Multiphonon radiationless phenomena in Mn2+-Doped Ca1-x Sr x F2 and BaF2 Fluorites |
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Authors: | I HernÁNDEZ F RodrÍGUEZ |
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Institution: | DCITIMAC, Facultad de Ciencias , Universidad de Cantabria , Santander , 39005 , Spain |
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Abstract: | This work investigates the surprising disappearance of the Mn2+ photoluminescence on passing from CaF2:Mn2+ to SrF2:Mn2+ or BaF2:Mn2+ using pressure spectroscopy. We show that the loss of luminescence in these systems is associated with non-radiative thermally activated processes whose activation energy and pre-exponential rates strongly depend on the crystal volume irrespective of the chemical composition. A salient feature is the PL enhancement observed in the cotunnite high-pressure phase along the series. This enhancement is explained in terms of the large volume reduction at the phase transition, as well as by the presence of low-symmetry crystal fields attained at the cation sites leading to an increase of the radiative transition rate by the electric-dipole mechanism. |
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Keywords: | High-pressure Spectroscopy Photoluminescence Radiationless Process Mn2+-doped Fluorites Fluorite-Cotunnite Phase Transition |
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