Crystal Growth and First-Principles Calculations of the Mid-IR Laser Crystal Dy3+:PbGa2S4

A Dy3+-doped PbGa2S4 crystal with low phonon energy has been proved to be able to achieve the direct lasing of a mid-infrared laser. The single-crystal growth of Dy3+:PbGa2S4 was investigated in this work. On the basic of the high-purity polycrystalline material synthesized using a pressure-assisted method, a Dy3+:PbGa2S4 single crystal with φ 21 × 50 mm3 was successfully grown using the Bridgman method with a crucible–capsule technique. To understand the cleavage character of the PbGa2S4 crystal and get further insight into its electronic and phonon properties, the electronic, phonon, and mechanical properties of the PbGa2S4 host were investigated using first-principles calculations. PbGa2S4 exhibits not only a large electronic energy gap (2.76 eV) but also a low phonon energy (392 cm–1) due to the incorporation of heavy Pb atoms between the interlayers. The high-frequency phonon bands of PbGa2S4 are mainly contributed by the vibrations of Ga–S atoms in the layer network formed by GaS4 units. However, th...