Equations of State and Phase Transformation of Depleted Uranium DU-238 by High Pressure-Temperature Diffraction Studies

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Physical Review B: Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.75.174104· OSTI ID:960007

Zhao, Y; Zhang, J; Brown, D; Korzekwa, D; Hixson, R

We have conducted in situ high-pressure diffraction experiments on depleted uranium (DU-238) at pressures up to 8.5 GPa and temperatures up to 1123 K. From the pressure (P)-volume (V)-temperature (T) measurements, thermoelastic parameters were derived for a-uranium based on a modified high-T Birch-Murnaghan equation of state and a thermal-pressure approach. With the pressure derivative of the bulk modulus K0' fixed at 4.0, we obtained ambient bulk modulus K0=117(2) GPa, temperature derivative of bulk modulus at constant pressure ({partial_derivative}K/{partial_derivative}T)P=-3.4(4)x10-2 GPa/K and at constant volume ({partial_derivative}K/{partial_derivative}T)v=-1.1(6)x10-2 GPa/K, volumetric thermal expansivity aT=a+bT, with a=1.2({+-}0.4)x10-5 K-1 and b=8.0({+-}0.7)x10-8 K-2, and the pressure derivative of thermal expansion ({partial_derivative}a/{partial_derivative}P)T=-2.5(5)x10-6 GPa-1 K-1. Within the experimental errors, the ambient bulk modulus and volumetric thermal expansion derived from this work are in good agreement with previous experimental results, whereas all other thermoelastic parameters represent the first determinations for the a phase of uranium. We also studied the a- phase transformation and obtained a phase boundary described by T (in K)=1032+7.4P (in GPa). Although the -phase uranium cannot be pressure quenched to ambient conditions, it was observed to be stable upon cooling from 1123 to 300 K at pressures of 7-8 GPa. These observations indicate that pressure, in addition to the commonly utilized alloying techniques, provides an alternative route for stabilizing the {gamma}-uranium at room temperature.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 960007
• Report Number(s): BNL--82993-2009-JA
• Journal Information: Physical Review B: Condensed Matter and Materials Physics, Journal Name: Physical Review B: Condensed Matter and Materials Physics Journal Issue: 17 Vol. 75; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
DEPLETED URANIUM
DIFFRACTION
EQUATIONS OF STATE
PHASE TRANSFORMATIONS
THERMAL EXPANSION
URANIUM
national synchrotron light source