Identification of electron and hole traps in lithium tetraborate (Li{sub 2}B{sub 4}O{sub 7}) crystals: Oxygen vacancies and lithium vacancies

Journal Article · Tue Jun 15 00:00:00 EDT 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3392802· OSTI ID:21476292

Swinney, M W; McClory, J W; Petrosky, J C ^[1]; Shan, Yang; Brant, A T; Halliburton, L E ^[2]; Adamiv, V T; Burak, Ya V ^[3]; Dowben, P A ^[4]

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1. Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio 45433 (United States)
2. Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)
3. Institute of Physical Optics, Dragomanov 23, L'viv 79005 (Ukraine)
4. Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States)

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to identify and characterize electrons trapped by oxygen vacancies and holes trapped by lithium vacancies in lithium tetraborate (Li{sub 2}B{sub 4}O{sub 7}) crystals. Our study includes a crystal with the natural abundances of {sup 10}B and {sup 11}B and a crystal highly enriched with {sup 10}B. The as-grown crystals contain isolated oxygen vacancies, lithium vacancies, and copper impurities, all in nonparamagnetic charge states. During an irradiation at 77 K with 60 kV x-rays, doubly ionized oxygen vacancies trap electrons while singly ionized lithium vacancies and monovalent copper impurities trap holes. The vacancies return to their preirradiation charge states when the temperature of the sample is increased to approximately 90 K. Hyperfine interactions with {sup 10}B and {sup 11}B nuclei, observed between 13 and 40 K in the radiation-induced EPR and ENDOR spectra, provide models for the two vacancy-related defects. The electron trapped by an oxygen vacancy is localized primarily on only one of the two neighboring boron ions while the hole stabilized by a lithium vacancy is localized on a neighboring oxygen ion with nearly equal interactions with the two boron ions adjacent to the oxygen ion.

• OSTI ID: 21476292
• Journal Information: Journal of Applied Physics, Vol. 107, Issue 11; Other Information: DOI: 10.1063/1.3392802; (c) 2010 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BORATES
BORON 10
BORON 11
CERAMICS
CHARGE STATES
COPPER
CRYSTALS
ELECTRON SPIN RESONANCE
ENDOR
HOLES
IMPURITIES
IRRADIATION
LITHIUM COMPOUNDS
OXYGEN
PARAMAGNETISM
TEMPERATURE DEPENDENCE
TRAPPING
TRAPS
VACANCIES
ALKALI METAL COMPOUNDS
BORON COMPOUNDS
BORON ISOTOPES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MAGNETISM
METALS
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
POINT DEFECTS
RESONANCE
STABLE ISOTOPES
TRANSITION ELEMENTS