DOCSLIB.ORG

Local Atomic Structures at Grain Boundaries in Gadolinium Doped

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Local Atomic Structures at Grain Boundaries in Gadolinium Doped Local Atomic Structures at Grain Boundaries in Gadolinium Doped Cerium Oxides Tomomi Kosaka1*, Kiminori Sato2 1 Department of Chemistry, Tokyo Gakugei University, Tokyo, Japan, 2 Department of Environmental Science, Tokyo Gakugei University, Tokyo, Japan (Received February 28, 2010 ; Final form May 12, 2010) ABSTRACT 1. INTRODUCTION Gadolinium doped ceria (GDC) is one of the promising Gadolinium doped ceria (GDC) prepared by candidate for electrolyte 71-6/ of solid oxide fuel cell coprecipitation method was investigated by x-ray owing to high conductivity of oxygen ions in the diffraction (XRD), complex impedance measurement, intermediate temperature range (773-973K). and positron lifetime spectroscopy. The grain boundary Substitution from Ce4+ to Gd3+ produces oxygen conductivity was found to be lower than that of bulk vacancies for compensating electric charge. Since the conductivity. XRD revealed the fluorite structure ionic radius of Gd3+ is similar to that of Ce4+, gross indicating that gadolinium is successfully doped into distortion isn't expected in ceria host lattice. The excess cerium oxide. Prior to sintering, the vacancy-sized free oxygen vacancies lead to higher ionic conductivity than volume and nanovoid were observed at interfaces for undoped ceria. among crystallites. The vacancy-sized free volumes It has been suggested that oxygen ionic conductivity shrank with increasing sintering temperatures and of ceria based electrolyte is influenced by constituent finally got dominant. The results suggest that the grains. Sameshima et al. Ill reported that the grain sintering process of GDC follows the kinetics of resistance for the diffusion of oxygen ions is responsible vacancy-sized free volumes and nanovoids at interfaces. for ionic conductivity for rare-earth doped ceria prepared by coprecipitation method. In principle, high temperature sintering over at 1573K is required for GDC to achieve density more than 90% with less open porosity. Such high temperature causes a replacement Keywords: GDC, solid state electrolyte, sintering, from Ce02 to Ce203, which leads to produce positron lifetime spectroscopy micro-cracks along with the degradation of conduction efficiency. Takamura et al. /8/ observed an enhancement '•E-mail: [email protected] of electric conductivity under the pressure of Gigapascal 373 Vol. 29, Nos. 5-6, 2010 Local Atomic Structures at Grain Boundaries In Gadolinium for acceptor-doped ceria nanoparticles. They attributed 2.2. Characterization the enhancement of electric conductivity under high The lattice parameters of GDC were calculated from pressure to the densification of granular particles. diffracted peaks measured by Cu Κα X-ray diffractmeter Positrons preferentially localize at atomic disorder as (Ultima IV, Rigaku corp.) operated at 40kV, 50mA. The e.g., grain boundary 191, and provide us the information scattering angles were calibrated using Si powder (NIST on local atomic structures at annihilation sites /10-11/. 640c). The crystallite size of GDC was estimated from Some experiments by positron annihilation (111) diffraction peak by Scherrer's equation. The bulk spectroscopy predicted the presence of vacancy-like density was measured by the Archimedes method using defects and larger free volumes associated with ion exchanged water. The Pt electrodes were formed on interfaces among crystallites for zirconia-based the both side of GDC pellet by heating at 1473 Κ using materials /12-13/. Garay et al./l 3/ proposed that defects Pt paste (Tanaka Kikinzoku TR-7070). The oxygen in negatively charged grain-boundary space region ionic conductivity of the pellet was measured in air correspond to positron trapping sites, since positrons are from 