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ORNL-2106 - the Molten Salt Energy Technologies Web Site

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ANP PROJECT PROGRESS REPORT<br />

RbF-CeF In addition to liquidus and solidus<br />

<strong>the</strong>rmal egects on cooling curves, solid transitions<br />

were noted at about 425 to 45OOC with mixtures<br />

in <strong>the</strong> 10 to 35 mole % CeF, range and at temper-<br />

atures ranging from about 500 to 58OoC with<br />

mixtures containing 33 to 60 mole % CeF,. These<br />

transitions probably account for <strong>the</strong> fact that<br />

particle sizes of crystalline phases are so small<br />

that microscopic identification is difficult and<br />

some phases even give poor x-ray diffraction<br />

patterns. The minimum liquidus temperature of<br />

approximately 615OC apparently occurs between<br />

42.5 and 50 mole % CeF,. Study of all three<br />

systems mentioned is continuing.<br />

THE SYSTEM LIF-COF<br />

L. M. Bratcher<br />

The recent availability of pure CsF prompted a<br />

re-examination of <strong>the</strong> LiF-CsF system which is<br />

of interest because a compound is formed such as<br />

that formed in <strong>the</strong> LiF-RbF system. l5 The results<br />

of <strong>the</strong> earlier studies were not published because<br />

of <strong>the</strong> scatter in <strong>the</strong> <strong>the</strong>rmal analysis data. While<br />

90<br />

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800<br />

700<br />

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$ 600<br />

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P 500<br />

400<br />

300<br />

<strong>the</strong> existence of o<strong>the</strong>r alkali-halide binary<br />

compounds is well established, no mention of<br />

. alkali-fluoride binary compounds has been found<br />

in <strong>the</strong> literature. The freezing point of <strong>the</strong> CsF<br />

used in <strong>the</strong> recent investigation was found to be<br />

700 f 5OC, which agrees with recently published<br />

values of 705OC (ref. 16) and 703OC (ref. 17).<br />

The <strong>the</strong>rmal analysis data shown in Fig. 2.1.7<br />

include some data from <strong>the</strong> earlier studies. The<br />

binary compound, believed to have <strong>the</strong> compo-<br />

sition LiFCsF, was easily recognized under <strong>the</strong><br />

microscope because it is birefringent, whereas<br />

both LiF and CsF are isotropic. However, for<br />

reasons that are not well understood at present,<br />

<strong>the</strong> mixtures examined to date gave ra<strong>the</strong>r poor<br />

x-ray diffraction patterns for <strong>the</strong> compound. The<br />

large number of lines observed suggests that <strong>the</strong><br />

compound is ei<strong>the</strong>r monoclinic or rhombohedral.<br />

"L. M. Bratcher et al., ANP Quar. Prog. Rep. June<br />

10, 1954. <strong>ORNL</strong>-1729, p 44.<br />

l60, Schmitz-Dumont<br />

Chem. 252, 329 (1944).<br />

and E. Schmitz, Z. anorg.<br />

17M. A. Bradig, H. Re Bronstain, and Wm. T. Smith,<br />

Jr., J. Am. Chem. SOC. 77, 1454 (1955).<br />

LiF 10 20 30 40 50 60 70 80 90 CsF<br />

CsF (mole %)<br />

Fig. 2.1.7. The System LiF-CsF.<br />

u<br />

t<br />

.<br />

.<br />

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