Luminescence of Pr³⁺ Impurity Centers and Defects in Sr₉Sc (PO₄)₇:Pr³⁺

Abstract

The spectroscopic characteristics and luminescence decay kinetics of Sr₉Sc(PO₄)₇:Pr³⁺(1%) were investigated using synchrotron radiation of ultraviolet (UV), vacuum ultraviolet (VUV) and X-ray ranges, as well as pulsed cathodoluminescence (PCL) methods at temperatures of 10, 90, and 295 K. The luminescence spectra contain three groups of bands and lines. In the UV range, the observed bands correspond to interconfigurational 5d → 4f transitions in Pr³⁺ ions. In the visible spectrum, the wide luminescence band of defects dominates, as well as narrow lines associated with intraconfigurational 4f → 4f transitions in Pr³⁺ ions. When excited by an electron beam (5 Hz), the main component with a decay time τ ∼ 17 ns dominates in the decay kinetics of the 5d → 4f luminescence. The decay kinetics of 5d → 4f luminescence upon excitation with high-frequency (τ ∼ 8 MHz) synchrotron radiation of the X-ray range contains a fast component (τ ∼ 15 ns) against the background of the slow component of the μs-range. An effective nonradiative energy transfer is observed from impurity centers to defects, as well as from the host to Pr³⁺ ions and defects.