A note on AmN and AmO

2650

Notes T A B L E I.--EQUILIBRIUM CONSTANTS A N D HEAT FOR THE REACTION

½GasOs(s) + GaF(g) -- GaOF(g) + |Ga(g)

T°

-logK

- - A ( F ' O T H ° ' s )-(cal. deg.-1 mole -I)

842 817 832 850 865 879 894 904

6.20 6"25 6.03 6.00 6.00 5"91 5"80 5.74

AH°'s (kcal/mole)

25 45 25 44 25 44 25 44 25 45 25 45 25 46 25 46 AH°98.av = 45 4- 1 keal/mole

The heat of atomization of GaOF(g) can be calculated from a thermochemical cycle based on the following data: AH°ss,l[GasOs(s)] ~- 258 kcal/mole](V); D°gs[(GaF)(g)] =- 138 4- 3.5 kcal/mole(S); AH°gs,,(Ga) = 64.5 4- 1 kcal/mole(e); D°os[(Ot)(g)] =- 119.2 4- 0.1 kcal/mole,(a) and the heat of Reaction (1), 45 4- 3 kcal/mole. This gives: AHt°os,atom[GaOF(g)] ----264 4- 6 kcal/mole and AH°Da,t[GaOF(D)] = -121 4- 6 kcal/mole. Acknowledgement--This work was financially supported by the National Aeronautics and Space Administration. Department of Chemistry Pace University Houston, Texas

K . F . ZMBOV* J. L. MARGRAVE

* On leave from the Boris Kidrich Institute of Nuclear Sciences, Belgrade, Yugoslavia. (*) L. BREWER, Chem. Rev. 52, 1 (1953). ~8) p. BRIX and G. HERZBERG, Can. d. Phys. 32, 110 (1954).

$. lnorg, nucL Chem.. 1967, VoL 29, pp. 2650 to 2652. Pergamon Press Ltd. Printed in Northern Ireland

A note on AmN and AmO (Received 23 March 1967) A~mmcavM monotride and monoxide in microchemical amounts were prepared from metallic americium. A part of m a r e used was supplied by Oak Ridge National Laboratory in a form of nitrate solution with the impurities: 1 VoNa, 1 VoCa, 3 ~o A1, 0.1 ~o La, 0.5 YoPr, 1 VoFe, and 0.5 YoNi. The cation exchange separation after NArrocI)gave a fairly good result in removing these impurities except praseodymium and trace curium. Spectroscopically pure americium solution was obtained by the subsequent cation exchange with 0.4 M ammonium g-hydroxyisobutylateas the eluant: ~) Americium trifluoride was then precipitated with hydrofluoric acid. After being dried in vaeuo at 200-400°C, the fluoride was reduced to metallic americium by lithium vapour at 1050°C. An apparatus after WALLMAN et al: s) was used for this reaction. (1) IC NArro, A Method o f Purification o f Americium UCRL-8748, Dec (1959). ~t) G. IL CHOPPIN, B. G. HARWY and S. G. THOMPSON,J. inorg, nucl. Chem. 2, 66 (1956). n) j. C. WALLMANand B. B. ~ G ~ , The Preparation of Americium Metal, Curium Metal, p. 74. UCRL-8369, July (1958).

Notes

2651

AmN Americium mononitride was prepared by the action of ammonia on americium hydride. About 1O0/~g of the metallic americium was placed in a carefully degassed quartz capillary, After the system was evacuated to 4 x 10-e torr, hydrogen purified by the diffusion through a heated palladium wall was admitted for the reaction at 250°C. The metal turned quickly into a black, voluminous hydride powder. Being evacuated again, the capillary was dipped into a CO~-butanol bath and was charged with sodium-dried ammonia gas to be condensed onto the hydride. Temperature was then raised gradually and the reaction was carried out at 800°C for 30 rain. Americium mononitride was prepared also by the direct reaction between nitrogen and metallic americium which resulted from thermal decomposition of its hydride. The reaction was conducted at 750°C for 1 hr. Purification of nitrogen was made by successive passages through an activated copper column at 200°C, a calcium chloride column and a trap cooled with CO,-butanol. AmN samples resulting from the above two procedures were investigated by X-ray diffraction as they were sealed in the reaction capillaries in vacuo. The products were lustrous and black. AmO Americium monoxide was prepared by the reaction of metaLlic americium with the sto/ch/ometric amount of oxygen which was generated from Ag~O by thermal decomposition. Metallic americium of several tens of micrograms was placed in a carefully degassed quarts capillary upper part of which was shaped into a small bulb. A small quartz cone containing the stoichiometric amount of Ag,O was then let into the bulb and the system was evacuated to 10-6 torr. During the evacuation, decomposition of Ag~O was prevented by cooling the bulb in CO2-butanol and liquid nitrogen baths successively. After being sealed off at the upper neck of the bulb, the system was transferred into a furnace for the reaction for 1 week. Although the temperature near the bulb was intended to be 850°C, the actual temperature near the end of the capillary, where metallic americium was placed, was most likely very much higher, since an unexpected recrystalliTation of the quartz capillary was observed. After being cooled, the capillm'y was sealed and separated from the bulb for the X-ray diffraction. The product was brittle, with greyish metallic lustre.

