-excess compositions. Impedance spectroscopy was utilized to analyze the effects of A-site nonstoichiometry on conduction mechanisms. Compositions with Bi-excess resulted in an electrically homogeneous microstructure with an increase in resistivity by ∼3–4 orders of magnitude and an associated activation energy of 1.57eV which was close to half of the optical bandgap. In contrast, an electrically heterogeneous microstructure was observed in both the stoichiometric and Na-excess compositions. In addition, the Na-excess compositions exhibited low resistivities (ρ∼103Ω-cm with characteristic peaks in the impedance data comparable to the recent observations of oxide ion conduction in (Bi0.5Na0.5TiO3. Long term annealing studies were also conducted at 800∘C to identify changes in crystal structure and electrical properties. The results of this study demonstrates that the dielectric and electrical properties of 0.94(Bi0.5Na0.5TiO3–0.06BaTiO3 ceramics are very sensitive to Bi/Na stoichiometry.

Crystal and magnetic study of the disordered perovskites Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3} and Ca(Fe{sub 0.5}Sb{sub 0.5})O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Retuerto, M., E-mail: mretuerto@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain); Martinez-Lope, M.J.; Garcia-Hernandez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain); Munoz, A. [Departamento de Fisica Aplicada, EPS, Universidad Carlos III, Avda. Universidad 30, E-28911 Leganes-Madrid (Spain); Fernandez-Diaz, M.T. [Institut Max Von Laue Paul Langevin, F-38042 Grenoble (France); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain)

2010-10-15

We have investigated the double perovskites Ca{sub 2}MSbO{sub 6} (M = Mn, Fe) that have been prepared by solid-state reaction (M = Fe) and wet chemistry procedures (M = Mn). The crystal and magnetic structures have been studied from X-ray (XRD) and neutron powder diffraction (NPD) data. Rietveld refinements show that the crystal structures are orthorhombic (space group Pbnm) with complete disorder of M and Sb cations, so the formula should be rewritten as Ca(M{sub 0.5}Sb{sub 0.5})O{sub 3}. Due to this disorder no evidences of Jahn-Teller distortion can be observed in the MnO{sub 6} octahedra of Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3}, in contrast with the ordered double perovskite Sr{sub 2}MnSbO{sub 6}. Ca(Fe{sub 0.5}Sb{sub 0.5})O{sub 3} behaves as an antiferromagnet with an ordered magnetic moment for Fe{sup 3+} of 1.53(4){mu}{sub B} and a propagation vector k = 0, as investigated by low-temperature NPD. The antiferromagnetic ordering is a result of the high degree of Fe/Sb anti-site disorder of the sample, which originates the spontaneous formation of Fe-rich islands, characterized by the presence of strong Fe-O-Fe antiferromagnetic couplings with enough long-range coherence to produce a magnetic contribution perceptible by NPD. By contrast, the magnetic structure of Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3} cannot be observed by low-temperature NPD because the magnitude of the ordered magnetic moments is below the detection threshold for neutrons.

Microsphere LiFe{sub 0.5}Mn{sub 0.5}PO{sub 4}/C composite as high rate and long-life cathode material for lithium-ion battery

Energy Technology Data Exchange (ETDEWEB)

Yang, Chun-Chen, E-mail: ccyang@mail.mcut.edu.tw [Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan, ROC (China); Battery Research Center of Green Energy, Ming Chi University of Technology, New Taipei City 243, Taiwan, ROC (China); Chen, Wei-Houng [Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan, ROC (China)

2016-04-15

LiFe{sub 0.5}Mn{sub 0.5}PO{sub 4}/C composite material (denoted as SP-LFMP/C) with macro/nano hierarchical porous structure by adding the composite carbon source (i.e., 100 nm polystyrene sphere and 300 nm carbon sphere) is fabricated via a spray dry process. The SP-LFMP/C composite exhibits a 3D hierarchical structure with a high surface area (34.63 m{sup 2} g{sup −1}) and a wide pore size distribution (2–100 nm). The characteristic properties of the samples are examined using X-ray diffraction, micro-Raman spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests. The SP-LFMP/C composite achieves discharge capacities of 161, 160, 157, 146, 137, and 115 mAh g{sup −1} at 0.2, 0.5, 1, 3, 5, and 10 C, respectively. Moreover, the SP-LFMP/C material also exhibits excellent cycling performance and stability at 55 °C during the 300 cycle test. These results indicate that the SP-LFMP/C cathode material is an excellent candidate for application in high-energy Li-ion batteries. - Highlights: • A microsphere LiFe{sub 0.5}Mn{sub 0.5}PO{sub 4}/C composite is prepared by a spray drying process. • The composite material shows a mesoporous 3D structure with a high surface area. • The SP-LFMP composite exhibits excellent high rate capability. • The SP-LFMP/C composite shows much higher tap density of 1.33 g cm{sup −3}.

Some properties of the psi(3.7) resonance, and features of the total hadronic cross section in e+e- annihilation from 2.4 GeV to 5.0 GeV c.m. energy

International Nuclear Information System (INIS)

Kadyk, J.A.; Abrams, G.S.; Briggs, D.D.

1975-01-01

An analysis of data at the psi(3.7) resonance gives a partial width to electrons, MMA ub e/ = 2.2 +- 0.5 keV, and limits on total width 200 keV + π - is observed with a branching ratio 0.31 +- 0.04, and psi(3.7) → psi(3.1) + anything has a branching ratio of 0.54 +- 0.08. The psi resonances appear to have the same G-parity. An enhancement occurs in the total hadronic cross section at a c.m. energy of about 4.1 GeV, rising to about 32 nb from a level of 18 nb adjacent to peak, which is about 300 MeV wide. The integrated cross section for the peak is about 5.5 nb-GeV, comparable to that for the psi(3.7) and psi(3.1) resonances. (U.S.)

Some properties of the psi(3.7) resonance, and features of the total hadronic cross section in e+e- annihilation from 2.4GeV to 5.0GeV c.m. energy

International Nuclear Information System (INIS)

Abrams, G.S.; Briggs, D.D.; Chinowsky, W.; Friedberg, C.E.; Goldhaber, G.; Hollebeek, R.J.; Litke, A.; Lulu, B.A.; Pierre, F.; Sadoulet, B.; Trilling, G.H.; Whitaker, J.S.; Wiss, J.E.; Zipse, J.E.

1975-01-01

An analysis of data at the psi(3.7) resonance gives a partial width to electrons GAMMA(e)=2.2+-0.5keV, and limits on total width 200keV + π - is observed with a branching ratio 0.31+-0.04, and psi(3.7)→psi(3.1) + anything has a branching ratio of 0.54+-0.08. The psi resonances appear to have the same G-parity. An enhancement occurs in the total hadronic cross section at a c.m. energy of about 4.1GeV, rising to about 32nb from a level of 18nb adjacent to peak, which is about 300MeV wide. The integrated cross section for the peak is about 5.5nb-GeV, comparable to that for the psi(3.7) and psi(3.1) resonances

CM5: A pre-Swarm magnetic field model based upon the comprehensive modeling approach

DEFF Research Database (Denmark)

Sabaka, T.; Olsen, Nils; Tyler, Robert

2014-01-01

We have developed a model based upon the very successful Comprehensive Modeling (CM) approach using recent CHAMP, Ørsted, SAC-C and observatory hourly-means data from September 2000 to the end of 2013. This CM, called CM5, was derived from the algorithm that will provide a consistent line of Leve...

Dielectric and impedance analysis of Li0.5La0.5Ti1-xZrxO3(x = 0.05 and 0.1 ceramics as improved electrolyte material for lithium-ion batteries

Directory of Open Access Journals (Sweden)

Babu K. Vijaya

2016-09-01

Full Text Available The most attractive property of Li0.5La0.5TiO3 (LLTO electrolytes is their high ionic conductivity. Studies have shown that LLTO is capable of existing in a state with an ionic conductivity of 10-3 S/cm, which is comparable to liquid electrolytes. In addition to the high ionic conductivity of the material, LLTO is electrochemically stable and able to withstand hundreds of cycles. So, the studies of the solid electrolyte material are very important for the development of lithium-ion batteries. In the present paper, Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1 have been prepared by a solid-state reaction method at 1300 °C for 6 hours to improve electrolyte materials for lithium-ion batteries. The phase identified by X-ray diffractometry and crystal structure corresponds to pm3m (2 2 1 space group (Z = 1. The frequency and temperature dependence of impedance, dielectric permittivity, dielectric loss and electric modulus of the Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1 have been investigated. The dielectric and impedance properties have been studied over a range of frequency (42 Hz to 5 MHz and temperatures (30 °C to 100 °C. The frequency dependent plot of modulus shows that the conductivity relaxation is of non-Debye type.

Coherent nanoscale islands on La0.5Ca0.5MnO3 thin films and the enhancement of magnetoresistance

International Nuclear Information System (INIS)

Gong, W. Z.; Zhao, B. R.; Cai, C.; Lin, Y.

2001-01-01

A low cost reproducible fabrication process has been developed to prepare La 0.5 Ca 0.5 MnO 3 (LCMO) films with well distributed uniform nanoscale dots using pulsed-laser deposition. It was found that the growth of the dots was closely related to the strain in the film during the growth process. The diameter and density of dots could be controlled within the range of 30--120 nm and 2 x 10 8 --2 x 10 9 /cm 2 , respectively. The magnetoresistance effect of such LCMO films is also enhanced, which may be caused by the spin-dependent scattering of carriers due to the existence of the dots. Copyright 2001 American Institute of Physics

Quarternair CuGaSeTe and CuGa0.5In 0.5Te2 Thin Films Fabrication Using Flash Evaporation

Directory of Open Access Journals (Sweden)

A Harsono Soepardjo

2010-10-01

Full Text Available Quarternair materials CuGaSeTe and CuGa0.5In 0.5Te2 are the basic materials to solar cell fabrication. These materials have high absorption coefficients around 103 - 105 cm-1 and band gap energy in the range of 1-5 eV. In this research, the films were made by flash evaporation method using quarternair powder materials of CuGaSeTe and CuGa0.5In 0.5Te2 to adhere in a glass substrate. After the films were obtained, the properties of these films will be characterized optically and electrically. The lattice parameter of the films and the crystalline film structure were obtained using X-Ray Diffraction (XRD spectroscopy. The XRD results show that the quarternair CuGaSeTe and CuGa0.5In 0.5Te2 films have a chalcopyrite structure. The absorption coefficient and the  band gap energy of the films were calculated using transmittance and reflectance patterns that measured using UV-VIS Difractometer. The films composition can be detected by using the Energy Dispersive Spectroscopy (EDS, while the films resistivity, mobility and the majority carrier of the films were obtained from Hall Effect experiments.

Accurate determination of Curium and Californium isotopic ratios by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 248Cm samples for transmutation studies

Energy Technology Data Exchange (ETDEWEB)

Gourgiotis, A.; Isnard, H.; Aubert, M.; Dupont, E.; AlMahamid, I.; Cassette, P.; Panebianco, S.; Letourneau, A.; Chartier, F.; Tian, G.; Rao, L.; Lukens, W.

2011-02-01

The French Atomic Energy Commission has carried out several experiments including the mini-INCA (INcineration of Actinides) project for the study of minor-actinide transmutation processes in high intensity thermal neutron fluxes, in view of proposing solutions to reduce the radiotoxicity of long-lived nuclear wastes. In this context, a Cm sample enriched in {sup 248}Cm ({approx}97 %) was irradiated in thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). This work describes a quadrupole ICP-MS (ICP-QMS) analytical procedure for precise and accurate isotopic composition determination of Cm before sample irradiation and of Cm and Cf after sample irradiation. The factors that affect the accuracy and reproducibility of isotopic ratio measurements by ICP-QMS, such as peak centre correction, detector dead time, mass bias, abundance sensitivity and hydrides formation, instrumental background, and memory blank were carefully evaluated and corrected. Uncertainties of the isotopic ratios, taking into account internal precision of isotope ratio measurements, peak tailing, and hydrides formations ranged from 0.3% to 1.3%. This uncertainties range is quite acceptable for the nuclear data to be used in transmutation studies.

Intermediate-to-low temperature protonic ceramic membrane fuel cells with Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}}-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} composite cathode

Energy Technology Data Exchange (ETDEWEB)

Lin, Bin; Ding, Hanping; Dong, Yingchao; Wang, Songlin; Zhang, Xiaozhen; Fang, Daru; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China)

2009-01-01

The perovskite-type Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}}-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BSCF-BZCY) composite oxides were synthesized by a modified Pechini method and examined as a novel composite cathode for intermediate-to-low temperature protonic ceramic membrane fuel cells (ILT-PCMFCs). Thin proton-conducting BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY) electrolyte and NiO-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (NiO-BZCY) anode functional layer were prepared over porous anode substrates composed of NiO-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} by a one-step dry-pressing/co-firing process. A laboratory-sized quad-layer cell of NiO-BZCY/NiO-BZCY({proportional_to}50 {mu}m)/BZCY({proportional_to}20 {mu}m)/BSCF-BZCY({proportional_to}50 {mu}m) was operated from 550 to 700 C with humidified hydrogen ({proportional_to}3% H{sub 2}O) as fuel and the static air as oxidant. A high open-circuit potential of 1.009 V, a maximum power density of 418 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.10 {omega} cm{sup 2} was achieved at 700 C. These investigations have indicated that proton-conducting BZCY electrolyte with BSCF perovskite cathode is a promising material system for the next generation solid oxide fuel cells (SOFCs). (author)

Microwave dielectric properties of La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Chen, Yih-Chien; Chen, Kuei-Chien; Hsu, Wei-Yu [Department of Electrical Engineering, Lunghwa University of Science and Technology, Gueishan Shiang, Taoyuan County (China)

2010-11-15

This study examined the potential applications of microwave dielectric properties of La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics in rectenna. The La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics were prepared by the conventional solid-state method with various sintering temperatures. An apparent density of 6.62 g/cm{sup 3}, a dielectric constant of 20.3, a quality factor of 51,700 GHz, and a temperature coefficient of resonant frequency of -78.2 ppm/K were obtained for La{sub 2.98/3}Ba{sub 0.01}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics that were sintered at 1550 C for 4 h. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effect of O- and Mn-doping on superconductivity in FeTe{sub 0.5}Se{sub 0.5} superconductor

Energy Technology Data Exchange (ETDEWEB)

Thakur, Gohil S.; Haque, Zeba; Ganguli, Ashok K. [Department of Chemistry, Indian Institute of Technology, New Delhi (India); Neha, Prakriti; Patnaik, Satyabrata [School of Physical Science, Jawaharlal Nehru University, New Delhi (India); Gupta, Laxmi C. [Department of Chemistry, Indian Institute of Technology, New Delhi (India); Visiting project scientist at the:Solid State and Nanomaterials Research Laboratory, Department of Chemistry, IIT Delhi (India)

2014-05-15

The effect of oxygen substitution at the selenium site and manganese substitution at the iron site in FeTe{sub 0.5}Se{sub 0.5} superconductor was investigated. It was found that upon partial O substitution, T{sub c} marginally decreases as seen in both resistivity and magnetization experiments. T{sub c} decreases even by a small amount of oxygen concentration (as low as 1 %). This observation is in contrast against an earlier work on Fe(Te/Se) samples,1 wherein T{sub c} as well as superconducting volume fraction were reported to increase in the samples annealed in air. Mn-doping leads to a decrease in T{sub c} in FeTe{sub 0.5}Se{sub 0.5}, which one would expect considering pair-breaking due to Mn{sup 2+}-ions. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Peng, Wei; Mao, Chaoliang; Liu, Zhen; Dong, Xianlin; Cao, Fei; Wang, Genshui, E-mail: genshuiwang@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

2015-03-02

The phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} lead-free ceramics were investigated systematically. The loss tangent of poled sample shows a broad peak when heating to about 80 °C, i.e., depolarization temperature T{sub d}. The polarization-electric field hysteresis loops at different temperature exhibit the feature of ferroelectric (FE)- antiferroelectric (AFE) phase transition and the co-existence of FE and AFE phase. The pyroelectric coefficients curve confirms its diffusion behaviors. The initial hysteresis loop and switching current curves under T{sub d} indicate the co-existence of FE and AFE phase. The domain morphology of transmission electron microscopy supports the co-existence of FE and AFE phase. Our work not only exhibit that the FE and AFE phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} ceramics but also they may be helpful for further investigation on lead-free ceramics.

Heavy ion irradiations on synthetic hollandite-type materials: Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16} (A=Cr, Fe, Al)

Energy Technology Data Exchange (ETDEWEB)

Tang, Ming, E-mail: mtang@lanl.gov [Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tumurugoti, Priyatham; Clark, Braeden; Sundaram, S.K. [Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States); Amoroso, Jake; Marra, James [Materials Science & Technology Directorate, Savannah River National Laboratory, Aiken, SC 29808 (United States); Sun, Cheng [Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lu, Ping [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Wang, Yongqiang [Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Jiang, Ying-Bing [TEM Laboratory, University of New Mexico, Albuquerque, NM 87131 (United States)

2016-07-15

The hollandite supergroup of minerals has received considerable attention as a nuclear waste form for immobilization of Cs. The radiation stability of synthetic hollandite-type compounds described generally as Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16} (A=Cr, Fe, Al) were evaluated by heavy ion (Kr) irradiations on polycrystalline single phase materials and multiphase materials incorporating the hollandite phases. Ion irradiation damage effects on these samples were examined using grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). Single phase compounds possess tetragonal structure with space group I4/m. GIXRD and TEM observations revealed that 600 keV Kr irradiation-induced amorphization on single phase hollandites compounds occurred at a fluence between 2.5×10{sup 14} Kr/cm{sup 2} and 5×10{sup 14} Kr/cm{sup 2}. The critical amorphization fluence of single phase hollandite compounds obtained by in situ 1 MeV Kr ion irradiation was around 3.25×10{sup 14} Kr/cm{sup 2}. The hollandite phase exhibited similar amorphization susceptibility under Kr ion irradiation when incorporated into a multiphase system. - Graphical abstract: 600 keV Kr irradiation-induced amorphization on single phase hollandites compounds occurred at a fluence between 2.5×10{sup 14} Kr/cm{sup 2} and 5×10{sup 14} Kr/cm{sup 2}. The hollandite phase exhibited similar amorphization susceptibility under Kr ion irradiation when incorporated into a multiphase system. This is also the first time that the critical amorphization fluence of single phase hollandite compounds were determined at a fluence of around 3.25×10{sup 14} Kr/cm{sup 2} by in situ 1 MeV Kr ion irradiation. Display Omitted.

Magnetoresistive memory in phase-separated La0.5Ca0.5MnO3

Energy Technology Data Exchange (ETDEWEB)

Sacanell, J. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina)]. E-mail: sacanell@cnea.gov.ar; Parisi, F. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina); Levy, P. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina); Ghivelder, L. [Instituto de Fisica, UFRJ, Rio de Janeiro (Brazil)

2004-12-31

We have studied a non-volatile memory effect in the mixed valent compound La0.5Ca0.5MnO3 induced by magnetic field (H). In a previous work (Phys. Rev. B 65 (2002) 104403), it has been shown that the response of this system upon application of H strongly depends on the temperature range, related to three well-differentiated regimes of phase separation occurring below 220K. In this work we compare memory capabilities of the compound, determined following two different experimental procedures for applying H, namely zero-field cooling and field cooling the sample. These results are analyzed and discussed within the scenario of phase separation.

Magnetoresistive memory in phase-separated La0.5Ca0.5MnO3

International Nuclear Information System (INIS)

Sacanell, J.; Parisi, F.; Levy, P.; Ghivelder, L.

2004-01-01

We have studied a non-volatile memory effect in the mixed valent compound La0.5Ca0.5MnO3 induced by magnetic field (H). In a previous work (Phys. Rev. B 65 (2002) 104403), it has been shown that the response of this system upon application of H strongly depends on the temperature range, related to three well-differentiated regimes of phase separation occurring below 220K. In this work we compare memory capabilities of the compound, determined following two different experimental procedures for applying H, namely zero-field cooling and field cooling the sample. These results are analyzed and discussed within the scenario of phase separation

Luminescent characteristics of UV excited Sr_0_._5Ca_0_._5TiO_3: Pr"3"+ reddish-orange phosphor

International Nuclear Information System (INIS)

Vidyadharan, Viji; Mohan P, Remya; Joseph, Cyriac; Unnikrishnan, N.V.; Biju, P.R.

2016-01-01

Pr"3"+ doped Sr_0_._5Ca_0_._5TiO_3 phosphors were synthesised by solid state reaction process. The structure, surface morphology and photoluminescence of the prepared phosphors were analysed using XRD, SEM and photoluminescence spectroscopy respectively. The XRD pattern confirmed orthorhombic perovskite structure of the Sr_0_._5Ca_0_._5TiO_3: x Pr"3"+ phosphor. Agglomeration of particles with irregular shapes is observed from the SEM images. The emission spectra of Sr_0_._5Ca_0_._5TiO_3: x Pr"3"+ phosphor shows the samples can be effectively excited with UV light at 336 nm and exhibit a strong reddish-orange emission at 611 nm. Concentration dependence of emission intensity shows concentration quenching effect on increasing Pr"3"+ concentration after x = 0.1 because of dipole–dipole interaction. Using Blasse's formula, critical distance for energy transfer was calculated. The CIE co-ordinates, CCT, colour purity and luminescence decay of the prepared phosphors were also calculated. These results offer the prepared phosphor as a suitable candidate for various photonic applications. - Highlights: • Sr_0_._5Ca_0_._5TiO_3: x Pr"3"+ perovskite structured phosphors were synthesized. • Under UV excitation, the PL spectra show strong reddish-orange emission. • The emission from "3P_J levels of Pr"3"+ were absent due to the presence of IVCT band. • Concentration quenching due to dipole–dipole interaction was observed. • For x = 0.1, sample shows a maximum emission intensity with 91.7% colour purity.

Spin canting and magnetic transition in NixZn1-xFe2O4 (x=0.0, 0.5 and 1.0) nanoparticles

Science.gov (United States)

Rani, Stuti; Raghav, Dharmendra Singh; Yadav, Prashant; Varma, G. D.

2018-04-01

Nanoparticles of NixZn1-xFe2O4(x=0.0, 0.5 and 1.0) have been synthesized via co-precipitation method and studied thestructural and magnetic properties. Rietveld refinement of X ray diffraction data of as synthesized samples revealthat the samples have mixed spinel structure with space group Fd-3m. The lattice parameter of the samples decreases as doping concentration of Ni ions increases. Magnetic measurements show paramagnetic to ferrimagnetic transition at room temperature on Ni doping in ZnFe2O4 nanoparticles. The magnetic measurements also show spin canting in samples possibly due to their nanocrystalline nature. The spin canting angles have been calculated with the help of Yafet-Kittel (Y-K) model. Furthermore, the Law of approach (LA) fitting of M-H curves indicates that the samples are highly anisotropicin nature. The Arrot plots of as synthesized samples also indicate the paramagnetic to ferrimagnetic transition. The correlation between the structural and observed magnetic properties of NixZn1-xFe2O4(x=0.0, 0.5 and 1.0) nanocrystals will be described and discussed in this paper.

Structural and magnetic properties of size-controlled Mn0.5Zn0 ...

Indian Academy of Sciences (India)

Abstract. Mn0.5Zn0.5Fe2O4 ferrite nanoparticles with tunable Curie temperature and saturation ... netic fluid is synthesized and magnetic characterization is reported. The monolayer ... the synthesis method – largely affects the macroscopic properties, giving rise to a wide variety of ..... available in sample C. TGA technique ...

Synthesis of nanocrystalline Zn0.5Mn0.5Fe2O4 via in situ polymerization technique

International Nuclear Information System (INIS)

Liu Xianming; Fu Shaoyun

2007-01-01

Nanocrystalline Zn 0.5 Mn 0.5 Fe 2 O 4 was synthesized through the pyrolysis of polyacrylate salt precursors prepared via in situ polymerization of the metal salts and acrylic acid. The pyrolysis behavior of the polymeric precursors was studied by use of thermal analysis. The as-obtained product was characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction (ED) pattern, scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) analysis. The results revealed that the particle size is in the range of 15-25 nm for Zn-Mn ferrites with good crystallinity. Magnetic properties of the sample at 300 K were measured using a vibrating sample magnetometer, which showed that the sample exhibited characteristics of superparamagnetism

Microstructure and electrical properties of (1−x)[0.8Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.2Bi{sub 0.5}K{sub 0.5}TiO{sub 3}]-xBiCoO{sub 3} lead-free ceramics

Energy Technology Data Exchange (ETDEWEB)

Wang, Ting [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Chen, Xiao-ming, E-mail: xmchen@snnu.edu.cn [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Qiu, Yan-zi [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Lian, Han-li [School of Science, Xi’an University of Posts and Telecommunications, Xi’an, 710121 (China); Chen, Wei-ting [Department of Electrical Engineering, National Cheng Kung University, Tainan City, 701, Taiwan (China)

2017-01-15

The (1−x)[0.8Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.2Bi{sub 0.5}K{sub 0.5}TiO{sub 3}]-xBiCoO{sub 3} (x = 0, 0.02, 0.05, abbreviated as BNKT, BNKT-002Co, BNKT-005Co, respectively) lead-free ferroelectric ceramics were prepared via the solid state reaction method. The phase structure, microstructure, dielectric, ferroelectric, pyroelectric, and piezoelectric properties of the ceramics were investigated comparatively by using a combination of characterization techniques. All the samples exhibit typical X-ray diffraction peaks of ABO{sub 3} perovskite structure. The doping of BiCoO{sub 3} causes a decrease in lattice parameters and an increase in grain size of the ceramics. The Raman spectroscopy results suggest a lattice distortion due to the doping. It is found that BNKT-002Co and BNKT-005Co have higher depolarization temperatures compared with BNKT. The Curie-Weiss law and modified Curie-Weiss law explored a diffuse phase transition character for all the samples. The results of ultraviolet–visible diffuse reflectance suggests that BiCoO{sub 3}-doped ceramics possess higher defect concentration. The impedance analysis shows a temperature dependent relaxation behavior, and the activation energy for the electrical responses varies with the change of BiCoO{sub 3} amount. The ferroelectric and piezoelectric properties of the ceramics decrease due to the doping of BiCoO{sub 3}. Based on the results of the Rayleigh analysis, it was suggested that the differences in the electrical properties among the ceramics are closely related to the change in oxygen vacancy concentration. - Highlights: • BNKT-xCo ceramics were prepared by solid-state reaction method. • Electrical properties of BNKT ceramics are changed by the doping of BiCoO{sub 3}. • The doping causes a decrease in lattice parameters and an increase in grain size. • T{sub d} of the ceramics increases with increasing x. • Oxygen vacancies play key role in determining electrical properties of the ceramics.

Electrical characteristics and preparation of (Ba0.5Sr0.5)TiO3 films by spray pyrolysis and rapid thermal annealing

International Nuclear Information System (INIS)

Koo, Horngshow; Ku, Hongkou; Kawai, Tomoji; Chen Mi

2007-01-01

Functional films of (Ba 0.5 Sr 0.5 )TiO 3 on Pt (1000 A)/Ti (100 A)/SiO 2 (2000 A)/Si substrates are prepared by spray pyrolysis and subsequently rapid thermal annealing. Barium nitrate, strontium nitrate and titanium isopropoxide are used as starting materials with ethylene glycol as solvent. For (Ba 0.5 Sr 0.5 )TiO 3 functional thin film, thermal characteristics of the precursor powder scratched from as-sprayed films show a remarkable peak around 300-400degC and 57.7% weight loss up to 1000degC. The as-sprayed precursor film with coffee-like color and amorphous-like phase is transformed into the resultant film with white, crystalline perovskite phase and characteristic peaks (110) and (100). The resultant films show correspondent increases of dielectric constant, leakage current and dissipation factor with increasing annealing temperatures. The dielectric constant is 264 and tangent loss is 0.21 in the resultant films annealed at 750degC for 5 min while leakage current density is 1.5x10 -6 A/cm 2 in the film annealed at 550degC for 5 min. (author)

The cross-plane thermoelectric properties of p-Ge/Si0.5Ge0.5 superlattices

International Nuclear Information System (INIS)

Ferre Llin, L.; Samarelli, A.; Weaver, J. M. R.; Dobson, P. S.; Paul, D. J.; Cecchi, S.; Chrastina, D.; Isella, G.; Etzelstorfer, T.; Stangl, J.; Müller Gubler, E.

2013-01-01

The electrical conductivity, Seebeck coefficients, and thermal conductivities of a range of p-type Ge/Si 0.5 Ge 0.5 superlattices designed for thermoelectric generation and grown by low energy plasma enhanced chemical vapor deposition have been measured using a range of microfabricated test structures. For samples with barriers around 0.5 nm in thickness, the measured Seebeck coefficients were comparable to bulk p-SiGe at similar doping levels suggesting the holes see the material as a random bulk alloy rather than a superlattice. The Seebeck coefficients for Ge quantum wells of 2.85 ± 0.85 nm increased up to 533 ± 25 μV/K as the doping was reduced. The thermal conductivities are between 4.5 to 6.0 Wm −1 K −1 which are lower than comparably doped bulk Si 0.3 Ge 0.7 but higher than undoped Si/Ge superlattices. The highest measured figure of merit ZT was 0.080 ± 0.011 obtained for the widest quantum well studied. Analysis suggests that interface roughness is presently limiting the performance and a reduction in the strain between the quantum wells and barriers has the potential to improve the thermoelectric performance

Study of low energy Si5- and Cs- implantation induced amorphization effects in Si(1 0 0)

International Nuclear Information System (INIS)

Lenka, H P; Joseph, B; Kuiri, P K; Sahu, G; Mahapatra, D P; Mishra, P; Ghose, D

2008-01-01

The damage growth and surface modifications in Si(1 0 0), induced by 25 keV Si 5 - cluster ions, as a function of fluence, φ, has been studied using atomic force microscopy (AFM) and channelling Rutherford backscattering spectrometry (RBS/C). RBS/C results indicate a nonlinear growth in damage from which it has been possible to get a threshold fluence, φ 0 , for amorphization as 2.5 x 10 13 ions cm -2 . For φ below φ 0 , a growth in damage as well as surface roughness has been observed. At a φ of 1 x 10 14 ions cm -2 , damage saturation coupled with a much reduced surface roughness has been found. In this case a power spectrum analysis of AFM data showed a significant drop in spectral density, as compared with the same obtained for a fluence, φ 0 . This drop, together with damage saturation, can be correlated with a transition to a stress relaxed amorphous phase. Irradiation with similar mass Cs - ions, at the same energy and fluence, has been found to result in a reduced accumulation of defects in the near surface region leading to reduced surface features.