673K to 973K conducted by complex impedance not trapped by positively charged spaces such as oxygen analyzer (Princeton applied research corp. VersaSTAT3) vacancies. in the frequency range from 100 μΗζ to 1MHz. The Here, our advances in the study of GDC by XRD, impedance data of GDC was analyzed using ZView complex impedance measurement, and positron lifetime software (Scribner Associates). spectroscopy are described/14/. We focus on the Positron lifetime spectroscopy was performed at evolution of local atomic structures at interfaces upon room temperature. The positron source (22Na), sealed in sintering to gain an insight into the densification a thin foil of Kapton, was mounted in a mechanism. sample-source-sample sandwich. Positron lifetime spectra (~ 106 coincidence counts) were recorded with a time resolution of 230 ps full-width at half-maximum 2. EXPERIMENTAL PROCEDURE (FWHM). The data were numerically analyzed using the 2.1. Materials POSITRONFIT code/16/. GDC was prepared by oxalate coprecipiation method /15/. The starting materials were Ce(N03)3-6H20, Gd(N03)3-6H20, H2C204'2H20. All 3. RESULTS AND DISCUSSION reagents were purchased from Wako Pure Chemical industries LTD. The cerium and gadolinium nitrate Figure 1 shows the XRD pattern of GDC sintered at solutions (0.2mol/l) were mixed at a molar ratio of 1073 Κ for 6h in air. The XRD pattern indicates that gadolinium of approximately 0.2. The mixed solution GDC has a fluorite type structure without any other was dropped into a stirred oxalic acid solution phases. The peaks denoted as Pt indicate the diffraction (0.4mol/l) to produce oxalate coprecipitate. The from sample holder. All peaks of GDC are shifted to coprecipitate was filtered, washed with ion exchanged low angle region against to the corresponded ones of water in several times, and dried at 313K for 8h. The Ce02 (denoted as solid bar) indicating the expansion of oxalate coprecipitate was calcined at 873K in air for lh interplanar spacing for GDC by Gd doping. The lattice to form GDC. The GDC powders were uniaxially parameter calculated for GDC is 0.54245 ±0.00006nm. pressed into a pellet with 10mm diameter and 2mm Hong and Virkar /17/ reported that the lattice thickness under the pressure of 20MPa. The GDC parameter,a for GDC is given by following equation: pellets were sintered from 873K to 1273K for 6h in air. 4 a = — [ΧΪΙ + (1 - x)r2 + (1 - 0.25x)r3 + 0.2Sjcr4] χ 0.9971 374 Kosaka and Sato High Temperature Materials and Processes (111) 05 λ 3 u ^ (220 ) (311) .ΐπ 2 (Λ 1 (200) • ο J wL—X 20 40 60 80 Diffraction angle, 29/° (Cu Κα) Fig. 1: XRD pattern of GDC sintered at 1073K for 6h in air. For comparison, the data of Ce02 taken from JCPDS No.34-394 is added. where x, ru r2, r3, and rA are the concentration of If the relative density of GDC is close to theoretical one, gadolinium ion, the radii of the gadolinium ion we can determine whether oxygen vacancy is formed or (0.1053nm), cerium ion (0.097nm), oxygen ion not/17/. In the case of our GDC sintered at 1273K, the (0.138nm) and the oxygen vacancy (0.1164nm), relative density is 80%. It may be thus unsuitable to respectively. The factor, 0.9971, was introduced for directly discuss the structure of GDC with the results of correcting the discrepancy between the lattice parameter Archimedes method. Based on the results of XRD measured for pure ceria (0.541 lnm; JCPDS No.34-394) reported above and experimental evidence confirming and the calculated value using this equation when χ = 0. the oxygen vacancy model/18/, we believe that Using the calculated lattice parameter and this equation, substitution of Ce44 with Gd3+ partially occurs and the Gd composition in GDC is estimated to be 0.1969. oxygen vacancies are successfully formed. Additional EDS measurements however revealed the Gd The typical complex impedance of samples consists of composition of Π0.26, which is significantly higher two