Growth habit of electrodeposited uranium dioxide single crystals

Growth habit of electrodeposited uranium dioxide single crystals

JOURNAL OF NUCLEAR GROWTH MATERIALS HABIT 2, No. 2 ( 1960) 18% 190, NORTH-HOLLAND OF ELECTRODEPOSITED SINGLE PUBLISHING URANIUM CO., AMSTERDA...

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JOURNAL

OF NUCLEAR

GROWTH

MATERIALS

HABIT

2, No. 2 ( 1960) 18% 190, NORTH-HOLLAND

OF ELECTRODEPOSITED SINGLE

PUBLISHING

URANIUM

CO., AMSTERDAM

DIOXIDE

CRYSTALS

K. G. ROI3IN8 UKAEA,

ililetallurgy

Division,

Atomic

Energy

Research

Rweived

14 April

An octahedral growth habit has been observed in crystals of uranium dioxide formed by vapour deposition 132)and in crystals grown from fused saltsi). A cubic growth habit was observed when vapour was condensed on ionic substratesz). uraninite is commonly Naturally occurring cubic, octahedral, or cube-octahedral, sometimes modified by (520}, { 1143 or { 335) forms 3).

Establishment,

HaraTe&

Didcot,

Berks.,

UK

1960

Separate single crystals of uranium dioxide were deposited by the Author on a platinum cathode (see fig. 1) by the electrolysis of a solution of uranyl chloride in fused sodium chloride-potassium chloride eutectic at 840” C under reducing conditions (to be reported later). These crystals were grown to a size of 3 mm across, and a mass of about 50 mg. The orientation of the crystals on the platinum cathode was random both in the case of fine grained and single crystal cathodes. The crystal habit was determined by goniometric and X-ray diffraction measurements and found to be octahedral. The (111) faces were modified by (loo} faces developing at a crystal

oio

Fig.

1.

Single crystals on platinum

of uranium cathode

dioxide

its formed

Fig.

2.

Stereogram uranium

( x 7). 189

of

electrolytically

dioxide

crystal.

deposited

190

R.

mass of about 5 mg, and further modified

G.

by

(331) faces at a crystal mass of about 10 mg. The (331) facets developed in pairs between the {Ill> faces of the cube-octahedra (see fig. 2).

Variation of oxygen content up to UOa.15 by atmosphere control did not influence the { 11 l}, {loo].

(331) habit.

Cleavage of the crystals occurred on {111} planes and interpenetrant twins on {ill} were occasionally observed. The {ill} cleavage of fused uranium dioxide has previously been reported 4).

ROBINS

References I) R. J. Bard, Los Alamos (USA) Report No. LA4-2076 (March

19.57)

7 J. T. \;C’aber, J. A. O’Rourke and R. Kleinberg, J. Klectrochem. 3,

C. Frondel,

and Thorium, Printing

Sot.

106 (1959)

Systematic

Off,

Geol.

96

Mineralogy

Surv.

Bull.

of Uranium

1064 (US

Govt

1958) 31

4) R. C;. Robins, and P. J. Baldock, J. Amer. &ram. Sot. 43 (1960)

228