ORNL-2106 - the Molten Salt Energy Technologies Web Site
ORNL-2106 - the Molten Salt Energy Technologies Web Site
ORNL-2106 - the Molten Salt Energy Technologies Web Site
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
\<br />
ANP PROJECT PROGRESS REPORT<br />
liquidus temperatures was noted in attempts to<br />
determine <strong>the</strong> melting point of pure ZnF,. Cooling<br />
curves showed liquidus effects ranging from<br />
885 to 94OoC and a second break at or near 845OC.<br />
Since ZnO was found in all <strong>the</strong> samples that<br />
were examined subsequent to <strong>the</strong> melting-point<br />
determinations, it seemed probable that <strong>the</strong><br />
liquidus temperature was affected by <strong>the</strong> amount<br />
of ZnO present. Confirmation of this postulate<br />
was obtained when a cooling curve obtained with<br />
oxide-free ZnF,, prepared by NH,F.HF treatment<br />
of ZnF, previously dried in an HF atmosphere,<br />
showed a <strong>the</strong>rmal effect only at 940 f 5OC. Be-<br />
cause of <strong>the</strong> large discrepancies between this<br />
value for <strong>the</strong> melting point of ZnF, and those<br />
reported in <strong>the</strong> literature (872OC by Puschin and<br />
Ba~kow,,~ and 875 f 3OC by Haendler, Patterson,<br />
23N. Puschin and A. Baskow, Z. anorg. Cbem. 81,<br />
359 (1913).<br />
92<br />
and Bernard2,), <strong>the</strong> slowly cooled ZnF, was<br />
analyzed chemically and spectrographically. It a<br />
was also carefully examined petrographically and<br />
by x-ray diffraction, along with a highly precise<br />
determination of cell parameters. Since no 3<br />
evidence was found of <strong>the</strong> presence of impurities<br />
in more than trace amounts, <strong>the</strong> melting points for<br />
ZnF, reported in <strong>the</strong> literature are believed to be<br />
erroneous, possibly because of oxide contamination,<br />
Thermal analysis data obtained with<br />
mixtures formed by adding 5, 10, 15, and 20 mole %<br />
ZnO to purified ZnF<br />
which melts ai 850 f 5<br />
show that <strong>the</strong> eutectic<br />
20 C contains approximately<br />
21.5 mole % ZnO. Only <strong>the</strong> pure components were<br />
found in <strong>the</strong> slowly cooled mixtures, and thus it<br />
appears that solid solutions do not occur, at least<br />
at room temperature.<br />
*,He M. Haandlar, W. L. Patterson, Jr,, and W. Je<br />
Bernard, I. Am. Chem. SOC. 74, 3167 (1952).