semicircles in the Nyquist plot (Figure 2(a)). The than above estimation. Further exploration is required impedance arc is interpreted with equivalent electrical on this matter. circuits (Figure 2(b)). One semicircle in high frequency 375 Vol. 29, Nos. 5-6, 2010 Local Atomic Structures at Grain Boundaries In Gadolinium (a) cj ω—> oo Ν H.. ω->0 \ Rl R{ +R2 ΖΊ a Bulk Grain boundary Ä R7 Λ Λ A Λ ΛΑ Γ^ννν— vvv Fig. 2: Illustrations of (a) the Nyquist plot of typical complex impedance for GDC, (b) the equivalent electrical circuit for interpreting complex impedance of GDC. range and the other in low frequency range may obtained. This value is close to the result (75 kJ /mol) correspond to the oxygen migration in the bulk and reported by Faber et al /19/. The activation energies of across the grain boundaries, respectively. Figure 3 grain boundary for GDC and Ce02 are relatively higher shows the Arrhenius plots of the ionic conductivity than that of bulk, suggesting that the diffusion of calculated from bulk and grain boundary resistance for oxygen ion is affected by the local structural disorders GDC and Ce02. The conductivity of grain boundary is at grain boundaries. lower than that of bulk in both samples. The bulk Figure 4 shows the results of positron lifetime conductivity of GDC at 773 Κ is estimated to be spectroscopy for GDC. Prior to sintering, two 3 1 4.0* 10" S cm" , which is 160 times higher than that of components τ\ (~ 260 ps) and τ2 (~ 500 ps) Ce02. The bulk activation energy of 78.9 kJ /mol is corresponding to a vacancy-sized free volume and a 376 Kosaka and Sato High Temperature Materials and Processes 1000/Τ (Κ ') Fig. 3: Arrhenius plots of the ionic conductivity calculated from bulk and grain boundary resistance for GDC and Ce02. 377 Vol. 29, Nos. 5-6, 2010 Local Atomic Structures at Grain Boundaries In Gadolinium 280 τ 1 Γ—,100 240 873 973 1073 1173 1273 1373 1473 sintering temperature / Κ 900 — I 1 1 1 50 • • • 800 40 700 30 j Ί/ - a it) .5 ; r ω 600 20 500 10 400 J 1 1 1 1 I Τ 873 973 1073 1173 1273 1373 1473 sintering temperature / Κ Fig.
Load more

Recommended publications
  • Gadolinium Information
    Gadolinium Information Gadolinium contrast agents are frequently utilized during MRI examinations in order to improve the exam and interpretation. They are not always needed. Your radiologist will determine whether or not gadolinium contrast is needed for your MRI examination. Gadolinium contrast agents are quickly eliminated from the body in healthy individuals. With normal functioning kidneys, the retention of gadolinium in soft tissues of the body is very small and may not even be detectable. However, some patients who receive multiple doses of contrast, including pregnant women and children, might be at increased risk of gadolinium remaining in the body for longer periods of time. To date, there are no known harmful effects of gadolinium remaining in the body for long periods of time in patients who have normal kidneys. In patients who have poorly functioning kidneys, a condition called nephrogenic systemic sclerosis (NSF) can occur. This causes debilitating thickening of the skin and other tissues. This only occurs in patients with poorly functioning kidneys. Your kidney function will be checked prior to receiving gadolinium contrast agent if needed. Other side-effects can occur even in patients with healthy kidneys. Some patients report pain, tiredness, and muscle aches after receiving gadolinium contrast but these conditions have not been directly linked to the administration of the gadolinium. Allergic reactions can also occur, as with any drug. If you have questions regarding your MRI examination today, please ask your MRI Technologist. MEDICATION GUIDE MULTIHANCE® (məl-tē-han(t)s) (gadobenate dimeglumine) Injection for intravenous use What is MULTIHANCE? • MULTIHANCE is a prescription medicine called a gadolinium-based contrast agent (GBCA).
    [Show full text]
  • Gadolinium Speciation
    Gadolinium Speciation Peter Caravan Martinos Center for Biomedical Imaging Institute for Innovation in Imaging Massachusetts General Hospital and Harvard Medical School Conflicts of Interest Stock ownership (>5%): Reveal Pharmaceuticals; Collagen Medical; Factor 1A LLC. Research grants: Pfizer; Pliant Pharmaceuticals; Biogen; Agilent; Pharmakea; Siemens. Consulting: Guerbet; Bayer; Collagen Medical; UCB Biopharma; Pfizer. What do we mean by speciation? What is the chemical form of the gadolinium in tissue? Chelated Gd Dissociated Gd The GBCA remains intact Dissociation of the GBCA Gd3+ ion Is Gd bound to a low molecular weight ligand? Is Gd part of some inorganic material like hydroxyapatite? Is Gd bound to a macromolecule? If so, which one? Where is the Gd distributed within tissue? Extra vs intracellular? In which cellular compartments? Why do we care about speciation? • The chemical form of Gd may inform its potential toxicity • Mineralized, insoluble Gd may be less toxic than soluble protein bound Gd (hypothesis) • The chemical form may also inform whether the Gd will be ultimately eliminated. Intact chelate may be expected to eventually clear the body (hypothesis). • The chemical form and location may guide chelation therapy strategies. Hierarchy of relevance of the data Human in vivo Human ex vivo Animal in vivo Animal ex vivo Solutions To model ex vivo Water solutions Tweedle MF. Gadolinium deposition: Is it chelated or dissociated gadolinium? How can we tell? Magn Reson Imaging. 2016;34(10):1377–82. How do GBCAs differ • Thermodynamics:
    [Show full text]
  • ACR Manual on Contrast Media
    ACR Manual On Contrast Media 2021 ACR Committee on Drugs and Contrast Media Preface 2 ACR Manual on Contrast Media 2021 ACR Committee on Drugs and Contrast Media © Copyright 2021 American College of Radiology ISBN: 978-1-55903-012-0 TABLE OF CONTENTS Topic Page 1. Preface 1 2. Version History 2 3. Introduction 4 4. Patient Selection and Preparation Strategies Before Contrast 5 Medium Administration 5. Fasting Prior to Intravascular Contrast Media Administration 14 6. Safe Injection of Contrast Media 15 7. Extravasation of Contrast Media 18 8. Allergic-Like And Physiologic Reactions to Intravascular 22 Iodinated Contrast Media 9. Contrast Media Warming 29 10. Contrast-Associated Acute Kidney Injury and Contrast 33 Induced Acute Kidney Injury in Adults 11. Metformin 45 12. Contrast Media in Children 48 13. Gastrointestinal (GI) Contrast Media in Adults: Indications and 57 Guidelines 14. ACR–ASNR Position Statement On the Use of Gadolinium 78 Contrast Agents 15. Adverse Reactions To Gadolinium-Based Contrast Media 79 16. Nephrogenic Systemic Fibrosis (NSF) 83 17. Ultrasound Contrast Media 92 18. Treatment of Contrast Reactions 95 19. Administration of Contrast Media to Pregnant or Potentially 97 Pregnant Patients 20. Administration of Contrast Media to Women Who are Breast- 101 Feeding Table 1 – Categories Of Acute Reactions 103 Table 2 – Treatment Of Acute Reactions To Contrast Media In 105 Children Table 3 – Management Of Acute Reactions To Contrast Media In 114 Adults Table 4 – Equipment For Contrast Reaction Kits In Radiology 122 Appendix A – Contrast Media Specifications 124 PREFACE This edition of the ACR Manual on Contrast Media replaces all earlier editions.
    [Show full text]
  • Cerium Oxide Nanoparticles and Gadolinium Integration
    Linköping Studies in Science and Technology Dissertation No. 1997 Peter Eriksson Peter FACULTY OF SCIENCE AND ENGINEERING Linköping Studies in Science and Technology, Dissertation No. 1997, 2019 Cerium Oxide Nanoparticles Department of Physics, Chemistry and Biology (IFM) Linköping University SE-581 83 Linköping, Sweden and Gadolinium Integration Cerium Oxide Integration Nanoparticles and Gadolinium Synthesis, Characterization and Biomedical Applications www.liu.se Peter Eriksson 2019 Linköping Studies in Science and Technology Dissertation No. 1997 Cerium Oxide Nanoparticles and Gadolinium Integration Synthesis, Characterization and Biomedical Applications Peter Eriksson Applied Physics Department of Physics, Chemistry & Biology Linköping University, Sweden Linköping 2019 Front cover: A cerium oxide nanoparticle with integrated gadolinium. Back cover: Cross-section of a gadolinium-cerium oxide nanoparticle and its displayed theragnostic properties: left) cerium undergo redox-reactions to scavenge reactive oxygen species and right) gadolinium shorten the T1-relaxation time of nuclei spins in water molecules. During the course of the research underlying this thesis, Peter Eriksson was enrolled in Forum Scientium, a multidisciplinary doctoral programme at Linköping University, Sweden. © Copyright 2019 Peter Eriksson, unless otherwise noted Peter Eriksson Cerium Oxide Nanoparticles and Gadolinium Integration; Synthesis, Characterization and Biomedical Applications ISBN: 978-91-7685-029-9 ISSN: 0345-7524 Linköping Studies in Science and Technology,
