NOTES
1974
s~ggestion‘~ that it can best be approximated by a solution of polyols is still the best characterization of its average behavior in view of the applicability of polymer solution theory. With a clear definition of the size of the stationary phase, through arguments like those above, investigation of this aspect of the problem can be made. The authors hope that this note will renew interest in some of the fundamental aspects of paper chromatography. This investigation was supported by a research grant, A-2402(Cl), from the National Institute of Health, Public Health Service. (14)A. J. P. Martin, Ann. Rev. Biochem., 19, 517 (1950).
X-RAY ANALYSES OF THE SOLID PHASES IN THE SYSTEM LiF-ThR BY L. A. HARRIS,G. D. WHITE Ceramic Laboratory, Metallurgy Division AND
I M+ S
S+ S M M+ M M W M
S M M M+ W+ M M W W+
W
R. E. THOMA
Vol. 63 TABLE I INDEXED POWDER PATTERN OF LisThF7 sin’ 0 sin2 e
Obsd. 0.0142 .0295 .0309 .0449 .0617 .0721 .0759 .0914 .lo90 .1233 ,1338 .1378 .1428 .1543 .1582 .1687 .1898 .1956 ,2048 ,2147
Calcd. hkl 0.0142 001 .0296 101 .0308 110 .0450 111 ,0616 200 .0722 102 ,0758 201 .0913 211
...
..
.1233 .1339 .1375 .1432 .1541 .1586 .1683 .1894 .1955 .2049 .2145
220 212 221 103 310 113 311 203 302 213 321
Reactor Chemistry Division, National Laboratory,‘ Oak Rdue, Tenn. Received April 86, I069
The phase equilibrium diagram for the system LiF-ThF4 has previously been determined a t this Laboratory by R. E. Thoma, et al., and shown to contain four distinct solid phases, none of which were observed to have polymorphic transformations, The reliability of these compound formulas has been established by the methods outlined in the phase equilibrium paper.2 The X-ray examination of the crystalline phases and the analyses of their structure is the concern of the following paper. Material Synthesis.-Solid-state synthesis of the four compounds was attempted in order to procure single-crystal specimens for positive structure identification and to obtain sufficient quantities of the individual phases for density determinations. Samples of powdered materials having the proper chemical compositions were thoroughly mixed, placed in nickel tubes, evacuated, sealed and positioned in a platinum-wound furnace. The samples were heated and held slightly below their melting temperatures for a period of ten days. Single crystals for LiaThF7 and LiThzFs were obtained in this manner; however, materials of sufficient purity for density measurements were attained only for LisThFl and Li7ThaFsl. Determinations of the phases formed by the above methods were based on the optical and X-ray examination of the cooled material. X-Ray Methods.-Debye-Scherrer films were taken of all four phases using a 114.6-mm. dia. camera and Cu KCY( X = 1.5418 8.)radiation. Rotation, Weissenberg and precession diffraction patterns for the single-crystal samples were obtained from the Metallurgy and Ceramics X-Ray Laboratory.
X-Ray Results Li3ThF7.-The data obtained from the DebyeScherrer film for LisThFv were indexed (Table I) and found to best fit a tetragonal unit cell whose lattice parameters are ,a0 = 6.206 f 0.006 A. and co = 6.470 f 0.002 A. and which contains two molecules with a calculated density p = 5.143 g./cc. The observed extinctions from the Weissenberg and precession photographs are compatible with space groups P4/nmm or P4/n. (1) Operated for the U.8. Atomio Energy Commission by the Union Carbide Corporation. (2) R. E. Thoma, H. Insley, B. S. Landau, H. A. Friedman and W. R. Grimes, “Phase Equilibria in the Fused Salt Systems LiF-ThF4NaF-1hF4,” presented at meeting of the Am. Chem. Soc., Chicago, Ill., September 1958
I WW-
WM+ WW W W W W W W WWW W
W W
WW+ WWW-
Obsd. 0.2271 .2473 .25lO .2571 .2615 .2663 .2772 .2819 .2892 .3087 .3195 ,3283 .3503 .3695 .3814 .3892 .4012 .4156 .4309 .4422 ,4623 .4741 .4943
Calcd. hkl 0.2272 004 .2466 400 .2511 223 .2571 322 .2610 401 .2665 303 .2774 330 .2819 312 .2884 204 .3082 420 .3187 412 ,3281 323 .3505 224 ,3704 105 .3813 314 .3898 413 .4007 610 .4149 511 .4320 215 .4420 432
...
