BETA-POLYMORPHS OF URANIUM AND THORIUM DISILICIDES

Journal Article · Sun Mar 01 04:00:00 EST 1959 · Nature

DOI:https://doi.org/10.1038/183673a0· OSTI ID:4204144

Brown, A; Norreys, J J

The BETA -USi/sub 2/'' and BETA -ThSi/sub 2/'' phases were prepared from mixtures containing 62 to 63 at.% Si as compared with 66.7~ Si required for formation of the alpha disilicides. X-ray-diffraction and metallographic studies indicate that the compositions are U3Si5 and Th/sub 3/Si/ sub 5/, and the cell dimensions are: U/sub 3/Si/sub 5/-- a/sub o/ = 3.843 plus or minus 0.001A, c/sub o/=4.069 plus or minus 0.001A. and Th/sub 3/Si/sub 5/--a/ sub o/=3.985 plus or minus 0.001 A. c/sub o/ = 4.228 plus or minus 0.001 A. In a study of rcactions in the U-- Th--Bi--Si systems, hexagonal phases with space group C6/mmm were found. These phases, like the M/sub 3/Si/sub 5/ compounds, have the AlB/sub 2/ structure but the cell dimensions are different. Heat treatment of the Th-- Si compound at 1200 to -1300 deg C produced alpha -- ThSi/sub 2/ which, when heated at 850 deg C, yields the new Th--Si phase, the true BETA -ThSr/sub 2/. The cell dimensions arent BETA -USi/sub 2/ -- a/sub o/ = 4.028 plus or minus 0.001 A, c/sub o/= 3.852 plus or minus 0.001 A, and BETA -ThSi/sub 2/-- a/sub o/= 4.136 plus or minus 0.001 A, c/sub o/ = 4.126 plus or minus 0.001 A. (T.R.H.)

• Research Organization: General Electric Co., Ltd., Wembley, Eng.
• Sponsoring Organization: USDOE
• NSA Number: NSA-13-022479
• OSTI ID: 4204144
• Journal Information: Nature, Journal Name: Nature Vol. Vol: 183
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ALLOTROPY
DIFFRACTION
HEAT TREATMENTS
HIGH TEMPERATURE
LATTICES
METALLOGRAPHY
METALLURGY AND CERAMICS
NUMERICALS
SILICIDES
THORIUM COMPOUNDS
URANIUM COMPOUNDS
X RADIATION