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Thermodynamic and Structural Evolution of Mechanically Milled and Swift Heavy Ion Irradiated Er 2Ti 2O 7 Pyrochlore

48 Pages Posted: 22 May 2019 First Look: Accepted

See all articles by Cheng-Kai Chung

Cheng-Kai Chung

University of California, Davis - Peter A. Rock Thermochemistry Laboratory and NEAT ORU

Eric C. O’Quinn

University of Tennessee, Knoxville - Department of Nuclear Engineering

Joerg C. Neuefeind

Government of the United States of America - Chemical and Engineering Materials Division

Antonio F. Fuentes

Cinvestav Unidad Saltillo

Hongwu Xu

Government of the United States of America - Earth and Environmental Sciences Division

Maik Lang

University of Tennessee, Knoxville - Department of Nuclear Engineering

Alexandra Navrotsky

University of California, Davis - Peter A. Rock Thermochemistry Laboratory and NEAT ORU

Abstract

Design and synthesis of thermodynamically metastable yet kinetically achievable materials possessing various desired functional and physical properties have recently drawn tremendous scientific-attention. In addition to conventional heat treatments and wet chemistry approaches, energy deposition into materials can induce unique nonequilibrium phases with distinct structures, chemistry, energetics, and properties. Mechanochemical synthesis and ion beam irradiation are two processing techniques that provide access to phases and states far from equilibrium. By a combination of high temperature oxide melt solution calorimetry, differential scanning calorimetry (DSC), neutron pair distribution function (PDF) analysis, and supplementary powder X-ray diffraction (XRD), the energetics and multiscale structural evolution on annealing of ball milled and swift heavy ion irradiated Er2Ti2O7 pyrochlore were investigated. Despite very similar structural modifications of local atomic arrangements and only minor differences in the long range structure, both types of damage yield significant difference in the energetics of the produced material. The energy of destabilization in the milled sample (70.2 ± 8.2 kJ/mol) is much less endothermic than that in the irradiated sample (457.3 ± 8.0 kJ/mol). The DSC profiles, supported by neutron scattering, X-ray diffraction, and solution calorimetry, reveal decoupled annealing events in different temperature ranges, separating crystallization of long range pyrochlore structure from annealing of short range weberite-like domains.

Keywords: Pyrochlore, Irradiation effect, Ball milling, Amorphization, Annealing

Suggested Citation

Chung, Cheng-Kai and O’Quinn, Eric C. and Neuefeind, Joerg C. and Fuentes, Antonio F. and Xu, Hongwu and Lang, Maik and Navrotsky, Alexandra, Thermodynamic and Structural Evolution of Mechanically Milled and Swift Heavy Ion Irradiated Er 2Ti 2O 7 Pyrochlore (May 21, 2019). Available at SSRN: https://ssrn.com/abstract=3392098 or http://dx.doi.org/10.2139/ssrn.3392098

Cheng-Kai Chung

University of California, Davis - Peter A. Rock Thermochemistry Laboratory and NEAT ORU

United States

Eric C. O’Quinn

University of Tennessee, Knoxville - Department of Nuclear Engineering

United States

Joerg C. Neuefeind

Government of the United States of America - Chemical and Engineering Materials Division

United States

Antonio F. Fuentes

Cinvestav Unidad Saltillo

Mexico

Hongwu Xu

Government of the United States of America - Earth and Environmental Sciences Division

United States

Maik Lang

University of Tennessee, Knoxville - Department of Nuclear Engineering

United States

Alexandra Navrotsky (Contact Author)

University of California, Davis - Peter A. Rock Thermochemistry Laboratory and NEAT ORU ( email )

United States

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