Comparison of short-range order in irradiated dysprosium titanates

Roman Sherrod,Igor M Gussev,Eric C O’Quinn,Joerg Neuefeind,Maik K Lang,Cale Overstreet

doi:10.1038/s41529-021-00165-6

Roman Sherrod, Igor M Gussev + Show 4 more

Open Access

https://doi.org/10.1038/s41529-021-00165-6

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Abstract

The structural response of Dy2TiO5 oxide under swift heavy ion irradiation (2.2 GeV Au ions) was studied over a range of structural length scales utilizing neutron total scattering experiments. Refinement of diffraction data confirms that the long-range orthorhombic structure is susceptible to ion beam-induced amorphization with limited crystalline fraction remaining after irradiation to 8 × 1012 ions/cm2. In contrast, the local atomic arrangement, examined through pair distribution function analysis, shows only subtle changes after irradiation and is still described best by the original orthorhombic structural model. A comparison to Dy2Ti2O7 pyrochlore oxide under the same irradiation conditions reveals a different behavior: while the dysprosium titanate pyrochlore is more radiation resistant over the long-range with smaller degree of amorphization as compared to Dy2TiO5, the former involves more local atomic rearrangements, best described by a pyrochlore-to-weberite-type transformation. These results highlight the importance of short-range and medium-range order analysis for a comprehensive description of radiation behavior.

Highlights

Dysprosium titanate oxide (Dy2TiO5) is a neutron absorbing material used in control rods in a number of nuclear reactors[1,2]
Dy2TiO5, like other A2TiO5 (A = trivalent lanthanides, Y3+) materials, commonly occurs in one of three types—an orthorhombic phase of space group Pnma (Fig. 1a), a hexagonal phase of space group P63/mmc, and cubic phases reported as Fm-3m, Fd3m, or F-43m depending on synthesis routes[5]
The orthorhombic phase is the equilibrium phase of Dy2TiO5 under ambient conditions and it reversibly transforms to a hexagonal hightemperature phase above 1370 °C, followed by a cubic hightemperature phase above 1680 °C, before melting at 1875 °C5

Summary

Introduction

Dysprosium titanate oxide (Dy2TiO5) is a neutron absorbing material used in control rods in a number of nuclear reactors[1,2]. Previous radiation-damage studies of different pyrochlore oxides using neutron total scattering analysis have revealed local structural changes that are not represented by the average, long- RESULTS AND DISCUSSION

Results

Conclusion