243Cm half-life determinaton

International Nuclear Information System (INIS)

Timofeev, G.A.; Kalygin, V.V.; Privalova, P.A.

1986-01-01

By molar ratios of 243 Cm mixture with 244 Cm and Pu nuclides formed as a result of Cm nuclides α-decay the 243 Cm half-life T α243 is determined. The 244 Cm half-life is measured earlier with high accuracy. The 243 Cm/ 244 Cm ratio measured by means of a mass spectrometer equals 0.989+-0.004. The obtained value T α243 =29.20+-0.14 years

Anode-supported single-chamber solid oxide fuel cell based on cobalt-free composite cathode of Nd0.5Sr0.5Fe0.8Cu0.2O3-δ-Sm0.2Ce0.8O1.9 at intermediate temperatures

Science.gov (United States)

Yin, Jie-Wei; Zhang, Chunming; Yin, Yi-Mei; Shi, Huangang; Lin, Ye; Lu, Jun; Ma, Zi-Feng

2015-07-01

As a candidate of cathode material of single-chamber solid oxide fuel cell (SC-SOFC), cobalt-free mixed ionic electronic conductor (MIEC) Nd0.5Sr0.5Fe0.8Cu0.2O3-δ (NSFCu) is synthesized by sol-gel method with ethylene diamine tetraacetic acid and citric acid as co-complexing agents. The XRD shows NSFCu is stable after CO2 treatment and chemical compatible with SDC at high temperatures. CO2-TPD (CO2-temperature programmed desorption) demonstrates both CO2 adsorption and desorption phenomenon on NSFCu surface. However, the polarization resistances (Rp) of NSFCu and SDC (10:4 in weight) composite electrodes showed no decay in 5% CO2. Single cell using N2-O2-CH4 mixed gas (CH4 to O2 ratio = 1.5) as fuel shows maximum power density of 635 mW cm-2 at 700 °C. These results suggest that NSFCu-SDC is a promising composite cathode material for application in single-chamber solid oxide fuel cell.

Nanocrystalline composites of transition metal molybdate (Ni1-xCoxMoO4; x = 0, 0.3, 0.5, 0.7, 1) synthesized by a co-precipitation method as humidity sensors and their photoluminescence properties

Science.gov (United States)

Jeseentharani, V.; Dayalan, A.; Nagaraja, K. S.

2018-04-01

In this study, nanocrystalline transition metal nickel-cobalt molybdate (Ni1-xCoxMoO4, NiCM; x = 0, 0.3, 0.5, 0.7, 1) composites were prepared using a simple co-precipitation method. The composites were characterized by thermogravimetric/differential thermal analysis, Fourier transform-infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The NiCM composites were studied to determine their possible use as humidity sensors, and photoluminescence (PL) measurements were obtained. The sensing study was performed in environments with different relative humidity levels (5-98%). The maximum sensitivity of 18624 ± 168 was observed with the Ni0.7Co0.3MoO4 composite where the humidity could be calculated according to the relationship: Sf = R5%/R98%, where R5% and R98% are the dc resistances at 5 and 98% RH, respectively. The photoluminescence measurements acquired at room temperature for the NiCMs included green and red emission peaks when excited at a wavelength (λex) of 520 nm.

Synthesis, characterization and mechanoluminescence of europium doped ZnxBa(1−x)Al2O4 (x=0, 0.4, 0.5, 0.6, 0.8, 1.0) phosphor

International Nuclear Information System (INIS)

Sajan, S.J.; Gopakumar, N.; Anjana, P.S.; Madhukumar, K.

2016-01-01

The samples of Zn x Ba (1−x) Al 2 O 4 :0.1%Eu (x=0, 0.4, 0.5, 0.6, 0.8, 1.0) were prepared via high temperature solid state reaction method. The phase formation of the powder samples were confirmed by taking X-ray diffraction analysis. The mechanoluminescence (ML) property of the samples by impact method was studied by using ML measuring apparatus. The variations in the ML peak intensity due to the impact velocity of a load falling from different heights and due to the variation of composition were investigated. The photoluminescence studies of the samples were also conducted.

Synthesis and characterization of the novel rare earth orthophosphates Y0.5Er0.5PO4 and Y0.5Yb0.5PO4

International Nuclear Information System (INIS)

Schildhammer, Daniel; Petschnig, Lucas L.; Fuhrmann, Gerda; Heymann, Gunter; Schottenberger, Herwig; Huppertz, Hubert; Tribus, Martina

2016-01-01

The new mixed rare earth (RE) orthophosphates Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 were synthesized by a classical solid state reaction in an electrical furnace at 1200 C. As starting materials, the corresponding rare earth oxides and diammonium hydrogen phosphate were used. The powder diffraction analyses revealed that the new compounds Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 crystallize in a zircon-type structure being isostructural with the rare earth orthophosphate YPO 4 . Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 crystallize in the tetragonal space group I4 1 /amd (no. 141) with four formula units in the unit cell. The structural parameters based on Rietveld refinements are a = 687.27(2), c = 601.50(2) pm, V = 0.28412(1) nm 3 , R p = 0.0143, and R wp = 0.0186 (all data) for Y 0.5 Er 0.5 PO 4 and a = 684.61(2), c = 599.31(2) pm, V = 0.28089(2) nm 3 , R p = 0.0242, and R wp = 0.0313 (all data) for Y 0.5 Yb 0.5 PO 4 . Furthermore, the structure of Y 0.5 Er 0.5 PO 4 was refined from single-crystal X-ray diffraction data: a = 687.78(5), c = 601.85(4) pm, V = 0.28470(5) nm 3 , R 1 = 0.0165, and wR 2 = 0.0385 (all data). In both compounds, the rare earth metal ions are eightfold coordinated by oxygen atoms, forming two unique interlocking tetrahedra with two individual RE-O distances. The tetrahedral phosphate groups [PO 4 ] 3- are slightly distorted in both compounds. The individual rare earth ions share a common position (Wyckoff site 4a). The presence of two rare earth ions in the structures of the new orthophosphates Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 was additionally confirmed by single-crystal EDX spectroscopy revealing a ratio of 1:1.

Composite cathode La0.15Bi0.85O1.5-Ag for intermediate-temperature solid oxide fuel cells

International Nuclear Information System (INIS)

Gao Zhan; Mao Zongqiang; Huang Jianbing; Gao Ruifeng; Wang Cheng; Liu Zhixiang

2008-01-01

Composites consisting of silver and lanthanum stabilized bismuth oxide (La 0.15 Bi 0.85 O 1.5 ) were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria as electrolyte. No stable phases were formed via reaction between La 0.15 Bi 0.85 O 1.5 and Ag. The microstructure of the interfaces between composite cathodes and Ce 0.8 Sm 0.2 O 1.5 electrolytes was studied by scanning electron microscopy after sintering at various temperatures. Impedance spectroscopy measurements revealed that the performance of cathode fired at 700 deg. C was the best. When the optimum fraction of Ag was 50 vol.%, polarization resistance values for the LSB-Ag50 cathode were as low as 0.14 Ω cm 2 at 700 deg. C and 0.18 Ω cm 2 at 650 deg. C. The steady-state polarization investigations on LSB and LSB-Ag50 cathodes were performed using typical three-electrode test cells in air. The results showed that the LSB-Ag50 composite cathode exhibited a lower overpotential and higher exchange current density than LSB, which indicated the electrochemical performance of LSB-Ag50 for the oxygen reduction reaction was superior to the LSB

Performance of La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} perovskite-structure anode material at lanthanum gallate electrolyte for IT-SOFC running on ethanol fuel

Energy Technology Data Exchange (ETDEWEB)

Huang, Bo; Wang, S.R.; Liu, R.Z.; Ye, X.F.; Nie, H.W.; Sun, X.F.; Wen, T.L. [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), 1295 Dingxi Road, Shanghai 200050 (China)

2007-05-01

Perovskite-structure La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} (LSCM) powders were prepared using a simple combustion process. Thermal analysis was carried out on the perovskite precursor to investigate the oxide-phase formation. The structural phase of the powders was determined by X-ray diffraction. These results showed that the decomposition of the precursors occurs in a two-step reaction and temperatures higher than 1100 C are required for these decomposition reactions. For the electrochemical characterization, LSCM anode materials and (Pr{sub 0.7}Ca{sub 0.3}){sub 0.9}MnO{sub 3} (PCM) cathode materials were screen-printed on two sides of dense La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3} (LSGM) electrolyte layers prepared by tape casting with a thickness of about 600 {mu}m, respectively. The morphology of the screen-printed La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} perovskite thick films (65 {mu}m) was investigated by field emission scanning electron microscope and showed a porous microstructure. In addition, fuel cell tests were carried out using humidified hydrogen or ethanol stream as fuel and oxygen as oxidant. The performance of the conventional electrolyte-supported cell LSCM/LSGM/PCM while operating on humidified hydrogen was modest with a maximum power density of 165, 99 and 62 mW cm{sup -2} at 850, 800 and 750 C, respectively, the corresponding values for the cell while operating on ethanol stream was 160, 101 and 58 mW cm{sup -2}, respectively. Cell stability tests indicate no significant degradation in performance has been observed after 60 h of cell testing when LSCM anode was exposed to ethanol steam at 750 C, suggesting that carbon deposition was limited during cell operation. (author)

Effect of oxygen content on the electrical transport and superconducting properties of Pb0.5Sr2.5Y0.6Ca0.4Cu2O7-y

International Nuclear Information System (INIS)

Ruan, K.Q.; China Univ. of Science and Technology, Hefei, AH; Jin, H.; China Univ. of Science and Technology, Hefei, AH; Feng, Y.; China Univ. of Science and Technology, Hefei, AH; Zhou, Y.Q.; China Univ. of Science and Technology, Hefei, AH; Chui, X.D.; China Univ. of Science and Technology, Hefei, AH; Wang, C.Y.; China Univ. of Science and Technology, Hefei, AH; Cao, L.Z.; China Univ. of Science and Technology, Hefei, AH; Wang, L.B.; Zhang, Y.H.

1997-01-01

Two kinds of methods have been used to synthesize Pb 0.5 Sr 2.5 Y 0.6 Ca 0.4 Cu 2 O 7-y samples. The synthesized sample using the first method shows superconductivity, while that using the second method exhibits a localized behavior at low temperatures Thermogravimetric analysis (TGA) and electrical transport measurements have been carried out on superconducting and nonsuperconducting samples grown under the two kinds of synthesis conditions and the effect of oxygen content on the transport and superconducting properties is discussed briefly. (orig.)

Low local recurrence rate without postmastectomy radiation in node-negative breast cancer patients with tumors 5 cm and larger

International Nuclear Information System (INIS)

Floyd, Scott R.; Buchholz, Thomas A.; Haffty, Bruce G.; Goldberg, Saveli; Niemierko, Andrzej; Raad, Rita Abi; Oswald, Mary J.; Sullivan, Timothy; Strom, Eric A.; Powell, Simon N.; Katz, Angela; Taghian, Alphonse G.

2006-01-01

Purpose: To assess the need for adjuvant radiotherapy following mastectomy for patients with node-negative breast tumors 5 cm or larger. Methods and Materials: Between 1981 and 2002, a total of 70 patients with node-negative breast cancer and tumors 5 cm or larger were treated with mastectomy and adjuvant systemic therapies but without radiotherapy at three institutions. We retrospectively assessed rates and risk factors for locoregional failure (LRF), overall survival (OS), and disease-free survival (DFS) in these patients. Results: With a median follow-up of 85 months, the 5-year actuarial LRF rate was 7.6% (95% confidence interval, 3%-16%). LRF was primarily in the chest wall (4/5 local failures), and lymphatic-vascular invasion (LVI) was statistically significantly associated with LRF risk by the log-rank test (p = 0.017) and in Cox proportional hazards analysis (p 0.038). The 5-year OS and DFS rates were 83% and 86% respectively. LVI was also significantly associated with OS and DFS in both univariate and multivariate analysis. Conclusions: This series demonstrates a low LRF rate of 7.6% among breast cancer patients with node-negative tumors 5 cm and larger after mastectomy and adjuvant systemic therapy. Our data indicate that further adjuvant radiation therapy to increase local control may not be indicated by tumor size alone in the absence of positive lymph nodes. LVI was significantly associated with LRF in our series, indicating that patients with this risk factor require careful consideration with regard to further local therapy

Part-II: Exchange current density and ionic diffusivity studies on the ordered and disordered spinel LiNi0.5Mn1.5O4 cathode

Science.gov (United States)

Amin, Ruhul; Belharouak, Ilias

2017-04-01

Additive-free pellets of Li1-xNi0.5Mn1.5O4 have been prepared for the purpose of performing ionic diffusivity and exchange current density studies. Here we report on the characterization of interfacial charge transfer kinetics and ionic diffusivity of ordered (P4332) and disordered (Fd 3 bar m) Li1-xNi0.5Mn1.5O4 as a function of lithium content at ambient temperature. The exchange current density at the electrode/electrolyte interface is found to be continuously increased with increasing the degree of delithiation for ordered phase (∼0.21-6.5 mA/cm2) at (x = 0.01-0.60), in contrast the disordered phase exhibits gradually decrease of exchange current density in the initial delithiation at the 4 V plateau regime (x = 0.01-0.04) and again monotonously increases (0.65-6.8 mA/cm2) with further delithiation at (x = 0.04-0.60). The ionic diffusivity of ordered and disordered phase is found to be ∼5 × 10-10cm2s-1 and ∼10-9cm2s-1, respectively, and does not vary much with the degree of delithiation. From the obtained results it appears that the chemical diffusivity during electrochemical use is limited by lithium transport, but is fast enough over the entire state-of-charge range to allow charge/discharge of micron-scale particles at practical C-rates.

Synthesis and characterization of Sm0.5Ba0.5MnO3-δ as anode materials for solid oxide fuel cells

International Nuclear Information System (INIS)

Abdalla, A. M.; Radenahmad, N.; Bakar, M. S. Abu; Petra, Pg M .I.; Azad, A. K.

2016-01-01

The material performance is a crucial issue in the current fuel cell technology, and for this reason we present this new series of Samarium family which can be used as electrode giving a high performance in a particular application. Sm 0 . 5 Ba 0 . 5 MnO 3-δ was prepared by solid state reaction method and characterized by using X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Rietveld analysis of XRD data shows that the material has an Orthorhombic crystal structure with cell parameter a = 3.883(1) Å b = 3.8742(5) Å c = 7. 762(4) Å, in the Pmmm space group. TGA analyses shows that the materials is going to decrease by 0.32%. The density of the materials was calculated from structural refinement and found to be 8.372 gm/cm 3 . (paper)

Effect of the grain size of the soil on the measured activity and variation in activity in surface and subsurface soil samples

International Nuclear Information System (INIS)

Sulaiti, H.A.; Rega, P.H.; Bradley, D.; Dahan, N.A.; Mugren, K.A.; Dosari, M.A.

2014-01-01

Correlation between grain size and activity concentrations of soils and concentrations of various radionuclides in surface and subsurface soils has been measured for samples taken in the State of Qatar by gamma-spectroscopy using a high purity germanium detector. From the obtained gamma-ray spectra, the activity concentrations of the 238U (226Ra) and /sup 232/ Th (/sup 228/ Ac) natural decay series, the long-lived naturally occurring radionuclide 40 K and the fission product radionuclide 137CS have been determined. Gamma dose rate, radium equivalent, radiation hazard index and annual effective dose rates have also been estimated from these data. In order to observe the effect of grain size on the radioactivity of soil, three grain sizes were used i.e., smaller than 0.5 mm; smaller than 1 mm and greater than 0.5 mm; and smaller than 2 mm and greater than 1 mm. The weighted activity concentrations of the 238U series nuclides in 0.5-2 mm grain size of sample numbers was found to vary from 2.5:f:0.2 to 28.5+-0.5 Bq/kg, whereas, the weighted activity concentration of 4 degree K varied from 21+-4 to 188+-10 Bq/kg. The weighted activity concentrations of 238U series and 4 degree K have been found to be higher in the finest grain size. However, for the 232Th series, the activity concentrations in the 1-2 mm grain size of one sample were found to be higher than in the 0.5-1 mm grain size. In the study of surface and subsurface soil samples, the activity concentration levels of 238 U series have been found to range from 15.9+-0.3 to 24.1+-0.9 Bq/kg, in the surface soil samples (0-5 cm) and 14.5+-0.3 to 23.6+-0.5 Bq/kg in the subsurface soil samples (5-25 cm). The activity concentrations of 232Th series have been found to lie in the range 5.7+-0.2 to 13.7+-0.5 Bq/kg, in the surface soil samples (0-5 cm)and 4.1+-0.2 to 15.6+-0.3 Bq/kg in the subsurface soil samples (5-25 cm). The activity concentrations of 4 degree K were in the range 150+-8 to 290+-17 Bq/kg, in the surface

Bilateral implantation of +2.5 D multifocal intraocular lens and contralateral implantation of +2.5 D and +3.0 D multifocal intraocular lenses: Clinical outcomes.

Science.gov (United States)

Nuijts, Rudy M M A; Jonker, Soraya M R; Kaufer, Robert A; Lapid-Gortzak, Ruth; Mendicute, Javier; Martinez, Cristina Peris; Schmickler, Stefanie; Kohnen, Thomas

2016-02-01

To assess the clinical visual outcomes of bilateral implantation of Restor +2.5 diopter (D) multifocal intraocular lenses (IOLs) and contralateral implantation of a Restor +2.5 D multifocal IOL in the dominant eye and Restor +3.0 D multifocal IOL in the fellow eye. Multicenter study at 8 investigative sites. Prospective randomized parallel-group patient-masked 2-arm study. This study comprised adults requiring bilateral cataract extraction followed by multifocal IOL implantation. The primary endpoint was corrected intermediate visual acuity (CIVA) at 60 cm, and the secondary endpoint was corrected near visual acuity (CNVA) at 40 cm. Both endpoints were measured 3 months after implantation with a noninferiority margin of Δ = 0.1 logMAR. In total, 103 patients completed the study (53 bilateral, 50 contralateral). At 3 months, the mean CIVA at 60 cm was 0.13 logMAR and 0.10 logMAR in the bilateral group and contralateral group, respectively (difference 0.04 logMAR), achieving noninferiority. Noninferiority was not attained for CNVA at 40 cm; mean values at 3 months for bilateral and contralateral implantation were 0.26 logMAR and 0.11 logMAR, respectively (difference 0.15 logMAR). Binocular defocus curves suggested similar performance in distance vision between the 2 groups. Treatment-emergent ocular adverse events rates were similar between the groups. Bilateral implantation of the +2.5 D multifocal IOL resulted in similar distance as contralateral implantation of the +2.5 D multifocal IOL and +3.0 D multifocal IOL for intermediate vision (60 cm), while noninferiority was not achieved for near distances (40 cm). Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Structural, magnetic and magnetocaloric properties of vanadium-doped manganites La0.65Ca0.35Mn1−xVxO3 (0 ⩽ x ⩽ 0.5)

International Nuclear Information System (INIS)

Marzouki-Ajmi, A.; Mansouri, M.; Cheikhrouhou-Koubaa, W.; Koubaa, M.; Cheikhrouhou, A.

2017-01-01

Highlights: • Our samples were prepared using solid state reaction method. • All samples crystallized in orthorhombic structure with Pbnm space group. • Presence of secondary phase LaVO 4 in V-doped samples. • Our samples exhibit PM-FM transition at Curie temperature. • The Curie temperature decreases with V-doping (262 K for x = 0 to 206 K for x = 0.5). • The Magnetic transition was found to be of second order. - Abstract: Structural, magnetic and magnetocaloric properties of polycrystalline La 0.65 Ca 0.35 Mn 1−x V x O 3 have been investigated. Our samples were prepared using the solid state reaction method at high temperatures. X-ray diffraction analysis show that all samples crystallized in the orthorhombic structure with Pbnm space group with presence of LaVO 4 as secondary phase. The SEM micrographs reveal micrometric grains with bimodal size distribution. Magnetic Measurements indicate that our samples exhibit a PM–FM transition, with a Curie temperature (T C ) decreasing from 262 K for x = 0 to 208 K for x = 0.5; in addition to the presence of the Griffiths phase in the paramagnetic region. Using the isothermal magnetization versus magnetic applied field, we have deduced that the occured magnetic transition is of second order. Moreover, we have calculated the magnetic entropy change, which reaches 5.25 J/kg K for La 0.65 Ca 0.35 Mn 0.5 V 0.5 O 3 compound under 5T. This value is associated to a relative cooling power (RCP) of 207 J/kg.

Dark-red-emitting CdTe0.5Se0.5/Cd0.5Zn0.5S quantum dots: Effect of chemicals on properties

International Nuclear Information System (INIS)

Yang, Ping; Zhang, Aiyu; Li, Xiaoyu; Liu, Ning; Zhang, Yulan; Zhang, Ruili

2013-01-01

CdTe 0.5 Se 0.5 /Cd 0.5 Zn 0.5 S core/shell quantum dots (QDs) with a tunable photoluminescence (PL) range from yellow to dark red (up to a PL peak wavelength of 683 nm) were fabricated using various reaction systems. The core/shell QDs created in the reaction solution of trioctylamine (TOA) and oleic acid (OA) at 300 °C exhibited narrow PL spectra and a related low PL efficiency (38%). In contrast, the core/shell QDs prepared in the solution of 1-octadecene (ODE) and hexadecylamine (HDA) at 200 °C revealed a high PL efficiency (70%) and broad PL spectra. This phenomenon is ascribed that the precursor of Cd, reaction temperature, solvents, and ligands affected the formation process of the shell. The slow growth rate of the shell in the solution of ODE and HDA made QDs with a high PL efficiency. Metal acetate salts without reaction with HDA led to the core/shell QDs with a broad size distribution. - Graphical abstract: CdTe 0.5 Se 0.5 /Cd 0.5 Zn 0.5 S quantum dots (QDs) with tunable photoluminescence, high PL efficiency, and high stability through organic synthesis, in which chemicals affected the properties of the QDs. Display Omitted - Highlights: • CdTe 0.5 Se 0.5 /Cd 0.5 Zn 0.5 S quantum dots created via organic synthesis. • Chemicals affected the properties of the quantum dots. • The quantum dots revealed high photoluminescence efficiency and stability. • The quantum dots with tunable photoluminescence in a range from yellow to dark red. • The QDs are utilizable for various applications such as biological labeling

Effects of thermal and electrical histories on structure and dielectric behaviors of (Li0.5Nd0.52+-modified (Bi0.5Na0.5TiO3-BaTiO3 ceramics

Directory of Open Access Journals (Sweden)

Jiwen Xu

2017-06-01

Full Text Available The effect of thermal and electrical histories on structure and dielectric behaviors is studied using 0.95(Bi0.5Na0.50.97(Li0.5Nd0.50.03TiO3-0.05BaTiO3 (abbreviated as BNTLN0.03-BT5 ceramic as a selected system. Subtle structure change caused by annealing treatment, and pronounced phase transition and domain switching by electrical poling, are observed to occur, respectively. The dielectric constant and its strong frequency dispersion in unpoled samples decrease evidently by electrical poling due to electric field-induced ordered domain. The high temperature Maxwell-Wagner relaxor behavior vanishes by annealing treatment due to the loss of electrical inhomogeneity with interface charging effects. Piezoelectric properties are improved evidently by annealing treatment at 900 °C, implying a new appropriate method to improve piezoelectric properties.

Morphometric study of uninvolved rectal mucosa 10 cm and 20 cm away from the malignant tumor.

Science.gov (United States)

Despotović, Sanja Z; Milićević, Novica M; Milosević, Dragoslav P; Despotović, Nebojsa; Erceg, Predrag; Bojić, Bozidar; Bojić, Danijela; Svorcan, Petar; Mihajlović, Gordana; Dorđević, Jelena; Lalić, Ivana M; Milićević, Zivana

2014-02-01

Recently, many details of the interplay between tumor cells and tumor-associated stromal elements leading to the progression of malignant disease were elucidated. In contrast, little is known about the role of uninvolved stromal tissue in the remote surrounding of the malignant tumor. Therefore, we performed a computer-aided morphometric study of rectal mucosa in samples taken 10 cm and 20 cm away from the malignant tumor during endoscopic examination of 23 patients older than 60 years. The samples of rectal mucosa from 10 healthy persons of corresponding age subjected to diagnostic rectoscopy during active screening for asymptomatic cancer were used as control. All structural elements of the rectal mucosa were studied and the number of nucleated cells in the lamina propria per 0.1 mm² of tissue was assessed. Our study revealed a reduced number of cells in the lamina propria of the rectal mucosa 10 cm and 20 cm away from the tumor lesion in both male and female patients. The decreased mucosal height and increased crypt number were registered in female patients 10 cm away from the tumor. The connective tissue of lamina propria showed a disorderly organization: the collagen fibers were frail, loosely arranged and signs of tissue edema were present. Small blood vessels and capillaries were much more frequently seen than in healthy tissue. Our results demonstrate the complex interactions between the cancer and remote mucosal tissue of the affected organ.

Microstructure and bio-corrosion behaviour of Mg-5Zn-0.5Ca -xSr alloys as potential biodegradable implant materials

Science.gov (United States)

Yan, Li; Zhou, Jiaxing; Sun, Zhenzhou; Yang, Meng; Ma, Liqun

2018-04-01

Magnesium alloys are widely studied as biomedical implants owing to their biodegradability. In this work, novel Mg-5Zn-0.5Ca-xSr (x = 0, 0.14, 0.36, 0.50, 0.70 wt%) alloys were prepared as biomedical materials. The influence of strontium (Sr) addition on the microstructure, corrosion properties and corrosion morphology of the as-cast Mg-5Zn-0.5Ca-xSr alloys is investigated by a variety of techniques such as scanning electron microscopy, x-ray diffraction, and electrochemical measurements. The Sr-free alloy is composed of three phases, namely, α-Mg, CaMg2 and Ca2Mg6Zn3, while the alloys with the Sr addition consist of α-Mg, CaMg2 and Ca2Mg6Zn3 and Mg17Sr2. Corrosion experiments in Hank’s solution show that the addition of a small amount of Sr can improve the corrosion resistance of the Mg-5Zn-0.5Ca alloy. The corrosion products include Mg(OH)2, Zn(OH)2, Ca(OH)2, and HA (Ca5(PO4)3(OH)). Mg-5Zn-0.5Ca-0.36Sr alloy has the minimum weight loss rate (0.68 mm/a), minimal hydrogen evolution (0.08 ml/cm2/d) and minimum corrosion current density (7.4 μA/cm2), indicating that this alloy shows the best corrosion resistance.

0.5% Liposome-encapsulated 5-aminolevulinic acid (ALA) photodynamic therapy for acne treatment.

Science.gov (United States)

An, Jee-Soo; Kim, Jeong-Eun; Lee, Dong-Hun; Kim, Byung-Yoon; Cho, Soyun; Kwon, In-Ho; Choi, Won-Woo; Kang, Seong-Min; Won, Chong-Hyun; Chang, Sung-Eun; Lee, Mi-Woo; Choi, Jee-Ho; Moon, Kee-Chan

2011-02-01

Photodynamic therapy using topical 5-aminolevulinic acid (ALA) has been successful in treating acne vulgaris, but sun avoidance for at least 48 hours after treatment is necessary due to the risk of post-treatment photosensitivity. Recently, a lower concentration of liposome-encapsulated 5-ALA was introduced to minimize this risk. To evaluate the efficacy and safety of liposome-encapsulated 0.5% 5-ALA in the photodynamic therapy of inflammatory acne and its effects on sebum secretion in Asian skin. Thirteen Korean subjects with inflammatory acne were administered 0.5% ALA spray before photoradiation treatment. Photoradiation was performed at 3.5-6.0 J/cm(2) three times during each of two visits, performed 2 weeks apart. Improvement of acne was evaluated subjectively and objectively based on the Korean Acne Grading System. Sebum secretion was measured quantitatively at each visit. The mean reduction in acne grade at the end of the treatment was 43.2%. Of the patients, 69.2% reported improvements in subjective skin oiliness, but fewer showed objective reductions in sebum secretion as determined by the Sebumeter® SM10. No serious adverse events were observed. Photodynamic therapy using liposome-encapsulated 0.5% 5-ALA improved inflammatory acne with minimal side effects in Asians.

