Krypton ion irradiation-induced amorphization and nano-crystal formation in pyrochlore Lu ₂ Ti ₂ O ₇ at room temperature

Abstract

Polycrystalline pyrochlore Lu 2 Ti 2 O 7 pellets are irradiated with 600-keV Kr 3+ ions up to a fluence of 1.45 × 10 16 Kr 3+ /cm 2 . Irradiation induced structural modifications are examined by using grazing incidence x-ray diffraction (GIXRD) and cross-sectional transmission electron microscopy (TEM). The GIXRD reveals that amorphous fraction increases with the increase of fluences up to 2 × 10 15 Kr 3+ /cm 2 , and the results are explained with a direct-impact model. However, when the irradiation fluence is higher than 2 × 10 15 Kr 3+ /cm 2 , the amorphous fraction reaches a saturation of ∼80%. Further TEM observations imply that nano-crystal is formed with a diameter of ∼10 nm within the irradiation layer at a fluence of 4 × 10 15 Kr 3+ /cm 2 . No full amorphization is achieved even at the highest fluence of 1.45 × 10 16 Kr 3+ /cm 2 (∼36 displacement per atom). The high irradiation resistance of pyrochlore Lu 2 Ti 2 O 7 at higher fluence is explained on the basis of enhanced radiation tolerance of nano-crystal structure.

Role of ion species in radiation effects of Lu2Ti2O7 pyrochlore

“…4(c), it is clear that the fraction of amorphous phase saturates at about 80%, which suggests a recovery effect at room temperature. This result agrees very well with a recently published work by Rong [42], where the amorphization fraction in Lu 2 Ti 2 O 7 also saturates at ~80% under 600 keV Kr 3+ ion irradiation. Since the Ne 2+ irradiations were done at cryogenic temperature, the defects are "frozen" once formed and the recovery is extremely inhibited.…”

Study on Irradiation Response of Nanocrystalline Phase in Sm-Doping Fluorapatite Glass-Ceramics under He Ion Irradiation

“…On the contrary, high temperature will promote the recrystallization of amorphization [ 35 ]. In this experiment, the formation of nanocrystals is the result of the competition between the amorphization and recrystallization [ 36 , 37 ]. The formation of nanocrystals introduces a higher interface density, which acts as good sinks for accumulation of defects [ 38 ].…”

A Comparison of Order-Disorder in Several Families of Cubic Oxides

“…Because the pyrochlore structure is a derivative of fluorite, it belongs to a large family of related structures. The interplay of short-and long-range order, especially in radiation-damaged pyrochlores, has drawn extensive attention as has amorphization and its recovery on annealing (Wang et al, 1998;Wang et al, 1999;Meldrum et al, 2001;Lian et al, 2002;Ewing et al, 2003;Lian et al, 2003a;Lian et al, 2004;Patel et al, 2008a;Patel et al, 2008b;Lang et al, 2009;Yudinsev et al, 2009;Lang et al, 2010;Xie et al, 2015;Shamblin et al, 2016a;Shamblin et al, 2016b;Kumari et al, 2016;Yang et al, 2017;Chung et al, 2018a;Chung et al, 2018b;Shamblin et al, 2018;Chung et al, 2019;Sherrod et al, 2021). Yet in a broader sense, pyrochlores are but one family of oxide materials.…”