Accession Number : ADA578956


Title :   Control of Grain Boundaries and Defects in Nano-Engineered Transparent Scintillator Ceramics


Descriptive Note : Technical rept. 15 Nov 2006-14 Mar 2012


Corporate Author : STANFORD UNIV CA GEBALLE LAB FOR ADVANCED MATERIALS


Personal Author(s) : Feigelson, R S ; Gaume, R ; Podowitz, S R


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a578956.pdf


Report Date : Mar 2013


Pagination or Media Count : 127


Abstract : This research program focused mainly on the relationship between macro-scale defects on the scintillator properties of optical ceramics. The former includes grain boundaries, porosity and solid phase inclusions, and the latter, lattice imperfections. The following important results were found: 1) Oxygen defects in hot pressed Eu-doped yttrium oxide ceramics dwarf the influence of grain boundary defects on scintillator light yield (5 to 250 micron grain size range). A direct relationship was found between the in-diffusion of oxygen during annealing and the decrease in the number of charge carrier traps. This oxygen up-take resulted in an increased in light yield. 2) Two novel micro-scale scintillation characterization techniques were developed. 3) Grain boundary recombination is Eu-doped yttrium oxide ceramics (grain sizes30 microns) was found to be minimal. Transmission electron microscopy showed that these ceramics had abrupt boundaries, 4) In vacuum sintered Ce-doped yttrium aluminum garnet ceramics, a relationship was found between cation non-stoichiometry, anti-site defects, and light yield. 5) in translucent Eu-doped strontium iodide ceramics produced by hot pressing, a relationship between transparency, grain texture and scintillation properties was identified.


Descriptors :   *CERAMIC MATERIALS , *GRAIN BOUNDARIES , *SCINTILLATION , *TRANSPARENCE , ANNEALING , CERIUM , DEFECTS(MATERIALS) , ELECTRON MICROSCOPY , EUROPIUM , GRAIN SIZE , MINIATURIZATION , POROSITY , RECOMBINATION REACTIONS , TRANSMITTANCE , TRANSPARENCIES , YIELD , YTTRIUM OXIDES


Subject Categories : Ceramics, Refractories and Glass
      Crystallography
      Optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE