Low temperature EPR spectra of Czochralski grown samples (upper spectra in both cases) and SCS oxyorthosilicates with 1% Ce (lower spectra) for (a) LSO and (b) YSO.
The simulated EPR spectra of Ce (upper trace in each graph) and the measured spectra (lower trace in each panel) for the various oxyorthosilicates are shown (a) bulk LSO, (b) SCS LSO, (c) bulk YSO, and (d) SCS YSO.
EPR spectra measured at 15 K of nanophosphor YSO:Ce for various Ce doping levels as indicated.
The percentages of the total Ce population for the and sites for SCS YSO as a function of Ce doping level.
Temperature dependent EPR spectra of the Ce resonance for SCS YSO with 1% Ce.
(a) Pure Lorentzian , (b) pure Gaussian , and (c) total linewidths for bulk LSO, bulk YSO, nanophospor LSO, and nanophosphor YSO derived from fitting the Ce resonance with Eq. (1). The solid lines are guides for the eye only.
The percentage of the total linewidth that is Lorentzian as a function of temperature.
Simulations of the EPR spectra resulted in the given and values ( was not detected).
The temperature-dependent EPR spectra were fit with a Voigt function [Eq. (1)] to obtain the Gaussian and Lorentzian linewidths. The Gaussian linewidths then allowed us to determine the ILs. The Lorentzian linewidths were converted to lifetimes and were fit to obtain the relaxation constant (A), the Orbach constant (C), and the energy splittings for both the typical case [Eq. (3)] and the phonon bottleneck case [Eq. (7), where possible].
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