Visualizing the alignment of lone pair electrons in La₃AsS₅Br₂ and La₅As₂S₉Cl₃ to form an acentric or centrosymmetric structure

Abstract

Acentric structures host numerous important applications such as second harmonic generation, nonreciprocal responses, etc. In this work, a heteroanionic system of La3AsS5Br2 and La5As2S9Cl3 exhibits a good example of how...

Rare-earth-based chalcogenides and their derivatives: an encouraging IR nonlinear optical material candidate

“…The NCS chalcohalide La 3 AsS 5 Br 2 with the monoclinic space group Cc (no. 9), 174 which is isostructural to the previously reported Pr 3 AsS 5 Cl 2 , 175 was successfully prepared using a salt flux growth method in 2023 by Wang's group.…”

“…In order to better illustrate the advantages of RE-based chalcogenide compounds and address the challenges in this field, this paper provides detailed explanations for 85 representative examples out of over 400 NCS compounds. 68–187 These examples are categorized into four groups based on the various asymmetric building motifs: (1) RE-based chalcogenides containing tetrahedral motifs; (2) RE-based chalcogenides containing lone-pair-electron motifs; (3) RE-based chalcogenides containing [BS 3 ] and [P 2 Q 6 ] motifs; and (4) RE-based chalcohalides and oxychalcogenides. Finally, the conclusions and perspectives for RE-based chalcogenides and their derivatives are provided for further exploration.…”

Hg3AsS4X (X = Cl and Br): two Hg-based chalcogenides as long-wave infrared nonlinear optical crystals with superior comprehensive performances

“…Inspired by the previous work mentioned above, we attempted to seek out Hg-based chalcogenides with favorable overall properties as potential IR NLO crystals. To improve NLO performance, metals (M = As, Sb, Sn and Te) with lone pair electrons, promoting preferable NLO effects, 30–35 were introduced to form trigonal pyramids as promising building units, facilitating synergetic tuning with Hg-based groups to balance the SHG effect, band gap, and birefringence comprehensively. Following the introduction of the above building units, the directivity of groups can also be adjusted and perfected for improved NLO performance according to the anionic group theory.…”