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Title: INTRINSIC TRAPPING SITES AND ION-LATTICE COUPLING PARAMETERS OF CERIUM-DOPED LUTETIUM OXYORTHOSILICATE

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab., Los Alamos, NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
766216
Report Number(s):
LA-UR-00-3131
TRN: US0005631
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Oct 2000
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; LUTETIUM SILICATES; CERIUM; DOPED MATERIALS; CRYSTAL LATTICES; COUPLING

Citation Formats

D. W. COOKE, R. E. MUENCHAUSEN, and ET AL. INTRINSIC TRAPPING SITES AND ION-LATTICE COUPLING PARAMETERS OF CERIUM-DOPED LUTETIUM OXYORTHOSILICATE. United States: N. p., 2000. Web.
D. W. COOKE, R. E. MUENCHAUSEN, & ET AL. INTRINSIC TRAPPING SITES AND ION-LATTICE COUPLING PARAMETERS OF CERIUM-DOPED LUTETIUM OXYORTHOSILICATE. United States.
D. W. COOKE, R. E. MUENCHAUSEN, and ET AL. 2000. "INTRINSIC TRAPPING SITES AND ION-LATTICE COUPLING PARAMETERS OF CERIUM-DOPED LUTETIUM OXYORTHOSILICATE". United States. doi:. https://www.osti.gov/servlets/purl/766216.
@article{osti_766216,
title = {INTRINSIC TRAPPING SITES AND ION-LATTICE COUPLING PARAMETERS OF CERIUM-DOPED LUTETIUM OXYORTHOSILICATE},
author = {D. W. COOKE and R. E. MUENCHAUSEN and ET AL},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2000,
month =
}

Conference:
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  • Optical absorption of single-crystal, cerium-doped lutetium oxyorthosilicate has been carefully measured in the temperature interval 10-300 K. Prominent Gaussian absorption peaks occur at 3.432{+-}0.002 eV (peak a), 3.502{+-}0.002 eV (peak b), 4.236{+-}0.0002 eV (peak c), and 4.746{+-}0.0002 eV (peak d), in excellent agreement with previously reported excitation spectra. The second moments are well described by the usual linear model, yielding the Huang-Rhys parameter (S) and vibrational quantum energies for the individual peaks. All absorption bands are characterized by S>5 indicating strong coupling between the Ce{sup 3+} ion and lattice. Temperature dependence of the band centroids exhibits contrasting behavior that ismore » dominated by higher-order coupling terms in the linear harmonic oscillator model or by crystal-field effects. Oscillator strengths of the 4f{yields}5d transitions are calculated from Smakula's formula and knowledge of the Ce{sup 3+} distribution between the two crystallographically inequivalent sites. Values for peaks b, c, and d range from approximately 0.003 to 0.004, and peak a spans magnitude approximately 0.012 to 0.018. From the known correlation between average Ce{sup 3+}-ion-ligand distance and oscillator strength, we tentatively conclude that peak a is correlated with the seven-oxygen-coordinated site, and peaks b, c, and d are associated with the six-oxygen-coordinated site. These results support the previously proposed two-activation-center model and identify the centers as the two crystallographically inequivalent substitutional sites. (c) 2000 The American Physical Society.« less
  • In this paper, the authors have discovered a new single crystal inorganic scintillator, cerium-doped lutetium oxyorthosilicate (Lu[sub 2]) (1 [minus] x)Ce[sub 2x](SiO[sub 4])O or (LSO), which has a number of advantages over existing scintillators. It has a scintillation emission intensity which is [approximately] 75% of NaI(T1) with a decay time of [approximately] 40 ns. The peak emission wavelength is 420 nm. It has a very high gamma-ray detection efficiency due to its density of 7.4 g/cm[sup 3] and its effective atomic number of 66. Its radiation length of 1.14 cm is only slightly longer than BGO (1.12 cm). Due tomore » its unique combination of high emission intensity, speed, and high density and atomic number, LSO appears to be an attractive candidate for diverse applications including medical imaging, high energy physics experiments, and geophysical exploration.« less
  • Shock experiments were performed in order to characterize the triboluminescent signature of cerium-doped lutetium oxyorthosilicate (LSO:Ce). This material shows prompt, nano-second timescale light emission when driven by explosive detonation. When properly applied to a surface, it may be used as a shock arrival sensor, and also for imaging the propagation of a shock front. Triboluminescent rise times, spectral content, and spatial resolution measurements are presented.
  • A new scintillation crystal, cerium-doped lutetium oxyorthosilicate (LSO) was recently discovered with light intensity 75% of NaI(T1), scintillation decay time of 12 ns (30%) and 42 ns (70%), effective Z of 66, and density of 7.4 g/cc. The fast decay time and scintillation light output of LSO are superior to those of BGO for PET and the stopping power of LSO for 511 keV photons is only slightly lower than BGO. In this study the authors directly compared the detection characteristics relevant to PET applications of small crystals of LSO (2 X 2 X 10 mm) with those of BGO.more » The energy resolution at 511 keV was 12% FWHM for LSO and 2 to 3 times wider for BGO. The coincidence timing of two opposing crystals, using a position sensitive PMT (Hamamatsu R2486), were 1.4 ns FWHM for LSO and more than 3 times higher for BGO. Using a fast PMT (Hamamatsu R3177) coincidence timing for LSO yielded 0.46 ns FWHM. These crystals are being used to simulate a small scale PET scanner and to investigate its imaging performance.« less
  • Temperature-dependent optical absorption of cerium-doped gadolinium oxyorthosilicate (Gd{sub 2}SiO{sub 5}:Ce) has been measured and analyzed for impurity-ion-lattice coupling parameters and oscillator strengths. Although the spectrum consists of overlapping Ce{sup 3+} bands and Gd{sup 3+} lines, two well-resolved Ce{sup 3+} bands with 10 K maxima at 3.32 eV (peak a) and 3.61 eV (peak b) are amenable to spectral analysis. These bands, previously assigned to Ce{sup 3+} ions occupying crystallographically inequivalent substitutional sites, are characterized by Gaussian line shapes and temperature-dependent half widths that are well described by the linear model of impurity-ion-lattice coupling. Huang-Rhys [Proc. R. Soc. A 204, 404more » (1950)] parameters of peaks a and b are 22.7 and 5.7, respectively, indicating strong ion-lattice coupling, with vibrational frequencies 1.83x10{sup 13} s{sup -1} (peak a) and 5.07x10{sup 13} s{sup -1} (peak b). Peak b centroid is approximately temperature independent, but peak a centroid shifts to higher energy with increasing temperature. This dependence is adequately described by including higher-order coupling terms in the ion-lattice interaction, although crystal-field contributions cannot be excluded. Absorption band oscillator strengths, f, are calculated from Smakula's [Z. Phys. 59, 603 (1930)] formula and knowledge of cerium concentration for the two inequivalent sites. In the interval 10-300 K, peak a f values range from (9.8 to 26.8)x10{sup -4} and peak b f values vary from (7.8 to 5.8)x10{sup -3}. From the known correlation between oscillator strength and metal-ion-ligand separation, we identify peaks a and b as the seven- and nine-oxygen-coordinated sites, respectively. (c) 2000 American Institute of Physics.« less