成果報告書詳細
管理番号20100000002048
タイトル*平成20年度中間年報 水素製造・輸送・貯蔵システム等技術開発 次世代技術開発・フィージビリティスタディ等 革新的な次世代技術の探索・有効性検証に関する研究開発 超高圧水素合成法による新規水素吸蔵合金の研究開発
公開日2011/5/10
報告書年度2008 - 2008
委託先名国立大学法人東北大学大学院工学研究科
プロジェクト番号P08003
部署名燃料電池・水素技術開発部
和文要約和文要約等以下本編抜粋:1.研究開発の内容及び成果等 本研究では超高圧法を用いた、新規水素貯蔵材料開発を目的としたLiをベースに希土類、遷移金属の他、軽元素の添加も探索範囲とし、超高圧合成法を用いて新規Li合金系水素貯蔵材料の探索を行う。得られた新規水素化物の水素放出温度や水素含有量の測定を行うとともに、放射光を用いたX線回折データやラマン分光法などによる分光学的データも利用して精密構造解析を行う。すなわち、下記のi)超高圧合成による新材料創製、ii)水素吸蔵・放出特性評価、iii)精密構造解析を実施し、目標の達成を図る。
英文要約High Pressure synthesis has been used for exploring novel compounds for hydrogen storage media. In this study, we focused on exploration of novel hydrides in Li-RE (RE = Y, La) systems. Cubic-anvil-type apparatus, which can yield high pressure of 2-5 GPa, was adopted in synthesizing new compounds of LiH-YH3 and LiH-TM-H.
Judging from XRD analyses of LiH-x%YH3 samples (x = 33-100) prepared at 973 K for 2 h under 5 GPa, only the FCC phase was observed in x = 33-90, but their lattice constants were estimated to be the same value of a = 0.528 nm. Since it is difficult to detect Li-based phase by XRD analysis, Li-rich samples might include the Li-based phases, such as LiH, Li2O and so on. In addition, for the sample of x = 95, YH3 phase was observed as a secondary phase besides the FCC phase. Judging from these results, composition of this FCC phase is suggested to be about x = 90. Moreover, the sample of x = 90 was found to exhibit CeH3-type structure, which is different from those of precursor materials, from Raman analysis. From these results, the FCC phase is suggested to be a novel hydride. Li content in the novel hydride was estimated to be 7 at% from Rietveld analysis. The novel hydride was decomposed at about 575 K with endothermic reaction. Hydrogen content of the hydride was estimated to be 3.52 mass%. The hydride was partially dehydrogenated at 575 K with decreasing its lattice constant down to 0.5206(1) nm. The dehydrogenated FCC hydride could absorb hydrogen under 5 MPa-H2 at 623 K, and formed FCC structure again. It seems this novel hydride could be absorb /desorb reversibly. Hydrogenation enthalpy of the hydride was estimated from endothermic peak to |Δ H| = 29.2 kJ/mol-H which is lower value than that of YH3 ambient pressure phase. Total hydrogen content of FCC hydride was estimated to be 3.52 mass%.
In Li-M-H system, two unidentified compounds, which had FCC and NaCl type crystal structures, could be synthesized under 5GPa. In Li-Ni-H system, FCC type unidentified compound was also synthesized.
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