Phase Transitions and Nonlinear Optical Property Modifications in BaGaSe.

Phase transitions can change the crystal structure and modify the physical properties of crystals. In this work, we investigate the phase transition behavior in BaGaSe, an important middle infrared (mid-IR) nonlinear optical (NLO) crystal, in the temperature range from room temperature to 1173 K. Interestingly, the BaGaSe crystal undergoes a reversible ferroelastic phase transition at = 528 K, resulting in the presence of a newly discovered phase (γ-phase) at the higher temperature.

Evolution of Structures and Optical Properties in a Series of Infrared Nonlinear Optical Crystals LiAgInSe (0 ≤ ≤ 1).

In this work, a number of new infrared nonlinear optical (NLO) crystals of LiAgInSe, in which the ratio of Li/Ag varies in a wide range from 0 to 1, are investigated. Structural analysis reveals that the space group of LiAgInSe evolved from 4̅2 in AgInSe to Pna2 in LiInSe as increases from low values (0, 0.2, 0.