Improved multiferroic properties in (1−x)BiFeO{sub 3}–xBaTi{sub 0.95}(Yb{sub 0.5}Nb{sub 0.5}){sub 0.05}O{sub 3} system (0≤x≤0.3)

Energy Technology Data Exchange (ETDEWEB)

Amouri, A., E-mail: amouri.amira00@gmail.com [Laboratoire des Matériaux Ferroélectriques (LMF), LR-Physique-Mathématiques et Applications, Université de Sfax, Faculté des Sciences de Sfax(FSS), Route de Soukra km3,5 B.P.1171, 3000 Sfax (Tunisia); Le laboratoire des Colloïdes, Verre, et Nanomatériaux, UMRCNRS 5587,Unité mixte de recherche 5587-CNRS-UM2-Université Montpellier 2, F-34095 Montpellier (France); Abdelmoula, N.; Khemakhem, H. [Laboratoire des Matériaux Ferroélectriques (LMF), LR-Physique-Mathématiques et Applications, Université de Sfax, Faculté des Sciences de Sfax(FSS), Route de Soukra km3,5 B.P.1171, 3000 Sfax (Tunisia)

2016-11-01

Polycrystalline samples of (1−x)BiFeO{sub 3}–xBaTi{sub 0.95}(Yb{sub 0.5}Nb{sub 0.5}){sub 0.05}O{sub 3} (x=0, 0.1, 0.2 and 0.3) were prepared by the conventional solid state reaction method. The phase purity and composition were cheeked using powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The grain size and morphology of the ceramics were confirmed by scanning electron microscopy (SEM). X-ray diffraction showed that these compounds crystallized, at room temperature, in the Rhomboedral R3c for x=0 and in tetragonal P4mm for compositions 0.1≤x≤0.3 distorted perovskite structures. The BaTi{sub 0.95}(Yb{sub 0.5}Nb{sub 0.5}){sub 0.05}O{sub 3} substitution led to an improvement of magnetic and ferroelectric properties at room temperature. The highest magnetization was reported for composition x=0.2 which was due to the enhancement of canting angles and the suppression of cycloid spin structure, as confirmed by {sup 57}Fe Mössbauer spectroscopy and the presence of Fe{sup 2+}, as detected by XPS. The electric polarization increased significantly for doped samples, which proves the enhancement of the ferroelectric behavior and resistivity of our ceramics. Large electric field induced strains were observed for 0.7BiFeO{sub 3}-0.3BaTi{sub 0.95}(Yb{sub 0.5}Nb{sub 0.5}){sub 0.05}O{sub 3}, as an evidence of piezoelectric behavior. These results show that BaTi{sub 0.95}(Yb{sub 0.5}Nb{sub 0.5}){sub 0.05}O{sub 3} doped BiFeO{sub 3} is a promising multiferroic material. - Highlights: • (1−x)BiFeO{sub 3}–xBa[Ti{sub 0.95}(Yb{sub 0.5}Nb{sub 0.5}){sub 0.05}]O{sub 3} is a new multiferroic system. • Doped BiFeO{sub 3} ceramics crystallize in tetragonal distorted perovskite. • Magnetic properties at room temperature were improved.

Measurement of the factor of dispersion in air for a field of 0,8* 8,0 CM 2

International Nuclear Information System (INIS)

Gomez-Tejedor Alonso, S.; Huertas Martinez, C.; Penedo Cobos, J. M.; Garcia Castejon, M. A.; Rincon Perezx, M.

2013-01-01

The measures of this factor of dispersion in air is usually performed with an ionization chamber cover a cap of balance of such thickness that is achieved the electronic balance, and must be covered completely the CAP by the radiation field. This procedure is not applicable for small fields. The need to measure the Sc of a field of 0.8 * 0.8 cm 2 for a new system of planning led us to try another measure procedure proposed in the literature, using detectors of semiconductor with a sheet of cerrobend by way of balance Cap. (Author)

Surface structure of Cr0.5 Ti0.5N coatings after heavy ions irradiation and annealing

International Nuclear Information System (INIS)

Kislitsin, Sergey; Gorlachev, Igor; Uglov, Vladimir

2015-01-01

Results of surface structure investigations of TiCrN coating on carbon steel after irradiation by helium, krypton and xenon heavy ions are reported in the present publication. The series of Cr50Ti50N coatings on carbon steel with thickness of 50,..., 300 nm were formed by vacuum arc deposition techniques. Specimens with TiCrN coating on carbon steel were irradiated by low energy 4 He +1 (22 keV) and 4 He +2 (40 keV) ions and high energy Xe +18 and Kr +14 ions with energy of 1.5 MeV/nucleon. Fluence of He ions was 1.0x10 17 ion.cm -2 , fluence of Xe and Kr ions was 5x10 14 -1.0x10 15 ion.cm -2 , irradiation temperature did not exceed 150 deg. C. Study of surface structure was performed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Methods of Roentgen diffractometry and Rutherford backscattering was applied for determination of structure and thickness of coating. In case of irradiation with Xe +18 and Kr +14 ions an investigation of surface morphology and structure was done after successive two hours vacuum annealing of irradiated samples at temperatures 400 deg. C, 500 deg. C and 600 deg. C. It was shown that after irradiation by Xe and Kr ions on the surface of coating convexities appear, surface density of which correlates with ion flux. In the case of Xe, ions irradiation generated convexities of spherical and elongated shape with dimensions ranging from ten to hundreds nm. In the case of Kr ions, only spherical globules were generated, dimensions of which are 10-30 nm. The most likely explanation of observed surface damage is that: convexities on the surface are generated at ion bombardment of specimens with coating. Convexities are the traces of ions passing through coating and they are due to structural reconstruction at energy release along a trajectory of ions braking. Convexities of elongated shape represent overlapping traces from two passing ions. When the projective range of Xe and Kr ions exceeds coating thickness, damage

Influence of structural disorder on the optical and transport properties of Co sub 0 sub . sub 5 sub 0 Ti sub 0 sub . sub 5 sub 0 alloy films

CERN Document Server

Kim, K W; Rhee, J Y; Kudryavtsev, Y V; Ri, H C

2000-01-01

Co sub 0 sub . sub 5 sub 0 Ti sub 0 sub . sub 5 sub 0 alloy films with a total thickness of about 100 nm were prepared by flash evaporation of the crushed alloy powders onto heated (730 K for the ordered state) and LN sub 2 -cooled (150 K for the disordered state) substrates. Structural analysis of the films was performed by suing transmission electron microscopy. The optical conductivity (OC) of the samples was measured at room temperature in a spectral range of 265 -2500 nm (4.7 - 0.5 eV). The resistivity measurements were carried out by using the four-probe technique in a temperature range of 4.2 - 300 K. The experimental OC spectra for the Co sub 0 sub . sub 5 sub 0 Ti sub 0 sub . sub 5 sub 0 alloys show the most significant change in the infrared region upon the order-disorder transformation. The structural disorder in the Co sub 0 sub . sub 5 sub 0 Ti sub 0 sub . sub 5 sub 0 alloy film leads to a change in the sign of the temperature coefficient of the resistivity from positive to negative. The observed...

Ferrites Ni0,5Zn0,5Fe2O4 doped with samarium: structural analysis, morphological and electromagnetic

International Nuclear Information System (INIS)

Costa, A.C.F.M.; Diniz, A.P.; Viana, K.M.S.; Cornejo, D.R.; Kiminami, R.H.G.A.

2010-01-01

This paper proposes to investigate the sintering at 1200 deg C/2h of Ni 0.5 Zn 0.5 Fe 2-x Sm x O 4 ferrite doped with 0.05; 0.075 e 0.1 mol of Sm synthesized by combustion reaction to evaluate the performance materials as absorbers of electromagnetic radiation. The influence of the concentration of samarium on the structure, morphology and electromagnetic properties of ferrites was studied. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic measurements and reflectivity measurements in the frequency range between 8-12 GHz. The results showed that increasing the concentration of samarium caused a decrease in particle size of the samples, encouraging, therefore, to obtain materials with better values of magnetization and reflectivity, allowing for use as absorbers in narrow-band frequency between 9-10 GHz. (author)

Rietveld refinement, impedance spectroscopy and magnetic properties of Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3} substituted Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Kumari, Rekha [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Ahlawat, Neetu, E-mail: neetugju@yahoo.co.in [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Agarwal, Ashish; Sanghi, Sujata [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Sindhu, Monica [Department of Physics, MKJK College, Rohtak 124001, Haryana (India); Ahlawat, Navneet [Matu Ram Institute of Engineering and Management, Rohtak 124001, Haryana (India)

2016-09-15

We herein presented the investigation on the structural, electrical and magnetic properties of (1−x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})–x(Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3}) polycrystalline ceramic samples, with x=0.1, 0.3, 0.5 and 0.7. These samples were prepared by conventional solid state reaction method and the crystalline phase of prepared ceramics was identified with the help of X-ray diffraction pattern. Rietveld analysis of the obtained XRD data confirmed that all the synthesized samples adopt the rhombohedral crystal structure with R3c space group. Impedance spectroscopic measurements were performed on all the compositions in the frequency range 10 Hz–5 MHz to probe the electrical microstructure of polycrystalline (1−x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})–x(Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3}) ceramics, which changes significantly as a function of x (content of BSFO). A significant increase in dielectric constant has been observed with increase in BSFO concentration, which was attributed to enhancement of oxygen vacancies. Detailed study of impedance complex plane plots revealed the presence of non-Debye type relaxation for all the prepared systems and enabled us to separate the contribution from grains and grain boundaries. Equivalent circuit model (R{sub g}CPE{sub g})(R{sub gb}CPE{sub gb})(R{sub e}CPE{sub e}) was employed to explain the impedance data for all the prepared samples. The activation energies obtained from electric modulus as well as dc conductivity increase with increase in BSFO content, which approaches the value 1 eV and indicates an Arrehenius type thermally activated process. Remnant magnetization (M{sub r}) and coercive field (H{sub c}) are found to be increase with BSFO concentration. - Highlights: • (1−x)NBT–xBSFO (x=0.1, 0.3, 0.5, 0.7) ceramics were prepared. • There is no change in crystal structure. • These can be used as data storage materials.

Bloqueio do nervo alveolar mandibular com ropivacaína a 0,5 % em gatos Bockage of the jaw’s alveolar nerve with 0.5% ropivacaine in cats

Directory of Open Access Journals (Sweden)

Vanessa Martins Fayad Milken

2006-04-01

Full Text Available Objetivou-se, com este experimento, avaliar a ação da ropivacaína a 0,5% no bloqueio do nervo alveolar mandibular de gatos. Vinte gatos adultos, sem raça definida, machos ou fêmeas, receberam clorpromazina (1,0mg kg-1, VO e propofol (3,0mg kg-1, IV. Ropivacaína a 0,5% foi administrada com uma agulha 13x3,8 em forma de "L", inserida no ângulo da mandíbula direita, aproximadamente 1,0cm rostral ao processo angular e 0,5cm dorsal à superfície medial do ramo da mandíbula, a fim de depositá-la próximo ao nervo alveolar mandibular, no forame mandibular. As freqüências cardíaca e respiratória foram mensuradas antes da administração da clorpromazina, 20 minutos após administração desta (T0, 20 minutos após o bloqueio do nervo alveolar mandibular com ropivacaína (T20 e, em intervalos de 20 minutos, até a volta da sensibilidade na região anestesiada. Observou-se o período de latência e a duração da anestesia por meio do pinçamento da pele e gengiva da região lateral direita da mandíbula. Encontrou-se início da anestesia após 22 minutos, com duração de 164,25 minutos. Os parâmetros de freqüência cardíaca e freqüência respiratória tiveram alterações, porém sem significado clínico para a espécie. A ropivacaína a 0,5% anestesia a região dos dentes pré-molares, molares, caninos, incisivos, pele e mucosa oral e lábio inferior, sem causar efeitos colaterais.This study intended to evaluate the 0.5% ropivacaine action on the alveolar mandibular nerve block in cats. Twenty adult cats, non-defined breed, male or female, received chlorpromazine (1.0 mg kg-1 VO and propofol (3,0 mg/kg IV. Ropivacaine at 0.5% was administrated with an "L" 13x3,8 needle, inserted in the angle of the right mandible, close to 1.0cm rostral to the angular process and 0.5cm dorsal to the medial surface of the mandible branch, intending to deposit close to the alveolar mandibular nerve, at the mandibular forame. The heart and respiratory

Characterization of Y1-xCaxBa2Cu4O8 (x=0.0˜ 0.1) with Double Cu-O Chains by Raman Spectra

Science.gov (United States)

Kodama, Yasuharu; Tanemura, Sakae; Ikeda, Teruki

1991-08-01

Raman spectra of Y1-xCaxBa2Cu4O8 (x=0.0, 0.02, 0.05 and 0.1) ceramic samples synthesized under high oxygen pressure were investigated. Seven clear peaks assigned to Ag modes were observed for the sample with x=0. With increasing x, the peaks at 238 cm-1, 332 cm-1, 430 cm-1 and 590 cm-1 were broadened. The origin of the broadening of the peaks at 238 cm-1 and 590 cm-1 is considered to be the destruction of the double Cu-O chains due to the substitution of Ca for Y.

Structural, Dielectric, and Electrical Properties of Bi1- x Pb x Fe1- x (Zr0.5Ti0.5) x O3

Science.gov (United States)

Panda, Niranjan; Pattanayak, Samita; Choudhary, R. N. P.

2015-12-01

Polycrystalline samples of Bi1- x Pb x Fe1- x (Zr0.5Ti0.5) x O3 (BPFZTO) with x = 0.0, 0.2, 0.3, and 0.4 were prepared by high-temperature solid-state reaction. Preliminary structural analysis of calcined powders of the materials by use of x-ray powder diffraction confirmed formation of single-phase systems with the tetragonal structure. Room-temperature scanning electron micrographs of the samples revealed uniform distribution of grains of low porosity and different dimensions on the surface of the samples. The frequency-temperature dependence of dielectric and electric properties was studied by use of dielectric and complex impedance spectroscopy over a wide range of frequency (1 kHz to 1 MHz) at different temperatures (25-500°C). The dielectric constant of BiFeO3 (BFO) was enhanced by substitution with Pb(Zr0.5Ti0.5)O3 (PZT) whereas the dielectric loss of the BPFZTO compounds decreased with increasing PZT content. A significant contribution of both grains and grain boundaries to the electrical response of the materials was observed. The frequency-dependence of the ac conductivity of BPFZTO followed Jonscher's power law. Negative temperature coefficient of resistance behavior was observed for all the BPFZTO samples. Conductivity by thermally excited charge carriers and oxygen vacancies in the materials was believed to be of the Arrhenius-type.

High temperature study on the thermal properties of few-layer Mo0.5W0.5S2 and effects of capping layers

Directory of Open Access Journals (Sweden)

Hong Gu

Full Text Available We investigated the thermal properties of few-layer Mo0.5W0.5S2 using a series of samples with different kinds of capping layers. Temperature-dependent Raman measurements were conducted in the range of 300–500 K, with power-dependent measurements also carried out. It indicated, for the few-layer Mo0.5W0.5S2, the temperature coefficients of the WS2-like E12g mode, MoS2-like E12g mode and A1g mode were −0.0155 cm−1/K, −0.0146 cm−1/K, and −0.0130 cm−1/K, respectively. And the thermal conductivity was estimated to be 44.8 W/mK. Moreover, the Mo0.5W0.5S2 samples coated with capping layers (ZrO2, HfO2 both showed a better thermal stability and a larger thermal conductivity than the one without. The results revealed that the capping layer should be an important factor in the thermal property. Keywords: Mo0.5W0.5S2, TMDs, Thermal properties, High temperature, Capping layers, Raman

Evaporation Rates of Chemical Warfare Agents Using 5-CM Wind Tunnels I. CASARM Sulfur Mustard (HD) from Glass

Science.gov (United States)

2008-10-01

tD Is- K CO CO o S o ooooooooooooo ooooooooooooo •* ** ** v V -a *J •« "cr co CM T...I IT flj UJ tfi V> <" r ft O O Is UJ 2 01 O C i* Jf ,* * * •* * # # if iJ- ;f s< * ;,* s* * *’ 0 I ./. •^ >s. a. t^ (SI ś...ex APPENDIX II 99 o CM u) o m o o IN U E ID TD ro i- O a c <B •a o 5 ** :.1- g £ h-ri * tf * CO 6; cr ft ui IO *A s

Ferroelectric and piezoelectric properties of lead-free BaTiO{sub 3} doped Bi{sub 0.5}Na{sub 0.5}TiO{sub 3} thin films from metal-organic solution deposition

Energy Technology Data Exchange (ETDEWEB)

Acharya, Susant Kumar [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Semiconductor Science and Technology, Basic Research Laboratory (BRL), Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Lee, Sang-Kwon; Hyung, Jung-Hwan [Department of Semiconductor Science and Technology, Basic Research Laboratory (BRL), Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Yang, Yun-Ho; Kim, Bok-Hee [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Ahn, Byung-Guk, E-mail: bkahn@jbnu.ac.kr [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

2012-11-05

Highlights: Black-Right-Pointing-Pointer Lead-free BNT-BT thin films from an optimized metal-organic solution deposition. Black-Right-Pointing-Pointer Phase and microstructure evolution with annealing temperature. Black-Right-Pointing-Pointer A relatively low leakage current density. Black-Right-Pointing-Pointer Good dielectric constant of 613 at a frequency of 1 kHz. Black-Right-Pointing-Pointer High remanent polarization and piezoelectric constant comparable to PZT thin films. - Abstract: Lead-free 0.94Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.06BaTiO{sub 3} (BNT-BT) piezoelectric thin films were prepared by metal-organic solution deposition onto a Pt/Ti/SiO{sub 2}/Si substrate. A dense and well crystallized thin film with a perovskite phase was obtained by annealing these films at 700 Degree-Sign C. Atomic force microscopy showed that these films were smooth and crack-free with an average grain size on the order of 200 nm. Thin films of 356 nm thickness exhibited a small signal dielectric constant and a loss tangent at 1 kHz of 613 and 0.044, respectively. Ferroelectric hysteresis measurements indicated a remanent polarization value of 21.5 {mu}C/cm{sup 2} with a coercive field of 164.5 kV/cm. The leakage current density of the thin film was 4.08 Multiplication-Sign 10{sup -4} A/cm{sup 2} at an applied electric field of 200 kV/cm. A typical butterfly-shaped piezoresponse loop was observed and the effective piezoelectric coefficient (d{sub 33}) of the BNT-BT thin film was approximately 51.6 pm/V.

Spectrophotometric Determination of Nano Amounts of Gallium (III) using 2-(5-Bromo-2-Pyridylazo)-5-Diethyl aminophenol Reagent in Water Samples

International Nuclear Information System (INIS)

Kandil, A.T.; Abd El-Atty, N.; El-Naggar, W.S.A.; Hafez, W.S.; Lasheen, T.A.

2014-01-01

The aim of the present work is to develop a simple and sensitive spectrophotometric method for determination of nano amounts of Ga(III) using 2-(5-Bromo-2-Pyridylazo)-5-Diethyl aminophenol (5-Br-PADAP) reagent. The factors affecting the determination procedure including absorption spectra, ph value, surfactant type and dye reagent concentration were studied and optimized. Interferences had also been evaluated. Maximum absorbance was obtained at 573 nm at ph 2.75, after 5 minutes mixing time. The proposed method was valid for Ga(III) concentration determination ranging from 0.005 to 1.25 Μg ml -1 in aqueous solution. However, the detection limit was decreased up to 0.001 Μg ml-1 in the presence of methanol. The ratio between Ga(III) and 5-Br-PADAP was found to be 1:1 with apparent molar absorptivity 1.12 × 10 5 l mol -1 cm -1 and coefficient of variation 0.44%. The elucidation of the complex composition was proved using FTIR technique. The method was applied for the determination of Ga(III) in some polluted water samples from different sources.

STRP Screening Sets for the human genome at 5 cM density

Directory of Open Access Journals (Sweden)

Marth Gabor

2003-02-01

Full Text Available Abstract Background Short tandem repeat polymorphisms (STRPs are powerful tools for gene mapping and other applications. A STRP genome scan of 10 cM is usually adequate for mapping single gene disorders. However mapping studies involving genetically complex disorders and especially association (linkage disequilibrium often require higher STRP density. Results We report the development of two separate 10 cM human STRP Screening Sets (Sets 12 and 52 which span all chromosomes. When combined, the two Sets contain a total of 782 STRPs, with average STRP spacing of 4.8 cM, average heterozygosity of 0.72, and total sex-average coverage of 3535 cM. The current Sets are comprised almost entirely of STRPs based on tri- and tetranucleotide repeats. We also report correction of primer sequences for many STRPs used in previous Screening Sets. Detailed information for the new Screening Sets is available from our web site: http://research.marshfieldclinic.org/genetics. Conclusion Our new human STRP Screening Sets will improve the quality and cost effectiveness of genotyping for gene mapping and other applications.

Electrical properties and phase transition of Ba(Zr{sub 0.05}Ti{sub 0.95}){sub 1−x}(Fe{sub 0.5}Ta{sub 0.5}){sub x}O{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Kruea-In, C. [Faculty of Science and Technology, Chiang Mai Rajabhat University (Thailand); Rujijanagul, G., E-mail: rujijanagul@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University (Thailand)

2015-09-15

Highlights: • Properties of of Ba(Zr{sub 0.05}Ti{sub 0.95}){sub 1−x}(Fe{sub 0.5}Ta{sub 0.5}){sub x}O{sub 3} ceramics were investigated. • Small amount of dopant produced a large change in dielectric and phase transition. • A phase diagram of Ba(Zr{sub 0.05}Ti{sub 0.95}){sub 1−x}(Fe{sub 0.5}Ta{sub 0.5}){sub x}O{sub 3} ceramics was proposed. • Dielectric tunability increased with increasing x concentration. - Abstract: In this work, properties of Ba(Zr{sub 0.05}Ti{sub 0.95}){sub 1−x}(Fe{sub 0.5}Ta{sub 0.5}){sub x}O{sub 3} ceramics with 0.00≤ x ≤0.07 were investigated. The ceramics were fabricated by a solid state reaction technique. X-ray diffraction analysis indicated that all samples exhibited single phase perovskite. Examination of the dielectric spectra revealed that the Fe and Ta additives promoted a diffuse phase transition, and the two phase transition temperatures, as observed in the dielectric curve of pure Ba(Zr{sub 0.05}Ti{sub 0.95})O{sub 3}, merged into a single phase transition temperature for higher x concentrations. The transformation was confirmed by ferroelectric measurements. In addition, the doped ceramics exhibited high relative dielectric tunability, especially for higher x concentration samples.

Rietveld refinement and dielectric properties of (Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})-(Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3}) ceramics

Energy Technology Data Exchange (ETDEWEB)

Kaswan, Kavita, E-mail: kaswan.kavita@gmail.com; Agarwal, Ashish; Sanghi, Sujata; Singh, Ompal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar-125001 (India)

2015-06-24

(1-x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})-x(Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3}) lead free ceramics (NBT, NBT-BBFO; x = 0.0, 0.1 respectively) have been synthesized by conventional solid state reaction method. Crystalline phase of sintered ceramics was investigated at room temperature using X-ray diffraction. Rietveld refinement of XRD data performed by FullProf revealed that both the samples exhibited rhombohedral structure with R3c space group. Dielectric properties of these ceramics were studied at different temperatures in a wide frequency range using impedance analyzer. Dielectric constant and dielectric loss were found to be increase with increase of BBFO content. The prepared ceramics exhibit a broad maximum in dielectric permittivity at 593K and dispersive permittivity at high temperatures. The NBT-BBFO sample shows a relaxor ferroelectric behavior at different frequencies.

Effects of proton irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

Science.gov (United States)

Nicoletta, C. A.

1973-01-01

The 1 ohm-cm and 10 ohm-cm silicon solar cells were exposed to 1.0 MeV protons at a fixed flux of 10 to the 9th power P/sq cm-sec and fluences of 10 to the 10th power, 10 to the 11th power, 10 to the 12th power and 3 X 10 to the 12th power P/sq cm. I-V curves of the cells were made at room temperature, 65 C and 165 C after each irradiation. A value of 139.5 mw/sq cm was taken as AMO incident energy rate per unit area. Degradation occurred for both uncovered 1 ohm-cm and 10 ohm-cm cells. Efficiencies are generally higher than those of comparable U.S. cells tested earlier. Damage (loss in maximum power efficiency) with proton fluence is somewhat higher for 10 ohm-cm cells, measured at the three temperatures, for fluences above 2 X 10 to the 11th power P/sq cm. Cell efficiency, as expected, changes drastically with temperature.

Onset response of bupivacaine 0.5% which has been added with sodium bicarbonate on epidural block

Directory of Open Access Journals (Sweden)

Marwoto Marwoto

2005-03-01

Full Text Available There are many advantages in using epidural anesthesia technique. However, there are also some constraints, such as the relatively long onset, particularly in the case of bupivacaine. Whereas the need of a rapid onset of anesthesia technique for emergency cares is increasing lately. The objective of this study was to find a method to hasten the onset of bupivacaine. This is a cross sectional randomized double blind controlled clinical trial performed on 40 patients who would undergo lower abdomen and extremity surgery with epidural block. We evaluated the onset of action of bupivacaine which has been added with sodium bicarbonate. Consecutive sampling method was applied to get the sample. The criteria of sample are ASA I – II patient, aged of 20-60 years old, 50-60 kg of weight, 150-170 cm of height. Patients were allocated randomly into two groups. The treatment group would get epidural block using mixture of 20 cc of bupivacaine 0,5 % + 0.5 cc of sodium bicarbonate 1.4 %, whereas the control group received 20 cc bupivacaine 0.5 % + 0.5 cc aqua bides. Time to reach sensoric block at the level of thoracal 10 dermatome using the pinprick method and time to reach motoric blockade using the bromage scale was recorded. The result of this study showed a significant shortening of the onset of sensory blockade (p<0.05 in the treatment group (10.2±1.4 minutes compared with the control group (19.5±1.3 minutes. The onset of motor blockade had also a significant shortening (p<0.05 in the treatment group(13.3±1.6 minutes compared with the control group (23.0±1.2 minutes. It was concluded that the addition of sodium bicarbonate can hasten the onset of bupivacaine on epidural block. (Med J Indones 2005; 14: 7-10Keywords : onset response, bupivacaine 0.5%, sodium bicarbonate, epidural block

Magnetic and conductivity study on Mn0.5Ru0.5Co2O4 spinel

International Nuclear Information System (INIS)

Bhowmik, R.N.; Ranganathan, R.

2003-01-01

The magnetic measurements suggest that Mn 0.5 Ru 0.5 Co 2 O 4 is a ferrimagnet with T c ≅ 140 K followed by irreversibility between zero field cooled and field cooled magnetization and peak in zero field cooled maximum at T m ≅ 100 K on decreasing the temperature. The scaling analysis of the conductivity (G) as a function of frequency (f) with functional form G p (f)/G o ∼ (f/f c ) n suggests two activated regimes at above and below of 210 K, respectively. The G o vs T shows semi-conducting behaviour of the sample. (author)

An ultrasonic therapeutic transducers using lead-free Na{sub 0.5}K{sub 0.5}NbO{sub 3}-CuNb{sub 2}O{sub 6} ceramics

Energy Technology Data Exchange (ETDEWEB)

Yang, Ming-Ru [Department of Electrical Engineering, National Cheng Kung University, Taiwan (China); Chu, Sheng-Yuan, E-mail: chusy@mail.ncku.edu.t [Department of Electrical Engineering, National Cheng Kung University, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China); Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Tsai, Cheng-Che [Department of Electronics Engineering and Computer Science, Tung-Fang Institute of Technology, Kaohsiung 829, Taiwan (China)

2010-10-08

Research highlights: {yields} In this paper, CN was added to NKN ceramics to decrease the sintering temperature and to improve the density and piezoelectric characteristics. The influence of CuNb{sub 2}O{sub 6} (CN) content on the microstructure, electrical properties, temperature stability, and mechanical properties of the synthesized samples was investigated. Results show that the samples synthesized with CN-doped not only improved the density but also exhibited superior piezoelectric characteristic, temperature stability of resonance frequency (TCF), and elastic stiffness coefficient than those of pure NKN piezoelectric ceramics. {yields} The bulk density (4.47 g/cm{sup 3}), k{sub p} (40%), k{sub t} (45%), Q{sub m} (1642), C{sub 33}{sup D} (19.64 x 10{sup 10} N/m{sup 2}), TCF (-0.011%/{sup o}C) and TCC (0.135%/{sup o}C) values for NKN-01CN ceramics obtained from experiments show excellent 'hard' piezoelectric properties. Furthermore, a lead-free NKN-01CN ultrasonic therapeutic transducer was successfully driven by a self-tuning circuit. - Abstract: In this work, we reports on the CuNb{sub 2}O{sub 6} (CN) modified lead-free Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) based piezoelectric ceramics were synthesized by solid-state reaction methods and sintered at 1075 {sup o}C for 3 h. A secondary phase of K{sub 4}CuNb{sub 8}O{sub 23} was found in the XRD pattern of NKN-based ceramics as the CN dopants is 1 mol%. Microstructural analyses of un-doped and CN-doped ceramics were performed in a scanning electron microscope. The influence of CN content on the microstructure, electrical properties, temperature stability, and mechanical properties of the synthesized ceramics was investigated. The results show that the synthesized ceramics with CN-doped not only had improved density but also exhibited superior piezoelectric characteristics, temperature stability of resonance frequency (TCF), and a better elastic stiffness coefficient than those of pure NKN piezoelectric

Magnetic and magnetocaloric properties of the alloys Mn2-xFexP0.5As0.5 (0⩽x⩽0.5)

Science.gov (United States)

Gribanov, I. F.; Golovchan, A. V.; Varyukhin, D. V.; Val'kov, V. I.; Kamenev, V. I.; Sivachenko, A. P.; Sidorov, S. L.; Mityuk, V. I.

2009-10-01

The results of investigations of the magnetic and magnetocaloric properties of alloys from the system Mn2-xFexP0.5As0.5 (0⩽x⩽0.5) are presented. The magnetization measurements are performed in the temperature interval 4.2-700K in magnetic fields up to 8T. The entropy changes ΔS with the magnetic field changing from 0 to 2, 4, 5, and 8T are determined from the magnetization isotherms obtained near temperatures of the spontaneous appearance of the ferromagnetic state (TC,TAF -FM1), and the curves ΔS(T0) are constructed. It is found that TC and TAF-FM1 decrease monotonically with increasing manganese concentration and that the ferromagnetic phase is completely suppressed in Mn1.5Fe0.5P0.5As0.5. It is found that the concentration dependences of the maximum entropy jump (and the corresponding cold-storage capacity) and the magnitudes of the ferromagnetic moment of the unit cell with maxima for x =0.9 and 0.8 show extremal behavior. The data obtained are compared with the ferromagnetic moments calculated from first principles by the Korringa-Kohn-Rostoker method using the coherent-potential approximation (KKR-CPA)—the discrepancy for 0.5⩽x⩽0.7 is attributed to the appearance of an antiferromagnetic component of the magnetic structure. It is concluded that the alloys Mn2-xFexP0.5As0.5 have promise for use in magnetic refrigerators operating at room temperature.

