Ladislav Kosa, Iveta Macková, Ivo Proks, Ondrej Pritula, Ľubomír Smrčok, Miroslav Boča, Håkan Rundlőf
March 1, 2008
Three thermal effects on heating/cooling of K2TaF7 in the temperature interval of 680–800°C were investigated by the DSC method. The values determined for the enthalpy change of the individual processes are: ΔtransIIHm(K2TaF7; 703°C) = 1.7(2) kJ mol−1, ΔtransIHm(K2TaF7; 746°C) = 19(1) kJ mol−1 and ΔtransIIIHm(K2TaF7; 771°C) = 13(1) kJ mol−1. The first thermal effect was attributed to a solid-solid phase transition; the second to the incongruent melting of K2TaF7 and the third to mixing of two liquids. These findings are supported by in situ neutron powder diffraction experiments performed in the temperature interval of 654–794°C.