..
.4738 .4937
404 305
Li.~ThiF,~.-The type compound designated M&Fal, where M represents an alkali atom and X a heavy atom such as uranium or thorium, has been observed by investigators of the fluoride phase equilibrium relationships a t this Laboratory.2-s In the system LiF-ThF4, a compound with the above chemical ratio was observed and determined to be optically uniaxial.2a A comparison of the Debye-Scherrer films for Li7UeF31 and Li7Th6Fal revealed both compounds to be isostructural. Single-crystal specimens of Li7U6Fnl which were available permitted the authors to determine the unit cell and probable space group of Li7Th6F31 by analogy. Table I1 presents the powder diffraction data for the Li7Th6FB1indexed with the help of the Weissenberg and precession photographs of Li7U6Fal. The compound has tetragonal symmetry with unit cell dimensions a0 = 15.10 i 0.002 A. and co = 6.60 I 0.02 A.; the calculated density is p = 4.387 g./cc., assuming two molecules per cell. The space group I4Ja was chosen on the basis of the systematic extinctions of reflections observed on the single-crystal photographs of Li7U6Fa1. TABLE I1 INDEXED POWDER PATTERN OF Li7TheFal I W+ 6 €4
S
SS SS M M W W M M+ S-
sin2 e hkl Calcd. Obsd. 0,0162 0.0162 101 ,0209 .a208 220 .0206 211 .0267 .0373 .0370 301 .0474 321 .0477 .0524 .0520 420 .0578 411 .0581 .Of348 202 .0650 .0752 222 .0755 .0787 ,0786 501 .OS93 .0890 521 .lo45 .lo40 620 .lo98 611 .1103 .1306 631 .1308 .1352 640 .1355
I
W W W
VW MS W M M W
M W
MW
W W
W+
sin2 e Obsd. Calcd. 0.1456 0.1458 .1480 ,1487 .1514 .1515 .1562 .1562 .1587 .1584 ,1664 .1668 .1722 .1730 .1826 .1829 .1876 ,1872 .1978 .1984 .2034 .2034 .2176 .2186 .2312 .2317 ,2346 .2348 .2390 .2394 .2416 ,2420 .2450 ,2453
hkl
303 602 721 323 622 800 651 811 660 523 831 004 822 921 633 662 851
c
NOTES
xov., 1959
1975
TABLEI11 INDEXED POWDER PATTERN OF LiThLFe I
Obsd.
VW M
0.0096 .0193 ,0376 .0465 .0579 .0674 .0748 .0774 .0839 .0937 ,1329 .1420 .I491 .1542 .1670
vs S
W M M M-
vw M
S S S S M
sin2 e
hkl
I
Obad.
0.0093 .0186 .0373 .0466 .0580 .0673 .0746 .0766 .0839 .0932 .1326 .1419 .1491 .1538 .1678
110 220 220 3 10 002 112 400 202 330 420 402 332 440 213 600
M W W+ W W
0.1864 .1912 .2048 .2237 .2327 ,2643 .2690 .2789 .2900 .2979 .3156 .3271 .3802 .3848 .4070
S S
M M M M-
vw W VW W+
TABLEIV INDEXED POWDER PATTERN OF LiTh+F1? I W M
vw S vs S W
vs S M
vw W S
vs S
sin’ e Obsd. Calcd. 0.0141 0.0141 .0181 .0181 .0283 ,0282 .0324 .0322 .0400 .0398 ,0469 .0463 .0567 .0565 .0710 ,0700 .0755 .0751 ,0885 .OS3 .096l .0963 ,1039 .lo38 .1314 .1311 .1413 .1412 .1442 .1443
hkl 220 002 220 202,221 003,311 222 400 420 421,313 500,422 511 304 442,601 620 305,540
I S S S 9S VS M W VW W M VW W M W M
W
sin2 e Obsd. Calcd. hkl 0.1468 0.1478 315 612 .1487 ,1486 .I586 .1588 630,325 ,1615 ,1620 000 .1809 711 .I810 .1872 .1871 720 .2005 .2008 505 .2029 .2025 614 731 .2089 ,2092 .2121 .2132 624 .2150 .2153 650,525 65 1 .2197 .a198 .2262 .2259 800 .2313 .2308 634 ,2358 ,2346 207 .2434 .2430 615 .2483 .2487 227,714
LisThF7 Li,ThaFsl LiThlFe LiTh4F17
Symmetry
Tetragonal Tetragonal Tetragonal Tetragonal
THE
6.206 f 0.006 15.10 I .002 11.307 =k ,009 12.984 =k .004
hkl
620 323 541 631 710,004 523 224 314 712 800 334 732 444 ‘ 215 305
SYSTEMLiF-Thf
Lattice parameters (A.) a0
Calcd.