X-ray diffraction The diffraction work was performed with a Debye-Scherrer camera of 18 cm dia., using CuK= radiation. The photographs of AmN and AmO indicated clearly that both of them belong to the face-eentred cubic system. (In the ca.so of oxide, several extra lines were observed especially in the lower scattering angle region. By the replacement of the capillary in an argon atmosphere, these extra lines was proved to be originated from the recrystaLlization of the reaction capillary.) All the DebyeScherrer rings obtained are listed in Table 1. For accurate determinationsof their lattice constants, the extrapolation function cos*0/sin 0 + cos*0/0 was utilized. The results are a = 5.000 =1=0.004 A for AmN from ammonia and americium hydride, a = 5.005 :k 0.005 A for AmN from nitrogen and americium, and a = 5.045 4- 0.003 A for AmO. That the latter value for AmN is slightly larger than the former is most likely attributed to the situation that the latter sample is actually a mixture or a solid solution between AmN and AmO, since the purification of nitrogen was presumably insufficient. The solid-solubility between AmN and AmO is well expected on the analogy of that between PuN and PuO: 6~ The value for AmO by ZACZ-IaaZA.SSN~Tj is a -- 4"96 :[: 0"01 A, differing considerably from the present. His value may, however, be doubtful, since he makes no statements on preparation and pumy of the sample. In several attempted preparations of metanic americium, M c W ~ N observed a face-centred cubic phase with a = 5.053-5.054 ]k which was suspected to be AmO. (8) Although "

c~ y . AK~OTO,B. B. CUNNINGnAM,D. B. McWHANand J. C. WALLMAN,Semiannual Report, p. 59. UCRL-8867, July (1959). cs~ y. AgIMcrro, Semiannaul Report, p. 74. UCRL-9093, Feb. (1960). ce~A. S. CO~'INnERRYand F. H. ELLIZNGER,The Intermetallic Compounds of Plutonium, P]826, Prec. Intern, Conf. Peaceful Uses Atom. Energy, Geneva, 1955, Vol. 9, p. 138 (1956). ~7)W. H. ZACRARIASEN,Acta Crystallogr. 2, 388 (1949). ~s~D. B. McWnAN, Crystal Structure and Physical Properties of Americium Metal, UCRI.,-9695, May (1961).

2652

Notes TABLE 1.--DIFFRACTION PATTERNSOF A m N AND AmO AmN*

oh/ dobs (A) {deale (A) 111 200 220 311 222 400 331 420 422 511 333 440 531 600 442 620

lobs

AmNt AmO dobs(A) dea,e (A) dobs (A) desle (A) lobs

Iea,e/Io

2"877 2.443 1-765 1.504 1"443 1"249 1"1473 1.1178 1-0204

2"887 2.500 1"768 1.508 1'443 1"250 1'1471 1.1180 1.0206

vs s m m vvw t m w w

2"886 2"506 1.772 1-509 1"441 1"261 1.1478 1-1194 1.0218

2"890 2"503 1.770 1.509 1"445 1"251 1.1482 1.1192 1.0216

2"926 2"529 1.784 1.522 1.458 1-261 1.1573 1.1279 1.0298

2-913 2"523 1-784 1.521 1"456 1"261 1.1574 1.1281 1.0928

vs s m m vw t w w vw

100 69 49 47 17 8 20 21 19

0.9624 0"8837 0.8453

0.9622 0-8839 0.8452

w t m

0.9630 0.8851 0.8458

0.9632 0.8848 0"8460

0.9707 0.8920 0-8528

0.9709 0.8918 0.8528

w t m

20 9 39

0.8337 0-7904

0"8333 0"7906

w m

0.835 u

0.8338

0.8410 0"7977

0.8408 0.7977

m w

30 38

a = 5"000 4- 0.004 A ] doale = 13"4 g/cm s.

a = 5"005 4- 0.005 A

a = 5-045 4- 0.003 A§

deale = 13"7 g/cma

* Prepared by the reaction of ammonia with americium hydride. t Prepared by the reaction of nitrogen with americium (suspected to be contaminated by AmO). :I: Calculated for Fm3m NaC1 type structure. § More accurate than the values reported on the U C R L Semicannula Reports previously. "'s~ the exact composition of the present sample remains unknown, the author believes that the present preparation of AmO is sound. In fact, PuO prepared by the analogous reaction, Pu + O2, was shown " as face-centred cubic, with a = 4.960 4- 0.005 A, in good agreement with the value by COFnt,mERRY.( 6 )

Acknowledgements--This work was performed at the Lawrence Radiation Laboratory, University of California, Berkeley, California, U.S.A. Continued guidance and encouragement of Prof. B. B. CUt~rNOHAM is gratefully acknowledged. Thanks are due to Messrs. S. YAMAGATA,Y. OISHI and C. ITO who enabled us to conduct the present work. Author is also grateful to Dr. K. NAITO for a part of pure americium source used in this study and also for his helpful advices. Advices and suggestions of Drs. S. FRE~, R. SATO, D. B. MCWHAN and the late Dr. J. C. WALLMA~q are greatly appreciated. Y. AKIMOTO

Central Research Laboratory Mitsubishi Metal Mining Co. Ltd., Omiya, Saitama, Japan J. inorg, nucl. Chem., 1967, Vol. 29. pp. 2652 to 2654. PergamonPress Ltd. Printedin NorthernIreland Chromium tripolyphosphate glags--a new inorganic ion-exchanger for a l k a l i m e t a l i o n s *

(Received 5 May 1967) A CHROMIUMpolyphosphate glass has been prepared which is stable over a wide pH range and has useful exchange properties.t Univalent ions are absorbed with a capacity comparable to or greater * Presented in part at the 4th Czechoslovakian Radiochemical Conference, Bratislava, Czechoslovakia, 1966. t Brit. Pat. Applic., 38960•66.