Paramagnetic and diamagnetic defects in e- and UV-irradiated TeO2 single crystal

A. Watterich, L. A. Kappers, O. R. Gilliam, R. H. Bartram, I. Földvári, L. Korecz

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2 Citations (Scopus)

Abstract

A study is reported of the influence of illumination on generation and decay of point defects in TeO2 crystals following electron irradiation at ∼400 K. Electron irradiation is believed to cause a large concentration of diamagnetic oxygen vacancies denoted by VOx and a smaller concentration of vacancies with one trapped electron denoted by VȮ. When the sample is UV illuminated at 330 nm and 77 K or lower, electron spin resonance (ESR) measurements show that the number of VȮ centers increases and a comparable gain of VO′ centers (three electrons in the vacancy) occurs. A brief illumination at 660 nm causes the VO′ signal to disappear and the VȮ signal to decrease and return to its original value. Changes in the crystal's optical absorption obtained from spectra measured with polarized light are given. When VO′ centers are removed by bleaching, or by thermal annealing, broad bands at 600 and 700 nm disappear and there are increases in optical absorption at 380, 440 and 480 nm. The source of these bands is discussed. These processes are reversed by a new UV illumination at 330 nm and 77 K. The growth and decay kinetics of VO′ centers and VȮ centers measured by ESR indicate the same rates of percentage change in their concentrations. Explanation of these reversible processes supports selected models for the three different vacancy centers.

Original languageEnglish
Pages (from-to)261-265
Number of pages5
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Volume191
Issue number1-4
DOIs
Publication statusPublished - May 2002

Fingerprint

Vacancies
Electron irradiation
Lighting
Single crystals
Light absorption
Defects
Paramagnetic resonance
single crystals
defects
Crystals
Electrons
illumination
Point defects
Oxygen vacancies
electron irradiation
Light polarization
Bleaching
electron paramagnetic resonance
optical absorption
Annealing

Keywords

  • Electron irradiation
  • ESR
  • Optical absorption
  • TeO color centers
  • UV illumination

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Instrumentation
  • Surfaces and Interfaces

Cite this

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title = "Paramagnetic and diamagnetic defects in e- and UV-irradiated TeO2 single crystal",
abstract = "A study is reported of the influence of illumination on generation and decay of point defects in TeO2 crystals following electron irradiation at ∼400 K. Electron irradiation is believed to cause a large concentration of diamagnetic oxygen vacancies denoted by VOx and a smaller concentration of vacancies with one trapped electron denoted by VȮ. When the sample is UV illuminated at 330 nm and 77 K or lower, electron spin resonance (ESR) measurements show that the number of VȮ centers increases and a comparable gain of VO′ centers (three electrons in the vacancy) occurs. A brief illumination at 660 nm causes the VO′ signal to disappear and the VȮ signal to decrease and return to its original value. Changes in the crystal's optical absorption obtained from spectra measured with polarized light are given. When VO′ centers are removed by bleaching, or by thermal annealing, broad bands at 600 and 700 nm disappear and there are increases in optical absorption at 380, 440 and 480 nm. The source of these bands is discussed. These processes are reversed by a new UV illumination at 330 nm and 77 K. The growth and decay kinetics of VO′ centers and VȮ centers measured by ESR indicate the same rates of percentage change in their concentrations. Explanation of these reversible processes supports selected models for the three different vacancy centers.",
keywords = "Electron irradiation, ESR, Optical absorption, TeO color centers, UV illumination",
author = "A. Watterich and Kappers, {L. A.} and Gilliam, {O. R.} and Bartram, {R. H.} and I. F{\"o}ldv{\'a}ri and L. Korecz",
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T1 - Paramagnetic and diamagnetic defects in e- and UV-irradiated TeO2 single crystal

AU - Watterich, A.

AU - Kappers, L. A.

AU - Gilliam, O. R.

AU - Bartram, R. H.

AU - Földvári, I.

AU - Korecz, L.

PY - 2002/5

Y1 - 2002/5

N2 - A study is reported of the influence of illumination on generation and decay of point defects in TeO2 crystals following electron irradiation at ∼400 K. Electron irradiation is believed to cause a large concentration of diamagnetic oxygen vacancies denoted by VOx and a smaller concentration of vacancies with one trapped electron denoted by VȮ. When the sample is UV illuminated at 330 nm and 77 K or lower, electron spin resonance (ESR) measurements show that the number of VȮ centers increases and a comparable gain of VO′ centers (three electrons in the vacancy) occurs. A brief illumination at 660 nm causes the VO′ signal to disappear and the VȮ signal to decrease and return to its original value. Changes in the crystal's optical absorption obtained from spectra measured with polarized light are given. When VO′ centers are removed by bleaching, or by thermal annealing, broad bands at 600 and 700 nm disappear and there are increases in optical absorption at 380, 440 and 480 nm. The source of these bands is discussed. These processes are reversed by a new UV illumination at 330 nm and 77 K. The growth and decay kinetics of VO′ centers and VȮ centers measured by ESR indicate the same rates of percentage change in their concentrations. Explanation of these reversible processes supports selected models for the three different vacancy centers.

AB - A study is reported of the influence of illumination on generation and decay of point defects in TeO2 crystals following electron irradiation at ∼400 K. Electron irradiation is believed to cause a large concentration of diamagnetic oxygen vacancies denoted by VOx and a smaller concentration of vacancies with one trapped electron denoted by VȮ. When the sample is UV illuminated at 330 nm and 77 K or lower, electron spin resonance (ESR) measurements show that the number of VȮ centers increases and a comparable gain of VO′ centers (three electrons in the vacancy) occurs. A brief illumination at 660 nm causes the VO′ signal to disappear and the VȮ signal to decrease and return to its original value. Changes in the crystal's optical absorption obtained from spectra measured with polarized light are given. When VO′ centers are removed by bleaching, or by thermal annealing, broad bands at 600 and 700 nm disappear and there are increases in optical absorption at 380, 440 and 480 nm. The source of these bands is discussed. These processes are reversed by a new UV illumination at 330 nm and 77 K. The growth and decay kinetics of VO′ centers and VȮ centers measured by ESR indicate the same rates of percentage change in their concentrations. Explanation of these reversible processes supports selected models for the three different vacancy centers.

KW - Electron irradiation

KW - ESR

KW - Optical absorption

KW - TeO color centers

KW - UV illumination

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