| Research Abstract |
The chemical analysis, X-ray diffractometry, FT/IR,Mossbauer effect, XPS measurement showed that the metal ions (Fe^<2+>, Ni^<2+>) in the CIO-layr (Carbon bearing iron oxide-layr) on the Ni(II)-ferrite form a kind of carbide-like linkage in the activation step. The CIO-layr is formed as a part of the spinel structure of the bulk Ni(II)-ferrite with a stoichiometric chemical composition. Fe^<2+> ion in the CIO-layr exists in the distorted spinel structure which contains a higher Content of Fe^<2+> ion than the normal spinel structure. The carbon element of the graphite in the CIO-layr can make a bonding with the Fe^<2+> ion in the CIO-layr under a lower partial pressure of O_2 at 300ﾟC.This would cause the formation of the carbide-like linkage and make it easy for O^2-ion to be released from CIO-layr. This Fe^<2+>-rich structure in the distorted spinel structure can be regarded as a distorted FeO structure, which would cause the O_2 gas evolution in the decomposition of the FeO structur
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e into the spinel phase and metallic phase. This was experimentally confirmed by the O_2 evolution reaction of the FeO/ZnO by-phase system under a lower oxygen partial pressure at 500ﾟC.Based on these O_2 evolution mechanism, a chemical structure with a higher reactivity of the O_2 release was designed. This offered a new route for developing the materials with a higher efficiency in the heat/chemical energy conversion system. Ultra-fine particles of the CIO-layred Ni(II)-ferrite was found to give an another way for increasing the O_2 evolution efficiency by 3 times. The results on the heat/chemical energy conversion experiment using a device specially designed and made, gave a poor efficiency for the CBNF.Therefore, a new system (combined cycle of 1st- and 2nd- Redox Systems), by which the heat/chemical energy conversion efficiency can be amplified, was designed and proved to be practically worked. This system was further studied to apply to the solar energy conversion into chemical energy at a lower temperature of 400-800ﾟC.The 2nd-Redox System was found to be used for solar energy/hydrogen energy conversion at the low temperatures. Less
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