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Crystals of the Sr 1 -x Ce x F 2 + x compositions close to the congruent one (x ~ 0.3) are fabricated by the vertical directional crystallization. It is shown that the use of CF 4 to form a fluorinating atmosphere dur ing growth leads to additional spurious absorption in the crystals in the range 350-600 nm. The use of PbF 2 and ZnF 2 for fluorination makes it possible to obtain colorless Sr 1 -x Ce x F 2 + x crystals of the desired optical quality from melt. The thermal conductivity of crystal with x ~ 0.28 in the temperature range 80-500 K lies within 1.50 ± 0.03 W m -1 K -1 . High ionic conductivity makes the Sr 1 -x Ce x F 2 + x crystals promising for appli cation in solid state ionics.