Growth and characterization of BaGa4Se7 crystal

High-quality crystals of BaGa4Se7, a newly developed IR nonlinear optical (NLO) material, were obtained via the Bridgman–Stockbarger technique. The FWHM of the (002) peak rocking curve is about 0.008° and the transmittance through a polished 2 mm thick (001) plate is around 65% over the wide range of 1–14 μm. Various thermophysical properties were measured on crystals. The thermal expansion behavior in BaGa4Se7 does not exhibit strong anisotropy with αa=9.24×10−6 K−1, αb=10.76×10−6 K−1, and αc=11.70×10−6 K−1 along the three crystallographic axes. The thermal diffusivity/thermal conductivity coefficients measured at 298 K are 0.50(2) mm2 s−1/0.74(3) W m−1 K−1, 0.42(3) mm2 s−1/0.64(4) W m−1 K−1, 0.38(2) mm2 s−1/0.56(4) W m−1 K−1, along the a, b, c crystallographic axis respectively. In addition, the surface laser damage threshold was measured to be 557 MW/cm2 using a Nd:YAG (1.064 μm) laser under conditions of 5 ns pulse width, 1 Hz frequency, and D=0.4 mm spot size.

► High quality BaGa4Se7 single crystals were obtained via the Bridgman–Stockbarger technique.
► The crystal shows high transmittance over the wide range of 1–14 μm.
► The thermal expansion behavior in BaGa4Se7 exhibit weak anisotropy along the a, b, and c axes.
► The surface laser damage threshold was about 3.7 times that of AgGaS2 under identical conditions.