ZnPS: A Promising Infrared Nonlinear-Optical Material with Excellent Overall Properties.

The thiophosphate ZnPS is reported for its potential application in infrared (IR) nonlinear optics. This nondeliquescent compound features a cubic closet packing of the (PS) groups, with Zn filling in three-quarters of the tetrahedral interspaces. The optical band gap of ZnPS is characterized as 3.12 eV, which is very beneficial to improving the laser damage threshold. Besides, ZnPS demonstrates good phase matchability (PM) with a strong second-harmonic-generation (SHG) response that is about 2.6 times that of AgGaS, achieving a valuable balance among good phase matchability, strong SHG response, and large optical band gap. The origin of these attractive optical properties is investigated in detail via theoretical calculations. Moreover, the differential scanning calorimetry curve indicates a congruent-melting thermal behavior of ZnPS, which is conducive to large single-crystal growth. The excellent comprehensive performance of ZnPS makes it a practically usable IR nonlinear-optical candidate.