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NaF*BeF2-2NaF*BeF2 triangle contained only
the three phases at the apexes, since the reaction
rate in the solid state is too slow to permit
equilibrium to be obtained. Second, examination
of quenched samples in the LiF-2NaF*LiF-2BeF2-
2NaF*BeF2 triangle showed that the ternary
eutectic (mp, 328OC) is above the upper limit of
stability of the compound and that the phases just
below the solidus temperature are those at the
apexes of the triangle.
The x-ray diffraction pattern of 5NaF*LiF-3BeF2
is related to that given by John', for low-temper-
ature 3NaF*LiFQBeF2. Quenched compositions
0 corresponding to 3NaF*LiFQBeF2 contained
2NaF-LiF*2BeF2, 2NoF-BeF2, and LiF just
below the sol idus temperature and 5Na F-Li F 03Be F 2,
2NaF-LiF*2BeF2, and LiF below 320OC. No
evidence has been found in this laboratory to
suggest that 3NaF*LiF*2BeF2 exists,
The locations of the phase boundaries and
ternary eutectics were deduced from the primary
and secondary phases observed in quenched
samples of the compositions within the compatibility
triangles and the temperatures at which the
phases appeared, as well as from previously
obtained thermal analysis data.
F
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W
THE SYSTEM NaF-RbF-BaF2
L. M. Bratcher
Thermal analysis data were obtained for a
number of compositions in the NaF-RbF-BeF,
system containing 50 mole % BeF,, and some of
the slowly cooled melts were examined petro-
graphically and by x-ray diffraction. The available
data show that the NaF-3RbF*BeF2 join is a
quasi-binary system which has a eutectic with
sit ion No F-RbF-Be F ,
ts at 640 f 5OC. The
kewise believed to be
h has a eutectic with
BeF, (43-38-19 mole %)
that melts at 6 . The Naf-RbF-BeF,
one or more ternary
join and RbFOBeF,
rmal analysis data
indicate that th ion of NaF lowers the
bF-BeF,. None of
the slowly cooled melts was completely homo-
12W. Jahn, Z. anorg. U. allgem. Chem. 277, 274
(1 954).
PERfOD ENDlNC JUNE 10, 1956
geneous, but the mixtures containing 45 and 50
mole % NaF were predominantly one phase, and
therefore there may be a compound with the compos
it ion 2Na F OR bF *BeF 2.
THE SYSTEM NaF-KF-LIF-UF,
R. J. Sheil
Data reported previously on the liquidus temper-
atures of mixtures formed by adding UF, to NaF-
KF-LiF (11.5-42.0.46.5 mole %) indicated that the
liquidus temperature varied quite rapidly with
changing UF, concentration, at least with mixtures
containing approximately 4 mole % UF, (ref. 13).
Visual observations of liquidus temperatures in
this system during this quarter gave values of
550, 570, and 595OC for mixtures containing 5.0,
7.5, and 10 mole % UF, respectively. The
values obtained by this method for the mixture
containing 10 mole % UF, agreed quite well with
earlier thermal analysis data. It now appears that
the liquidus temperatures of mixtures in this
system containing 0 to 10 mole % UF, are not so
strongly dependent upon UF, concentrations as
the earlier datal3 had indicated.
ALKALI FLUORIDE-CeF3 SYSTEM§
L. M. Bratcher
Preliminary data on the NaF-CeF, and RbF-CeF3
systems were given in the previous report.14
Study of the LiF-CeF, system was initiated
recently, and thermal analysis data obtained with
five compositions in this system showed that
there is a eutectic containing approximately
19 mole % CeF, that melts at 755 f 5OC. For the
NaF-CeF, system, extrapolation of thermal data
obtained with mixtures containing 10, 15, and
20 mole % CeF, indicates that the eutectic which
melts at 725 k 10°C contains approximately 28
mole % CeF,. A compound reported to be present
in this system has not yet been identified. The
RbF-CeF, system has been studied more than the
other two systems mentioned, but thermal analysis
data and studies of slowly cooled melts have so
far failed to give a clear picture of phase relations.
It appears that at least two compounds are formed
that possibly have the formulas 3RbFCeF, and
13R. J. Sheil, ANP Quar. Prog. Rep. Dec. 10, 1954,
ORNL-1816, p 59.
I4L. M. Bratcher, ANP Quar. Prog. Rep. March 10,
1956, ORNL-2061, P 78.
89