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Title: Correlation between Cr 3+ Luminescence and Oxygen Vacancy Disorder in Strontium Titanate under MeV Ion Irradiation

Abstract

Strontium titanate (SrTiO 3), a model system with a strongly correlated electronic structure, has attracted much attention recently because of its outstanding physicochemical properties and considerable potentials for technological applications. The capability to control oxygen vacancy profiles and their effect on valence states of cations will increase significantly the functionality of devices based on transition metal oxides. This work presents new insights into the near-infrared luminescence emission of Cr 3+ centers in stoichiometric SrTiO 3 induced using 3 MeV protons at temperatures of 100 K, 170 K, and room temperature. The study covers a wide spectral range, including near-infrared, visible, and near-UV regions. Our main purpose is to investigate the role of the oxygen vacancies introduced by energetic charged particles on the shape and yield of induced luminescence spectra, in particular to explore the interplay between the Cr 3+ luminescence at 1.55 eV and oxygen disorder. A clear correlation is found between the decay of the Cr luminescence yield during irradiation and the growth of a band at 2.0 eV, well-resolved below 170 K, which has been very recently attributed to d–d transitions of electrons self-trapped as Ti 3+ in the close vicinity of oxygen vacancies. This correlation suggests irradiation-inducedmore » oxidation of the Cr 3+ (Cr 3+ → Cr n+, n > 3) via trapping of irradiation-induced holes, while the partner electrons are self-trapped as Ti 3+. Here, these new results provide effective guidelines for further understanding the electronic and photocatalytic behavior of STO:Cr 3+.« less

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [4]; ORCiD logo [5]
  1. Univ. of Tennessee, Knoxville, TN (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States); Missouri Univ. of Science and Technology, Rolla, MO (United States)
  3. Centro de Microanalisis de Materiales, Madrid (Spain)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1394589
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 36; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE

Citation Formats

Crespillo, Miguel L., Graham, Joseph T., Agullo-Lopez, Fernando, Zhang, Yanwen, and Weber, William J. Correlation between Cr3+ Luminescence and Oxygen Vacancy Disorder in Strontium Titanate under MeV Ion Irradiation. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.7b04352.
Crespillo, Miguel L., Graham, Joseph T., Agullo-Lopez, Fernando, Zhang, Yanwen, & Weber, William J. Correlation between Cr3+ Luminescence and Oxygen Vacancy Disorder in Strontium Titanate under MeV Ion Irradiation. United States. doi:10.1021/acs.jpcc.7b04352.
Crespillo, Miguel L., Graham, Joseph T., Agullo-Lopez, Fernando, Zhang, Yanwen, and Weber, William J. 2017. "Correlation between Cr3+ Luminescence and Oxygen Vacancy Disorder in Strontium Titanate under MeV Ion Irradiation". United States. doi:10.1021/acs.jpcc.7b04352.
@article{osti_1394589,
title = {Correlation between Cr3+ Luminescence and Oxygen Vacancy Disorder in Strontium Titanate under MeV Ion Irradiation},
author = {Crespillo, Miguel L. and Graham, Joseph T. and Agullo-Lopez, Fernando and Zhang, Yanwen and Weber, William J.},
abstractNote = {Strontium titanate (SrTiO3), a model system with a strongly correlated electronic structure, has attracted much attention recently because of its outstanding physicochemical properties and considerable potentials for technological applications. The capability to control oxygen vacancy profiles and their effect on valence states of cations will increase significantly the functionality of devices based on transition metal oxides. This work presents new insights into the near-infrared luminescence emission of Cr3+ centers in stoichiometric SrTiO3 induced using 3 MeV protons at temperatures of 100 K, 170 K, and room temperature. The study covers a wide spectral range, including near-infrared, visible, and near-UV regions. Our main purpose is to investigate the role of the oxygen vacancies introduced by energetic charged particles on the shape and yield of induced luminescence spectra, in particular to explore the interplay between the Cr3+ luminescence at 1.55 eV and oxygen disorder. A clear correlation is found between the decay of the Cr luminescence yield during irradiation and the growth of a band at 2.0 eV, well-resolved below 170 K, which has been very recently attributed to d–d transitions of electrons self-trapped as Ti3+ in the close vicinity of oxygen vacancies. This correlation suggests irradiation-induced oxidation of the Cr3+ (Cr3+ → Crn+, n > 3) via trapping of irradiation-induced holes, while the partner electrons are self-trapped as Ti3+. Here, these new results provide effective guidelines for further understanding the electronic and photocatalytic behavior of STO:Cr3+.},
doi = {10.1021/acs.jpcc.7b04352},
journal = {Journal of Physical Chemistry. C},
number = 36,
volume = 121,
place = {United States},
year = 2017,
month = 8
}

Journal Article:
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  • The influence of swift heavy ion irradiation (SHII) on surface phonon mode (SPM) and green emission in nanocrystalline CdS thin films grown by chemical bath deposition is studied. The SHII of nanocrystalline CdS thin films is carried out using 70 MeV Ni ions. The micro Raman analysis shows that asymmetry and broadening in fundamental longitudinal optical (LO) phonon mode increases systematically with increasing ion fluence. To analyze the role of phonon confinement, spatial correlation model (SCM) is fitted to the experimental data. The observed deviation of SCM to the experimental data is further investigated by fitting the micro Raman spectra usingmore » two Lorentzian line shapes. It is found that two Lorentzian functions (LFs) provide better fitting than SCM fitting and facilitate to identify the contribution of SPM in the observed distortion of LO mode. The behavior of SPM as a function of ion fluence is studied to correlate the observed asymmetry (Γ{sub a}/Γ{sub b}) and full width at half maximum of LO phonon mode and to understand the SHII induced enhancement of SPM. The ion beam induced interstitial and surface state defects in thin films, as observed by photoluminescence (PL) spectroscopy studies, may be the underlying reason for enhancement in SPM. PL studies also show enhancement in green luminescence with increase in ion fluence. PL analysis reveals that the variation in population density of surface state defects after SHII is similar to that of SPM. The correlation between SPM and luminescence and their dependence on ion irradiation fluence is explained with the help of thermal spike model.« less