    [Show full text]
  • Evaluating the Potential of Chelation Therapy to Prevent and Treat
    www.nature.com/scientificreports OPEN Evaluating the potential of chelation therapy to prevent and treat gadolinium deposition from Received: 29 December 2017 Accepted: 23 February 2018 MRI contrast agents Published: xx xx xxxx Julian A. Rees1, Gauthier J.-P. Deblonde1, Dahlia D. An 1, Camille Ansoborlo1, Stacey S. Gauny1 & Rebecca J. Abergel1,2 Several MRI contrast agent clinical formulations are now known to leave deposits of the heavy metal gadolinium in the brain, bones, and other organs of patients. This persistent biological accumulation of gadolinium has been recently recognized as a deleterious outcome in patients administered Gd- based contrast agents (GBCAs) for MRI, prompting the European Medicines Agency to recommend discontinuing the use of over half of the GBCAs currently approved for clinical applications. To address this problem, we fnd that the orally-available metal decorporation agent 3,4,3-LI(1,2- HOPO) demonstrates superior efcacy at chelating and removing Gd from the body compared to diethylenetriaminepentaacetic acid, a ligand commonly used in the United States in the GBCA Gadopentetate (Magnevist). Using the radiotracer 153Gd to obtain precise biodistribution data, the results herein, supported by speciation simulations, suggest that the prophylactic or post-hoc therapeutic use of 3,4,3-LI(1,2-HOPO) may provide a means to mitigate Gd retention in patients requiring contrast-enhanced MRI. Te use of gadolinium-based contrast agents (GBCAs) for magnetic resonance imaging (MRI) has been ubiqui- tous in radiology for nearly three decades1. Recently however, it has come to light that the suboptimal biological stability of GBCAs can lead to accumulation of Gd in patients’ bone and brain tissue, as well as to kidney damage and associated systemic conditions due to compromised renal function2–4.
    [Show full text]
  • Europium-DTPA: a Gadolinium Analogue Traceable by Fluorescence Microscopy
    1137 Dyke Award Europium-DTPA: A Gadolinium Analogue Traceable by Fluorescence Microscopy Allen D. Elster1 A lanthanide series chelate, europium(Eu)-DTPA, was synthesized to serve as a Susan C. Jackels2 histochemical analogue for the widely used MR contrast agent gadolinium(Gd)-DTPA. Nina S. Allen3 Eu and Gd, being neighboring elements on the periodic table, share many fundamental Ron C. Marrache2 properties, including ionic radius, valence, and chemical reactivity. Eu-DTPA, however, possesses one important physical property not shared by Gd-DTPA: luminescence under ultraviolet light. The feasibility of detecting Eu-DTPA in animal tissues under fluorescence microscopy was systematically evaluated and documented. Distinctive orange-red luminescence of Eu-DTPA could be observed in the kidneys, livers, dura, choroid, and pituitary glands of rats after intravascular injection. No lumi­ nescence was detected in areas of brain beyond an intact blood-brain barrier. When the brain was locally injured by an experimental laceration, however, leakage of Eu-DTPA was detected. Electron probe microanalysis confirmed the parallel presence or absence of simultaneously injected Eu-DTPA and Gd-DTPA in all tissues studied. Fluorescence microscopy with Eu-DTPA has thus been validated as a method for tracing the distri­ bution of Gd-DTPA at the microscopic level. AJNR 10:1137-1144, November/December 1989 The recent development of paramagnetic MR contrast agents such as gadolinium (Gd)-DTPA has been received by the radiologic community with justifiable enthu­ siasm. Like their iodinated counterparts in CT, MR contrast agents appear to offer increased sensitivity and specificity for detecting and characterizing a number of diseases affecting the nervous system [1-11 ].
