This paper describes ultrapurification of isotopically enriched calcium and molybdenum com pounds and 40Ca100MoO4 calcium molybdate growth charge in order to remove radioactive uranium, thorium, and radium impurities. 40Ca100MoO4 single crystals grown from such charges are needed for the fabrication of scintillator elements of the cryogenic detector for the AMoRE project: a search for 100Mo neutrinoless double-beta decay.
We developed a technique for ultrapurification of isotopically enriched calcium formate and obtained a product with a 226Ra (214Bi) content of 1.4 mBq/kg. A 40Ca100MoO4 calcium molybdate growth charge was prepared through precipitation from aqueous solution. Its purity was as follows: 0.3 × 10–7 wt % U, 0.9 × 10–7 wt % Th, and 1.6 mBq/kg 226Ra.
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