Computational and Experimental Studies of the Radiation Response of Gd2Ti2O7 Pyrochlore

Conference · Fri Dec 16 00:00:00 EST 2005

OSTI ID:891156

Devanathan, Ram; Weber, William J

The structure and property changes in Gd2Ti2O7 (polycrystalline pyrochlore) were examined following irradiation with 1 MeV Kr+, 0.6 MeV Bi+ and 4 MeV Au2+ ions over the temperature range 30-950 K. Gd2Ti2O7 readily amorphizes with a low temperature (30 K) critical dose for amorphization of {approx} 0.15 displacements per atom (dpa). The critical temperature above which amorphization does not occur is about 1190 K. Nano-indentation studies reveal that the structural changes were accompanied by decreases of 15% in the Young's modulus. 1 MeV Kr+ irradiation of amorphous Gd2Ti2O7 at 1065 K resulted in ion-beam-assisted recrystallization. These experimental studies were complemented with molecular dynamics simulations of low energy recoils in Gd2Ti2O7 and Gd2Zr2O7 using a Buckingham type potential. The displacement threshold energy surface in both pyrochlores is highly anisotropic. Displacement energies are higher for all sublattices in the titanate pyrochlore compared to the zirconate. Ti sublattice displacements require energies in excess of 100 eV, and result in multiple displacements and defect clusters. The formation of these clusters might impede dynamic defect recovery and facilitate amorphization.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 891156
• Report Number(s): PNNL-SA-45177; 8208; TRN: US0604903
• Resource Relation: Conference: Environmental Issues and Waste Management Technologies in the Ceramic and Nuclear Industries XI, Ceramic Transactions, 176(43-54
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CERAMICS
CRITICAL TEMPERATURE
IRRADIATION
PYROCHLORE
RECRYSTALLIZATION
GADOLINIUM OXIDES
TITANIUM OXIDES
RESPONSE FUNCTIONS
MOLECULAR DYNAMICS METHOD
ATOMIC DISPLACEMENTS
Pyrochlore
radiation response
ion implantation
molecular dynamics
displacement threshold energy
Environmental Molecular Sciences Laboratory