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We report results of the optical properties of Dy-doped CsPbCl₃and KPb₂Cl₅bulk crystals for potential applications in yellow solid-state laser development. The crystals were synthesized from purified starting materials and melt-grown by vertical Bridgman technique. Optical transmission measurements revealed characteristic absorption bands from intra-4f transitions of Dy³⁺ions. Direct optical excitation at 455 nm (⁶H_15/2→⁴I_15/2) resulted in dominant yellow emission bands at ∼575 nm from the⁴F_9/2excited state of Dy³⁺ions. In addition, both crystals exhibited weaker emission lines in the blue (∼483 nm) and red (∼670 nm) regions. The peak emission-cross sections for the yellow transition (⁴F_9/2→⁶H_13/2) were determined to be ∼0.22 × 10⁻²⁰cm²for Dy: CsPbCl₃(λ_peak= 576.5 nm) and ∼0.59 × 10⁻²⁰cm²for Dy: KPb₂Cl₅(λ_peak= 574.5 nm). The spectral properties and decay dynamics of the⁴F_9/2excited state were evaluated within the Judd-Ofelt theory to predict total radiative decay rates, branching ratios, and emission quantum efficiencies.

 

We report results of the crystal growth and characterization of undoped and Dy-doped TlPb2Br5 for applications in infrared (IR) lasers and nuclear radiation detection. TlPb2Br5 (TPB) was synthesized from commercial starting materials of PbBr2 and TlBr and further purified through a combination of zone-refinement and directional solidification. For doping experiments, 2 wt% of DyBr3 was added to the purified TPB material. Crystal growth of TPB and Dy: TPB was carried out in a two-zone tube furnace by a vertical Bridgman method. Following optical excitation at ~1.36um, the Dy: TPB crystal exhibited efficient mid-IR emission bands centered at 2.87um and 4.35um with room-temperature lifetimes of 9.5 ms and 5.2 ms, respectively. The peak emission cross-sections were determined to be ~0.8x10-20 cm2 and ~0.5x10-20 cm2, respectively, which makes Dy: TPB a promising candidate for mid-IR laser applications. Besides its potential as a solid-state laser host, an undoped TPB crystal was also tested for gamma-ray detection. Using Cs-137 and Am-241 sources resulted in energy resolutions for gamma-rays as good as 1-2% (FWHM) at room-temperature under non-optimized conditions.