A3Mn2Sb3S8 (A = K and Rb): a new type of multifunctional infrared nonlinear optical material based on unique three-dimensional open frameworks

Abstract

Exploring inorganic materials with two or more different physical properties has become an important and emerging topic in solid-state chemistry. Despite considerable progress achieved recently, however, multifunctional infrared nonlinear-optical (IR-NLO) chalcogenides is still rarely reported. In this paper, the first quaternary manganese thioantimonates, A3Mn2Sb3S8 (A = K and Rb), were discovered by a facile surfactant−thermal method. Both compounds are isostructural and belong to the tetragonal space group I4 @#x0305;2m (No.121). Their structures are composed of unique three-dimensional non-centrosymmetric [Mn2Sb3S8]3− frameworks and intervening alkali A+ cations. Significantly, A3Mn2Sb3S8 (A = K and Rb) not only show type-I phase-matching features with moderate second-harmonic generation (SHG) effects and strong laser-induced damage thresholds, but also display interesting temperature-dependent paramagnetism and intriguing photocurrent responses. In addition, the highly polarizable [Sb3S7]5– group in this type of structure is an unprecedented NLO-active motif, which can be instrumental in designing new IR-NLO materials with suitable birefringence and strong SHG efficiency based on the experimental and theoretical research results. This study will contribute to enrich the diversity of lone-pair cation-based NLO-active units and opens new avenue for discovering other multifunctional IR-NLO materials.