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AN IRREVERSIBILITY PHENOMENA IN ELECTRICAL CONDUCTIVITY OF THE MELTS IN SODIUM IRON PHOSPHATE SYSTEM

F. Y. Chen1)and E. D. Delber2) 1) State Key Laboratory of Solidification Process , Northwestern Polytechnic University , Xi’an 710072 , China 2) Department of Ceramics Engineering , University of Missouri Rolla , Rolla , Mo 654301 , USA

金属学报(英文版)

Theelectricalresistivityofsodium iron phosphate melts wasinvestigated asa functionoftem peratureand composition. Irreversibility was found in thetemperature dependent electricalresistivityinthe melts withlow Na2 Ocontentduringtheheating andcoolingcycle. Theirre versibility wasreduced withincreasing Na2 Ocontent. Theelectricalresistivity tendedto de creaseslightly withtime. Theelectricalconduction ofthe meltscontainingsimulatedindustry waste wassimilartothatofthe melts withsimilarsodacontent. Thetemperature dependent electricalresistivity and activation energy ofthese melts was discussed using the Motttheory and wascorrelatedtothe Fe(II) contentinthe melts

关键词: irreversibility , null , null

Sintering of Doped, Nanocrystalline CeO_2 Powders Prepared under Hydrothermal Conditions

Yanchun ZHOU(Institute of Metal Research , Chinese Academy of Sciences , Shenyang , 110015 , China)M.N.Rahaman (Ceramic Engineering Department , University of Missouri-Rolla , Rolla , MO 65401 , USA)

材料科学技术(英文)

Nanocrystalline CeO2 powders (particle size ≈10-15 nm), doped with up to 20 at.-% of Mg,Ca or Y were prepared by chemical precipitation under hydrothermal conditions. The particle size and shape of the powders change slightly with the dopant concentrations. The the of the dopants on the sintering of the compacted powders was investigated during heating at a constant rate of 10℃/min. The elemental composition and the concentration of the dopant has significant efFect on the densification and grain growth. Compared to undoped CeO2, the dopants produce a shift in the densification curve to higher temperatures. For the same dopant concentration and under identical sintering conditions, the Ca doped samples reach nearly full density with the smallest grain size (≈50 nm), however, the Mg doped sample has the lowest density (≈95% of the theoretical) with the largest grain size (≈1 μm)

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