THE CHEMISTRY AND METALLURGY OF NEPTUNIUM

Technical Report · Sat Oct 31 04:00:00 EST 1959

OSTI ID:4291465

McKay, H A.C.; Waldron, M B; Nairn, J S

Gram quantities of neptunium were isolated from process wastes. NpO/sub 2/ and Np/sub 3/O/sub 8/ were prepared by the ignition of precipitated Np(V) hydroxide, the former at high temperatures (600 or 1000 deg C) and the latter at lower temperatures (150 or 300 deg C) in air. Their stoichiometry and crystal structure were studied as well as the decomposition of NpO/sub 2/ on heating. NpF/sub 4/ was prepared by heating NpO/sub 2/ to 600 deg C in a stream of HF and O/sub 2/, and its structure confirmed. Reduction of NpF/sub 4/ with excess Ca in an argon atmosphere yielded Np metal in 98.7% yield. The use of Fe(II) and N/sub 2/H/sub 4/ to reduce neptunium to the IV-state in nitric acid solution and of 9 to oxidize it to the VI-state was studied. Electron transfer spectra due to Np(IV) complexes with nitrate, sulfate, and chloride and to Np(VI) complexes with nitrate and sulfate were observed in the ultralviolet. The threshold wavelengths fall in the order expected from the electron affinities and ionization potentials of the ions concerned. Correlations can be made with spectral changes at longer wavelengths due to complexing. No such charges could be found in the Np(V) spectrum between 400 and 1000 m mu over a range 1 to 8M in nitrate ion. The extraction of Np(IV) and Np(VI) from nitrate solutions by dibutyl carbitol and tributly phosphate was investigated. Physical property measurements were carried out on 20 g of neptunium metal. These demonstrated the existence of three allotropic modifications alpha , BETA , and gamma between 20 deg C and the melting point 640 plus or minus 5 deg C. The specific heat of the alpha phyisc over the range 60 to 200 deg C varies between 0.03 and 0.04 cal/ g deg C which gives a value for the atomic heat in excess of the theoretical Dulong and Petit value. The alpha phase has a Vickers hardness number of 355; the Meyer index and number are 2.19 and 458, respectively. (auth)

• Research Organization: Atomic Energy Research Establishment, Harwell, Berks, Eng.; United Kingdom Atomic Energy Atuthority, Risley, Lancs, Eng.
• NSA Number: NSA-13-006342
• OSTI ID: 4291465
• Report Number(s): A/CONF.15/P/304
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AIR
CHEMISTRY
COMBUSTION
CONFIGURATION
CRYSTALS
DECOMPOSITION
GASES
HEATING
LATTICES
NEPTUNIUM HYDROXIDES
NEPTUNIUM OXIDES
PREPARATION
PYROLYSIS
TEMPERATURE