Norihito Ikemiya1, Sigeta Hara1, Hirohumi Maki2 and Kazumi Ogino1
1Department Materials Science & Processing, Faculty of Engineering, Osaka University, Suita
Densities and surface tensions of LiF-MF3 (M: Nd, Gd, La) binary systems were measured under Ar gas by the maximum bubble pressure method. The results obtained were as follows:
(1) Molar volume of the melt in the LiF-LaF3 system satisfied the additive rule on volume, while those for two other binary systems deviated positively from the additive rule near the eutectic composition.
(2) Surface tensions of melts in these binary systems are deviated negatively from Guggenheim's equation for ideal solution.
(3) Assuming that the binary melts behave as the regular solution, for the LiF-LaF3 system the interaction energy ω calculated from the thermochemical data is in good agreement with that computed from the surface tension by Guggenheim's equation. For the LiF-NdF3 system, the computed value of ω from the surface tension is three times larger than that from the thermochemical data and it is similar to that for the LiF-GdF3 system. We concluded that behavior of LaF3 is different from that of NdF3, GdF3 in LiF-MF3 (M: Nd, Gd, La) systems.
surface tension, density, binary melt, LiF, NdF3, GdF3, LaF3
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