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Title: XANES study of Fe-implanted strontium titanate

Abstract

Properties of strontium titanate SrTiO{sub 3} (STO) depend to a great extent on the substitutional dopants and defects of crystal structure. The ion beam implantation method was used for doping STO (001) crystals with Fe at different doses. Implanted samples were then annealed at 350°C in oxygen to induce recrystallization and remove oxygen vacancies produced during ion implantation process. The effect of Fe doping and post-implantation annealing was studied by X-ray Absorption Near Edge Spectroscopy (XANES) method and Superconducting Quantum Interference Device (SQUID). XANES allowed to monitor the change in structure of STO crystals and in the local environment of Fe following the implantation and annealing steps. SQUID measurements revealed correlation between magnetic moment and Fe implantation dose. Ferromagnetic hysteresis was observed on selected Fe-implanted STO at 5 K. The observed magnetic properties can be correlated with the several Fe oxide phases in addition to the presence of O/Ti vacancies.

Authors:
; ; ;  [1]
  1. Department of Physics and Astronomy, and Department of Chemistry, University of Western Ontario, London, ON N6A 5B7 (Canada)
Publication Date:
OSTI Identifier:
22265949
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1590; Journal Issue: 1; Conference: International conference on electronic, photonic, plasmonic and magnetic properties of nanomaterials, London (Canada), 12-16 Aug 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; ABSORPTION; ABSORPTION SPECTROSCOPY; ANNEALING; CRYSTALS; DOPED MATERIALS; DOSES; MAGNETIC MOMENTS; MAGNETIC PROPERTIES; OXIDES; OXYGEN; RECRYSTALLIZATION; SQUID DEVICES; STRONTIUM; STRONTIUM TITANATES; X RADIATION; X-RAY SPECTROSCOPY

Citation Formats

Lobacheva, O., Goncharova, L. V., Chavarha, M., and Sham, T. K. XANES study of Fe-implanted strontium titanate. United States: N. p., 2014. Web. doi:10.1063/1.4870200.
Lobacheva, O., Goncharova, L. V., Chavarha, M., & Sham, T. K. XANES study of Fe-implanted strontium titanate. United States. doi:10.1063/1.4870200.
Lobacheva, O., Goncharova, L. V., Chavarha, M., and Sham, T. K. Mon . "XANES study of Fe-implanted strontium titanate". United States. doi:10.1063/1.4870200.
@article{osti_22265949,
title = {XANES study of Fe-implanted strontium titanate},
author = {Lobacheva, O. and Goncharova, L. V. and Chavarha, M. and Sham, T. K.},
abstractNote = {Properties of strontium titanate SrTiO{sub 3} (STO) depend to a great extent on the substitutional dopants and defects of crystal structure. The ion beam implantation method was used for doping STO (001) crystals with Fe at different doses. Implanted samples were then annealed at 350°C in oxygen to induce recrystallization and remove oxygen vacancies produced during ion implantation process. The effect of Fe doping and post-implantation annealing was studied by X-ray Absorption Near Edge Spectroscopy (XANES) method and Superconducting Quantum Interference Device (SQUID). XANES allowed to monitor the change in structure of STO crystals and in the local environment of Fe following the implantation and annealing steps. SQUID measurements revealed correlation between magnetic moment and Fe implantation dose. Ferromagnetic hysteresis was observed on selected Fe-implanted STO at 5 K. The observed magnetic properties can be correlated with the several Fe oxide phases in addition to the presence of O/Ti vacancies.},
doi = {10.1063/1.4870200},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1590,
place = {United States},
year = {Mon Mar 31 00:00:00 EDT 2014},
month = {Mon Mar 31 00:00:00 EDT 2014}
}
  • Highlights: Black-Right-Pointing-Pointer The origin of RT-ferromagnetism in iron implanted strontium titanate. Black-Right-Pointing-Pointer Metallic iron nanoclusters form during implantation and define magnetic behaviour. Black-Right-Pointing-Pointer Paramagnetic at room temperature iron-substituted strontium titanate identified. -- Abstract: Thin magnetic films were synthesized by means of implantation of iron ions into single-crystalline (1 0 0) substrates of strontium titanate. Depth-selective conversion electron Moessbauer spectroscopy (DCEMS) indicates that origin of the samples magnetism is {alpha}-Fe nanoparticles. Iron-substituted strontium titanate was also identified but with paramagnetic behaviour at room temperature. Surface magneto-optical Kerr effect (SMOKE) confirms that the films reveal superparamagnetism (the low-fluence sample) or ferromagnetism (themore » high-fluence sample), and demonstrate absence of magnetic in-plane anisotropy. These findings highlight iron implanted strontium titanate as a promising candidate for composite multiferroic material and also for gas sensing applications.« less
  • Synchrotron micro-XANES spectroscopy (SmX) is used to examine the amount and distribution of Fe{sup 2+} and Fe{sup 3+} in five samples of fayalite previously studied by Moessbauer spectroscopy. Rockport fayalite is homogeneous and the Fe in it is completely reduced. Olivine from Qianan is almost completely oxidized, and probably contains finely intergrown silica, laihunite, and hematite with hematite predominating. Pantelleria olivine has an oxidized rim around a reduced core, suggesting either a post-crystallization reaction with fayalite and oxygen going to laihunite and hematite or a change in prevailing oxidation during growth. The texture of olivine from the Mourne Mountains suggestsmore » exsolution from a fayalite-laihunite solid solution, based on the substitution of three Fe{sup 3+} atoms for two Fe{sup 3+} and one vacancy, that was stable at high temperature. Laihunite from the type locality (Lai-He village) shows 1--3 {micro}m mottling between light and dark areas in backscatter images, but these areas cannot correspond to pure fayalite and laihunite exsolution because the bulk Fe{sup 3+}/{Sigma}Fe of such a combination would not correspond to the SmX value of 67% Fe{sup 3+}. Rather, the texture observed in backscatter is interpreted to represent alternating areas of magnetite-rich and laihunite-rich compositions with a similar (i.e., 67% Fe{sup 3+}/{Sigma}Fe) extent of oxidation.« less
  • A crystal potential has been derived for strontium titanate and used to calculate the intrinsic defect properties of the room temperature cubic phase. Interactive potentials for a number of uni-, di-, tri-, and tetra-valent metal ions with O{sup 2{minus}}, sr{sup 2+}, and Ti{sup 4+} has been derived by well-tried methods, using HFSCF calculations of the ionic charge densities and the conserved density approximation. Kinetic energy, exchange, and correlation contributions to the total interaction energy are approximated by the corresponding contributions to an electron gas of the same charge density as the sum of the two SCF ionic charge densities atmore » each separation R. These impurity-host lattice potentials are then used to calculate the solubility of these ions in cubic SrTiO{sub 3} as well as the possible mobility of these substituents.« less
  • No abstract prepared.