    [Show full text]
  • Enriched Gadolinium As Burnable Absorber For
    PHYSOR 2004 – The Physics of Fuel Cycles and Advanced Nuclear Systems: Global Developments Chicago, Illinois, April 25-29, 2004, on CD-ROM, American Nuclear Society, Lagrange Park, IL. (2004) Enriched Gadolinium as Burnable Absorber for PWR Klaes-Håkan Bejmer*1 and Ola Seveborn2 1Vattenfall Bränsle AB, S-162 87 Stockholm, Sweden 2Sernanders väg 5-518, S-752 61 Uppsala, Sweden Abstract This paper is a summary of a master of thesis work in reactor physics made by Ola Seveborn. The work was done at Vattenfall Bränsle AB and Ola was guided through the work by the corresponding author of this paper. The results presented are calculations for Ringhals 3, which is a Westinhouse 3- loop PWR within the Vattenfall Group. The fuel is characterized by 17x17 assemblies of AFA type containing 3.80-3.95 w/o 235U and 8 rods containing 2 w/o Gadolinium with an enrichment of 70 w/o 157Gd. The calculations were performed with the Studsvik-Scandpower code package based on the CASMO-4 lattice code and the SIMULATE-3 nodal code. The results are compared to the corresponding calculations for fuel with 5 w/o gadolinium with natural isotopic constitution. The depletion of the cores was done separately for the reference and enriched case. The results show that the gains in average for the five cycles studied are about 70 EFPH per cycle. This is an effect of the lower gadolinium content needed. Also less parasitic absorption of enriched gadolinium in the end of the fuel life contributes to the increased cycle lengths. The abruptly increased reactivity and internal power peaking factor around 10 MWd/kgU do not affect the core design negatively.
    [Show full text]
  • GADOLINIUM Element Symbol: Gd Atomic Number: 64
    GADOLINIUM Element Symbol: Gd Atomic Number: 64 An initiative of IYC 2011 brought to you by the RACI KAYE GREEN www.raci.org.au GADOLINIUM Element symbol: Gd Atomic number: 64 Spectroscopic lines due to gadolinium were first observed in 1880 by Swiss chemist Jean Charles Galissard de Marignac in samples of several rare earth oxide minerals. Then in 1886, French chemist Paul Émile Lecoq de Boisbaudran separated gadolinia, a rare earth oxide, from yttria. Elemental gadolinium was isolated only recently, and like the mineral gadolinite, is named after Finnish chemist and geologist Johan Gadolin. Elemental gadolinium is a reactive silvery-white metal, which exists in nature in the oxide minerals monazite and bastnäsite, together with other rare earth metals. Ironically, only trace amounts of gadolinium are present in the mineral gadolinite. Historically, Australia has exported significant quantities of monazite from heavy mineral sands mined in Western Australia, New South Wales and Queensland for the extraction of rare earth metals including gadolinium. However, China is both the largest supplier and user of these metals. Gadolinium has the highest thermal neutron capture cross-section of any known element and in its common trivalent oxidation state it has a single electron in each of its seven 4f valence orbitals, which gives it the equal largest number of unpaired electrons of any element. These chemical properties give rise to important medical and industrial applications for gadolinium compounds, including use as intravenous contrast agents to enhance images in medical magnetic resonance imaging and use in targeting tumours in neutron capture therapy. Gadolinium compounds are also employed for neutron shielding in nuclear reactors and for making green phosphors for colour TV tubes and compact discs.
    [Show full text]
  • Morphology and Structural Stability of Bismuth-Gadolinium Co-Doped Ceria Electrolyte Nanopowders
    inorganics Article Morphology and Structural Stability of Bismuth-Gadolinium Co-Doped Ceria Electrolyte Nanopowders Grazia Accardo 1 , Luca Spiridigliozzi 2 , Gianfranco Dell’Agli 2,* , Sung Pil Yoon 1 and Domenico Frattini 3 1 Center of Hydrogen-Fuel Cell Research, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu, Seoul 136-791, Korea; [email protected] (G.A.); [email protected] (S.P.Y.) 2 Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino (FR) Italy; [email protected] 3 Graduate School of Energy and Environment, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea; [email protected] * Correspondence: [email protected]; Tel.: +39-776-2993682 Received: 28 August 2019; Accepted: 26 September 2019; Published: 28 September 2019 Abstract: The reduction of the sintering temperature of doped ceria ceramics remains an open challenge for their real exploitation as electrolytes for intermediate temperature solid oxide fuel cell (IT-SOFCs) at the industrial level. In this work, we have used Bi (0.5 and 2 mol %) as the sintering aid for Gd (20 mol %)-doped ceria. Nano-sized powders of Bi/Gd co-doped ceria were easily synthesized via a simple and cheap sol-gel combustion synthesis. The obtained powders showed high sinterability and very good electrochemical properties. More importantly, even after prolonged annealing at 700 ◦C, both of the powders and of the sintered pellets, no trace of structural modifications, phase instabilities, or Bi segregation appeared. Therefore, the use of a small amount of Bi can be taken into account for preparing ceria-based ceramic electrolytes at low sintering temperatures.
