Abstract

A method for the preparation of extra-pure Na₂CO₃ powder has been developed. The method is based on a fractional crystallization of Na₂CO₃ from its saturated solutions and its conversion into sodium formate, followed by a melt crystallization. To obtain the final product Na₂CO₃, the recrystallized sodium formate was thermally decomposed. The contents of Th and U in the purified powder were below 10 ppt, the concentrations of Mn, Co, Ba, and Pb were not above 3 ppb, the concentrations of Cu and Sr were on the level of tens of ppb, and the K concentration was about 200 ppb. The ICP-MS analysis showed that the purity of the obtained powder significantly surpasses that for commercial products in 99.997 and 99.999% purity grades. The sodium carbonate powder thus obtained is going to be used as initial material for growing scintillation single crystals in experiments searching for the neutrinoless double beta decay (0νββ) or dark matter.

中文翻译：

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结晶技术制备超纯Na 2 CO 3粉体用于低背景闪烁晶体的生长

摘要

已经开发了制备超纯Na ₂ CO ₃粉末的方法。该方法基于Na ₂ CO ₃从其饱和溶液中的分步结晶并转化为甲酸钠，然后进行熔融结晶。获得最终产品Na ₂ CO ₃，将重结晶的甲酸钠热分解。纯化粉末中的Th和U含量低于10 ppt，Mn，Co，Ba和Pb的浓度不超过3 ppb，Cu和Sr的浓度为几十ppb，而K浓度约为200 ppb。ICP-MS分析表明，所获得粉末的纯度等级为99.997和99.999％，大大超过了商业产品。如此获得的碳酸钠粉末将用作寻找无中微子双β衰变（0νββ）或暗物质的实验中生长闪烁单晶的原料。