Mechanism of γ-irradiation induced phase transformations in nanocrystalline Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} ceramics

Energy Technology Data Exchange (ETDEWEB)

Jagadeesha Angadi, V. [Department of Physics, Bangalore University, Bangalore, Karnataka 560056 (India); Anupama, A.V.; Choudhary, Harish K.; Kumar, R. [Materials Research Centre, Indian Institute of Science, Bangalore, 560012 (India); Somashekarappa, H.M. [Center for Application of Radioisotopes and Radiation Technology, Mangalore University, Mangalore 574199 (India); Mallappa, M. [Department of Chemistry, Government Science College, Bangalore 560001 (India); Rudraswamy, B. [Department of Physics, Bangalore University, Bangalore, Karnataka 560056 (India); Sahoo, B., E-mail: bsahoo@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore, 560012 (India)

2017-02-15

The structural, infrared absorption and magnetic property transformations in nanocrystalline Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} samples irradiated with different doses (0, 15, 25 and 50 kGy) of γ-irradiation were investigated in this work and a mechanism of phase transformation/decomposition is provided based on the metastable nature of the Mn-atoms in the spinel lattice. The nano-powder sample was prepared by solution combustion route and the pellets of the sample were exposed to γ-radiation. Up to a dose of 25 kGy of γ-radiation, the sample retained the single phase cubic spinel (Fd-3m) structure, but the disorder in the sample increased. On irradiating the sample with 50 kGy γ-radiation, the spinel phase decomposed into new stable phases such as α-Fe{sub 2}O{sub 3} and ZnFe{sub 2}O{sub 4} phases along with amorphous MnO phase, leading to a change in the surface morphology of the sample. Along with the structural transformations the magnetic properties deteriorated due to breakage of the ferrimagnetic order with higher doses of γ-irradiation. Our results are important for the understanding of the stability, durability and performance of the Mn-Zn ferrite based devices used in space applications. - Graphical abstract: The nanocrystalline Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} ceramic sample transforms to crystalline α-Fe{sub 2}O{sub 3} and ZnFe{sub 2}O{sub 4} phases (and amorphous MnO phase) at a γ-irradiation dose of 50 kGy, as MnO goes out of the spinel lattice. The high energy γ-irradiation causes structural damage to the nanomaterials leading to change in morphology of the sample as seen in the SEM images. - Highlights: • Mn atoms are more unstable in the Mn-Zn ferrite spinel lattice than Zn-atoms. • Displacement of Mn atoms by γ-radiation from the lattice renders phase transformation. • In Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}, Mn-ferrite cell transforms to crystalline α-Fe{sub 2}O{sub 3} and amorphous MnO. • The stable ZnFe{sub 2}O

Investigation of structural and magnetic properties of Ni0.5Zn0.5Fe2O4 nano powders prepared by self combustion method

International Nuclear Information System (INIS)

Sudheesh, V.D.; Nehra, J.; Vinesh, A.; Sebastian, V.; Lakshmi, N.; Dutta, Dimple P.; Reddy, V.R.; Venugopalan, K.; Gupta, Ajay

2013-01-01

Graphical abstract: Display Omitted Highlights: ► Ni 0.5 Zn 0.5 Fe 2 O 4 prepared by self combustion with uniform/nonuniform heating. ► Characterized using TEM, XRD, in-field Mössbauer and DC magnetometry. ► Leads to bimodal (S1) and very narrow size distribution (S2) type nano samples. ► S1 has magnetic properties of bulk Ni 0.5 Zn 0.5 Fe 2 O 4 . ► Although very even sized, S2 large magnetic anisotropy distribution. -- Abstract: Nano powders of Ni 0.5 Zn 0.5 Fe 2 O 4 have been synthesized by the self-combustion method at a relatively low temperature of 473 K under conditions of non-uniform and uniform heating. Rietveld fitting of X-ray diffractograms confirm the formation of the pure spinel phase in both samples. Transmission electron microscopy indicates that the sample prepared under non-uniform heating has a bimodal particle size distribution (average values 16 nm and 6 nm) while the one prepared under uniform heating has a very narrow particle size distribution (average size 4 nm). Low temperature, in-field Mössbauer spectroscopic studies clearly show surface spin contributions. The hyperfine fields and Curie temperature of the non-uniformly heated sample are in good agreement with those reported for the corresponding bulk samples. Despite having a very narrow particle size distribution, the uniformly heated sample has a large anisotropy distribution which is evident in the broad transition visible in the temperature dependent magnetization curve. It is also corroborated by the fact that the experimental magnetization curve at room temperature requires two Langevin functions for satisfactory reproduction.

Microstructural analysis nanoferritas Mn{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} e Mn{sub 0,65}Zn{sub 0,35}Fe{sub 2}O{sub 4} synthesized by combustion reaction; Analise microestrutural de nanoferritas Mn{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} e Mn{sub 0,65}Zn{sub 0,35}Fe{sub 2}O{sub 4} sintetizadas por reacao de combustao

Energy Technology Data Exchange (ETDEWEB)

Diniz, V.C.S.; Figueiredo, A.R.; Costa Junior, A.D.S.; Diniz, H.M.; Vieira, D.A.; Costa, A.C.F.M., E-mail: veronicacristhina@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais

2014-07-01

The MnZn ferrites are ferrimagnetic materials that have been studied and used in various technological fields. In this work investigated the microstructural characteristics of ferrites and Mn{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} Mn{sub 0,65}Zn{sub 0,35}Fe{sub 2}O{sub 4} synthesized by combustion reaction in 200g scale production. The samples were characterized by XRD, crystallinity, crystallite size, X-ray fluorescence and scanning electron microscopy. Given the results it was observed that for both samples the synthesis combustion reaction was efficient for the production of single-phase ferrites with high crystallinity. With respect to the analysis of X-ray fluorescence was noted that the experimental values composition were consistent with the theoretical values calculated for both samples. Regarding morphology for both samples, the formation of the porous powders with feature consisting of dense clumps in the form of irregular foam was observed. (author)

Ionic conductivity of Bi{sub 2}Ni{sub x}V{sub 1−x}O{sub 5.5−3x/2} (0.1 ≤ x ≤ 0.2) oxides prepared by a low temperature sol-gel route

Energy Technology Data Exchange (ETDEWEB)

Rusli, Rolan; Patah, Aep, E-mail: ismu@chem.itb.ac.id; Prijamboedi, Bambang, E-mail: ismu@chem.itb.ac.id; Ismunandar, E-mail: ismu@chem.itb.ac.id [Inorganic and Physical Chemistry Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Abrahams, Isaac [Materials Research Institute, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

2014-03-24

Solid oxides fuel cells (SOFCs) is one technology that could contribute toward future sustainable energy. One of the most important components of an SOFC is the electrolyte, which must have high ionic conductivity. Cation substitution of vanadium in Bi{sub 4}V{sub 2}O{sub 11} yields a family of fast oxide ion conducting solids known collectively as the BIMEVOXes (bismuth metal vanadium oxide), which have the potential to be applied as electrolytes in SOFCs. The purpose of this work is to study the effect of Ni concentration, when used as a dopant, on the ionic conductivity of Bi{sub 2}Ni{sub x}V{sub 1−x}O{sub 5.5−3x/2} (BINIVOX) oxides (0.1 ≤ x ≤ 0.2) when prepared by a sol gel method. The gels were calcined at 600 °C for 24 h to produce pure BINIVOX. These oxides were found to exhibit the γ-phase structure with tetragonal symmetry in space group I4/mmm. Ionic conductivity of BINIVOX at 300 °C were 6.9 × 10{sup −3} S cm{sup −1}, 1.2 × 10{sup −3} S cm{sup −1}, and 8.2 × 10{sup −4} S cm{sup −1}, for x = 0.1; 0.15; and 0.2; respectively; and at 600 °C were 1.1 × 10{sup −1} S cm{sup −1}, 5.3 × 10{sup −2} S cm{sup −1}, and 2.8 ×10{sup −2} S cm{sup −1}, for x = 0.1; 0.15; and 0.2; respectively.

Structural and magnetic properties of Fe{sub 76}P{sub 5}(Si{sub 0.3}B{sub 0.5}C{sub 0.2}){sub 19} amorphous alloy

Energy Technology Data Exchange (ETDEWEB)

Lavorato, G.C. [INTECIN (FIUBA-CONICET), Paseo Colon 850, Capital Federal (Argentina); Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Fiore, G. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Tiberto, P. [INRIM, Electromagnetism Division, Torino (Italy); Baricco, M. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Sirkin, H. [INTECIN (FIUBA-CONICET), Paseo Colon 850, Capital Federal (Argentina); Moya, J.A., E-mail: jmoya.fi.uba@gmail.com [GIM - IESIING, Universidad Catolica de Salta, INTECIN (UBA-CONICET) (Argentina)

2012-09-25

Highlights: Black-Right-Pointing-Pointer Fe{sub 76}P{sub 5}(Si{sub 0.3}B{sub 0.5}C{sub 0.2}){sub 19} amorphous alloy in ribbons and 1 mm and 2 mm rod samples. Black-Right-Pointing-Pointer Good glass forming ability with {Delta}T = 50 K and {gamma} = 0.37 and off-eutectic composition. Black-Right-Pointing-Pointer Good soft magnetic properties with magnetization saturation of 1.44 T. Black-Right-Pointing-Pointer Geometrical factors are the primary causes of magnetic losses in frequencies above 10 Hz. - Abstract: Recently, bulk amorphous alloys were produced in the Fe-B-Si-P-C system with high glass forming ability, excellent magnetic properties and the advantage of containing no expensive glass-forming elements, such as Ga, Y, Cr or Nb, having, therefore, a good perspective of commercial applications. In the present work, the Fe{sub 76}P{sub 5}(Si{sub 0.3}B{sub 0.5}C{sub 0.2}){sub 19} amorphous alloy prepared by two quenching techniques has been studied. Amorphous ribbons of about 40 {mu}m thick were obtained by planar-flow casting together with cylinders having 1 and 2 mm diameter produced by copper mold injection casting. All the samples appear fully amorphous after X-ray diffraction analysis. A comprehensive set of thermal data (glass, crystallization, melting and liquidus temperatures) were obtained as well as a description of the melting and solidification processes. Mechanical microhardness tests showed that the samples have a hardness of 9.7 {+-} 0.3 GPa. Good soft-magnetic properties were obtained, including a high magnetization of 1.44 T and a low coercivity (4.5 A/m for ribbons and 7.5 A/m in the case of 1 mm rod samples, both in as-cast state). Thermomagnetic studies showed a Curie temperature around 665 K and the precipitation of new magnetic phases upon temperatures of 1000 K. Furthermore, the frequency dependence of magnetic losses at a fixed peak induction was studied. The results suggest the occurrence of a fine magnetic domain structure in bulk

Magnetic properties and EXAFS study of nanocrystalline Fe2Mn0.5Cu0.5Al synthesized using mechanical alloying technique

International Nuclear Information System (INIS)

Nanto, Dwi; Yang, Dong-Seok; Yu, Seong-Cho

2014-01-01

Nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al has been synthesized by the mechanical alloying technique and studied as a function of milling time. Alloy nature of Fe 2 Mn 0.5 Cu 0.5 Al was observed in a sample milled for 96 h. The magnetic saturation is 4.0 μ B /f.u., which coincidently follows Slater–Pauling rule at 5 K. Nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al has enhanced saturate magnetization compared to any other fabrication of Fe 2 MnAl reported. Cu element plays an important role in site competes with other elements and may result in the enhancement of saturate magnetization. In accordance to the magnetic results and EXAFS pattern, it was revealed that the dynamics of magnetic properties were confirmed as structural changes of nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al

Preparation and piezoelectric properties of (K0.5Na0.5)NbO3 lead-free piezoelectric ceramics with pressure-less sintering

International Nuclear Information System (INIS)

Du Hongliang; Li Zhimin; Tang Fusheng; Qu Shaobo; Pei Zhibin; Zhou Wancheng

2006-01-01

Lead-free piezoelectric ceramics (K 0.5 Na 0.5 )NbO 3 (abbreviated as KNN) with the relative density of 97.6% have been synthesized by press-less sintering owing to the careful control of processing conditions. The phase structure of KNN ceramics with different sintering temperature and heating rate was analyzed. Results show that the pure perovskite phase with orthorhombic symmetry is in all ceramics specimens. The effect of heating rate and sintering temperature on microstructure and piezoelectric properties of KNN ceramics was investigated. The densification behavior and piezoelectric properties of KNN ceramics were enhanced by improving heating rate and sintering temperature. Pure KNN ceramics sintered at 1120 deg. C with heating rate of 5 deg. C/min showed optimized densification and piezoelectric properties (ρ = 4.4 g/cm 3 , d 33 = 120 pC/N -1 , k p = 0.40 and T c = 400 deg. C). The results show that KNN is a promising candidate for lead-free piezoelectric ceramics

A high stability Ni-La0.5Ce0.5O2-δ asymmetrical metal-ceramic membrane for hydrogen separation and generation

Science.gov (United States)

Zhu, Zhiwen; Sun, Wenping; Wang, Zhongtao; Cao, Jiafeng; Dong, Yingchao; Liu, Wei

2015-05-01

In this work, hydrogen permeation properties of Ni-La0.5Ce0.5O2-δ (LDC) asymmetrical cermet membrane are investigated, including hydrogen fluxes (JH2) under different hydrogen partial pressures, the influence of water vapor on JH2 and the long-term stability of the membrane operating under the containing-CO2 atmosphere. Ni-LDC asymmetrical membrane shows the best hydrogen permeability among LDC-based hydrogen separation membranes, inferior to Ni-BaZr0.1Ce0.7Y0.2O3-δ asymmetrical membrane. The water vapor in feed gas is beneficial to hydrogen transport process, which promote an increase of JH2 from 5.64 × 10-8 to 6.83 × 10-8 mol cm-2 s-1 at 900 °C. Stability testing of hydrogen permeation suggests that Ni-LDC membrane remains stable against CO2. A dual function of combining hydrogen separation and generation can be realized by humidifying the sweep gas and enhance the hydrogen output by 1.0-1.5 times. Ni-LDC membrane exhibits desirable performance and durability in dual-function mode. Morphologies and phase structures of the membrane after tests are also characterized by SEM and XRD.

Beam backgrounds in the ATLAS detector during LHC loss map tests at beta*=40cm and beta*=80cm at Ebeam=6.5 TeV

CERN Document Server

The ATLAS collaboration

2017-01-01

In this note the beam-background measurements with the ATLAS detector during lossmap tests of the LHC are described. Loss maps taken at beta*=40 cm and the normal 2015 setting of beta*=80 cm are compared. In the first case several collimator settings were explored, resulting in significant changes of beam backgrounds in ATLAS. Besides the studies of the dependence of background on collimation, which are important for optimisation of the LHC performance, these tests provide a clean environment to study the relative importance of beam halo losses on the experiment. The results show that the halo-related component of beam background in ATLAS decreases exponentially with increasing aperture of the tertiary collimators, the slope in terms of nominal sigma being about -0.5. From the data it is also shown that in normal operation conditions of LHC run 2 the beam halo losses contribute at most at the percent level to the total background, the dominant part coming from beam-gas interactions. The data are also used to ...

The effect of texture in (Bi3.5Nd0.5)(Ti2.97Nb0.03)O12 ceramics

Science.gov (United States)

Cao, Ziping; Ding, Aili; Zheng, Xinsen; Qiu, Pingsun; Cheng, Wenxiu

2004-11-01

(Bi3.5Nd0.5) (Ti2.97Nb0.03)O12 ferroelectric ceramics was successfully prepared by a hot-pressing method. XRD diffraction confirms that the samples hold different texture in the sliced planes parallel and perpendicular to the hot-pressing axis, respectively. The anisotropy of ferroelectric, dielectric and piezoelectric properties were all observed in the textured ceramics. Due to the great improvement of ferroelectric and piezoelectric properties, the sample which was sliced along the direction parallel to the hot-pressing axis can be considered as a good candidate of high temperature piezoelectric materials.

Thermoelectric properties of c-GeSb{sub 0.75}Te{sub 0.5} to h-GeSbTe{sub 0.5} thin films through annealing treatment effects

Energy Technology Data Exchange (ETDEWEB)

Vora-ud, Athorn, E-mail: athornvora-ud@snru.ac.th [Program of Physics, Faculty of Science and Technology, Sakon Nakhon Rajabhat University, Mueang District, Sakon Nakhon 47000 (Thailand); Thermoelectrics Research Center, Research and Development Institution, Sakon Nakhon Rajabhat University, Mueang District, Sakon Nakhon 47000 (Thailand); Horprathum, Mati, E-mail: mati.horprathum@nectec.or.th [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Eiamchai, Pitak [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Muthitamongkol, Pennapa; Chayasombat, Bralee; Thanachayanont, Chanchana [National Metal and Materials Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Pankiew, Apirak [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Klamchuen, Annop [National Nanotechnology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Naenkieng, Daengdech; Plirdpring, Theerayuth; Harnwunggmoung, Adul [Thermoelectric and Nanotechnology Research Center, Faculty of Science and Technology, Rajamangala University of Technology Suvarnabhumi, Huntra Phranakhon, Si Ayutthaya 13000 (Thailand); Charoenphakdee, Anek [NANO-Thermoelectrics Research Center, Division of Applied Physics, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Mueng Nakorn Ratchasima 30000 Thailand (Thailand); Somkhunthot, Weerasak [Program of Physics, Faculty of Science and Technology, Loei Rajabhat University, Muang District, Loei 42000 (Thailand); and others

2015-11-15

Germanium–Antimony–Tellurium (Ge–Sb–Te) thin films were deposited on silicon wafers with 1-μm silicon dioxide (SiO{sub 2}/Si) by pulsed dc magnetron sputtering from a 99.99% GeSbTe target of 1:1:1 ratio at ambient temperature. The samples were annealed at 573, 623, 673, and 723 K for 3600 s in a vacuum state. The effects of the annealing treatment on phase identification, atomic composition, morphology and film thickness, carrier concentration, mobility, and Seebeck coefficient of the Ge–Sb–Te samples have been investigated by grazing-incidence X-ray diffraction, auger electron spectroscopy, field-emission scanning electron microscopy, Hall-effect measurements, and steady state method, respectively. The results demonstrated that the as-deposited Ge–Sb–Te sample was amorphous. Atomic composition of as-deposited and annealed films at 573 K and 623 K were GeSb{sub 0.75}Te{sub 0.5} while annealed films at 673 K and 723 K were GeSbTe{sub 0.5} due to Sb-rich GeSb{sub 0.75}Te{sub 0.5}. The samples annealed at 573 K and 623 K showed the crystal phases of cubic structure (c-GeSb{sub 0.75}Te{sub 0.5}) into hexagonal structure (h-GeSbTe{sub 0.5}) after annealing at 673 K and 723 K. The study demonstrated the insulating condition from the as-deposited GeSbTe film, and the changes towards the thermoelectric properties from the annealing treatments. The GeSbTe films annealed at 673 K yielded excellent thermoelectric properties with the electrical resistivity, Seebeck coefficient, and power factor at approximately 1.45 × 10{sup −5} Ωm, 71.07 μV K{sup −1}, and 3.48 × 10{sup −4} W m{sup −1} K{sup −2}, respectively. - Highlights: • GeSbTe thin films were successfully sputtered for thermoelectric properties. • GeSbTe films were examined among physical, electrical and thermoelectric properties. • Thermoelectric properties were discussed based on composition of the films.

Photoluminescence and scintillation properties of Ce-doped Sr2(Gd1-xLux)8(SiO4)6O2 (x = 0.1, 0.2, 0.4, 0.5, 0.6) crystals

Science.gov (United States)

Igashira, Takuya; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-05-01

Apatite crystals with chemical compositions of 0.5% Ce-doped Sr2(Gd1-xLux)8(SiO4)6O2 (x = 0.1, 0.2, 0.4, 0.5, 0.6) were synthesized by the Floating Zone method, and then we evaluated their photoluminescence (PL) and scintillation properties. All the Ce-doped samples exhibited PL and scintillation with an intense broad emission in 400-550 nm in which the origin was attributed to the 5d-4f transition of Ce3+, and the emission peak became broader with increasing the concentration of Lu3+. Both PL and scintillation decay time profiles were best-approximated by a sum of two exponential decay functions, and the origin of slower component was attributed to the 5d-4f transition of Ce3+. In the X-ray induced afterglow measurements, the Ce-doped Sr2(Gd0.4Lu0.6)8(SiO4)6O2 sample exhibited the lowest afterglow level. Furthermore, the Ce-doped Sr2(Gd0.5Lu0.5)8(SiO4)6O2 and Sr2(Gd0.4Lu0.6)8(SiO4)6O2 samples showed a clear full energy deposited peak under 5.5 MeV 241Am α-ray irradiation, and the estimated absolute scintillation light yields were around 290 and 1300 ph/5.5 MeV-α, respectively.

Thermoelectric properties of p-type pseudo-binary (Ag0.365Sb0.558Te) x -(Bi0.5Sb1.5Te3)1-x (x=0-1.0) alloys prepared by spark plasma sintering

International Nuclear Information System (INIS)

Cui, J.L.; Xue, H.F.; Xiu, W.J.; Jiang, L.; Ying, P.Z.

2006-01-01

In this paper, pseudo-binary (Ag 0.365 Sb 0.558 Te) x -(Bi 0.5 Sb 1.5 Te 3 ) 1- x (x=0-1.0) alloys were prepared using spark plasma sintering technique, and the composition-dependent thermoelectric properties were evaluated. Electrical conductivities range from 7.9x10 4 to 15.6x10 4 Ω -1 m -1 at temperatures of 507 and 318 K, respectively, being about 3.0 and 8.5 times those of Bi 0.5 Sb 1.5 Te 3 alloy at the corresponding temperatures. The optimal dimensionless figure of merit (ZT) of the sample with molar fraction x=0.025 reaches 1.1 at 478 K, whereas that of the ternary Bi 0.5 Sb 1.5 Te 3 alloy is 0.58 near room temperature. The results also reveal that a direct introduction of Ag 0.365 Sb 0.558 Te in the Bi-Sb-Te system is much more effective to the property improvement than naturally precipitated Ag 0.365 Sb 0.558 Te in the Ag-doped Ag-Bi-Sb-Te system. - Graphical abstract: The temperature dependence of the dimensionless thermoelectric figure of merit ZT for different (Ag 0.365 Sb 0.558 Te) x -(Bi 0.5 Sb 1.5 Te 3 ) 1- x (x=0-1.0) alloys prepared by spark plasma sintering

Radiofrequency Ablation Combined with Renal Arterial Embolization for the Treatment of Unresectable Renal Cell Carcinoma Larger Than 3.5 cm: Initial Experience

International Nuclear Information System (INIS)

Yamakado, Koichiro; Nakatsuka, Atsuhiro; Kobayashi, Shigeki; Akeboshi, Masao; Takaki, Haruyuki; Kariya, Zentaro; Kinbara, Hiroyuki; Arima, Kiminobu; Yanagawa, Makoto; Hori, Yasuhide; Kato, Hiromi; Sugimura, Yoshiki; Takeda, Kan

2006-01-01

The purpose of the study was to evaluate the feasibility, safety, and therapeutic effects of the combination of renal arterial embolization and radiofrequency (RF) ablation to reinforce the anticancer effect on renal cell carcinomas (RCCs) measuring 3.5 cm or larger. This study was undertaken to evaluate this combined therapy on large RCCs-based tumor geometry. Eleven patients with 12 RCCs 3.5 cm or larger in diameter (3.5-9.0 cm) underwent combined therapy. Two were exophytic tumors, and the remaining 10 tumors had components extending into the renal sinus fat. Tumor vessels were selectively embolized in nine patients and the renal artery was completely embolized in two patients with polyvinyl alcohol or ethanol mixed with iodized oil. RF ablation was percutaneously done under the computed tomographic (CT)-fluoroscopic guidance. Response to treatment was evaluated by dynamic contrast-enhanced CT and magnetic resonance (MR) imaging. Tumor enhancement was eliminated after a single RF session in nine tumors (75%), after two sessions in two tumors (17%), and after four sessions in one tumor (8%). Both exophytic tumors (100%) and 7 of 10 tumors having components in the renal sinus fat (70%) were completely ablated with a single RF session. All tumors remained controlled during a mean follow-up period of 13 months and showed significant reduction in tumor sizes (5.2 ± 1.7 cm to 3.6 ± 1.4 cm, p < 0.001). A delayed abscess developed in the ablated lesion in a patient, which was percutaneously drainaged. Combined therapy as described in this report is a feasible, relatively safe, and promising treatment method for large RCCs regardless of tumor geometry

The U5.0 Undulator for the ALS

International Nuclear Information System (INIS)

Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

1991-05-01

The U5.0 Undulator, an 89 period, 5 cm period length, 4.6 m long insertion device has been designed and is in fabrication. This undulator will be the first high brightness source, in the 50 to 1500 eV range, for the Advanced Light Source (ALS) and is scheduled for completion in 1992. A modular hybrid configuration utilizing Nd-Fe-B permanent magnet material and vanadium permendur is used that achieves 0.837 Tesla effective peak field. Correction of the vertical field integral is with permanent magnet rotors at the ends. Gap adjustment is with an arrangement of roller screws, chains drives, a gear reduction unit and a stepper motor driven by a closed loop control system. The vacuum chamber design is a two-piece, machined and welded 5083-H321 aluminum construction of 5.1 m length. Magnetic design, subsystem design and fabrication progress are presented. 12 refs., 4 figs., 2 tabs

Alveolar architecture of clear cell renal carcinomas (≤5.0 cm) show high attenuation on dynamic CT scanning

International Nuclear Information System (INIS)

Fujimoto, Hiroyuki; Wakao, Fumihiko; Moriyama, Noriyuki; Tobisu, Kenichi; Kakizoe, Tadao; Sakamoto, Michiie

1999-01-01

To establish the correlation between tumor appearance on CT and tumor histology in renal cell carcinomas. The density and attenuation patterns of 96 renal cell carcinomas, each ≤5 cm in greatest diameter, were studied by non-enhanced CT and early and late after bolus injection of contrast medium using dynamic CT. The density and attenuation patterns and pathological maps of each tumor were individually correlated. High attenuated areas were present in 72 of the 96 tumors on early enhanced dynamic CT scanning. All 72 high attenuated areas were of the clear cell renal cell carcinoma and had alveolar architecture. The remaining 24 tumors that did not demonstrate high attenuated foci on early enhanced scanning included three clear cell, nine granular cell, six papillary, five chromophobe and one collecting duct type. With respect to tumor architecture, all clear cell tumors of alveolar architecture demonstrated high attenuation on early enhanced scanning. Clear cell renal cell carcinomas of alveolar architecture show high attenuation on early enhanced dynamic CT scanning. A larger number of patients are indispensable to obtaining clear results. However, these findings seem to be an important clue to the diagnosis of renal cell carcinomas as having an alveolar structure. (author)

Density determination in Pino Radiata (D.Don) samples using 59.5 keV gamma radiation attenuation; Determinacion de densidad en muestras de Pino Radiata (D. Don) mediante atenuacion de radiacion gamma de 59.5 KeV

Energy Technology Data Exchange (ETDEWEB)

Dinator, Maria I; Morales, Jose R; Aliaga, Nelson [Chile Univ., Santiago (Chile). Dept. de Fisica; Karsulovic, Jose T; Sanchez, Jaime; Leon, Adolfo [Chile Univ., Santiago (Chile). Dept. de Tecnologia de la Madera

1997-12-31

A non destructive method to determine wood samples density is presented. The photon mass attenuation coefficient in samples of Pino radiata (D.Don) was measured at 59.5 keV with a radioactive source of Am-241. The value of 0.192 {+-} 0.002 cm{sup 2}/g was obtained with a gamma spectroscopy system and later used on the determination of the mass density in sixteen samples of the same species. Comparison of these results with those of gravimetric method through a linear regression showed a slope of 1.001 and a correlation factor of 0.94. (author). 3 refs., 4 figs.

