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981.
La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM8282), La0.8Sr0.2Ga0.8Mg0.15Co0.05O3−δ (LSGMC5) and La0.8Sr0.2Ga0.8Mg0.115Co0.085O3−δ (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb–Wagner polarization within the temperature range of 973–1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10−5 atm) and low oxygen partial pressure regions (<10−15 atm). However, the electrical conductivity in LSGM8282 had no dependency on the oxygen partial pressure. At temperatures higher than 1073 K, PO2 dependencies of the free electron conductivities in LSGM8282, LSGMC5 and LSGMC8.5 were about −1/4, and PO2 dependencies of the electron hole conductivities were about 0.25, 0.12 and 0.07, respectively. Oxygen ion conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high and low oxygen partial pressure regions, which was due to the increase in the concentration of oxygen vacancies. The change in the concentration of oxygen vacancies and the valence of cobalt with oxygen partial pressure were determined using a thermo-gravimetric technique. Both the electronic conductivity and oxygen ion conductivity in cobalt doped lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number. 相似文献
982.
983.
984.
《International Journal of Hydrogen Energy》2019,44(4):2258-2265
Various metal nanoparticle catalysts supported on Vulcan XC-72 and carbon-nanomaterial-based catalysts were fabricated and compared and assessed as substitutes of platinum in microbial electrolysis cells (MECs). The metal-nanoparticle-loaded cathodes exhibited relatively better hydrogen production and electrochemical properties than cathodes coated with carbon nanoparticles (CNPs) and carbon nanotubes (CNTs) did. Catalysts containing Pt (alone or mixed with other metals) most effectively produced hydrogen in terms of overall conversion efficiency, followed by Ni alone or combined with other metals in the order: Pt/C (80.6%) > PtNi/C (76.8%) > PtCu/C (72.6%) > Ni/C (73.0%) > Cu/C (65.8%) > CNPs (47.0%) > CNTs (38.9%) > plain carbon felt (38.7%). Further, in terms of long-term catalytic stability, Ni-based catalysts degraded to a lesser extent over time than did the Cu/C catalyst (which showed the maximum degradation). Overall, the hydrogen generation efficiency, catalyst stability, and current density of the Ni-based catalysts were almost comparable to those of Pt catalysts. Thus, Ni is an effective and inexpensive alternative to Pt catalysts for hydrogen production by MECs. 相似文献
985.
986.
Liang Guo Hong Zhang Dongxu Zhao Bin YaoBinghui Li Zhenzhong ZhangDezhen Shen 《Materials Letters》2011,65(10):1495-1498
The horizontal ZnO nanorods (NRs) were grown by using a low temperature hydrothermal method between the lithographic ZnO interdigital electrodes. In order to horizontally grow the ZnO nanorods, the vertical growth was restrained by coating with the photoresist on the surface nucleation sites. By controlling the distance between the electrodes, only the electrodes for an interval of 7 μm can be connected by the horizontal nanorods to form device. The electrical property of the device was measured. The detector showed a narrow ultraviolet photoresponse with a response peak at 379 nm, which was according with the peak of the photoluminescence. The mechanism of photoresponse was discussed. 相似文献
987.
Asm Sabbir Ahmed Gary H. Kramer 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,659(1):543-548
This study described the performance of an array of HPGe detectors, made by ORTEC. In the existing system, a metal end cap was used in the detector construction. In general, the natural metal contains some radioactive materials, create high background noises and signals during in vivo counting. ORTEC proposed a novel carbon fiber to be used in end cap, without any radio active content. This paper described the methodology of developing a model of the given HPGe array-detectors, comparing the detection efficiency and cross talk among the detectors using two end cap materials: either metal or carbon fiber and to provide a recommendation about the end cap material. The detector's counting efficiency were studied using point and plane sources. The cross talk among the array detectors were studied using a homogeneous attenuating medium made of tissue equivalent material. The cross talk was significant when single or multiple point sources (simulated to heterogeneous hot spots) were embedded inside the attenuating medium. With carbon fiber, the cross talk increased about 100% for photon energy at about 100 keV. For a uniform distribution of radioactive material, the cross talk increased about 5-10% when the end cap was made of carbon instead of steel. Metal end cap was recommended for the array of HPGe detectors. 相似文献
988.
M. Matsubayashi A. FaenovT. Pikuz Y. FukudaY. Kato R. YasudaH. Iikura T. NojimaT. Sakai 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,651(1):90-94
Neutron imaging by color center formation in LiF crystals was applied to a sensitivity indicator (SI) as a standard samples for neutron radiography. The SI was exposed to a 5 mm pinhole-collimated thermal neutron beam with an LiF crystal and a neutron imaging plate (NIP) for 120 min in the JRR-3M thermal neutron radiography facility. The image in the LiF crystal was read out using a laser confocal microscope. All gaps were clearly observed in images for both the LiF crystal and the NIP. The experimental results showed that LiF crystals have excellent characteristics as neutron imaging detectors in areas such as high spatial resolution. 相似文献
989.
Christopher J. Stapels Erik B. JohnsonXiao J. Chen Thomas H. PrettymanEric R. Benton James F. Christian 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,652(1):342-346
The compact, robust nature of the CMOS solid-state photomultiplier (SSPM) allows the creation of small, low-power scintillation-based radiation measurement devices. Monitoring space radiation including solar protons and secondary neutrons generated from high-energy protons impinging on spacecraft is required to determine the dose to astronauts. Small size and highly integrated design are desired to minimize consumption of payload resources.RMD is developing prototype radiation measurement and personal dosimeter devices using emerging scintillation materials coupled to CMOS SSPM’s for multiple applications. Spectroscopic measurements of high-energy protons and gamma-rays using tissue-equivalent, inorganic scintillators coupled to SSPM devices demonstrate the ability of an SSPM device to monitor the dose from proton and heavy ion particles, providing real time feedback to astronauts. Measurement of the dose from secondary neutrons introduces additional challenges due to the need to discriminate neutrons from other particle types and to accurately determine their energy deposition. We present strategies for measuring neutron signatures and assessing neutron dose including simulations of relevant environments and detector materials. 相似文献
990.
M. Ellis P.R. HobsonP. Kyberd J.J. NebrenskyA. Bross J. FaganT. Fitzpatrick R. FloresR. Kubinski J. KriderR. Rucinski P. RubinovC. Tolian T.L. Hart D.M. KaplanW. Luebke B. FreemireM. Wojcik G. BarberD. Clark I. ClarkP.J. Dornan A. FishS. Greenwood R. HareA. Jamdagni V. KaseyM. Khaleeq J. LeaverK.R. Long E. McKigney T. Matsushita C. Rogers T. SashalmiP. Savage M. Takahashi A. TapperK. Yoshimura P. CookeR. Gamet H. SakamotoY. Kuno A. SatoT. Yano M. YoshidaC. MacWaters L. ConeyG. Hanson A. Klier D. ClineX. Yang D. Adey 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,659(1):136-153