Funct. Mater. 2018; 25 (3): 594-600.


On the features of crystallization methods used for the purification of aqueous solutions of cesium iodide

V.L.Cherginets, T.V.Ponomarenko, T.P.Rebrova, A.G.Varich, A.L.Rebrov, Yu.N.Datsko

Institute for Scintillation Materials, STC Institute for Single Crystals, National Academy of Sciences of Ukraine, 60 Nauky Ave., 61072 Kharkiv, Ukraine


Comparative analysis of CsI purification methods: mass crystallization with natural cooling (MC), low-temperature directed crystallization without stirring (LTDC/ws) and low-temperature mixed crystallization (LTMC) is presented. The MC routine possesses the highest cooling rate (6-10°C/h) and the smallest effective purification coefficients (β = 0.07-0.2) from Na, K and Rb, however the yield of the product per stage is only 60 %. The low-temperature methods are characterized by low cooling rate of ~1°C/h and higher yields of the purified product per stage (95-97 %) and β values closer to 1 than those for MC; the purification occurs especially hardly in the case of LTDC/ws (β ~ 0.9).The mentioned crystallization methods do not provide the removal of Tl which is accumulated in the product. With respect to efficiency of the purification 1 stage of MC is equivalent to 3-4 stages of LTMC or 10-11 stages of LTDC/ws and the yield of the product (CsI) is 60 %, 85-90 % and 55-70 %, respectively. The LTMC method seems the most promising for the obtaining of extra pure CsI of enhanced quality due to low enough values of β for Na, K and Rb (β = 0.46-0.6) and considerably smaller than in the case of MC rate of cooling (a degree of overcooling).

cesium iodide, mass crystallization, low-temperature, crystallization, admixture distribution.

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