Conducting, magnetic polyaniline/Ba{sub 0.25}Sr{sub 0.75} Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19} nanocomposite: Fabrication, characterization and application

Energy Technology Data Exchange (ETDEWEB)

Ezzati, S. Noushin, E-mail: sn.ezzati@iau-saveh.ac.ir [Young Researchers and Elite Club, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Rabbani, Mahboubeh [Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Leblanc, Roger M. [Department of Chemistry, University of Miami, Coral Gables, FL 33124 (United States); Asadi, Ebadullah, E-mail: ebadasadi@gmail.com [Department of Chemistry, University of Miami, Coral Gables, FL 33124 (United States); Department of Chemistry, Amirkabir University of Technology, P. O. Box: 15875-4413, Tehran (Iran, Islamic Republic of); Ezzati, S. Mohammad H. [Young Researchers and Elite Club, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Rahimi, Rahmatollah [Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Azodi-Deilami, Saman [Young Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

2015-10-15

In this contribution, Ni/Mn doped Barium Strontium Ferrite nanoparticles (Ba{sub 0.25}Sr{sub 0.75}Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19}) and conducting polyaniline/Ba{sub 0.25}Sr{sub 0.75}Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19} nanocomposite were fabricated successfully through sol–gel method and in-situ polymerization technique, respectively. Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy analysis (EDX), X-ray powder diffraction (XRD), Mössbauer spectroscopic measurements and Fourier transform infrared spectroscope (FT-IR) analyses were adopted to confirm the composition, morphology and structure of materials. The obtained results revealed the formation of hexagonal M-type rod-shape ferrite with average particle size of about 45 nm (according to XRD data, using Debye–Scherre formula). The saturation magnetization of ferrite nanoparticles and PANI/Ferrite nanocomposite reported 44.03 and 9.85 emu/g, respectively, using vibrant sample magnetometer (VSM). Standard four-point-probe technique was employed to measure the conductivity of samples. Also optical characteristic of samples was examined by means of UV–Vis and Diffuse Reflectance Spectra (DRS) techniques which proved the formation of conducting coating of emeraldine on the surface of magnetic nanoparticles. Also the UV–vis studies indicated that the ferrite nanoparticles have an optical band gap of 1.8 eV while the values of 1.65 and 2.66 eV obtained for PANI/Ferrite nanocomposite. Finally, the microwave absorption properties of prepared nanoferrite and nanocomposite at different thicknesses (2, 3 and 4 mm) were determined at the X-band (8–12 GHz) using vector network analyzer (VNA). In this study, minimum reflection loss of −21.68 dB and maximum available bandwidth of 4.8 GHz were obtained for PANI/Ferrite (20 wt% ferrite) at the frequency of 10.6 GHz. The results suggested the fabricated nanocomposite could be a suitable candidate for

Electrical conductivity of Sr{sub 2−x}VMoO{sub 6−y} (x = 0.0, 0.1, 0.2) double perovskites

Energy Technology Data Exchange (ETDEWEB)

Childs, Nicholas B.; Smith, Richard; Key, Camas [Department of Physics, EPS 264, Montana State University, Bozeman, Montana 59717 (United States); Weisenstein, Adam; Sofie, Stephen [Department of Mechanical Engineering, Roberts 220, Montana State University, Bozeman, Montana 59717 (United States)

2013-06-28

Electrical conductivity of Sr{sub 2-x}VMoO{sub 6-y} (x = 0.0, 0.1, 0.2) double perovskites has been investigated in a reducing atmosphere at temperatures up to 800 °C. This material has a key application in solid oxide fuel cell anodes as a mixed ion and electron conductor. A solid state synthesis technique was used to fabricate materials and crystal structure was verified through x-ray diffraction. Subsequent to conventional sintering in a reducing environment, elemental valence states were indentified through x-ray photoemission spectroscopy on the double perovskite material before and after annealing in a hydrogen environment. Samples exhibited metallic like conduction with electrical conductivities of 1250 S/cm (Sr{sub 2}VMoO{sub 6-y′}), 2530 S/cm (Sr{sub 1.8}VMoO{sub 6-y″}), and 3610 S/cm (Sr{sub 1.9}VMoO{sub 6-y‴}) at 800 °C in 5% H{sub 2}/95% N{sub 2}, with a substantial increase in conductivity upon cooling to room temperature. Room temperature electrical conductivity values for Sr{sub 1.9}VMoO{sub 6-y‴} make it a candidate as the highest electrically conductive oxide known. Highly insulating secondary surface phases, Sr{sub 3}V{sub 2}O{sub 8}, and SrMoO{sub 4}, begin to reduce at 400 °C in a hydrogen environment, as confirmed by X-ray photoemission and thermal gravimetric analysis. This reduction, from V{sup 5+} and Mo{sup 6+} to lower valence states, leads to a large increase in sample electrical conductivity.

Effect of zinc substitution on the structural, electrical and magnetic properties of nano-structured Ni0.5Co0.5Fe2O4 ferrites

Science.gov (United States)

Babu, K. Vijaya; Sailaja, B.; Jalaiah, K.; Shibeshi, Paulos Taddesse; Ravi, M.

2018-04-01

A series of Ni0.5Co0.5-xZnxFe2O4 (x = 0, 0.02, 0.04 and 0.06) nanoferrites were synthesized by sol-gel method using citric acid as chelating reagent. The synthesized ferrite systems are characterized by XRD, SEM, FTIR, ESR and dielectric techniques. The formation of cubic spinel phase belonging to space group Fd3m is identified from the X-ray diffraction patterns. SEM showed the particles are in spherical shape with an average grain size 5-10 nm. FTIR spectra portrait the fundamental absorption bands in the range 400-600 cm-1 relating to octahedral and tetrahedral sites. Dielectric properties are investigated over the frequency range of 20 Hz to 1 MHz at room temperature. A difference in dielectric constant (εr) and dissipation factor (tanδ) of the ferrites has been observed. The dielectric constant and dielectric loss tangent decreases exponentially with increase in frequency. The obtained results are good agreeing with the reported values.

Low temperature plasma-enhanced ALD TiN ultrathin films for Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based ferroelectric MIM structures

Energy Technology Data Exchange (ETDEWEB)

Kozodaev, M.G.; Chernikova, A.G.; Markeev, A.M. [Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); Lebedinskii, Y.Y. [Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); National Research Nuclear University MEPhI, Moscow Engineering Physics Institute, Kashirskoye Shosse 31, 115409 Moscow (Russian Federation); Polyakov, S.N. [Technological Institute for Superhard and Novel Carbon Materials, Tsentral' naya str. 7a, 142190, Troitsk, Moscow (Russian Federation)

2017-06-15

In this work chemical and electrical properties of TiN films, grown by low temperature plasma-enhanced atomic layer deposition (PE-ALD) process from TiCl{sub 4} and NH{sub 3}, were investigated. Electrical resistivity as low as 250 μOhm x cm, as well as the lowest Cl impurity content, was achieved at 320 C. Full-ALD Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based metal-ferroelectric-metal capacitor with TiN electrodes was fabricated and its electrical properties were investigated. It was also shown that the proposed PE-ALD process provides an early film continuity, which was confirmed by ultrathin fully continuous film growth. Such ultrathin (3 nm) and fully continuous TiN film was also successfully implemented as the top electrode to Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based ferroelectric capacitor. Angle-resolved X-ray photoelectron spectroscopy (AR-XPS) was used for its thickness determination and a visible wake-up effect in underlying Hf{sub 0.5}Zr{sub 0.5}O{sub 2} layer was clearly observed. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Estimation of Joule heating and its role in nonlinear electrical response of Tb0.5Sr0.5MnO3 single crystal

Science.gov (United States)

Nhalil, Hariharan; Elizabeth, Suja

2016-12-01

Highly non-linear I-V characteristics and apparent colossal electro-resistance were observed in non-charge ordered manganite Tb0.5Sr0.5MnO3 single crystal in low temperature transport measurements. Significant changes were noticed in top surface temperature of the sample as compared to its base while passing current at low temperature. By analyzing these variations, we realize that the change in surface temperature (ΔTsur) is too small to have caused by the strong negative differential resistance. A more accurate estimation of change in the sample temperature was made by back-calculating the sample temperature from the temperature variation of resistance (R-T) data (ΔTcal), which was found to be higher than ΔTsur. This result indicates that there are large thermal gradients across the sample. The experimentally derived ΔTcal is validated with the help of a simple theoretical model and estimation of Joule heating. Pulse measurements realize substantial reduction in Joule heating. With decrease in sample thickness, Joule heating effect is found to be reduced. Our studies reveal that Joule heating plays a major role in the nonlinear electrical response of Tb0.5Sr0.5MnO3. By careful management of the duty cycle and pulse current I-V measurements, Joule heating can be mitigated to a large extent.

Photoassociation spectroscopy of 87Rb2 (5s1/2+5p1/2)0u+ long-range molecular states: Coupling with the (5s1/2+5p3/2)0u+ series analyzed using the Lu-Fano approach

International Nuclear Information System (INIS)

Jelassi, H.; Viaris de Lesegno, B.; Pruvost, L.

2006-01-01

We report on photoassociation of cold 87 Rb atoms providing the spectroscopy of (5s 1/2 +5p 1/2 )0 u + long-range molecular states, in the energy range of [-12.5, -0.7 cm -1 ] below the dissociation limit. A Lu-Fano approach coupled to the LeRoy-Bernstein formula is used to analyze the data. The Lu-Fano graph exhibits the coupling of the molecular series with the (5s 1/2 +5p 3/2 )0 u + one, which is due to spin effects in the molecule. A two-channel model involving an improved LeRoy-Bernstein formula allows us to characterize the molecular series, to localize (5s 1/2 +5p 3/2 )0 u + levels, to evaluate the coupling, and to predict the energy and width of the first predissociated level of (5s 1/2 +5p 3/2 )0 u + series. An experimental spectrum confirms the prediction

Formation of perovskite-type compounds La0.5Ca0.5Mn1-xTixO3 (0≤x≤0.5)

International Nuclear Information System (INIS)

Wang, K.-Y.; Arcas, J.; Chen, D.-X.; Hernando, A.

1997-01-01

A series of perovskite-type compounds La 0.5 Ca 0.5 Mn 1-x Ti x O 3 is prepared by solid-state reaction. It is found that a single-phase tetragonal structure can be obtained for x≤0.5; the lattice parameters increase and magnetization at μ 0 H=0.2. T decreases with increasing x. (orig.)

Fabrication and magnetic properties of Ni0.5Zn0.5Fe2O4 nanofibres by electrospinning

International Nuclear Information System (INIS)

Jun, Xiang; Xiang-Qian, Shen; Fu-Zhan, Song; Ming-Quan, Liu

2009-01-01

NiZn ferrite/polyvinylpyrrolidone composite fibres were prepared by sol–gel assisted electrospinning. Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres with a pure cubic spinel structure were obtained subsequently by calcination of the composite fibres at high temperatures. This paper investigates the thermal decomposition process, structures and morphologies of the electrospun composite fibres and the calcined Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres at different temperatures by thermo-gravimetric and differential thermal analysis, x-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The magnetic behaviour of the resultant nanofibres was studied by a vibrating sample magnetometer. It is found that the grain sizes of the nanofibres increase significantly and the nanofibre morphology gradually transforms from a porous structure to a necklace-like nanostructure with the increase of calcination temperature. The Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres obtained at 1000 °C for 2 h are characterized by a necklace-like morphology and diameters of 100–200 nm. The saturation magnetization of the random Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres increases from 46.5 to 90.2 emu/g when the calcination temperature increases from 450 to 1000 °C. The coercivity reaches a maximum value of 11.0 kA/m at a calcination temperature of 600 °C. Due to the shape anisotropy, the aligned Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres exhibit an obvious magnetic anisotropy and the ease magnetizing direction is parallel to the nanofibre axis. (condensed matter: structure, thermal and mechanical properties)

Ion mobility and conductivity in the M{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} (M=K, Rb) solid solutions with fluorite structure

Energy Technology Data Exchange (ETDEWEB)

Kavun, V. Ya., E-mail: kavun@ich.dvo.ru [Institute of Chemistry FEBRAS, 159, Pr. 100-letya Vladivostoka, Vladivostok 690022 (Russian Federation); Uvarov, N.F. [Institute of Solid State Chemistry and Mechanochemistry, SB RAS, 18, Kutateladze Str., Novosibirsk 630128 (Russian Federation); Slobodyuk, A.B.; Polyantsev, M.M.; Merkulov, E.B. [Institute of Chemistry FEBRAS, 159, Pr. 100-letya Vladivostoka, Vladivostok 690022 (Russian Federation); Ulihin, A.S. [Institute of Solid State Chemistry and Mechanochemistry, SB RAS, 18, Kutateladze Str., Novosibirsk 630128 (Russian Federation); Goncharuk, V.K. [Institute of Chemistry FEBRAS, 159, Pr. 100-letya Vladivostoka, Vladivostok 690022 (Russian Federation)

2017-05-15

Ionic mobility and conductivity in the K{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} and Rb{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} (x=0.05, 0.09) solid solutions with the fluorite structure have been investigated using the methods of {sup 19}F NMR, X-ray diffraction and impedance spectroscopy. Types of ionic motions in the fluoride sublattice of solid solutions have been established and temperature ranges of their realization have been determined (150–450 K). Diffusion of fluoride ions is a dominating type of ionic motions in the fluoride sublattice of solid solutions under study above 350 K. Due to high ionic conductivity, above 10{sup –3} S/cm at 450 K, these solid solutions can be used as solid electrolytes in various electrochemical devices and systems. - Graphical abstract: Temperature dependence of the concentration of mobile (2, 4) and immobile (1, 3) F ions in the K{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} solid solutions. - Highlights: • Studied the ion mobility, conductivity in M{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} solid solutions (M=K, Rb). • An analysis of {sup 19}F NMR spectra made it possible to identify types of ion mobility. • The main type of ion motion above 300 K in solid solutions is a diffusion of ions F{sup –}. • The ionic conductivity of the solid solutions studied more than 10{sup –3} S/cm at 450 K.

Sinterability studies on K0.5Na0.5NbO3 using laser as energy source

International Nuclear Information System (INIS)

Tian Xiaoyong; Dittmar, Anne; Melcher, Joerg; Heinrich, Juergen G.

2010-01-01

The sinterability of K 0.5 Na 0.5 NbO 3 (KNN) ceramics by a laser beam has been investigated in the present research. A 100 W CO 2 laser with a beam diameter of 0.6 mm has been used to sinter the KNN specimens prepared on a uniaxial pressing machine. The relations between laser power and thickness of densified layer, crystallographic structures and phase compositions have been studied. A comparison has been made between laser and furnace sintered KNN samples according to the SEM, XRD and XRF results. The possibility of KNN used for the layer-wise laser direct sintering 3D components has been confirmed in this paper.

Structural and electrical properties of La{sub 0.5}Ca{sub 0.5}Mn{sub 0.95}Fe{sub 0.05}O{sub 3+{delta}} perovskite

Energy Technology Data Exchange (ETDEWEB)

Mohamed, E.A., E-mail: emanattamohammed@yahoo.com [Department of Physics, Faculty of Science (Girl' s Branch), Al Azhar University, Nasr City, Cairo (Egypt)

2012-12-05

Highlights: Black-Right-Pointing-Pointer La{sub 0.5}Ca{sub 0.5}Mn{sub 0.95}Fe{sub 0.05}O{sub 3+{delta}} synthesis has been achieved by co-precipitation process. Black-Right-Pointing-Pointer Moessbauer results show an evidence for the local distortion of Mn(Fe)O{sub 6} octahedron. Black-Right-Pointing-Pointer Metal-Semiconductor transition temperature (T{sub p}) is observed. - Abstract: La{sub 0.5}Ca{sub 0.5}Mn{sub 0.95}Fe{sub 0.05}O{sub 3+{delta}} was synthesized by co-precipitation method. The structure refinement by using the Rietveld method indicates that the sample was single phase with the presence of small impurities (Mn{sub 3}O{sub 4}) and crystallizes in an orthorhombic (Pbmn) structure. The room temperature (RT) Moessbauer spectrum shows clear evidence of the local structural distortion of the Mn(Fe)O{sub 6} octahedron on the basis of non-zero nuclear quadrupole interactions for high-spin Fe{sup 3+} ions. The Jahn-Teller coupling strength (E{sub JT}) was estimated from the Moessbauer results. Metal-Semiconductor transition temperature (T{sub p}) is observed at 80 K. At high temperature (T{sub P} < T < {theta}{sub D}/2) conductivity data satisfy the variable range hopping (VRH) model. For T > {theta}{sub D}/2 the small polaron hopping model is more appropriate than the VRH model.

Highly efficient and robust cathode materials for low-temperature solid oxide fuel cells: PrBa0.5Sr0.5Co(2-x)Fe(x)O(5+δ).

Science.gov (United States)

Choi, Sihyuk; Yoo, Seonyoung; Kim, Jiyoun; Park, Seonhye; Jun, Areum; Sengodan, Sivaprakash; Kim, Junyoung; Shin, Jeeyoung; Jeong, Hu Young; Choi, YongMan; Kim, Guntae; Liu, Meilin

2013-01-01

Solid oxide fuel cells (SOFC) are the cleanest, most efficient, and cost-effective option for direct conversion to electricity of a wide variety of fuels. While significant progress has been made in anode materials with enhanced tolerance to coking and contaminant poisoning, cathodic polarization still contributes considerably to energy loss, more so at lower operating temperatures. Here we report a synergistic effect of co-doping in a cation-ordered double-perovskite material, PrBa0.5Sr0.5Co(2-x)Fe(x)O(5+δ), which has created pore channels that dramatically enhance oxygen ion diffusion and surface oxygen exchange while maintaining excellent compatibility and stability under operating conditions. Test cells based on these cathode materials demonstrate peak power densities ~2.2 W cm(-2) at 600°C, representing an important step toward commercially viable SOFC technologies.

DEEP 21 cm H I OBSERVATIONS AT z ∼ 0.1: THE PRECURSOR TO THE ARECIBO ULTRA DEEP SURVEY

International Nuclear Information System (INIS)

Freudling, Wolfram; Zwaan, Martin; Staveley-Smith, Lister; Meyer, Martin; Catinella, Barbara; Minchin, Robert; Calabretta, Mark; Momjian, Emmanuel; O'Neil, Karen

2011-01-01

The 'ALFA Ultra Deep Survey' (AUDS) is an ongoing 21 cm spectral survey with the Arecibo 305 m telescope. AUDS will be the most sensitive blind survey undertaken with Arecibo's 300 MHz Mock spectrometer. The survey searches for 21 cm H I line emission at redshifts between 0 and 0.16. The main goals of the survey are to investigate the H I content and probe the evolution of H I gas within that redshift region. In this paper, we report on a set of precursor observations with a total integration time of 53 hr. The survey detected a total of eighteen 21 cm emission lines at redshifts between 0.07 and 0.15 in a region centered around α 2000 ∼ 0 h , δ ∼ 15 0 42'. The rate of detection is consistent with the one expected from the local H I mass function. The derived relative H I density at the median redshift of the survey is ρ H I [z = 0.125] = (1.0 ± 0.3)ρ 0 , where ρ 0 is the H I density at zero redshift.

The effect of texture in (Bi3.5Nd0.5)(Ti2.97Nb0.03)O12 ceramics

International Nuclear Information System (INIS)

Cao, Ziping; Ding, Aili; Zheng, Xinsen; Qiu, Pingsun; Cheng, Wenxiu

2004-01-01

(Bi 3.5 Nd 0.5 ) (Ti 2.97 Nb 0.03 )O 12 ferroelectric ceramics was successfully prepared by a hot-pressing method. XRD diffraction confirms that the samples hold different texture in the sliced planes parallel and perpendicular to the hot-pressing axis, respectively. The anisotropy of ferroelectric, dielectric and piezoelectric properties were all observed in the textured ceramics. Due to the great improvement of ferroelectric and piezoelectric properties, the sample which was sliced along the direction parallel to the hot-pressing axis can be considered as a good candidate of high temperature piezoelectric materials. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Differentiation of large (≥5 cm) gastrointestinal stromal tumors from benign subepithelial tumors in the stomach: Radiologists’ performance using CT

Energy Technology Data Exchange (ETDEWEB)

Choi, Ye Ra [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Kim, Se Hyung, E-mail: shkim7071@gmail.com [Department of Radiology, Seoul National University Hospital (Korea, Republic of); The Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of); Kim, Sun-Ah [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Shin, Cheong-il [Department of Radiology, Seoul National University Hospital (Korea, Republic of); The Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of); Kim, Hyung Jin; Kim, Seong Ho [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Han, Joon Koo; Choi, Byung Ihn [Department of Radiology, Seoul National University Hospital (Korea, Republic of); The Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of)

2014-02-15

Purpose: To identify significant CT findings for the differentiation of large (≥5 cm) gastric gastrointestinal stromal tumors (GIST) from benign subepithelial tumors and to assess whether radiologists’ performance in differentiation is improved with knowledge of significant CT criteria. Materials and methods: One-hundred twenty patients with pathologically proven large (≥5 cm) GISTs (n = 99), schwannomas (n = 16), and leiomyomas (n = 5) who underwent CT were enrolled. Two radiologists (A and B) retrospectively reviewed their CT images in consensus for the location, size, degree and pattern of enhancement, contour, growth pattern and the presence of calcification, necrosis, surface ulceration, or enlarged lymph nodes. CT findings considered significant for differentiation were determined using uni- and multivariate statistical analyses. Thereafter, two successive review sessions for the differentiation of GIST from non-GIST were independently performed by two other reviewers (C and D) with different expertise of 2 and 9 years using a 5-point confidence scale. At the first session, reviewers interpreted CT images without knowledge of significant CT findings. At the second session, the results of statistical analyses were provided to the reviewers. To assess improvement in radiologists’ performance, a pairwise comparison of receiver operating curves (ROC) was performed. Results: Heterogeneous enhancement, presence of necrosis, absence of lymph nodes, and mean size of ≥6 cm were found to be significant for differentiating GIST from schwannoma (P < 0.05). Non-cardial location, heterogeneous enhancement, and presence of necrosis were differential CT features of GIST from leiomyoma (P < 0.05). Multivariate analyses indicated that absence of enlarged LNs was the only statistically significant variable for GIST differentiating from schwannoma. The area under the curve of both reviewers obtained using ROC significantly increased from 0.682 and 0.613 to 0.903 and 0

Programming Models for Three-Dimensional Hydrodynamics on the CM-5 (Part II)

International Nuclear Information System (INIS)

Amala, P.A.K.; Rodrigue, G.H.

1994-01-01

This is a two-part presentation of a timing study on the Thinking Machines CORP. CM-5 computer. Part II is given in this study and represents domain-decomposition and message-passing models. Part I described computational problems using a SIMD model and connection machine FORTRAN (CMF)

A family of oxide ion conductors based on the ferroelectric perovskite Na0.5Bi0.5TiO3.

Science.gov (United States)

Li, Ming; Pietrowski, Martha J; De Souza, Roger A; Zhang, Huairuo; Reaney, Ian M; Cook, Stuart N; Kilner, John A; Sinclair, Derek C

2014-01-01

Oxide ion conductors find important technical applications in electrochemical devices such as solid-oxide fuel cells (SOFCs), oxygen separation membranes and sensors. Na0.5Bi0.5TiO3 (NBT) is a well-known lead-free piezoelectric material; however, it is often reported to possess high leakage conductivity that is problematic for its piezo- and ferroelectric applications. Here we report this high leakage to be oxide ion conduction due to Bi-deficiency and oxygen vacancies induced during materials processing. Mg-doping on the Ti-site increases the ionic conductivity to ~0.01 S cm(-1) at 600 °C, improves the electrolyte stability in reducing atmospheres and lowers the sintering temperature. This study not only demonstrates how to adjust the nominal NBT composition for dielectric-based applications, but also, more importantly, gives NBT-based materials an unexpected role as a completely new family of oxide ion conductors with potential applications in intermediate-temperature SOFCs and opens up a new direction to design oxide ion conductors in perovskite oxides.

Magnetic and electrical transport properties of La0.5A0.5CoO3 nanoparticles (A = Sr, Ca, and Ba)

International Nuclear Information System (INIS)

Roy, B.; Das, S.

2011-01-01

Research highlights: → La 0.5 A 0.5 CoO 3 (A = Sr, Ca, and Ba) nanoparticles prepared by sol-gel technique. → Size-induced metal-insulator transition in Sr- and Ba-doped samples. → Broad paramagnetic to ferromagnetic transition with large magnetic irreversibility. → Co 3+ ions in intermediate and Co 4+ in a mixture of intermediate and high spin states. → ac magnetization suggests magnetic cluster glass nature of the samples. - Abstract: We have investigated the effect of particle size on the electrical transport and magnetic properties of La 0.5 A 0.5 CoO 3 (A = Sr, Ca, and Ba) nanoparticles synthesized by sol-gel technique. A size-induced metal to insulator transition is observed in the resistivity behaviour of Sr- and Ba-doped samples as the dimension changes from higher to lower ones. The magnetoresistance exhibits almost linear behaviour throughout the studied field range. The zero-field-cooled (ZFC) and field-cooled (FC) magnetizations display a broad paramagnetic to ferromagnetic transition at T C with a large magnetic irreversibility. The magnetization results indicate that Co 3+ ions are in the intermediate spin state but Co 4+ ions stay in a mixture of intermediate and high spin states. The observed frequency dependent shoulder in the in-phase and the peak in the out of phase component of the ac susceptibility indicate the glassy nature of the samples. The analysis of the ac magnetization results suggests that the magnetic behaviour is consistent with the cluster glass model.

Determination of the absolute efficiency of an organic scintillator for neutrons with energies between 0.5 and 800 MeV

International Nuclear Information System (INIS)

Howe, S.D.; Lisowski, P.W.; Russell, G.J.; King, N.S.P.; Donnert, H.J.

1984-01-01

We have determined the absolute efficiency of an NE-213 scintillator for neutrons with energies from 0.5 to 800 MeV. The detector was 5.1 cm in diameter and 2.5 cm deep. The efficiencies were obtained for detector thresholds of 0.011, 0.48, 1.12, and 4.48 MeVee. Our results are compared to predictions of the STANTON computer code. (orig.)

Field induced ferromagnetic fraction enlargement in phase separated La_0.5Ca_0.5MnO_3

Science.gov (United States)

Ghivelder, Luis; Freitas, R. S.; Sacanel, J.; Parisi, F.; Levy, P.

2001-03-01

A systematic study of the magnetic and transport properties of a series of phase separated La_0.5Ca_0.5MnO3 compounds is reported. The investigated samples all have the same composition but different grain sizes, which modifies the volume fraction of the coexisting ferromagnetic (FM) and antiferromagnetic charge-ordered (AFM-CO) phases. Magnetoresistance and magnetization measurements were performed with two different experimental procedures: a standard field-cooled cooling (FC) mode, and a second method in which the field is turned on only while measuring each data point, and switched off while cooling the samples. Magnetization and magnetoresistance measurements display big differences when comparing the data obtained with the different procedures. The overall results are interpret in terms of a field induced FM fraction enlargement. In transport measurements this effect yield a percolative transition. Magnetization data shows evidence for the formation of AFM-CO regions within the FM phase. * e-mail: luisghiv@if.ufrj.br

The U5.0 Undulator for the ALS

International Nuclear Information System (INIS)

Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

1991-01-01

the U5.0 Undulator, and 89 period, 5 cm period length, 4.6 m long insertion device has been designed, is being fabricated and is scheduled for completion in early 1992. This undulator will be the first high brightness source, in the 50 to 1500 eV range, for the Advanced Light Source (ALS) at the Lawrence Berkeley Laboratory. A hybrid magnetic configuration using Nd-Fe-B permanent magnet material and vanadium permendur poles has been selected to achieve the field quality needed to meet performance requirements. The magnetic structure is modular with each half consisting of 5 assembly sections, which provide the periodic structure, and end structures, for entrance and exit correction, mounted on a steel backing beam. Each assembly section consists of 35 half-period pole assemblies bolted to a mount. The required 0.837 Tesla effective peak field at a 1.4 cm gap has been verified with model measurements. Vertical field integral correction is accomplished with the end structures, each having an arrangement of permanent magnet rotors which will be adjusted to minimize electron beam missteering over the undulator operating field range. To reduce the effect of environmental fields, the steel backing beams are connected through parallel, low-reluctance, Ni-Fe hinges. The magnetic structure is connected through four roller-nuts to the drive system that provides gap adjustment with an arrangement of roller screws, chain drives, a gear reduction unit and a stepper motor driven by a closed loop control system. Magnetic structure and drive system support are from a 2.4 m high structure which includes a support base with four vertical supports. The vacuum chamber design is a two-piece machined and welded 5083-H321 aluminum construction of 5.1 m length. Pumping is with a combination of ion, TSP and NEG pumps. Magnetic design, subsystem design and fabrication progress are presented

Uranium sandwich targets of 0.1 to 100 mg.cm-2 prepared by electron beam gun evaporation

International Nuclear Information System (INIS)

Folger, H.; Klemm, J.

1978-01-01

Metallic uranium layers of 0.1 to 100 mg.cm -2 between different backings and protecting layers were prepared for bombardments with heavy ions such as argon, krypton, xenon, lead, or uranium at energies of up to 8 MeV/u at the UNILAC of the GSI. An experimental set-up for the preparation of thick and oxygen-free sandwich targets using a 6 kVA electron beam gun was installed in a high vacuum apparatus. Then deposition and evaporation rates for uranium were investigated as a function of the electron beam gun power. It turned out that reproducible evaporation rates of up to 7 mg.s -1 were achieved when uranium pieces of 20 to 40 grams were used. Specific evaporation rates and vapor pressures for different temperatures were calculated. Some of these data are compared to measured values, especially evaporation rates at the evaporation point. The preparation, composition, and usage of uranium sandwich targets is described in detail. It concerns uranium layers of 0.1 to 100 mg.cm -2 deposited onto backings of carbon, titanium, nickel, gold, or glass. Evaporated films of carbon, titanium, nickel, or gold of 0.01 to 0.2 mg.cm -2 are used to protect the uranium layers from oxidation

ASCA and XMM-Newton observations of the galactic supernova remnant G311.5−0.3

Directory of Open Access Journals (Sweden)

Pannuti T.G.

2017-01-01

Full Text Available We present an analysis of X-ray observations made with ASCA and XMM-Newton of the Galactic supernova remnant (SNR G311.5−0.3. Prior infrared and radio observations of this SNR have revealed a shell-like morphology at both wavelengths. The spectral index of the radio emission is consistent with synchrotron emission, while the infrared colors are consistent with emission from shocked molecular hydrogen. Also previous CO observations have indicated an interaction between G311.5−0.3 and an adjacent molecular cloud. Our previous analysis of the pointed ASCA observation made of this SNR detected X-ray emission from the source for the first time but lacked the sensitivity and the angular resolution to rigorously investigate its X-ray properties. We have analyzed an archival XMM-Newton observation that included G311.5−0.3 in the field of view: this is the first time that XMM-Newton data has been used to probe the X-ray properties of this SNR. The XMM-Newton observation confirms that the X-ray emission from G311.5−0.3 is centrally concentrated and supports the classification of this source as a mixed-morphology SNR. In addition, our joint fitting of extracted ASCA and XMM-Newton spectra favor a thermal origin for the X-ray emission over a non-thermal origin. The spectral fitting parameters for our TBABS×APEC fit to the extracted spectra are NH = 4.63+1.87 −0.85×1022 cm −2 and kT = 0.68+0.20−0.24 keV. From these fit parameters, we derive the following values for physical parameters of the SNR: ne = 0.20 cm −3, np = 0.17 cm −3, MX = 21.4 M· and P/k = 3.18×106 K cm −3.

