Luminescence and Scintillation Properties of CexLa1-xF3 Monocrystals

A.J. Wojtowicz, M. Balcerzyk Institute of Physics, N. Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland and A. Lempicki Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA 02215, USA

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In this communication we present our results concerning luminescence and scintillation properties of mixed cerium-lanthanum trifluoride monocrystals, CexLa1-xF3. The luminescence, luminescence excitation spectra and decays are complex, indicating the presence of Ce3+ ions in regular and parasitic "perturbed" sites. The efficient energy transfer from regular Ce3+ ions (emitting at 286 and 303 nm) to "perturbed" Ce3+ ions (emitting at 340 nm) and the lack of the fast energy migration between Ce3+ ions are responsible for non-exponential decays of the short-wavelength emission and a relatively long rise-time of the long-wavelength emission. The short-wavelength emission decays are described by the Inokuti-Hirayama model of statistically distributed donors and acceptors. Our estimates of oscillator strengths, at 13.1 × 10-3 for Ce3+, and 13.5 × 10-3 for Ce3+per, confirm that the d-f transition on the Ce3+ ion in a different site must be responsible for the long-wavelength emission. Calculations of the Ce-Ce and Ce-Ceper energy transfer rates give 7.7 × 105 s-1 and 1.56 × 109 s-1. The concentration of "perturbers" in good CeF3 samples has been reduced down to about 0.11%. It is likely that the constant and significant progress made by crystal growers (Optovac Inc.) may eventually produce a superior material for applications in high energy and nuclear physics.

DOI: 10.12693/APhysPolA.84.963 PACS numbers: 78.90.+t, 78.55.-m, 61.80.Ed, 29.40.-n