    [Show full text]
  • BNL-79513-2007-CP Standard Atomic Weights Tables 2007 Abridged To
    BNL-79513-2007-CP Standard Atomic Weights Tables 2007 Abridged to Four and Five Significant Figures Norman E. Holden Energy Sciences & Technology Department National Nuclear Data Center Brookhaven National Laboratory P.O. Box 5000 Upton, NY 11973-5000 www.bnl.gov Prepared for the 44th IUPAC General Assembly, in Torino, Italy August 2007 Notice: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The publisher by accepting the manuscript for publication acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. This preprint is intended for publication in a journal or proceedings. Since changes may be made before publication, it may not be cited or reproduced without the author’s permission. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party’s use or the results of such use of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof or its contractors or subcontractors.
    [Show full text]
  • Tuning the Doping of Europium in Gadolinium Borate Microparticles At
    This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Article Cite This: ACS Omega 2019, 4, 14497−14502 http://pubs.acs.org/journal/acsodf Tuning the Doping of Europium in Gadolinium Borate Microparticles at Mesoscale Toward Efficient Production of Red Phosphors † ‡ † ‡ † † ‡ ‡ † ‡ Simin Cui, , Xianglei He, , Dan Wang,*, Jie-Xin Wang, , Yuan Pu,*, and Jian-Feng Chen , † ‡ State Key Laboratory of Organic-Inorganic Composites and Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029, China *S Supporting Information ABSTRACT: The ideal product of rare-earth-doped phosphors should have uniform particle size distribution and homogeneous doping ions in each particle, and therefore, intensified micromixing at mesoscale is highly required. In this article, inspired by the concept of “mesoscience”,we 3+ demonstrate the tuning of Eu doping in GdBO3 microparticles at mesoscale by a high-gravity-assisted reactive precipitation-coupled calcination process. The high-gravity environment and tiny droplets generated by the high-gravity rotating packed bed (RPB) reactor lead to significant intensification of mass transfer and micromixing, which are beneficial for the homogeneous doping of Eu3+ in the host material during reactive precipitation in liquid solution. Under excitation at 395 nm, the emission spectra of the Eu3+-doped phosphors exhibit a narrow- band red emission centered at 625 nm and the highest intensity was observed at x = 0.2. The RPB products show higher intensity than that of the control group even when the reaction time was shortened to 1/6.
    [Show full text]
  • Benefits and Detriments of Gadolinium from Medical Advances to Health
    molecules Review Benefits and Detriments of Gadolinium from Medical Advances to Health and Ecological Risks 1, 1, 2, 1, Colin Unruh y , Nicolas Van Bavel y, Max Anikovskiy * and Elmar J. Prenner * 1 Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; [email protected] (C.U.); [email protected] (N.V.B.) 2 Department of Chemistry, University of Calgary, Calgary, AB T2N 1N4, Canada * Correspondence: [email protected] (M.A.); [email protected] (E.J.P.) These authors contributed equally to this work. y Academic Editors: Mark von Itzstein and Harri Lönnberg Received: 2 November 2020; Accepted: 4 December 2020; Published: 7 December 2020 Abstract: Gadolinium (Gd)-containing chelates have been established as diagnostics tools. However, extensive use in magnetic resonance imaging has led to increased Gd levels in industrialized parts of the world, adding to natural occurrence and causing environmental and health concerns. A vast amount of data shows that metal may accumulate in the human body and its deposition has been detected in organs such as brain and liver. Moreover, the disease nephrogenic systemic fibrosis has been linked to increased Gd3+ levels. Investigation of Gd3+ effects at the cellular and molecular levels mostly revolves around calcium-dependent proteins, since Gd3+ competes with calcium due to their similar size; other reports focus on interaction of Gd3+ with nucleic acids and carbohydrates. However, little is known about Gd3+ effects on membranes; yet some results suggest that Gd3+ interacts strongly with biologically-relevant lipids (e.g., brain membrane constituents) and causes serious structural changes including enhanced membrane rigidity and propensity for lipid fusion and aggregation at much lower concentrations than other ions, both toxic and essential.
    [Show full text]