Ferrites Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} doped with samarium: structural analysis, morphological and electromagnetic; Ferritas Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} dopada com samario: analise estrutural, morfologica e eletromagnetica

Energy Technology Data Exchange (ETDEWEB)

Costa, A.C.F.M.; Diniz, A.P., E-mail: anacristina@dema.ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academinca de Engenharia de Materiais; Viana, K.M.S. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, PE (Brazil). Escola de Ciencias e Tecnologia; Cornejo, D.R. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

2010-07-01

This paper proposes to investigate the sintering at 1200 deg C/2h of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2-x}Sm{sub x}O{sub 4} ferrite doped with 0.05; 0.075 e 0.1 mol of Sm synthesized by combustion reaction to evaluate the performance materials as absorbers of electromagnetic radiation. The influence of the concentration of samarium on the structure, morphology and electromagnetic properties of ferrites was studied. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic measurements and reflectivity measurements in the frequency range between 8-12 GHz. The results showed that increasing the concentration of samarium caused a decrease in particle size of the samples, encouraging, therefore, to obtain materials with better values of magnetization and reflectivity, allowing for use as absorbers in narrow-band frequency between 9-10 GHz. (author)

Effects of processing parameters on the synthesis of (K0.5Na0.5)NbO3 nanopowders by reactive high-energy ball milling method.

Science.gov (United States)

Nguyen, Duc Van

2014-01-01

The effects of ball milling parameters, namely, the ball-to-powder mass ratio and milling speed, on the synthesis of (K0.5Na0.5)NbO3 nanopowders by high-energy ball milling method from a stoichiometric mixture containing Na2CO3, K2CO3, and Nb2O5 were investigated in this paper. The results indicated that the single crystalline phase of (K0.5Na0.5)NbO3 was received in as-milled samples synthesized using optimized ball-to-powder mass ratio of 35 : 1 and at a milling speed of 600 rpm for 5 h. In the optimized as-milled samples, no remaining alkali carbonates that can provide the volatilizable potassium-containing species were found and (K0.5Na0.5)NbO3 nanopowders were readily obtained via the formation of an intermediate carbonato complex. This complex was mostly transformed into (K0.5Na0.5)NbO3 at temperature as low as 350°C and its existence was no longer detected at spectroscopic level when calcination temperature crossed over 700°C.

Neutron structural studies of La3.5-x-y(Y)yBa3.5-xCa2xCu7Oz (x = y = 0.0 and 0.5) system

International Nuclear Information System (INIS)

Subbarao, M.V.; Kulkarni, R.G.; Rajagopal, H.; Sequeira, A.S.

1997-01-01

By mixing equal amounts of La 4-x Ca x Ba 3 Cu 7 O z and La 3 Ba 4-x Ca x Cu 7 O z in the proportion of 1 : 1, a series of superconductors part of La replaced by Y with the nominal composition of La 3.5-x-y )(Y) y Ba 3.-5-x Ca 2x Cu 7 O z (LYCP) have been prepared. Two samples with x = y = 0.0 (A) and x = y = 0.5 (B) characterized by x-ray diffraction display tetragonal triple perovskite structure. In order to investigate the effect of substituents (Ca/Y) on structure of this system, neutron diffraction measurements have been carried out at 300 K and λ n =1.216A at Dhruva reactor

Ga2O3 Schottky rectifiers with 1 ampere forward current, 650 V reverse breakdown and 26.5 MW.cm-2 figure-of-merit

Science.gov (United States)

Yang, Jiancheng; Ren, F.; Tadjer, Marko; Pearton, S. J.; Kuramata, A.

2018-05-01

A key goal for Ga2O3 rectifiers is to achieve high forward currents and high reverse breakdown voltages. Field-plated β-Ga2O3 Schottky rectifiers with area 0.01 cm2, fabricated on 10 μm thick, lightly-doped drift regions (1.33 x 1016 cm-3) on heavily-doped (3.6 x 1018 cm-3) substrates, exhibited forward current density of 100A.cm-2 at 2.1 V, with absolute current of 1 A at this voltage and a reverse breakdown voltage (VB) of 650V. The on-resistance (RON) was 1.58 x 10-2 Ω.cm2, producing a figure of merit (VB2/RON) of 26.5 MW.cm-2. The Schottky barrier height of the Ni was 1.04 eV, with an ideality factor of 1.02. The on/off ratio was in the range 3.3 x 106 - 5.7 x 109 for reverse biases between 5 and 100V. The reverse recovery time was ˜30 ns for switching from +2V to -5V. The results show the capability of β-Ga2O3 rectifiers to achieve exceptional performance in both forward and reverse bias conditions.

Effects of Sr2+ doping on the electrical properties of (Bi0.5Na0.50.94Ba0.06TiO3 ceramics

Directory of Open Access Journals (Sweden)

Amrita Singh

2015-03-01

Full Text Available The influence of SrTiO3 addition on the microstructure and various electrical properties of (Bi0.5Na0.50.94Ba0.06TiO3 (BNTBT6 ceramics, fabricated by a conventional high temperature solid state reaction, was investigated. Analysis of X-ray diffraction patterns revealed the formation of phase pure materials with tetragonal unit cell structure, tetragonality parameter c/a in the interval from 0.9940 to 1.0063 and crystallite sizes ranging from 33–76 nm for addition of 0.2 to 1 wt.% of SrTiO3. SEM studies indicated that Sr2+ doping led to decrease in grain size and non-homogeneity of grain distribution for higher SrTiO3 amount (>0.6 wt.%. Complex impedance, modulus, and conductivity studies indicated the presence of grains and grain boundary contribution, non-Debye type of relaxation and NTCR behaviour of the test ceramic samples. Temperature dependent real part of complex permittivity showed peaks at 475 °C and the dielectric loss tangent showed peaks corresponding to 125 °C and 475 °C for almost all compositions. AC activation energies, computed using Arrhenius relation in the temperature range of 325–500 °C for the BNTBT6 ceramic compositions having SrTiO3 concentration from 0.2 to 1.0 wt.%, were seen to have maximal values at the lowest measurement frequency. Amongst the different chosen doped BNTBT6 ceramic compositions, the composition having 0.6 wt.% of SrTiO3 showed the best ferroelectric and piezoelectric response with maximum value of Pr (8.24 µC/cm2, minimum value of Ec (5.73 kV/mm and maximum d33 value (∼46 pC/N.

Development, validation and testing of a skin sampling method for assessment of metal exposure.

Science.gov (United States)

Erfani, Behnaz; Midander, Klara; Lidén, Carola; Julander, Anneli

2017-07-01

Nickel, cobalt and chromium are frequent skin sensitizers. Skin exposure results in eczema in sensitized individuals, the risk being related to the skin dose. To develop a self-sampling method for quantification of skin exposure to metals, to validate the method, and to assess its feasibility. Defined metal doses (0.01-5 µg) were applied to the fingers of 5 participants. Skin areas (2 cm 2 ) were sampled with 1% HNO 3 , either as 0.1 ml on a swab, or as 0.5 ml on a wipe. Furthermore, 17 participants performed self-sampling by swab after 2 h of leisure activity. Samples were extracted in 1% HNO 3 and analysed by inductively coupled plasma mass spectrometry. The sampling efficiency by swab was 46%, as compared with 93% for acid wipe sampling, for all tested doses. Most metal from the skin dose was detected in the first swab (33-43%). Despite lower sampling efficiency by swab, skin doses of metals following 2 h of leisure activity without hand washing were quantified in all participants, and ranged from 0.0016 to 0.15 µg/cm 2 , from 0.00014 to -0.0020 µg/cm 2 and from 0.00048 to -0.027 µg/cm 2 for nickel, cobalt, and chromium, respectively. The results indicate a future potential of skin sampling by swab to detect and monitor metals on skin by self-sampling. This will contribute to better knowledge of metal skin exposure among dermatitis patients, workers, and the general population. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Liquid phase interaction in TiC0,5N0,5-TiNi-Mo and TiC0,5N0,5-TiNi-Ti-Mo

International Nuclear Information System (INIS)

Askarova, L.Kh; Grigorov, I.G.; Zajnulin, Yu.G.

1998-01-01

Using the methods of X ray diffraction analysis, electron microscopy and X ray spectrum microanalysis a study was made into specific features of phase and structure formation in alloys TiC 0,5 N 0,5 -TiNi-Mo and TiC 0,5 N 0,5 -TiNi-Mo in the presence of a liquid phase at temperatures of 1380-1600 deg C. It is revealed that the physical and chemical processes taking place during the liquid-phase sintering result in the formation of a three-phase alloy consisting of nonstoichiometric titanium carbonitride TiC 0.5-x N 0.5-x , a molybdenum base solid solution of titanium, nickel and carbon Mo(Ti, Ni, C) and one of two intermetallic compounds, either TiNi or Ni 3 Ti. Metallic element concentration in individual phase constituents of the alloy is determined by means of X ray spectrum microanalysis

Investigation of structural and electrical properties of (1 - x) Bi0.5Mg0.5TiO3-(x) PbTiO3 ceramic system

International Nuclear Information System (INIS)

Rai, Radheshyam; Sinha, Abinhav; Sharmac, Seema; Sinha, N.K.P.

2009-01-01

[(BiMg 0.5 Ti 0.5 O 3 ) 1-x ][PbTiO 3 ] x (BMT-PT) ceramic powders of different compositions were prepared by solid-state reaction method. X-ray diffraction analysis of the compounds suggest the structural change (rhombohedral to tetragonal) in these ceramics. SEM photographs exhibit the uniform distribution of grains with less porosity. Polarization vs. electric field (P-E) studies show maximum remanent polarization (P r ∼ 7.9 μC/cm 2 ) for composition x = 0.34. The dielectric peaks were found to be broadened that indicates the existence of diffuse phase transition. Diffusivity (γ) study of phase transition in these compounds provided values between 1 and 2 indicating the variation of degree of disorderness in the system.

Simulation of 1.5-mm-thick and 15-cm-diameter gated silicon drift X-ray detector operated with a single high-voltage source

Science.gov (United States)

Matsuura, Hideharu

2015-04-01

High-resolution silicon X-ray detectors with a large active area are required for effectively detecting traces of hazardous elements in food and soil through the measurement of the energies and counts of X-ray fluorescence photons radially emitted from these elements. The thicknesses and areas of commercial silicon drift detectors (SDDs) are up to 0.5 mm and 1.5 cm2, respectively. We describe 1.5-mm-thick gated SDDs (GSDDs) that can detect photons with energies up to 50 keV. We simulated the electric potential distributions in GSDDs with a Si thickness of 1.5 mm and areas from 0.18 to 168 cm2 at a single high reverse bias. The area of a GSDD could be enlarged simply by increasing all the gate widths by the same multiple, and the capacitance of the GSDD remained small and its X-ray count rate remained high.

Enhancing pitting corrosion resistance of AlxCrFe1.5MnNi0.5 high-entropy alloys by anodic treatment in sulfuric acid

International Nuclear Information System (INIS)

Lee, C.P.; Chen, Y.Y.; Hsu, C.Y.; Yeh, J.W.; Shih, H.C.

2008-01-01

High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al x CrFe 1.5 MnNi 0.5 (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 Ωcm 2 as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 Ωcm 2 ). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H 2 SO 4 solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al 0.3 CrFe 1.5 MnNi 0.5 alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe 1.5 MnNi 0.5 and Al 0.3 CrFe 1.5 MnNi 0.5 alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al x CrFe 1.5 MnNi 0.5 alloys optimized their surface structures and minimized their susceptibility to pitting corrosion

Optical gain tuning within IR region in type-II In0.5Ga0.5As0.8P0.2/GaAs0.5Sb0.5 nano-scale heterostructure under external uniaxial strain

Science.gov (United States)

Singh, A. K.; Rathi, Amit; Riyaj, Md.; Bhardwaj, Garima; Alvi, P. A.

2017-11-01

Quaternary and ternary alloy semiconductors offer an extra degree of flexibility in terms of bandgap tuning. Modifications in the wave functions and alterations in optical transitions in quaternary and ternary QW (quantum well) heterostructures due to external uniaxial strain provide valuable insights on the characteristics of the heterostructure. This paper reports the optical gain in strained InGaAsP/GaAsSb type-II QW heterostructure (well width = 20 Å) under external uniaxial strain at room temperature (300 K). The entire heterostructure is supposed to be grown on InP substrate pseudomorphically. Band structure, wave functions, energy dispersion and momentum matrix elements of the heterostructure have been computed. 6 × 6 diagonalised k → ·p → Hamiltonian matrix of the system is evaluated and Luttinger-Kohn model has been applied for the band structure and wavefunction calculations. TE mode optical gain spectrum in the QW-heterostructure under uniaxial strain along [110] is calculated. Optical gain of the heterostructure as a function of 2D carrier density and temperature variation is investigated. The variation of the peak optical gain as a function of As and Sb fractions in InGaAsP as a barrier and GaAsSb as a well respectively is exhibited. For a charge carrier injection of 5 ×1012 /cm2 , the TE optical gain is 3952 cm-1 at room temperature under no external uniaxial strain. Significant increase in TE mode optical gain is observed under high external uniaxial strain (1, 5 and 10 GPa) along [110] within IR (Infrared region) region.

Synthesis, structural, optical, electrical and Mössbauer spectroscopic studies of Co substituted Li{sub 0.5}Fe{sub 2.5}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Sharma, Parul [School of Physics & Materials Science, Shoolini University, Solan, HP (India); Thakur, Preeti, E-mail: preetithakur@shooliniuniversity.com [School of Physics & Materials Science, Shoolini University, Solan, HP (India); Mattei, Jean Luc; Queffelec, Patrick [Laboratoire des Sciences et Techniques, de l’Information, de la Communication et de la Connaissance, UMR CNRS 6285, 6 av. Le Gorgeu, CS 93837, 29238 BREST CEDEX 3 (France); Thakur, Atul [School of Physics & Materials Science, Shoolini University, Solan, HP (India); Nanotechnology Wing, Innovative Science Research Society, Shimla 171001 (India)

2016-06-01

A series of cobalt substituted lithium ferrite Li{sub 0.5}Co{sub x}Fe{sub 2.5−x}O{sub 4} with x=0, 0.2, 0.4 was prepared by a chemical technique called citrate precursor method. In this technique citric acid was used as a reducing agent. Structural, morphological, topographical, optical, electrical, and magnetic properties were studied by using X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, DC resistivity, Mössbauer Spectroscopy. XRD patterns showed characteristic (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), (4 4 0) peaks which confirmed the inverse spinel phase. SEM and TEM support the formation of cubic nanoparticles. FTIR studies reported the ferrite peaks between 400 cm{sup −1} and 800 cm{sup −1} confirming the inverse spinel structure. Five optical Raman modes (A{sub 1g}+E{sub g}+3F{sub 2g}), characteristics of the cubic spinel structure with (P4{sub 3}32) space group are also observed. Electrical DC resistivity studied from room temperature to 300 °C showed the semiconducting behavior of lithium ferrite. Porosity, transition temperature and activation energy are found to decrease with cobalt ion concentration. The room temperature Mössbauer spectra of all the samples showed normal Zeeman Splitting sextets supporting the formation of ferromagnetic phase. With increase in cobalt content, the value of hyperfine field at A site is found to vary from 53.15 to 54.96 T whereas at B site it vary from 54.79 to 52.82 T. The obtained results have been explained based on possible mechanisms, models and theories. - Highlights: • XRD studies confirmed the spinel structure. • In FTIR studies, two frequency metal oxide bands are observed. • Raman spectra confirmed the symmetric and anti-symmetric band position. • Mössbauer spectroscopy reveals the two magnetic sextets.

Moessbauer and X-ray Study of Fe1-xAlx, 0.2≤x≤0.5, Samples Produced by Mechanical Alloying

International Nuclear Information System (INIS)

Oyola Lozano, D.; MartInez, Y. Rojas; Bustos, H.; Perez Alcazar, G. A.

2004-01-01

In this work we report the magnetic and structural properties obtained by Moessbauer spectroscopy and X-ray diffraction, of the Fe 1-x Al x , 0.2≤x≤0.5, alloys produced by mechanical alloying. Alloys with x=0.2, 0.3, 0.4 and 0.5, were for milled 12, 24, 36, and 48 hours. All the obtained alloys are in the bcc phase. The obtained Moessbauer spectra are characteristic of disordered ferromagnetic system. The lattice parameter remains nearly constant (∼2.91 A) for all the milling times and compositions. The mean grain sizes in the (110) and (211) direction are nearly constants with the milling time but vary from 15.5 to 11 nm and from 10.5 to 8.5 nm when Al content grow between x=0.2 to x=0.4, respectively. The difference between the mean grain sizes in these two directions shows that the grains are of prolate spheroid form.

Structural and Mössbauer spectroscopy characterization of bulk and nanostructured TiFe{sub 0.5} Ni{sub 0.5}/graphite compounds and their hydrides

Energy Technology Data Exchange (ETDEWEB)

Martínez, M. A. R., E-mail: fisicorodriguez@gmail.com; André-Filho, J.; Félix, L. L.; Coaquira, J. A. H.; Garg, V. K.; Oliveira, A. C. [Universidade de Brasília, Instituto de Física, Núcleo de Física Aplicada (Brazil); Mestnik-Filho, J. [Instituto de Pesquisas energéticas e Nucleares, IPEN-CNEN/SP (Brazil)

2015-06-15

The structural and hyperfine properties of bulk TiFe{sub 0.5}Ni{sub 0.5} intermetallic and ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite compounds and their hydrides have been studied. The bulk and nanostructured TiFe{sub 0.5}Ni{sub 0.5} compounds crystallize in the cubic crystal structure of CsCl (B2). After hydrogenation, the formation of hydrogen-poor phase (∝-phase) and hydride phase (β-phase) have been determined for the bulk compound. However, the formation of the ∝-phase and the hydrogen-richest phase (γ-phase) and other secondary phases have been determined for the ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite sample. It has been determined that the ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite sample presents a large amount of the γ-phase which indicates that the presence of graphite nearby nanostructured intermetallic grains enhances the absorption of hydrogen. Mossbauer results are consistent with the structural results. Meanwhile, no significant changes in the isomer shift (IS) value has been determined for the α-phase with respect to the intermetallic compound, a strong increase in the IS value has been determined for the β- and γ-phases with respect to the ∝-phase. That increase indicates a decrease of the s-electron density at the Fe nuclei due to the charge transfer from the metal to the nearby hydrogen atoms.

Effect of vanadium doping on structural, magnetic and magnetocaloric properties of La{sub 0.5}Ca{sub 0.5}MnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Mansouri, M., E-mail: mansourimoufida23@yahoo.fr [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Omrani, H. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Cheikhrouhou-Koubaa, W. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Centre de Recherche en Informatique, Multimédia et Traitement Numérique des Données, BP 275, Sakiet Ezzit, 3021 Sfax (Tunisia); Koubaa, M. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Madouri, A. [Laboratoire de Photonique et Nanostructure, LPN-CNRS, Route de Nozay, 91460 Marcoussis (France); Cheikhrouhou, A. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia)

2016-03-01

We report the effect of vanadium doping on structural, magnetic and magnetocaloric properties of La{sub 0.5}Ca{sub 0.5}Mn{sub 1−x}V{sub x}O{sub 3} (x=0.05; 0.1). Our samples were elaborated using the conventional solid state reaction method at high temperatures. X-Ray powder diffraction at room temperature indicates that our samples crystallize in the orthorhombic structure with Pbnm space group. Magnetic measurements reveal a paramagnetic-ferromagnetic transition with decreasing temperature. Magnetocaloric studies show that the maximum of the magnetic entropy change and the relative cooling power (RCP) are found to be 2.42 J Kg{sup −1} K{sup −1} and 162.75 J Kg{sup −1} for x=0.05 and 3.12 J Kg{sup −1} K{sup −1} and 221.31 J Kg{sup −1} for x=0.1 under a field change of 5 T. - Highlights: • The La{sub 0.5}Ca{sub 0.5}Mn{sub 1−x}V{sub x}O{sub 3}(x=0.05 and x=0.1) compounds were synthesized using conventional solid state reaction method. • T{sub C} increases with V content from 187 K for x=0.05 to 263 K for x=0.1 • Large magnetocaloric effect is reported based on second order phase transition. • Noticeable |∆S{sub M}| at 5 T field makes the system useful for magnetic refrigeration.

The 15th Internatonal Conference Quality in Resarch (Qir) 2017 Preparation and Ionic Conductivity of Li3.9Ca0.1Ti5O12 Using Waste Chicken Eggshells as ca Source for Anode Material of Lithium-Ion Batteries

Science.gov (United States)

Subhan, Achmad; Setiawan, Dedy; Ahmiatri Saptari, Sitti

2018-03-01

Li3.9Ca0.1Ti5O12 has been synthesized as anode material for lithium-ion batteries parallel with Li4Ti5O12 anode material using solid state reaction method in an air atmosphere. LiOH.H2O, TiO2, and waste chicken eggshells in the form of CaCO3 were chosen as sources of Li, Ti, and Ca respectively and prepared using stoichiometric. The phase structure, morphology, and electrochemical impedance of as-prepared samples were characterized using XRD, SEM, and EIS. The XRD characterization revealed that in Li3.9Ca0.1Ti5O12 sample, all amount of dopant had entered the lattice structure of Li4Ti5O12. The EDX image also detect the existence of Ca in the structure of Li3.9Ca0.1Ti5O12. The EIS characterization revealed that the Li3.9Ca0.1Ti5O12 sample had lower electrochemical impedance compared to the Li4Ti5O12 sample. The diffusion coefficient were obtained by Faraday’s method, and exhibited that the Li3.9Ca0.1Ti5O12 sample (1.46986 × 10-12 cm2/s) had higher ionic conductivity than the Li4Ti5O12 sample (4.40995 × 10-16 cm2/s). According to the cycle performance test, the Li3.9Ca0.1Ti5O12 sample also had higher charge-discharge capacity and stability compared to the Li4Ti5O12 sample.

Synthesis and Characterization of Nano-Crystalline Cu and Pb0.5-Cu0.5- ferrites by Mechanochemical Method and Their Electrical and Gas Sensing Properties

Directory of Open Access Journals (Sweden)

V. B. GAIKWAD

2011-11-01

Full Text Available In the present communication, we have reported the synthesis of nanocrystalline ferrites of the type CuFe2O4 and Pb0.5Cu0.5Fe2O4 by mechanochemical alloying at 960 0C. The samples prepared were characterized by X-ray diffraction (XRD, VSM, FT-IR, UV-DRS, and SEM. The average particle size was determined by XRD pattern using Scherrer equation and it is 7.295 nm, 4.484 nm for CuFe2O4, and Pb0.5Cu0.5Fe2O4. The surface morphology of the samples is characterized by scanning electron microscopy (SEM. Magnetic studies were carried out using vibrating sample magnetometer (VSM and shows very high coercive field for the mixed ferrite. UV-DRS studies were performed to investigate the band gap of synthesized nanocrystalline material. Electrical properties show semiconducting nature of synthesized ferrites. The thick films of the material were prepared by screen printing method. The gas sensing properties were studied towards reducing gases like CO, NH3 and H2S and it was revealed that CuFe2O4 is the most sensitive and selective to H2S gas at relatively lower operating temperature 200 0C. Furthermore Pb0.5Cu0.5Fe2O4 also shows the response to H2S at operating temperature 300 0C.

Quantum dots of Cd0.5Mn0.5Te semimagnetic semiconductor formed by the cold isostatic pressure method

International Nuclear Information System (INIS)

Contreras, O.; Power, Ch.; Quintero, M.; Morocoima, M.; Tovar, R.; Quintero, E.; Gonzalez, J.; Munoz-San Jose, V.; Broto, J.M.; Snoeck, E.

2005-01-01

Cd 0.5 Mn 0.5 Te is a semimagnetic semiconductor, which crystallizes in the zinc-blende structure (ZB) and exhibits a magnetic spin glass like transition at 21 K. Under pressure it shows a first-order phase transition around 2.6 GPa to the NaCl like structure. In this work, the pressure cycled method using a Paris-Edinburgh cell up to 8 GPa has been applied to Cd 0.5 Mn 0.5 Te samples in order to obtain recovered nanocrystals. The nanoparticles have been characterized by EDX and electron microscopy. The X-ray and electron diffraction results confirmed the existence of nanocrystals in the ZB phase with an average size of 7 nm. Magnetization measurements made in the range of 2-300 K at low field show that the temperature of the magnetic transition decreases when the crystallites' size is reduced

Material sampling for rotor evaluation

International Nuclear Information System (INIS)

Mercaldi, D.; Parker, J.

1990-01-01

Decisions regarding continued operation of aging rotating machinery must often be made without adequate knowledge of rotor material conditions. Physical specimens of the material are not generally available due to lack of an appropriate sampling technique or the high cost and inconvenience of obtaining such samples. This is despite the fact that examination of such samples may be critical to effectively assess the degradation of mechanical properties of the components in service or to permit detailed examination of microstructure and surface flaws. Such information permits a reduction in the uncertainty of remaining life estimates for turbine rotors to avoid unnecessarily premature and costly rotor retirement decisions. This paper describes the operation and use of a recently developed material sampling device which machines and recovers an undeformed specimen from the surface of rotor bores or other components for metallurgical analysis. The removal of the thin, wafer-like sample has a negligible effect on the structural integrity of these components, due to the geometry and smooth surface finish of the resulting shallow depression. Samples measuring approximately 0.03 to 0.1 inches (0.76 to 2.5 mm) thick by 0.5 to 1.0 inch (1.3 to 2.5 cm) in diameter can be removed without mechanical deformation or thermal degradation of the sample or the remaining component material. The device is operated remotely from a control console and can be used externally or internally on any surface for which there is at least a three inch (7.6 cm) working clearance. Application of the device in two case studies of turbine-generator evaluations are presented

Synthesis and characterization of Na(Gd0.5Lu0.5)F4: Nd3+,a core-shell free multifunctional contrast agent.

Science.gov (United States)

Mimun, L Christopher; Ajithkumar, G; Rightsell, Chris; Langloss, Brian W; Therien, Michael J; Sardar, Dhiraj K

2017-02-25

Compared to conventional core-shell structures, core-shell free nanoparticles with multiple functionalities offer several advantages such as minimal synthetic complexity and low production cost. In this paper, we present the synthesis and characterization of Nd 3+ doped Na(Gd 0.5 Lu 0.5 )F 4 as a core-shell free nanoparticle system with three functionalities. Nanocrystals with 20 nm diameter, high crystallinity and a narrow particle size distributions were synthesized by the solvothermal method and characterized by various analytical techniques to understand their phase and morphology. Fluorescence characteristics under near infrared (NIR) excitation at 808 nm as well as X-ray excitation were studied to explore their potential in NIR optical and X-ray imaging. At 1.0 mol% Nd concentration, we observed a quantum yield of 25% at 1064 nm emission with 13 W/cm 2 excitation power density which is sufficiently enough for imaging applications. Under 130 kVp (5 mA) power of X-ray excitation, Nd 3+ doped Na(Gd 0.5 Lu 0.5 )F 4 shows the characteristic emission bands of Gd 3+ and Nd 3+ with the strongest emission peak at 1064 nm due to Nd 3+ . Furthermore, magnetization measurements show that the nanocrystals are paramagnetic in nature with a calculated magnetic moment per particle of ~570 μB at 2T. These preliminary results support the suitability of the present nanophosphor as a multimodal contrast agent with three imaging features viz. optical, magnetic and X-ray.

Investigation on structural, Mössbauer and ferroelectric properties of (1−x)PbFe{sub 0.5}Nb{sub 0.5}O{sub 3}–(x)BiFeO{sub 3} solid solution

Energy Technology Data Exchange (ETDEWEB)

Dadami, Sunanda T.; Matteppanavar, Shidaling; Shivaraja, I. [Department of Physics, JB Campus, Bangalore University, Bangalore 560056 (India); Rayaprol, Sudhindra [UGC-DAE-Consortium for Scientific Research, Mumbai Centre, BARC Campus, Mumbai 400085 (India); Angadi, Basavaraj, E-mail: brangadi@gmail.com [Department of Physics, JB Campus, Bangalore University, Bangalore 560056 (India); Sahoo, Balaram [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India)

2016-11-15

In this study, (1−x)PbFe{sub 0.5}Nb{sub 0.5}O{sub 3}(PFN)–(x)BiFeO{sub 3}(BFO) multiferroic solid solutions with x=0.0, 0.1, 0.2, 0.3 and 0.4 were synthesized through single step solid state reaction method and characterized thoroughly through X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR), Raman, Mössbauer spectroscopy and ferroelectric studies. The room temperature (RT) XRD studies confirmed the formation of single phase with negligible amount of secondary phases (x=0.2 and 0.4). The zoomed XRD patterns of (1−x)PFN–(x)BFO solid solutions showed the clear structural phase transition from monoclinic (Cm) to rhombohedral (R3c) at x=0.4. The Raman spectra of the (1−x)PFN–(x)BFO solid solutions showed the composition dependent phase transition from monoclinic (Cm) to rhombohedral (R3c). With increasing x in PFN, the modes related monoclinic symmetry changes to those of rhombohedral symmetry. The RT Mössbauer spectroscopy results evidenced the existence of composition dependent phase transition from paramagnetic to weak antiferromagnetic ordering and weak antiferromagnetic to antiferromagnetic ordering. The Mössbauer spectroscopy showed paramagnetic behavior with a doublet for x=0.0, 0.1 and 0.2 are shows the weak antiferromagnetic with paramagnetic ordering. For x=0.3 and 0.4 shows the sextet pattern and it is a clear evidence of antiferromagnetism. The ferroelectric (P–E) loops at RT indicate the presence of small polarization, as the x concentration increases in PFN, the remnant polarization and coercive field were decreased, which may due to the increase in the conductivity and leaky behavior of the samples. - Highlights: • Structural, Mössbauer, ferroelectric studies on (1−x)PFN–xBiFeO{sub 3} multiferroics. • Composition dependent changes in crystallographic and magnetic structure. • System exhibits phase transition from monoclinic to rhombohedral with x. • Supporting results from Raman

Superconducting properties of Zn and Al double-doped Mg1-x(Zn0.5Al0.5)xB2

DEFF Research Database (Denmark)

Xu, G.J.; Grivel, Jean-Claude; Abrahamsen, A.B.

