Optical properties of Pr3+-, Ce3+-, and Eu2+-doped ternary lead halides

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 Ce 3+ -, and Eu 3+ - doped KPb 2 Cl 5 as well as Pr 3+ doped KPb 2 Cl 5 and KPb 2 Br 5 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 (Pr 3+ ) 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: KPb 2 Cl 5 and Pr: KPb 2 Br 5 corresponding to the 4f-4f transitions of 3 F 4 / 3 F 3 → 3 H 4 , 3 F 2 / 3 H 6 → 3 H 4 , and 3 H 5 → 3 H 4 , respectively. Large emission cross-sections in the range of (4.8-6.1) x 10 -20 cm 2 (near-IR, ~1.6 μm) and (5.5-6.0) x 10 -20 cm 2 (mid-IR, ~4.6 μm) were observed for both crystals. Emission characteristics of the ~1.6 μm Pr 3+ transition including IR to visible upconversion emission studies were also discussed. Under Xenon lamp excitation, preliminary spectroscopic results showed allowed 5d-4f Ce 3+ emission centered at ~375 nm in Ce 3+ doped KPb 2 Cl 5 . In addition, commercial Ce:YAG and Ce:YAP crystals are included in this study for comparison. Pr 3+ and Eu 2+ 5d-4f emissions were not observed from Pr 3+ /Eu 2+ doped KPb 2 Cl 5 crystals.