<報文>高レベル放射性廃棄物の固定化に関する研究 : II アルカリ土金属塩と含水酸化チタンとの反応

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Titanates with the perovskite-type structure are expected as the most suitable materials which are capable of keeping the radwaste for the long period. Thus the fomation of titanates of calcium, strontium and barium by the reactions of their nitrates, carbonates and hydroxides with titanium dioxide hydrate was studies by means of thermogravimetry and X-ray diffraction. The chemical reactivity of the reagents was compared with each other using initial and final temperatures of the reactions on TG curves. When heated in air, TiO₂. H₂O was converted into anatase between 330 and 570℃after losing the combined water, then to rutile above 800℃. The reactions of Ca(NO₃)₂, Sr(NO₃)₂ and Ba(NO₃)₂ with TiO₂・H₂O were found to occur at lower temperatures than the decomposition of the nitrates by 10, 20 and 30℃, respectively. The products were mainly the monotitanates with high crystallinity. The reactions of the cabonates with TiO₂・H₂O began at slightly lower temperatures than those of the decomposition of the carbonates, but the former finished at lower temperatures than the latter by 100℃ or more. The reactivity of the hydroxides were higher than those of the nitrates and the carbonates.
横浜国立大学の論文