2004-01-01

(XRD), ac susceptibility, magnetization and resistivity. The double doping leads to decreases in both the lattice parameters a and c, and the T-c decreases with increasing dopant content. A systematical comparison with Al doped- and Li, Al double doped MgB2 of structure, superconducting transition......A series of polycrystalline samples of Mg1-x(Zn0.5Al0.5)(x)B-2 (0less than or equal toxless than or equal to0.8) were prepared by solid state reaction method and their structure, superconducting transition temperature (T-c) and transport properties were investigated by means of X-ray diffraction...

Grain boundary defect compensation in Ti-doped BaFe{sub 0.5}Nb{sub 0.5}O{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Sun, Xiaojun; Deng, Jianming; Liu, Saisai; Yan, Tianxiang; Fang, Liang; Liu, Laijun [Guilin University of Technology, Key Laboratory of Nonferrous Materials and New Processing Technology, Ministry of Education, College of Materials Science and Engineering, Guangxi Universities Key Laboratory of Non-ferrous Metal Oxide Electronic Functional Materials and Devices, Guilin (China); Peng, Biaolin [Guangxi University, School of Physical Science and Technology and Guangxi Key Laboratory for Relativistic Astrophysics, Nanning (China); Jia, Wenhao [Shanghai Getong Enterprise Co., Ltd., Shanghai (China); Mei, Zaoming [Henan LiHeng Building Materials Co., Ltd., Zhengzhou (China); Su, Hongbo [Henan Province Product Quality Supervision and Inspection Center, Zhengzhou (China)

2016-09-15

Giant dielectric ceramics Ba(Nb{sub 0.5}Fe{sub 0.5-x}Ti{sub x})O{sub 3} (BNFT) have been fabricated by a conventional solid-state reaction. According to X-ray diffraction analysis, the crystal structure of these ceramics can be described by the cubic centrosymmetric with Pm-3m space group. The real part (ε') of dielectric permittivity and dielectric loss (tan δ) of the BNFT ceramics was measured in a frequency range from 40 Hz to 100 MHz at room temperature. The (ε') of all these samples displays a high value (∝6500) and a small frequency-dependence from 1 kHz to 1 MHz. We have established a link between conductivity activation energy and defect compensation at grain boundaries. The Ti{sup 4+}-doped Ba(Nb{sub 0.5}Fe{sub 0.5})O{sub 3} as a donor makes a great influence on the grain boundary behavior, which restricts the migration of oxygen vacancy and depresses dielectric loss factor for Ba(Nb{sub 0.5}Fe{sub 0.5})O{sub 3} ceramics. (orig.)

Hydrogen diffusion in La1.5Nd0.5MgNi9 alloy electrodes of the Ni/MH battery

International Nuclear Information System (INIS)

Volodin, A.A.; Denys, R.V.; Tsirlina, G.A.; Tarasov, B.P.; Fichtner, M.; Yartys, V.A.

2015-01-01

Highlights: • Hydrogen diffusion in the La 1.5 Nd 0.5 MgNi 9 alloy electrode was studied. • Various techniques of low amplitude potentiostatic data treatment were used. • D H demonstrates a maximum (2 × 10 −11 cm 2 /s) at 85% of discharge of the electrode. • Maximum is associated with a conversion of β-hydride into a solid α-solution. • Optimization of material and electrode will allow high discharge rates. - Abstract: Hydrogen diffusion in the La 1.5 Nd 0.5 MgNi 9 battery electrode material has been studied using low amplitude potentiostatic experiments. Complex diffusion behavior is examined in frames of electroanalytical models proposed for the lithium intercalation materials. Hydrogen diffusion coefficient D H changes with hydrogen content in the metal hydride anode electrode and has a maximum of ca. 2 × 10 −11 cm 2 /s at ca. 85% of discharge. Such a behavior differs from the trends known for the transport in lithium battery materials, but qualitatively agrees with the data for the highly concentrated β-PdH x

Study on structural refinement and electrochemical behaviour of Ba0.5Sr0.5Co0.8Fe0.2O3-δ as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFC)

Science.gov (United States)

Kautkar, Pranay R.; Shirbhate, Shraddha C.; Acharya, Smita A.

2018-05-01

Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) was prepared by ethylene glycol-citrate combined sol-gel combustion route and calcined at optimized temperature 1050°C. The X-ray Diffraction (XRD) data revealing the crystal purity of BSCF cathode was refined by the Cubic-type structure having the space group Pm-3m by Rietveld analysis. Refined lattice parameter of BSCF cathode is a = 3.9759 Å and unit cell volume is 62.85 (4) Å3, Co/Fe-O bond length from VESTA program figured out to be 1.987 (3) Å. Electron density distribution (EDD) of the unit cell of BSCF cathode shows the bonding feature with oxygen ions, this could represent oxygen vacancies are present in the lattice. These results reflected in electrochemical impedance spectra measurement of symmetric cell. Area of specific resistance (ASR) of the BSCF cathode was found to be 0.17 Ω.cm2 at 700°C and respective activation energy (Ea) 1.15 eV. It shows surface exchange at cathode interface, surface diffusion and self-diffusion happened through Ce0.85Sd0.15O1.95 (SDC15) electrolyte.

Synthesis and luminescence characterization of Pr3+ doped Sr1.5Ca0.5SiO4 phosphor

Science.gov (United States)

Vidyadharan, Viji; Mani, Kamal P.; Sajna, M. S.; Joseph, Cyriac; Unnikrishnan, N. V.; Biju, P. R.

2014-12-01

Luminescence properties of Pr3+ activated Sr1.5Ca0.5SiO4 phosphors synthesized by solid state reaction method are reported in this work. Blue, orange red and red emissions were observed in the Pr3+ doped sample under 444 nm excitation and these emissions are assigned as 3P0 → 3H4, 3P0 → 3H6 and 3P0 → 3F4 transitions. The emission intensity shows a maximum corresponding to the 0.5 wt% Pr3+ ion. The decay analysis was done for 0.05 and 0.5 wt% Pr3+ doped samples for the transition 3P0 → 3H6. The life times of 0.05 and 0.5 wt% Pr3+ doped samples were calculated by fitting to exponential and non-exponential curve respectively, and are found to be 156 and 105 μs respectively. The non-exponential behaviour arises due to the statistical distribution of the distances between the ground state Pr3+ ions and excited state Pr3+ ions, which cause the inhomogeneous energy transfer rate. The XRD spectrum confirmed the triclinic phase of the prepared phosphors. The compositions of the samples were determined by the energy dispersive X-ray spectra. From the SEM images it is observed that the particles are agglomerated and are irregularly shaped. IR absorption bands were assigned to different vibrational modes. The well resolved peaks shown in the absorption spectra are identical to the excitation spectra of the phosphor samples. Pr3+ activated Sr1.5Ca0.5SiO4 phosphors can be efficiently excited with 444 nm irradiation and emit multicolour visible emissions. From the CIE diagram it can be seen that the prepared phosphor samples give yellowish-green emission.

Dark-red-emitting CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots: Effect of chemicals on properties

Energy Technology Data Exchange (ETDEWEB)

Yang, Ping, E-mail: mse_yangp@ujn.edu.cn; Zhang, Aiyu; Li, Xiaoyu; Liu, Ning; Zhang, Yulan; Zhang, Ruili

2013-08-15

CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S core/shell quantum dots (QDs) with a tunable photoluminescence (PL) range from yellow to dark red (up to a PL peak wavelength of 683 nm) were fabricated using various reaction systems. The core/shell QDs created in the reaction solution of trioctylamine (TOA) and oleic acid (OA) at 300 °C exhibited narrow PL spectra and a related low PL efficiency (38%). In contrast, the core/shell QDs prepared in the solution of 1-octadecene (ODE) and hexadecylamine (HDA) at 200 °C revealed a high PL efficiency (70%) and broad PL spectra. This phenomenon is ascribed that the precursor of Cd, reaction temperature, solvents, and ligands affected the formation process of the shell. The slow growth rate of the shell in the solution of ODE and HDA made QDs with a high PL efficiency. Metal acetate salts without reaction with HDA led to the core/shell QDs with a broad size distribution. - Graphical abstract: CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots (QDs) with tunable photoluminescence, high PL efficiency, and high stability through organic synthesis, in which chemicals affected the properties of the QDs. Display Omitted - Highlights: • CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots created via organic synthesis. • Chemicals affected the properties of the quantum dots. • The quantum dots revealed high photoluminescence efficiency and stability. • The quantum dots with tunable photoluminescence in a range from yellow to dark red. • The QDs are utilizable for various applications such as biological labeling.

Preparation and electrochemical properties of La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 (x = 0, 0.30, 0.33, 0.36, 0.39) hydrogen storage alloys

International Nuclear Information System (INIS)

Tian, Xiao; Wei, Wei; Duan, Ruxia; Zheng, Xinyao; Zhang, Huaiwei; Tegus, O.; Li, Xingguo

2016-01-01

The as-cast alloy with the composition of La_0_._7_0Ni_2_._4_5Co_0_._7_5Al_0_._3_0 was prepared by vacuum arc melting. La–Mg–Ni-based La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 hydrogen storage alloy has been synthesized by high-energy vibratory milling blending of the La_0_._7_0Ni_2_._4_5Co_0_._7_5Al_0_._3_0 as-cast alloy and elemental Mg, followed by an isothermal annealing. The microstructures and electrochemical properties of the La_0_._7_0Ni_2_._4_5Co_0_._7_5Al_0_._3_0 and La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloys were investigated by XRD, SEM and electrochemical measurements. The XRD analysis and Rietveld refinement showed that the as-cast La_0_._7_0Ni_2_._4_5Co_0_._7_5Al_0_._3_0 alloy consists of single LaNi_5 phase, whereas the La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloys contain the LaNi_5 and (La, Mg)_2Ni_7. The electrochemical measurements indicated that the maximum discharge capacity and discharge potential characteristic of the La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloys increases first and then decreases with increasing x. The maximum discharge capacity and discharge potential characteristic of alloy reaches the optimum when x is 0.36. The cyclic stability of the La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloy with a smaller quantity of Mg is better than that of the alloy with a larger quantity of Mg. - Highlights: • La–Mg–Ni-based alloy was synthesized by melting, milling and subsequent annealing. • Mg atoms exist in the La_2Ni_7 phase prior to LaNi_5 phase. • The La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloys consist of the LaNi_5 and (La, Mg)_2Ni_7. • The more Mg element the alloys contain, the easier aggregation Mg atom is. • The C_m_a_x of La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloy first increases and then decreases with rising x.

Influence of the divalent and trivalent ions substitution on the structural and magnetic properties of Mg{sub 0.5−x}Cd{sub x}Co{sub 0.5}Cr{sub 0.04}Tb{sub y}Fe{sub 1.96−y}O{sub 4} ferrites prepared by sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Mustafa, Ghulam, E-mail: ghulammustafabzu@gmail.com [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Islam, M.U. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Zhang, Wenli [SKLETFID, University of Electronic Science and Technology of China, Chengdu 610054 (China); Anwar, Abdul Waheed [Department of Physics, University of Engineering and Technology, Lahore 54890 (Pakistan); Jamil, Yasir [Department of Physics, University of Agriculture, Faisalabad 38040 (Pakistan); Murtaza, Ghulam; Ali, Ihsan; Hussain, Mudassar [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Ali, Akbar [Department of Basic Sciences, Riphah International University, Islamabad 44000 (Pakistan); Ahmad, Mukhtar, E-mail: ahmadmr25@yahoo.com [Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

2015-08-01

A series of the divalent and trivalent co-substituted Mg{sub 0.5−x}Cd{sub x}Co{sub 0.5}Cr{sub 0.04}Tb{sub y}Fe{sub 1.96−y}O{sub 4} spinel ferrite systems (where x=0–0.5 in steps of 0.1 and y=0.00–0.10 in steps 0.02) are synthesized by sol–gel auto combustion method. The product materials were characterized by the thermo gravimetric analysis and differential scanning calorimetry (TGA/DSC), Fourier transform infrared spectra (FTIR), nitrogen adsorption (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM). The X-ray diffraction patterns and Fourier transform infrared spectroscopy confirm spinel nanocrystalline phase. The crystallite size is determined by Scherer's formula from 36.6 to 69.4 nm. The X-ray density is found in the range of 5.09–6.43 (g/cm{sup 3}). The morphological features are studied using scanning electron microscope and AFM. Saturation magnetization (M{sub s}) and remanence (M{sub r}) magnetization extracted from M–H loops exhibit the decreasing trends 21.4–16 emu/g and 9.1–6.3 emu/g, respectively. A significant decrease in the intrinsic parameters is observed in the prepared samples due to the weakening of the A–B interaction as iron enters into the tetrahedral A-site. The coercivity lies in the range of 300–869 Oe as a function of co-substitution contents. The coercivity of the sample with x=0.1, y=0.02 was found maximum i.e. 869 Oe. The obtained results suggest that the investigated materials may be potential candidates for high density recording media applications. - Highlights: • Effects of co-substitution (Cd{sup 2+}, Tb{sup 3+}) on structural and magnetic parameters are studied. • XRD patterns revealed that first three samples are single phase while others are biphasic. • The M{sub s} was decreased from 21.4 to 16 emu/g with increasing co-substituted contents. • The values of coercivity lie in range of 300–869 Oe for all

Limits on variations in fundamental constants from 21-cm and ultraviolet Quasar absorption lines.

Science.gov (United States)

Tzanavaris, P; Webb, J K; Murphy, M T; Flambaum, V V; Curran, S J

2005-07-22

Quasar absorption spectra at 21-cm and UV rest wavelengths are used to estimate the time variation of x [triple-bond] alpha(2)g(p)mu, where alpha is the fine structure constant, g(p) the proton g factor, and m(e)/m(p) [triple-bond] mu the electron/proton mass ratio. Over a redshift range 0.24 < or = zeta(abs) < or = 2.04, (Deltax/x)(weighted)(total) = (1.17 +/- 1.01) x 10(-5). A linear fit gives x/x = (-1.43 +/- 1.27) x 10(-15) yr(-1). Two previous results on varying alpha yield the strong limits Deltamu/mu = (2.31 +/- 1.03) x 10(-5) and Deltamu/mu=(1.29 +/- 1.01) x10(-5). Our sample, 8 x larger than any previous, provides the first direct estimate of the intrinsic 21-cm and UV velocity differences 6 km s(-1).

Structure and electrical properties of new Aurivillius oxides (K0.16Na0.84)0.5Bi4.5Ti4O15 with manganese modification

International Nuclear Information System (INIS)

Fang, Pinyang; Liu, Peng; Xi, Zengzhe; Long, Wei; Li, Xiaojuan

2014-01-01

Highlights: • Manganese modified KNBT ceramics were synthesized using the solid state process. • d 33 and T c of KNBT ceramics were improved by manganese modification. • d 33 and T c of KNBT-Mn50 ceramic were 28 pC/N and 657 °C, respectively. - Abstract: Aurivillius oxides, (K 0.16 Na 0.84 ) 0.5 Bi 4.5 Ti 4 O 15 (KNBT) with manganese doping, were synthesized by using the conventional solid state reaction method. Influence of manganese doping on structure and electric properties of the KNBT ceramics was investigated. Phase analysis was performed by X-ray diffraction analyses (XRD) and Raman spectroscopy. Microstructural morphology was assessed by the scanning electron microscopy (SEM). Piezoelectric performances of manganese modified KNBT ceramics were improved significantly compared with that of the KNBT ceramic. The maximum of piezoelectric coefficient (d 33 ) was found to be 28 pC/N for the KNBT-Mn50 ceramic, together with high Curie temperature (T c ∼ 657 °C) and high resistivity (higher than 10 6 Ω cm). In addition, excellent temperature stability of piezoelectric performances was exhibited for manganese modified KNBT lead-free piezoelectric ceramics

Local activation time sampling density for atrial tachycardia contact mapping: how much is enough?

Science.gov (United States)

Williams, Steven E; Harrison, James L; Chubb, Henry; Whitaker, John; Kiedrowicz, Radek; Rinaldi, Christopher A; Cooklin, Michael; Wright, Matthew; Niederer, Steven; O'Neill, Mark D

2018-02-01

Local activation time (LAT) mapping forms the cornerstone of atrial tachycardia diagnosis. Although anatomic and positional accuracy of electroanatomic mapping (EAM) systems have been validated, the effect of electrode sampling density on LAT map reconstruction is not known. Here, we study the effect of chamber geometry and activation complexity on optimal LAT sampling density using a combined in silico and in vivo approach. In vivo 21 atrial tachycardia maps were studied in three groups: (1) focal activation, (2) macro-re-entry, and (3) localized re-entry. In silico activation was simulated on a 4×4cm atrial monolayer, sampled randomly at 0.25-10 points/cm2 and used to re-interpolate LAT maps. Activation patterns were studied in the geometrically simple porcine right atrium (RA) and complex human left atrium (LA). Activation complexity was introduced into the porcine RA by incomplete inter-caval linear ablation. In all cases, optimal sampling density was defined as the highest density resulting in minimal further error reduction in the re-interpolated maps. Optimal sampling densities for LA tachycardias were 0.67 ± 0.17 points/cm2 (focal activation), 1.05 ± 0.32 points/cm2 (macro-re-entry) and 1.23 ± 0.26 points/cm2 (localized re-entry), P = 0.0031. Increasing activation complexity was associated with increased optimal sampling density both in silico (focal activation 1.09 ± 0.14 points/cm2; re-entry 1.44 ± 0.49 points/cm2; spiral-wave 1.50 ± 0.34 points/cm2, P density (0.61 ± 0.22 points/cm2 vs. 1.0 ± 0.34 points/cm2, P = 0.0015). Optimal sampling densities can be identified to maximize diagnostic yield of LAT maps. Greater sampling density is required to correctly reveal complex activation and represent activation across complex geometries. Overall, the optimal sampling density for LAT map interpolation defined in this study was ∼1.0-1.5 points/cm2. Published on behalf of the European Society of

Study of magnetic properties and magnetoelectric effect in (x) Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}+(1-x)PZT composites

Energy Technology Data Exchange (ETDEWEB)

Bammannavar, B.K. [Department of Studies in Physics, Karnatak University, Dharwad 580003 (India); Naik, L.R., E-mail: naik_36@rediffmail.com [Department of Studies in Physics, Karnatak University, Dharwad 580003 (India)

2012-03-15

Magnetoelectric (ME) composites consisting of ferrite phase (x) Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}+ferroelectric phase (1-x)Pb Zr{sub 0.8}Ti{sub 0.2}O{sub 3} (Lead Zirconate Titanate-PZT) in which x (mol%) varies between 0 and 1 (0.0{<=}x{<=}1.0) was synthesized by double sintering ceramic method. The presence of constituent phases of ferrite, ferroelectric and their composites was confirmed by X-ray diffraction studies. The hysteresis measurement was used to study magnetic properties such as saturation magnetization (M{sub S}) and magnetic moment ({mu}{sub B}). The existence of single domain (SD) particle in the ferrite phase and mixed (SD+MD) particle in the composites was studied from AC susceptibility measurements. ME voltage coefficient for each mol% of ferrite phase was measured as a function of applied DC magnetic field and at the same time influence of magnetic field on ME response and resistivity of composites was studied. The maximum ME voltage coefficient of 0.84 mV/cm Oe was observed for 15% of ferrite phase and 85% of ferroelectric phase in the composites. - Highlights: Black-Right-Pointing-Pointer AC susceptibility measurement shows SD particles of the ferrite phase and mixed (SD+MD) particles in the composites. Black-Right-Pointing-Pointer Maximum ME voltage coefficient of 0.84 mV/cm Oe was observed 15 % of ferrite phase and 85 % of ferroelectric phase in composites. Black-Right-Pointing-Pointer These composites are useful in preparing ME devices as they show better ME voltage coefficients.

A study on vertical distribution of radionuclides in the soil layers 0-30 cm deep in relation to their particle size

International Nuclear Information System (INIS)

Megumi, K.; Sato, Y.; Matsunami, T.; Fukuda, K.; Ishiyama, T.; Kimura, S.; Tsujimoto, T.

1991-01-01

It is fundamentally important to have a detailed knowledge of distribution of radionuclides in soils in natural environments for an understanding of behavior of nuclides during a lengthy period beyond the limit of the possible in experimental systems. Core soil samples (30 cm) were taken from surface of the ground in the central parts (Osaka and Wakasa) of Japan. Each core sample was sliced into 5 cm sections and the parts of the soil larger than 10 mesh were excluded by standard sieves. Some of the samples were further sieved into four classes of soil particles, such as, 10-60, 60-100, 100-200 and more than 200 mesh. The concentrations of U-series nuclides ( 238 U, 226 Ra, 210 Pb), Th-series nuclides ( 232 Th, 228 Ra), 40 K and 137 Cs in the samples were determined by gamma ray spectrometry and photon activation analysis. The photon activation analysis with a planer type of Ge detector was made by irradiating the samples with bremsstrahlung of tungsten target from electron accelerator, 16 MeV, at Res. Inst. for Advanced Sci. and Tech., Univ. of Osaka Pref. Fallout 137 Cs and 210 Pb deposition in the soil layers showed vertical variation mainly depending on the organic substances contents, the ratios of water contents and particle sizes at each location. A good correlation was found between the concentrations of these two nuclides. This correlation is available to evaluate of the 137 Cs contamination levels in soils. The concentrations of 238 U, 226 Ra, 232 Th, 228 Ra and 40 K contained originally in soils, changed slightly with the depth and the vertical distributions of these nuclides were found to relate mainly to the soil particle size in the layer. This tendency was evidently observed in the soil originating from the weathering of granite rock. (author)

Investigation of spectroscopic properties and energy transfer between Ce and Dy in (Lu{sub 0.2}Gd{sub 0.8−x−y}Ce{sub x}Dy{sub y}){sub 2}SiO{sub 5} single crystals

Energy Technology Data Exchange (ETDEWEB)

Strzęp, A. [Institute of Low Temperature and Structure Research PAS, Wroclaw (Poland); Martin, I.R. [Faculty of Physics, Universidad de La Laguna, S/C de Tenerife (Spain); Malta Consolider Team and Instituto de Materiales y Nanotecnología (IMN), Universidad de La Laguna, S/C de Tenerife (Spain); Głowacki, M. [Institute of Physics PAS, Warsaw (Poland); Ryba-Romanowski, W. [Institute of Low Temperature and Structure Research PAS, Wroclaw (Poland); Berkowski, M. [Institute of Physics PAS, Warsaw (Poland); Pérez-Rodríguez, C. [Faculty of Physics, Universidad de La Laguna, S/C de Tenerife (Spain); Malta Consolider Team and Instituto de Materiales y Nanotecnología (IMN), Universidad de La Laguna, S/C de Tenerife (Spain)

2015-10-15

In this paper we present results of spectroscopic investigations of single crystals with general formula (Lu{sub 0.2}Gd{sub 0.8−x−y}){sub 2}SiO{sub 5} codoped with x% of Ce{sup {sub 3}{sub +}} and y% of Dy{sup {sub 3}{sub +}} ions. Investigated materials exhibit strong optical anisotropy what can be easily observed in polarized absorption and emission spectra. Based on room temperature polarized absorption spectra calculations in framework of phenomenological Judd–Ofelt model was carried out. Intensity parameters Ω{sub t} were evaluated to be Ω{sub 2}=7.08 (±0.39), Ω{sub 4}=2.76 (±0.44), and Ω{sub 6}=3.36 (±0.21) [10{sup −20} cm{sup 2}] for sample doped with 1% of cerium and Ω{sub 2}=10.72 (±0.33), Ω{sub 4}=1.98 (±0.37), and Ω{sub 6}=2.11 (±0.18) [10{sup −20} cm{sup 2}] for sample doped with 3% of cerium. Influence of cerium admixture on Judd Ofelt intensity parameters is discussed. Value of experimental lifetime of {sub 4}F{sub 9/2} multiplet of Dy{sup 3+} ion in sample doped with 1 at% Ce is 0.5 ms (τ{sub rad}=0.45 ms), while for sample doped with 3 at% of Ce, experimental lifetime is 0.45 ms (τ{sub rad}=0.43 ms). Absorption bands located between 440 and 460 nm, can be utilized for optical pumping of material by GaN laser diodes. Intense and broad emission bands at 465–495 and 560–590 nm, with experimental branching ratio strongly depending on polarization, give high chance for obtaining white luminophore, due to appropiate mixing of blue and yellow luminescence. By means of a pump and probe experiment optical amplification was demonstrated in the codoped sample with 1 at% of Ce and 1 at% Dy at 575 nm corresponding to the emission of Dy{sup 3+} with a high net gain coefficient of 34 cm{sup −1}. Such high amplification was obtained under 359 nm excitation (at the maximum of intense absorption band of Ce{sup 3+} ions). - Highlights: • Influence of anisotropy on properties of LGSO: Ce, Dy crystals was investigated. • ET between Ce

Study of the behavior of the compound Mg2Ni0.5Co0.5 front to hydriding process

International Nuclear Information System (INIS)

Martinez, C; Ordonez, S; Serafini, D; Guzman, D; Bustos, O

2012-01-01

This paper study the behavior of the compound Mg 2 Ni 0,5 Co 0,5 during the hydriding process. Elemental powders of Mg, Ni and Co, with an atomic ratio of 2:0,5:0,5 were mechanically alloyed using a high energy mill SPEX 8000D for 36h. The amorphous and crystalline structure of the samples was characterized through X-ray diffraction The hydriding process was performed by the volumetric technique Sievert at 90 o C and a pressure of 20 bar H 2 . The desorption process was evaluated by differential scanning calorimetry. Based on the results we can conclude that the amorphous structure absorbs more hydrogen, reaching a maximum of 3.6 wt% H2, besides the incorporation of cobalt act as catalyst for the absorption of H2 obtaining values higher than those reported in the Mg-Ni system amorphous state. The desorption process is influenced by the type of structure that presents the alloy

Effect of sintering condition on the microstructure and electrical properties of lead-free (Na0.5K0.5NbO3 - Bi0.5(Na0.83K0.170.5TiO3 ceramics

Directory of Open Access Journals (Sweden)

Wang Chun Huy

2017-01-01

Full Text Available In this work, the piezoelectric ceramic system of the (1-x(Na0.5K0.5NbO3 - xBi(Na0.83K0.17TiO3 with composition close to the morphotropic phase boundary is studied. (Na0.5K0.5NbO3 with 0∼5 mole% Bi(Na0.83K0.17TiO3 has been prepared following the conventional mixed oxide process. The effect of sintering time on the properties of 0.97(Na0.5K0.5NbO3-0.03Bi(Na0.83K0.17TiO3 ceramics is discussed. For 0.97(Na0.5K0.5NbO3-0.03Bi(Na0.83K0.17TiO3 ceramics, the electromechanical coupling coefficients of the thickness mode kt and the piezoelectric constant d33 reach 0.46 and 155 p/CN, respectively, at the sintering of 1100 °C for 3 h. Dielectric and piezoelectric properties have maximum values at the sintering temperature of 1100 °C for 5 h. For 0.97(Na0.5K0.5NbO3 -0.03Bi(Na0.83K0.17TiO3 ceramics, the electromechanical coupling coefficients of the thickness mode kt and the piezoelectric constant d33 reach 0.56 and 190, respectively, at the sintering of 1100 °C for 5 h. The effect of prolonging the sintering time to the 0.97(Na0.5K0.5NbO3-0.03Bi(Na0.83K0.17TiO3 system is a helpful method on ceramic processing to improve densification and properties.

The effectiveness of 0.5–0.7% tetracycline gel to reduced subgingival plaque bacteria

Directory of Open Access Journals (Sweden)

Ernie Maduratna Setiawati

2008-09-01

Full Text Available Background: The tetracycline was an antimicrobial agent, that a broad spectrum. In addition to the antimicrobial effects, their efficacy was also anticollagenase and removal of the smear layer on the root surface. Purpose: The aim of the study was to evaluate effectiveness tetracycline gel 0.5–0.7% to reduction subgingival plaque bacteria. Method: A laboratory experimental study was conducted to investigate the effectiveness tetracycline gel 0.5–0.7%. Samples were divided into 5 groups with different concentration. The antimicrobial effect was performed using spectrophotometer. The statistical test was used One-Way ANOVA with significant difference 5% and subsequently Tukey-HSD test. Result: The study showed that tetracycline gel 0.5% has the highest antimicrobial has the highest antimicrobial effect. Conclusion: Tetracycline gel with 0.5% concentration is effective in inhibiting the growth of subgingival plaque bacteria.

Fourier Transform Spectroscopy of 18O-Enriched Carbonyl Sulfide from 1825 to 2700 cm -1

Science.gov (United States)

Strugariu, T.; Naı̈m, S.; Fayt, A.; Bredohl, H.; Blavier, J.-F.; Dubois, I.

1998-06-01

We have measured the Fourier transform spectrum of carbonyl sulfide from 1825 to 2700 cm-1, using a sample enriched in both18O (94.0%) and17O (1.54%). A careful calibration yields a line-position accuracy between 1.5 and 3.0 10-5cm-1. We have observed and analyzed 118 infrared bands of which 93 are measured for the first time: 55 for18O12C32S, 20 for18O12C34S, 11 for18O12C33S, 1 for18O12C36S, 12 for17O12C32S, 4 for17O12C34S, 2 for17O12C33S, and 13 for18O13C32S. Intensities are also reported and analyzed for all those bands. The intensity accuracy is better than 10%, and the precision of approximately 1% allows us to determine some Herman-Wallis coefficients.

