Effectively designing infrared nonlinear optical materials with magnetism, MMn₆Ga₆S₁₆ (M = Ca, Sr, Ba, and Pb), aided by stable open frameworks

Infrared nonlinear optical (NLO) materials are crucial to the development of laser technology. However, finding ways to effectively synthesize them is still a big challenge. Herein, aided by a stable open framework, four IR NLO materials, MMn₆Ga₆S₁₆ (M = Ca, Sr, Ba, and Pb), have been effectively synthesized in a high-temperature vacuum sealing system. They all crystallize in a non-centrosymmetric (NCS) space group, P, and their structures feature a three-dimensional open framework composed of Mn–S single and double chains and Ga–S single and double chains, in which these one-dimensional chains increase the structural flexibility and adjustability to accommodate varied cations with different ionic radii. Remarkably, MMn₆Ga₆S₁₆ (M = Ca, Sr, Ba, and Pb) exhibit not only comprehensive NLO performances including appropriate NLO responses and band gaps and a wide transmission range but also para-magnetism in magnetic properties, indicating that MMn₆Ga₆S₁₆ (M = Ca, Sr, Ba, and Pb) are potential IR multifunctional materials. This work suggests that a stable open framework can be used to construct varied structures, which brings a new platform for effectively designing multifunctional materials.