Simulation of Two-Dimensional Images for Ion-Irradiation Induced Change in Lattice Structures and Magnetic States in Oxides by Using Monte Carlo Method

Akihiro Iwase,Shigeru Nishio

doi:10.3390/qubs5020013

Akihiro Iwase, Shigeru Nishio

Open Access

https://doi.org/10.3390/qubs5020013

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Abstract

A Monte Carlo method was used to simulate the two-dimensional images of ion-irradiation-induced change in lattice structures and magnetic states in oxides. Under the assumption that the lattice structures and the magnetic states are modified only inside the narrow one-dimensional region along the ion beam path (the ion track), and that such modifications are affected by ion track overlapping, the exposure of oxide targets to spatially random ion impacts was simulated by the Monte Carlo method. Through the Monte Carlo method, the evolutions of the two-dimensional images for the amorphization of TiO2, the lattice structure transformation of ZrO2, and the transition of magnetic states of CeO2 were simulated as a function of ion fluence. The total fractions of the modified areas were calculated from the two-dimensional images. They agree well with the experimental results and those estimated by using the Poisson distribution functions.

Highlights

It is well known that, in a lot of polymers, the energetic ion irradiation and the subsequent chemical etching produce one-dimensional holes with small diameters [1].Resultant perforated membranes have been used as filters for small particles [1,2]
We refer the result of anatase TiO2 by Ishikawa et al as an example of the ion irradiation induced amorphization [21]. They irradiated TiO2 films with 230 MeV Xe+15 ions and measured the x ray diffraction (XRD) spectra. They have shown that the XRD peak intensity decreases in an exponential manner as a function of ion fluence
As only the non-amorphized area contributes to the x ray diffraction, the intensity of the XRD peak is proportional to the fraction of zero impact (r = 0) area, A(Φ, 0), which is not amorphized by the irradiation

Summary

Introduction

It is well known that, in a lot of polymers, the energetic ion irradiation and the subsequent chemical etching produce one-dimensional holes with small diameters [1].Resultant perforated membranes have been used as filters for small particles [1,2]. It is well known that, in a lot of polymers, the energetic ion irradiation and the subsequent chemical etching produce one-dimensional holes with small diameters [1]. In some ceramics irradiated with swift heavy ions, one-dimensional areas, in which the lattice structures and the physical properties are strongly modified, are produced along the ion beam path. Such one-dimensional structures are called “ion-tracks” [3]. A lot of studies have been performed in order to investigate the individual ion-track structures and their dependence on the electronic stopping power, Se, of the irradiating ions [10,11,12,13,14,15]. The effects of the ion-track overlapping on lattice structures of target materials, which appear for the high fluence irradiation, have been investigated so far [10,16,17,18,19,20,21,22]

Results

Discussion

Conclusion