Gd2O3 doped 0.82Bi0.5Na0.5TiO3–0.18Bi0.5K0.5TiO3 lead-free piezoelectric ceramics

International Nuclear Information System (INIS)

Fu, Peng; Xu, Zhijun; Chu, Ruiqing; Li, Wei; Wang, Wei; Liu, Yong

2012-01-01

Highlights: ► Gd 2 O 3 doped BNKT18 piezoelectric ceramics were designed and prepared. ► The electrical properties of the BNKT18 ceramics are improved with the addition of Gd 2 O 3 . ► The BNKT18 ceramics doped with 0.4 wt.% Gd 2 O 3 has better electrical properties. -- Abstract: Gd 2 O 3 (0–0.8 wt.%)-doped 0.82Bi 0.5 Na 0.5 TiO 3 –0.18Bi 0.5 K 0.5 TiO 3 (BNKT18) lead-free piezoelectric ceramics were synthesized by a conventional solid-state process. The effects of Gd 2 O 3 on the microstructure, the dielectric, ferroelectric and piezoelectric properties were investigated. X-ray diffraction (XRD) data shows that Gd 2 O 3 in an amount of 0.2–0.8 wt.% can diffuse into the lattice of BNKT18 ceramics and form a pure perovskite phase. Scanning electron microscope (SEM) images indicate that the grain size of BNKT18 ceramics decreases with the increase of Gd 2 O 3 content; in addition, all the modified ceramics have a clear grain boundary and a uniformly distributed grain size. At room temperature, the ferroelectric and piezoelectric properties of the BNKT18 ceramics have been improved with the addition of Gd 2 O 3 , and the BNKT18 ceramics doped with 0.4 wt.% Gd 2 O 3 have the highest piezoelectric constant (d 33 = 137 pC/N), highest relative dielectric constant (ε r = 1023) and lower dissipation factor (tan δ = 0.044) at a frequency of 10 kHz. The BNKT18 ceramics doped with 0.2 wt.% Gd 2 O 3 have the highest planar coupling factor (k p = 0.2463).

Coexistence of room temperature ferroelectricity and ferrimagnetism in multiferroic BiFeO3-Bi0.5Na0.5TiO3 solid solution

International Nuclear Information System (INIS)

Tian, Z.M.; Wang, C.H.; Yuan, S.L.; Wu, M.S.; Ma, Z.Z.; Duan, H.N.; Chen, L.

2011-01-01

Highlights: → In this study, the coexistence of ferroelectrics and ferrimagnetism have been observed at room temperature for the (1 - x)BiFeO 3 -xBi 0.5 Na 0.5 TiO 3 (x = 0.37) solid solutions. → X-ray diffraction and Raman spectroscopy measurements show a single-phase perovskite structure with no impurities identified. → A magnetic transition from paramagnetic (PM) to ferrimagnetic (Ferri) ordering is observed for the solution with Curie temperature T C ∼ 330 K. - Abstract: The structure, ferroelectric and magnetic properties of (1 - x)BiFeO 3 -xBi 0.5 Na 0.5 TiO 3 (x = 0.37) solid solution fabricated by a sol-gel method have been investigated. X-ray diffraction and Raman spectroscopy measurements show a single-phase perovskite structure with no impurities identified. Compared with pure BiFeO 3 , the coexistence of ferroelectricity and ferrimagnetism have been observed at room temperature for the solution with remnant polarization P r = 1.41 μC/cm 2 and remnant magnetization M r = 0.054 emu/g. Importantly, a magnetic transition from ferrimagnetic (FM) ordering to paramagnetic (PM) state is observed, with Curie temperature T C ∼ 330 K, being explained in terms of the suppression of cycloid spin configuration by the structural distortion.

Structural characterization, morphology and magnetic ferrite Ni_0_,_4Zn_0_,_5Fe_2Cu_0_,_1O_4

International Nuclear Information System (INIS)

Santos, P.T.A.; Fernandes, P.C.; Santos, P.T.A.; Costa, A.C.F.M.

2011-01-01

In this work the system Ni_0_,_4Zn_0_,_5Fe_2Cu_0_,_1O_4 was obtained by combustion reaction using urea as fuel in order to evaluate their structural characteristics, and morphological imaging. The resulting samples were characterized by XRD, BET, SEM / EDS and magnetic measurements. The synthesis by combustion reaction was effective for producing samples of ferrites with crystallite size 13 nm. The X-ray diffraction showed the major phase of the inverse spinel and traces of ZnO second phase. The resulting morphology showed the formation of soft agglomerates with interparticle porosity, and mapping by SEM / EDS indicated a good distribution of elements Ni, Cu, Zn, Fe and O constituent of ferrite. The ferrite showed superparamagnetic behavior with a value of saturation magnetization of 5.60 emu / g. (author)

Microstructural Control and Characterization of Bi2V0.9Cu0.1O5.35 (BICUVOX) Ceramics

Science.gov (United States)

Razmyar, Soheil

2011-12-01

The widespread commercialization of solid-oxide fuel cells (SOFCs) and solid-oxide electrolyte cells (SOECs) is primarily limited by material degradation issues related to the required high temperature operation (>800°C). Applications of stabilized zirconia based electrolytes, which are the most commonly used oxide ion conductors, have been limited to this high temperature regime due to its low oxygen ion conductivity below 800°C. Solid electrolytes made of the BIMEVOX compositional family of materials (Bi2MexV 1-xO5.5-delta where Me=Cu, Co, Mg, Ni, Fe...) exhibit high oxide ionic conductivity similar to YSZ at a low temperature (300--600°C). Among these materials copper-substituted bismuth vanadate (Bi2V0.9Cu0.1O5.35, BICUVOX), was reported to have the highest ionic conductivity at 400°C (0.02 S/cm). It's one of the most important drawbacks of using BICUVOX, as a SOFC electrolyte is the low mechanical strength, which makes it unusable for most electrolyte supported applications. This research aims at improving mechanical strength by careful control of synthesis processing and sintering processes, thus making BICUVOX a viable material option for intermediate temperature SOFC. A co-precipitation method was used to synthesize submicron BICUVOX powder. The powder was utilized to fabricate a thin (< 250 microm) BICUVOX electrolyte membrane, with 2.5 cm2 active area and high mechanical strength. The fabricated BICUVOX membranes were densified to 97% theoretical density at lower sintering temperature and shorter time (675°C/1 h), and shows fine grain size (<1.5microm) and high mechanical strength (159 MPa).

Luminescence and magnetic behaviour of almond like (Na0.5La0.5)MoO4:RE3+ (RE = Eu, Tb, Dy) nanostructures

International Nuclear Information System (INIS)

Krishnan, Rajagopalan; Thirumalai, Jagannathan; Thomas, Sabu; Gowri, Mahasampath

2014-01-01

Graphical abstract: Monodispersed almond-like (Na 0.5 La 0.5 )MoO 4 :RE 3+ nanostructures synthesized by employing ethylene-diamine tetra acetic acid (EDTA) using hydrothermal route at 200 °C for 24 h. These nanoparticles were found to be novel bi-functional candidates suitable for high-quality luminescence and magnetic applications. - Highlights: • Almond like structures of (Na 0.5 La 0.5 )MoO 4 :RE 3+ were synthesized by hydrothermal method. • Time dependent self-assembly could be the dominant process for the formation of 3D networks. • Luminescence properties of nanosamples were studied in comparison with bulk sample. • Room temperature magnetic properties of bulk and nanophosphors were investigated. - Abstract: Tetragonal phase (Na 0.5 La 0.5 )MoO 4 :RE 3+ (RE = Eu, Tb, Dy) with almond like hierarchical structures assembled from nanosheets building blocks were successfully synthesized by employing disodium ethylenediaminetetraacetic acid (Na 2 EDTA) using hydrothermal route at 200 °C for 24 h. Field emission scanning electron microscope, transmission electron microscope, and X-ray diffraction patterns were used to characterize the morphology, size, and crystal structure with good resolution. The sequestering agent EDTA acts as quadridentate ligand coordinated with metal ions [Na + , La 3+ /RE 3+ ] facilitating the formation of self-organized 3D networks. The growth mechanism for the formation of almond like nanostructures is explicated in four paths: dissolution, adsorption, in situ transformation in acidic and basic media and the effective collision. Photoluminescence excitation and emission spectra reveals a spectral blue shift which was observed in the nanosamples towards shorter wavelengths compared with the bulk sample. Upon UV irradiation, both bulk and nanostructure show strong luminescence in the red region due to the 5 D 0 → 7 F 2 transition in Eu 3+ . Also, Tb 3+ and Dy 3+ doped (Na 0.5 La 0.5 )MoO 4 phosphor exhibit green and yellow

Loading Cd0.5Zn0.5S Quantum Dots onto Onion-Like Carbon Nanoparticles to Boost Photocatalytic Hydrogen Generation.

Science.gov (United States)

Zhou, Xiaolong; Wang, Xina; Feng, Xi; Zhang, Kun; Peng, Xiaoniu; Wang, Hanbin; Liu, Chunlei; Han, Yibo; Wang, Hao; Li, Quan

2017-07-12

Carbon dots (C dots, size < 10 nm) have been conventionally decorated onto semiconductor matrixes for photocatalytic H 2 evolution, but the efficiency is largely limited by the low loading ratio of the C dots on the photocatalyst. Here, we propose an inverse structure of Cd 0.5 Zn 0.5 S quantum dots (QDs) loaded onto the onionlike carbon (OLC) matrix for noble metal-free photocatalytic H 2 evolution. Cd 0.5 Zn 0.5 S QDs (6.9 nm) were uniformly distributed on an OLC (30 nm) matrix with both upconverted and downconverted photoluminescence property. Such an inverse structure allows the full optimization of the QD/OLC interfaces for effective energy transfer and charge separation, both of which contribute to efficient H 2 generation. An optimized H 2 generation rate of 2018 μmol/h/g (under the irradiation of visible light) and 58.6 μmol/h/g (under the irradiation of 550-900 nm light) was achieved in the Cd 0.5 Zn 0.5 S/OLC composite samples. The present work shows that using the OLC matrix in such a reverse construction is a promising strategy for noble metal-free solar hydrogen production.

Strain mediated magnetoelectric coupling induced in (x) Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-(1−x) MgFe{sub 2}O{sub 4} composites

Energy Technology Data Exchange (ETDEWEB)

Manjusha [Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Yadav, K.L., E-mail: klyadav35@yahoo.com [Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Adhlakha, Nidhi [Elettra-Sincrotrone Trieste S.C.p.A, Area Science Park, I-34012 Trieste (Italy); Shah, Jyoti; Kotnala, R.K. [CSIR-National Physical Laboratory, New Delhi 110012 (India)

2017-06-01

Particulate composites of ferroelectric and ferrite phases having general formula (x)Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-(1−x)MgFe{sub 2}O{sub 4} (x=0, 0.5, 0.6, 0.7, 0.8 and 1.0), equivalently denoted as (x)BNT-(1−x)MgFO were synthesized by solid state reaction method. From X-ray diffraction analysis, the structural transformation from tetragonal to rhombohedral corresponding to BNT phase was observed in composites with x=0.5 to x=0.8. Shifting of (012) BNT peak towards left (x=0.5, 0.8) and right side (x=0.6, 0.7) observed due to occupation of Bi{sup 3+} ions at interstitial and substitutional sites into host MgFO lattice respectively. BNT produced strain in MgFO lattice. Scanning electron micrographs show closely packed microstructure with grain size variations from 0.62 to 2.90 µm. The value of magnetoelectric (ME) coupling coefficient increases from 2.42 (x=0.5) to 4.79 (x=0.8) mV/cm. Oe due to strain produced in MgFO and BNT lattices.

Electric-pulse-induced resistance switching effect in the bulk of La0.5Ca0.5MnO3 ceramics

Directory of Open Access Journals (Sweden)

M. L. Wu

2014-04-01

Full Text Available In the majority of contributions, the electrical–pulse-induced resistance (EPIR switching effect of perovskite manganites is thought to originate from the extrinsic interfacial Schottky barrier between the metal electrode and the surface of sample. In this work, La0.5Ca0.5MnO3 (LCMO ceramic samples were synthesized by solid state reaction and the transport properties, especially, the EPIR effect and memristor behavior were investigated under 4-wire method using silver-glue as electrodes. Although the I-V characteristic of LCMO shows an ohmic linearity under the 4-wire mode at room temperature, a stable and remarkable EPIR can still be observed when the pulse voltage is more than a critical value. This bulk EPIR effect is novel for rare - earth doped manganites.

Influence of Chromium Doping on Electrical and Magnetic Behavior of Nd0.5Sr0.5MnO3 System

Science.gov (United States)

Lalitha, G.; Pavan Kumar, N.; Venugopal Reddy, P.

2018-04-01

With a view to understand the influence of chromium doping at the Mn site on the electrical and magnetic behavior of the Nd0.5Sr0.5MnO3 manganite system, a series of samples were prepared by the citrate sol-gel route method. The samples were characterized structurally by XRD. A systematic investigation of electrical resistivity over a temperature range 5-300 K was carried out mainly to understand the magneto-transport behavior in these materials. Studies on the variation of magnetization with temperature over a temperature range 80-330 K were undertaken. Investigation of magnetization at different magnetic fields at two different temperatures, viz. 80 and 300 K, was also carried out. The results show that chromium doping gave typical electrical and magnetic properties. It has been concluded that the coexistence of charge ordered and ferromagnetic phases induced by chromium doping plays an important role in the low-temperature behavior of the system.

Design and construction of an adiabatic calorimeter for samples of less than 1 cm3 in the temperature range T = 15 K to T = 350 K

International Nuclear Information System (INIS)

Lang, Brian E.; Boerio-Goates, Juliana; Woodfield, Brian F.

2006-01-01

A small-scale adiabatic calorimeter has been constructed as part of a larger project to study the thermodynamics of nanomaterials and to facilitate heat capacity measurements on samples of insufficient quantity to run on our current large-scale adiabatic apparatus. This calorimeter is designed to measure the heat capacity of samples whose volume is less than 0.8 cm 3 over a temperature range of T = 13 K to T = 350 K. Heat capacity results on copper, sapphire, and benzoic acid show the accuracy of the measurements to be better than ±0.4% for temperatures higher than T = 50 K. The reproducibility of these measurements is generally better than ±0.25%

Magnetic impurity effect on charge and magnetic order in doped La1.5Ca0.5CoO4

Science.gov (United States)

Horigane, K.; Hiraka, H.; Tomiyasu, K.; Ohoyama, K.; Louca, D.; Yamada, K.

2012-02-01

Neutron scattering experiments were performed on single crystals of magnetic impurity doped cobalt oxides La1.5Ca0.5CoO4 to characterize the charge and spin orders. We newly found contrasting impurity effects. Two types of magnetic peaks are observed at q = (0.5,0,L) with L = half-integer and integer in La1.5Ca0.5CoO4, while magnetic peak at L = half-integer (integer) was only observed in Mn (Fe)-substituted sample. Although Mn and Fe impurities degrade charge and magnetic order, Cr impurity stabilizes the ordering at x = 0.5. Based on the crystal structural analysis of Cr doped sample, we found that the excess oxygen and change of octahedron around Co3+ were realized in Cr doped sample.

Synthesis and characterization of the novel rare earth orthophosphates Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Schildhammer, Daniel; Petschnig, Lucas L.; Fuhrmann, Gerda; Heymann, Gunter; Schottenberger, Herwig; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie; Tribus, Martina [Innsbruck Univ. (Austria). Inst. fuer Mineralogie und Petrographie

2016-02-01

The new mixed rare earth (RE) orthophosphates Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4} were synthesized by a classical solid state reaction in an electrical furnace at 1200 C. As starting materials, the corresponding rare earth oxides and diammonium hydrogen phosphate were used. The powder diffraction analyses revealed that the new compounds Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4} crystallize in a zircon-type structure being isostructural with the rare earth orthophosphate YPO{sub 4}. Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4} crystallize in the tetragonal space group I4{sub 1}/amd (no. 141) with four formula units in the unit cell. The structural parameters based on Rietveld refinements are a = 687.27(2), c = 601.50(2) pm, V = 0.28412(1) nm{sup 3}, R{sub p} = 0.0143, and R{sub wp} = 0.0186 (all data) for Y{sub 0.5}Er{sub 0.5}PO{sub 4} and a = 684.61(2), c = 599.31(2) pm, V = 0.28089(2) nm{sup 3}, R{sub p} = 0.0242, and R{sub wp} = 0.0313 (all data) for Y{sub 0.5}Yb{sub 0.5}PO{sub 4}. Furthermore, the structure of Y{sub 0.5}Er{sub 0.5}PO{sub 4} was refined from single-crystal X-ray diffraction data: a = 687.78(5), c = 601.85(4) pm, V = 0.28470(5) nm{sup 3}, R{sub 1} = 0.0165, and wR{sub 2} = 0.0385 (all data). In both compounds, the rare earth metal ions are eightfold coordinated by oxygen atoms, forming two unique interlocking tetrahedra with two individual RE-O distances. The tetrahedral phosphate groups [PO{sub 4}]{sup 3-} are slightly distorted in both compounds. The individual rare earth ions share a common position (Wyckoff site 4a). The presence of two rare earth ions in the structures of the new orthophosphates Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4} was additionally confirmed by single-crystal EDX spectroscopy revealing a ratio of 1:1.

Electrical behaviors of c-axis textured 0.975Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}–0.025BiCoO{sub 3} thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Guo, Feifei [Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080 (China); Yang, Bin, E-mail: binyang@hit.edu.cn [Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080 (China); Zhang, Shantao, E-mail: stzhang@mail.nju.edu.cn [Department of Materials Science and Engineering and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Liu, Danqing [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150080 (China); Wu, Fengmin [Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080 (China); Wang, Dali [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150080 (China); Cao, Wenwu [Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080 (China); Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States)

2013-10-15

The thin films of 0.975Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}–0.025BiCoO{sub 3} (BNT-BC) have been successfully deposited on (1 1 1) Pt/Ti/SiO{sub 2}/Si (1 0 0) substrates by pulse laser deposition and their ferroelectric, dielectric, local piezoelectric properties and temperature dependent leakage current behaviors have been investigated systematically. X-ray diffraction indicates the films are single phased and c-axis oriented. The thin films exhibit ferroelectric polarization–electric field (P–E) hysteresis loop with a remnant polarization (P{sub r}) of 10.0 μC/cm{sup 2} and an excellent fatigue resistance property up to 5 × 10{sup 9} switching cycles. The dielectric constant and dielectric loss are 500 and 0.22 at 1 kHz, respectively. The tunability of the dielectric constant is about 12% at 20 kV/mm. The piezo-phase response hysteresis loop and piezo-amplitude response butterfly curve are observed by switching spectroscopy mode of piezoelectric force microscope (SS-PFM) and the piezoelectric coefficient d{sub 33} is about 19–63 pm/V, which is comparable to other reports. The dominant leakage current conduction mechanisms are ohmic conduction at low electric field and Schottky emission at high electric field, respectively. Our results may be helpful for further work on BNT-based thin films with improved electric properties.

Multiaxial creep of fine grained 0.5Cr-0.5Mo-0.25V and coarse grained 1Cr-0.5Mo steels

International Nuclear Information System (INIS)

Browne, R.J.; Flewitt, P.E.J.; Lonsdale, D.

1991-01-01

To explore the multiaxial creep response of materials used for electrical power generating plant, two steels, a fine grained 0.5Cr-0.5Mo-0.25V steel in a normalised and tempered condition with high creep ductility and a coarse grained 1Cr-0.5Mo steel in a quenched and tempered condition with low uniaxial creep ductility, have been selected. A range of multiaxial stress testing techniques which span the stress states that would allow identification of any technique dependent variables has been used. The deformation and failure of the normalised and tempered 0.5Cr-0.5Mo-0.25V steel for a range of multiaxial test techniques and, therefore, stress states may be described by an equivalent stress criterion. The results from the multiaxial tests carried out on the fully bainitic 1Cr-0.5Mo steel show that the multiaxial stress rupture criterion (MSRC) varies with stress state; at high triaxiality (notch), it is controlled by the maximum principal stress, whereas at low triaxiality (shear) it is dependent on both maximum principal stress and equivalent stress. Furthermore, a simple description of stress state based on maximum principal and equivalent stress does not define this uniquely, since the MSRC derived from uniaxial and torsion testing does not describe the failure of notch, tube, or double shear tests. (author)

Suitability of Sr{sub 0.5}Ba{sub 0.5-x}Ce{sub x}Fe{sub 12-y}Ni{sub y}O{sub 19} co-precipitated nanomaterials for inductor applications

Energy Technology Data Exchange (ETDEWEB)

Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.co [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Farooq, Saima [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2010-03-18

The present investigation deals with the synthesis and characterization of Ce-Ni ions substituted nanocrystalline strontium-barium hexaferrites (Sr{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19}) by the chemical co-precipitation method, with focus on the optimization of annealing temperature for the hexagonal phase development. The synthesis involves co-precipitation of aqueous solutions of water-soluble salts of strontium, barium and iron, at pH 9 using an ammonium hydroxide solution as a precipitating agent. The optimum temperature of annealing, necessary for the hexagonal phase development, is determined on the basis of thermo-gravimetric analysis (TGA). The co-precipitate is annealed at a temperature of 1323 K for 6 h, to produce a single magnetoplumbite phase of Sr-Ba hexaferrites, with the corresponding average crystallite size ranging from 36 to 48 nm. Observed changes in the lattice structure determined by the powder X-ray diffraction (XRD) studies are not in contradiction with the results of TGA. DC-electrical resistivity increases from 1.8 x 10{sup 10} to 12.5 x 10{sup 10} {Omega} cm, whereas the drift mobility, dielectric constant and dielectric loss tangent decrease with increasing the Ce-Ni content of the samples. Material of above-mentioned characteristics is considered to be suitable for applications in the microwave and surface mount devices (SMD) for fabricating the multilayer chip inductors (MLCI).

Hot rolling effect on the characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy

International Nuclear Information System (INIS)

Sungkono; Siti Aidah

2015-01-01

Characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy after hot rolling have been studied. The objective of this research was to obtain of hot rolling effect on the characteristics of microstructures, hardness and phases formed in Zr-0.6Nb-0.5Fe-0.5Cr alloy. The hot rolling process of alloy carried out at temperature of 800 °C with retention time of 1.5 and 2 hours and a thickness reduction between 5 to 25 %. The results of this experiment showed that the Zr-0.6Nb-0.5Fe-0.5Cr alloy has Widmanstaetten structure with microstructure evolving into deformed columnar grains and deformed elongated grains with increasing thickness reduction. Besides, the longer the retention time at temperature of 800 °C is the larger are the grain structures and formation of α-Zr and Zr_3Fe phase. The hardness of Zr-0.6Nb-0.5Fe-0.5Cr alloy has same trends i.e the larger thickness reduction gives higher hardness. The Zr-0.6Nb-0.5Fe-0.5Cr alloy can under go hot rolling deformation at a thickness reduction of 25 % and the formation of α-Zr and Zr_3Fe can increased of hardness and strength of Zr-0.6 Nb-0.5 Fe-0.5 Cr alloy. (author)

Emergence of Griffiths phase and glassy mixed phase in Sm0.5Ca0.5MnO3 nanomanganites

International Nuclear Information System (INIS)

Giri, S.K.; Yusuf, S.M.; Mukadam, M.D.; Nath, T.K.

2014-01-01

Graphical abstract: A detailed investigation on the effect of grain size on formation of Griffiths phase, and glassy mixed phase in CE-type antiferromagnetic Sm 0.5 Ca 0.5 MnO 3 manganite are carried out. A rigorous measurement of linear and non-linear ac magnetic susceptibilities, time dependent relaxation and aging phenomena in Sm 0.5 Ca 0.5 MnO 3 nanomanganite confirm the existence of a glassy mixed phase in the low temperature regime. The signature of Griffiths phase in nanosized manganite has been confirmed from the detailed ac and dc magnetization studies. The existence of Griffiths phase is verified through the anomalous behavior of the low field temperature dependent an inverse ac and dc magnetic susceptibility. Based on experimental results, the glassy phase of nanomanganites has been attributed to the phase separation effect and interaction between the ferromagnetic clusters. A phenomenological core/shell model has also been proposed based on the surface disorder to explain the observed Griffiths phase in these nanosized manganites. Fig. 1: (Left) The plot of inverse of ac susceptibility χ ac -1 measured at f = 1 Hz and H ac = 2 Oe as a function of temperature for S750 sample. Inset shows the same for S550 sample. (Right) A schematic of the proposed model to describe the magnetic state of the Sm 0.5 Ca 0.5 MnO 3 system at different average sizes. Highlights: • Effect of grain size on Griffiths phase and glassy mixed phase is discussed. • GP is confirmed by dc, linear and non-linear ac magnetization in nanomanganites. • Glassy mixed phase is discussed by time dependent relaxation and aging phenomena. • The existence of GP is verified through an inverse ac and dc magnetic susceptibility. • A phenomenological core/shell model has been proposed based on surface disorder. -- Abstract: A detailed investigation on the effect of grain size on formation of Griffiths phase (GP), and glassy mixed phase in CE-type antiferromagnetic Sm 0.5 Ca 0.5 MnO 3

Ethylbenzene dehydrogenation over Mg3Fe0.5−xCoxAl0.5 catalysts derived from hydrotalcites: Comparison with Mg3Fe0.5−yNiyAl0.5 catalysts

KAUST Repository

Atanda, Luqman A.; Balasamy, Rabindran J.; Khurshid, Alam; Al-Ali, Ali A S; Sagata, Kunimasa; Asamoto, Makiko; Yahiro, Hidenori; Nomura, Kiyoshi; Sano, Tsuneji; Takehira, Katsuomi; Al-Khattaf, Sulaiman S.

2011-01-01

A series of Mg3Fe0.5-xCoxAl0.5 (x = 0-0.5) catalysts were prepared from hydrotalcite precursors and their activities in the dehydrogenation of ethylbenzene were compared with those of a series of Mg3Fe0.5-yNiyAl0.5 (y = 0-0.5) catalysts also derived

Visualization of the Diffusion Pathway of Protons in (NH4)2Si0.5Ti0.5P4O13 as an Electrolyte for Intermediate-Temperature Fuel Cells.

Science.gov (United States)

Sun, Chunwen; Chen, Lanli; Shi, Siqi; Reeb, Berthold; López, Carlos Alberto; Alonso, José Antonio; Stimming, Ulrich

2018-01-16

We demonstrate that (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 is an excellent proton conductor. The crystallographic information concerning the hydrogen positions is unraveled from neutron-powder-diffraction (NPD) data for the first time. This study shows that all the hydrogen atoms are connected though H bonds, establishing a two-dimensional path between the [(Si 0.5 Ti 0.5 )P 4 O 13 2- ] n layers for proton diffusion across the crystal structure by breaking and reconstructing intermediate H-O═P bonds. This transient species probably reduces the potential energy of the H jump from an ammonium unit to the next neighboring NH 4 + unit. Both theoretical and experimental results support an interstitial-proton-conduction mechanism. The proton conductivities of (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 reach 0.0061 and 0.024 S cm -1 in humid air at 125 and 250 °C, respectively. This finding demonstrates that (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 is a promising electrolyte material operating at 150-250 °C. This work opens up a new avenue for designing and fabricating high-performance inorganic electrolytes.

Experimental determination of kQ factors for cylindrical ionization chambers in 10 cm × 10 cm and 3 cm × 3 cm photon beams from 4 MV to 25 MV.

Science.gov (United States)

Krauss, A; Kapsch, R P

2014-08-07

For the ionometric determination of absorbed dose to water, Dw, in megavoltage photon beams from a linear accelerator, beam-quality-dependent correction factors, kQ, are used for the ionization chambers. By using a water calorimeter, these factors can be determined experimentally and with substantially lower standard uncertainties compared to calculated values of the kQ, which are published in various dosimetry protocols. In this investigation, kQ for different types of cylindrical ionization chambers (NE 2561, NE 2571, FC 65 G) were determined experimentally in 10 cm × 10 cm photon beams from 4 MV to 25 MV (corresponding beam quality index TPR20,10 from 0.64 to 0.80). The measurements were carried out at the linear accelerator facility of the Physikalisch-Technische Bundesanstalt. It is shown that the kQ factors for a single ionization chamber in 10 cm × 10 cm photon beams can be measured with a relative standard uncertainty of 0.31%. In addition to these measurements in 10 cm × 10 cm fields, kQ factors for the NE 2561 chamber were also determined in smaller 3 cm × 3 cm photon beams between 6 MV and 25 MV. In this case, relative standard uncertainties between 0.35 % and 0.38 % are achieved for the kQ factors. It is found for this ionization chamber, that the ratio of the kQ factors in 3 cm × 3 cm and in 10 cm × 10 cm beams increases with increasing TPR20,10 to reach a value of 1.0095 at TPR20,10 = 0.8 with a relative standard uncertainty of 0.4 %.

Luminescent characteristics of UV excited Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: Pr{sup 3+} reddish-orange phosphor

Energy Technology Data Exchange (ETDEWEB)

Vidyadharan, Viji; Mohan P, Remya; Joseph, Cyriac; Unnikrishnan, N.V.; Biju, P.R., E-mail: prb.mgu@gmail.com

2016-02-15

Pr{sup 3+} doped Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3} phosphors were synthesised by solid state reaction process. The structure, surface morphology and photoluminescence of the prepared phosphors were analysed using XRD, SEM and photoluminescence spectroscopy respectively. The XRD pattern confirmed orthorhombic perovskite structure of the Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} phosphor. Agglomeration of particles with irregular shapes is observed from the SEM images. The emission spectra of Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} phosphor shows the samples can be effectively excited with UV light at 336 nm and exhibit a strong reddish-orange emission at 611 nm. Concentration dependence of emission intensity shows concentration quenching effect on increasing Pr{sup 3+} concentration after x = 0.1 because of dipole–dipole interaction. Using Blasse's formula, critical distance for energy transfer was calculated. The CIE co-ordinates, CCT, colour purity and luminescence decay of the prepared phosphors were also calculated. These results offer the prepared phosphor as a suitable candidate for various photonic applications. - Highlights: • Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} perovskite structured phosphors were synthesized. • Under UV excitation, the PL spectra show strong reddish-orange emission. • The emission from {sup 3}P{sub J} levels of Pr{sup 3+} were absent due to the presence of IVCT band. • Concentration quenching due to dipole–dipole interaction was observed. • For x = 0.1, sample shows a maximum emission intensity with 91.7% colour purity.