1355
V O L U M E 2 8 , NO. 8, A U G U S T 1 9 5 6 Formula \Yeiglit. 102(i.13. Densit!.. 3 1 1 g:inis per c(3. (i-ra).); 3.165 (flotation). O P T I C A L I'ROPERTIEE
Itefritctivc Iitdic.es (5893 .k.). n x = 1.533: n y = 1.553: RZ = 1.383: acomrtriv mean 1.5362. hlolecular refraction 104.2 cc. (based oil measured density). Optic Orientntion X = b; Y .i c = 14".
Optic Axial Angle (5893 .I.), 2V, = 76" with strong diapersion r > v. Color. Yellow with moderate absorptioii 2 > Y > X . Fluorescence. Strong, excited by a mercury vapor lamp. THERMAL DATA. Heated in air, crystals decompose at 84" C. This is evidenced by irregular interference colors. mottled extinctions and, eventualiv, clouding - of crvstals. _
I
WORKdone under the auspices of the Atomic Energy Commission.
134. Pentapotassium Diuranyl Enneafluoride, K,(UO,),F, E U G E N E STARITZKY, D O N T. C R O M E R , and D. 1. W A L K E R 1 The University of California, Los Alamos Scientific Laboratory, Los Alamor, diuranyl enneafluoride prepared by P mixing dilute aqueous solutions of uranyl nitrate and potassium fluoride. Uranium by chemical analysis v a s 52.2'%, wds
ENTAP~IASSIL-u
calculated 52.52c;.
N. M.
X-RAYDIFFRACTION DATA Diffraction Symbol. 12/mlC-c-. Observed development of crystal forms and failure to detect a piezoelectric effect make it probable that the space group is C2/c (C!h).
CRYbT.41, ~ I O R P I I O L O G Y
System and Class. llonoclinic, prismatic. Axial Elements a:b:c = 3.215:1:1.877; p = 101' 14'. Baker ( 1 ) described the crystals of this compound as triclinic with axial elements a : b : c = 0.6222:1:0.568; a = 72" 38'; @ = 116' 23'; -, = 111' 57'. hIorphologica1, x-ray, and optical nieasuremrnts show the symmetry to be monoclinic. Baker's measurements ran also be reconciled with requirements of monoclinic syninietry by the transformation (02i/001/201) v+ich converts the "triclinic" poles (OlO), (loo), (IJO), (OOl), ( E 2 ) , ( 1 T i ) to monoclinic poles (loo), (OOI), (iOl), ( l l l ) , (310), ( l l l ) , respectively. 100
Partial Powder X-Ray Diffraction Pattern of Kj(C02)gFy d , .I., d , A., hki 200
110
002 202 111 111 400 202 310 311 112 302 31 1 112 812
a02 .ill 312
.,IO
113
Calcd. 9.71 5.85 5.68 5.38 5,33 5.08 4.85 4.54 4.45 4.35 4.20 4.10, 3.97 3.96) 3.76 3.38 3.30 3.301 3,281 3.27f
0bsd.o
1/11 t
5:i4
