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The luminescent properties of rare-earth doped solids have been under intense exploration for a wide range of applications ranging from displays and lasers to scintillators. In this work, the material purification, crystal growth, and spectroscopic properties of Ce3+-, and Eu3+- doped KPb2Cl5 as well as Pr3+ doped KPb2Cl5 and KPb2Br5 were investigated for possible applications in infrared lasers and radiation detectors. The studied materials were synthesized through careful purification of starting materials including multi-pass zone-refinement and halogination. The growth of the purified materials was then carried out through vertical or horizontal Bridgman technique. The trivalent praseodymium ion (Pr3+) offers a large number of laser transitions in the visible and infrared (IR) spectral regions. Using ~1.45 μm and 1.9 μm pumping, IR emissions at ~1.6, ~2.4, and ~4.6 μm were observed from Pr: KPb2Cl5 and Pr: KPb2Br5 corresponding to the 4f-4f transitions of 3F4/3F3→3H4, 3F2/3H6→3H4, and 3H5→3H4, respectively. Large emission cross-sections in the range of (4.8-6.1) x 10-20 cm2 (near-IR, ~1.6 μm) and (5.5-6.0) x 10-20 cm2 (mid-IR, ~4.6 μm) were observed for both crystals. Emission characteristics of the ~1.6 μm Pr3+ transition including IR to visible upconversion emission studies were also discussed. Under Xenon lamp excitation, preliminary spectroscopic results showed allowed 5d-4f Ce3+ emission centered at ~375 nm in Ce3+ doped KPb2Cl5. In addition, commercial Ce:YAG and Ce:YAP crystals are included in this study for comparison. Pr3+ and Eu2+ 5d-4f emissions were not observed from Pr3+/Eu2+ doped KPb2Cl5 crystals.
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