0.1864 .1911 .2056 .2242 0.2330,O.2320 0.2656 .2693 .2786 .2910 .2982 .3159 .3283 .3811 .3858 .4044
were tentatively indexed (Table IV) and found to best fit a tetragonal unit cell whose lattice parameters are a,, = 12.984 f 0.004 A. and co = 11.46 f 0.02 A. The absence of single-crystal data allows for the possibility of error due to pseudosymmetry. The data assembled from the X-ray analyses of the four crystalline phases in the system LiF-ThF4 are summarized in Table V. Future detailed structure determinations are planned for all four compounds. Acknowledgment.-The authors wish to thank H. L. Yakel, Jr., and R. M. Steele for their aid with the single-crystal determinations. Our thanks are also due to M. P. Haydon for density calculations. In addition, we are grateful for the support of other members of the Ceramic Laboratory.
TABLEV CRYSTALLOGRAPHIC DATA8s4s6 FOR PHASES IN Phase
sin2 e
Calcd.
EO
6.470 f 0.002 6.60 I .02 6.399 f .008 11.46 =k .02
Space group
P4/nmm or P4/n 14~a
Body-centered (1)
.......... . .
Density, g./cc;
5.143 4.387
... ...
HEAT AND ENTROPY OF FUSION OF MERCURIC BROMIDE’
LiThzFg.--The phase LiTh2Fg, which was reported to be optically uniaxial,2 gave reflections which were indexed (Table 111) from DebyeScherrer film and single-crystal data. The unit cell is tetragonal with lattice parameters a,, = 11.307 I 0.009 A. and co = 6.399 0.008 A. From the Weissenberg photographs the only systematic extinctions observed were those that arise from a body-centered cell. LiThiFI,.-This phase was reported to be optically biaxial with a variable optic angle (2V).2 The data obtained from the DebyeScherrer films
To study the constitution of molten salt mixtures with mercuric bromide as solvent, an accurate value of the cryoscopic constant, based preferably on a calorimetrically determined heat of fusion, is essential. Beckmann,2 Olivari,8 and Jander and
(3) C. J. Barton, W. R. Grimes, H. Insley. R. E. Moore and R. E. Thoma, THIEJOURNAL, 62, 605 (1958). (4) C. J. Barton, H. A. Friedman, W. R. Grimes, H. Insley. R. E. Moore and R. E. Thoma, J . A m . Ceram. SOL, 41, 63 (1958). (5) R. E. Thoma, H. Insley. B. 8. Landau, E. A. Friedman and W. R. Grimea, ibid.. 41, 538 (1958).
(1) Part I1 in the series: “Structure of Molten Mercuric Halides.” Thin work was made posaible in part by support reaeived from the U.8. Air Force, Air Research and Development Command,Office of Saientifia Research, under Contraot No. AF-49(638)-50. (2) E. Beckmann, 2.anoro. Chem., 06, 175 (1909). (a) F. Olivari, Atti Accod. Lincei, a l l , 718 (1912).
*
BY GEORQE J. JANZAND JEROMEGOODKIN Department of Chemistry. Reneeelaer Polytechnic Imtitute, T r o y , N . Y . Received April 8, 1969
