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ORNL-2106 - the Molten Salt Energy Technologies Web Site

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ANP PROJECT PROGRESS REPORT<br />

TABLE 2.1.1. COMPOUNDS* OF ZrF, OR UF, WITH ALKALI FLUORIDES<br />

4:l 3: 1 2:l 3:2 5:3 5 :4 7:6<br />

~~ ~<br />

3LiF*ZrF4 (c) 2LiF*ZrF4 (c)<br />

3NoF*ZrF4 (c) 2NaF-ZrF, (I) 3NoF-2ZrF4 (S) 7Na F*6Zr F, (c)<br />

3KF-ZrF4 (c) 2KF=ZrF4 (I) 3KF*2ZrF4 (I)<br />

3RbF*ZrF4 (c) 2RbF-ZrF4 (I) 5RbF*4ZrF4 (c)<br />

4LiF*UF, (I) 7LiF*6UF4 (I)<br />

3NaF*UF4 (c) 2NaF*UF4 (I) 5NoF*3UF4 (I) 7NoF*6UF4 (c)<br />

3KF*UF4 (c) 2KF*UF4 (I) 7KF*6UF4 (c)<br />

3RbF*UF4 (c) 2RbF*UF4 (I) 7RbF*6UF4 (I)<br />

1:l 3:4 2:3 1 :2 1 :3 1 :4 1 :6<br />

3LiF*4ZrF4 (I)<br />

NaF-ZrF, (M) 3NaF*4ZrF4 (I)<br />

KF-ZrF, (c)<br />

RbF*ZrF, (c) RbF*2ZrF4 (I)<br />

NaF*2UF4 (S)<br />

KF*2UF4 (I)<br />

LiF-dlJF, (I)<br />

RbF-UF, (c) 2RbF*3UF4 (I) RbF*3UF4 (I) RbF*6UF4 (I)<br />

t<br />

(c) Congruent compound.<br />

(I) Incongruent compound.<br />

(M) Metastable compound.<br />

(S) Subsolidus compound.<br />

A series of incongruent compounds, 2MF*ZrF,<br />

and 2MF*UF,, are observed in all <strong>the</strong> diagrams,<br />

except those containing LiF. The compound<br />

2LiF*UF, does not exist, and 2LiF*ZrF4 has a<br />

relatively low melting point but is congruent. All<br />

<strong>the</strong> incongruent 2MF*ZrF, and 2MF*UF, com-<br />

pounds, except <strong>the</strong> 2NaF*UF4 material, melt to<br />

form <strong>the</strong> compounds 3MF*ZrF4 or 3MF*UF, and<br />

liquid.<br />

The low-melting-point central portion of <strong>the</strong><br />

binary mixtures, that is, <strong>the</strong> mixtures with 35 to<br />

55 mole % ZrF, or UF, as shown in Fig. 2.1.2,<br />

exhibits many variations in compound types. The<br />

occurrence of <strong>the</strong> unusual compound 7MF.6ZrF4<br />

or 7MF*6UF4 is remarkable. The compound has<br />

80<br />

<strong>the</strong> same crystal system wherever it occurs, and it<br />

displays no polymorphism. One member, <strong>the</strong><br />

compound 7NaF*6ZrF4, forms an extensive<br />

interstitial solid solution series with <strong>the</strong> next<br />

lower ZrF, compound.<br />

Compounds formed from mixtures with high<br />

concentrations of ZrF, or UF, are invariably<br />

incongruent, but <strong>the</strong>y display wide variations in<br />

degree of incongruency. These compounds, as<br />

shown in Fig. 2.1.3, occur at widely varying<br />

compositions in <strong>the</strong> range 55 to 95 mole % ZrF,<br />

or UF,. Several of <strong>the</strong> diagrams in this series<br />

are considered to be preliminary, and <strong>the</strong> systems<br />

those diagrams depict are still being studied.<br />

-<br />

G<br />

S<br />

a<br />

c

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