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REPORT DATE (DD-MM-YYYY)
19-12-2006
REPORT TYPE
Journal Article
DATES COVERED
SPONSOR/MONITOR'S ACRONYM(S)
AFRL-RY-HS
SPONSOR/MONITOR'S REPORT NUMBER(S)
AFRL-RY-HS-TP-2008-0023
ABSTRACTRoom-temperature photoluminescence has been studied in II-type bulk ZnO crystals representing three different growth methods and having free-carrier concentrations (II) ranging from 10 13 to 10 18 cm-:1. The near-band-edge emission has both free-exciton and free-exciton-phonon contributions, with the strength of the phonon coupling dependent on sample defect concentrations. Band-gap shrinkage effects are used to explain a decrease in emission energy for the higher n values. Band filling and hand nonparabolicity are predicted to he important for II> 10 19 cm-·1. At 300 K, in the absence of free carriers. the free-exciton energy is 3.312±0.004 eV.
SUBJECT TERMS
A new methanol adduct of cerium trichloride of composition CeCl3(CH3OH)4 was crystallized from a solution growth in methanol. Large single crystals (more than several cubic centimeters) have been grown in controlled temperature baths. The molecular adduct of composition Ce2Cl6(CH3OH)8 is determined from X-ray crystal structure analysis, and this molecule undoubtedly persists in solution as well. Motivations for studying these compounds are their promising unique scintillation properties for radiation detection applications and the model structural systems they provide for the realization of new low-dimensional quantum magnets. This material apparently represents the first example of a metal-organic scintillator that is applicable to X-ray, γ-ray, and neutron detection.
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