Ion tracks and microstructures in barium titanate irradiated with swift heavy ions: A combined experimental and computational study

W. Jiang, R. Devanathan, C. J. Sundgren, M. Ishimaru, K. Sato, T. Varga, S. Manandhar, A. Benyagoub

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Tetragonally structured barium titanate (BaTiO3) single crystals were irradiated using 635 MeV 238U+ ions to fluences of 1 × 107, 5 × 1010 and 1.4 × 10 12 ions cm-2 at room temperature. Irradiated samples were characterized using ion channeling, X-ray diffraction, helium ion microscopy and transmission electron microscopy. The results show that the ion-entry spot on the surface has an amorphous core of up to ∼10 nm in diameter, surrounded by a strained lattice structure. Satellite-like defects around smaller cores are also observed and are attributed to the imperfect epitaxial recrystallization of thermal-spike-induced amorphization. The critical value of the electronic stopping power for creating observable amorphous cores is determined to be ∼22 keV nm-1. Molecular dynamics simulations show an amorphous track of ∼1.2 nm in radius under thermal energy deposition at 5 keV nm -1; the radius increases to ∼4.5 nm at 20 keV nm-1. A linear fit of the core diameter as a function of the square root of the energy deposition rate suggests a reduction in the diameter by an average of ∼8.4 nm due to thermal recrystallization if electron-phonon coupling efficiency of 100% is assumed. The simulation also reveals details of the bonding environments and shows different densities of the amorphous zones produced at different energy deposition rates.

Original languageEnglish
Pages (from-to)7904-7916
Number of pages13
JournalActa Materialia
Volume61
Issue number20
DOIs
Publication statusPublished - 2013 Dec

Keywords

  • Barium titanate
  • Ion track
  • Molecular dynamics simulation
  • Swift heavy ion irradiation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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