Accession Number:

AD1053909

Title:

Optically Stimulated Luminescence from Ag-doped Lithium Tetraborate (Li2B4O7) Crystals

Descriptive Note:

Technical Report,01 Oct 2014,24 Mar 2016

Corporate Author:

AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States

Personal Author(s):

Report Date:

2016-03-24

Pagination or Media Count:

85.0

Abstract:

Silver-doped lithium tetraborate Li2B4O7 crystals emit optically stimulated luminescence OSL in response to stimulating light around 400 nm. Photoluminescence, optical absorption, and electron paramagnetic resonance EPRwere used to identify the defects in the crystal that cause this OSL. Lithium tetraborate crystals have Ag ions at Li sites and at interstitial sites. Upon ionization at room temperature via x rays, electron-hole pairs are generated. The electrons are trapped at Ag occupying interstitial sites, while the holes are trapped at Ag at lithium sites. The trapped electron centers become Ag0 4d105s1 and the trapped hole centers, or recombination centers, become Ag2 4d9. Evidence for these centers is seen in EPR at room temperature. Optical absorption of the irradiated crystal showed a broad peak near 370 nm. Bleaching with 400 nm light decreased the EPR signals of the Ag0 and Ag2 centers. When the crystal was stimulated with 400 nm light, OSL was produced with 270 nm emission. The effects of the stimulating lights flux on OSL were observed by using xenon lamp and diode laser sources. OSL, with the laser at 405nm, decayed faster, and provided insight on the existence of a competing electron trap, oxygen vacancies.

Subject Categories:

  • Solid State Physics
  • Optics
  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE