In-Phase Alignments of Asymmetric Building Units in Ln₄GaSbS₉(Ln = Pr, Nd, Sm, Gd−Ho) and Their Strong Nonlinear Optical Responses in Middle IR

Abstract

New noncentrosymmetric rare-earth metal gallium thioantimonates, Ln(4)GaSbS(9) were synthesized from stoichiometric element mixtures at 950 °C by high-temperature solid-state reactions. These compounds crystallize in orthorhombic space group Aba2 (no.41) with a = 13.799(3)-13.427(5) Å, b = 14.187(3)-13.756(5) Å, c = 14.323(3)-13.954(5) Å, V = 2804(2)-2577 (2) Å(3), and Z = 8 on going from Ln = Pr to Ho. The asymmetric building units, bimetallic polar (Sb(2)S(5)) units, and dimeric (GaS(4))(2) tetrahedra are in-phase aligned as an infinite single anionic chain of {[(Ga(2)S(6))(Sb(2)S(5))](10-)}(∞) that is further packed in a noncentrosymmetric pseudolayer motif perpendicular to the c axis. Three of the title compounds show large powder second harmonic generation (SHG) effects at 2.05 μm, and two of them also exhibit large transparency ranges (1.75 or 0.75 to 25 μm) in the middle-IR region. Significantly, the Sm-member exhibits the strongest SHG response among sulfides to date with intensity approximately 3.8 times that of the benchmark AgGaS(2). The band structures, indirect band gap nature, bonding strengths, and lone pair effects around Sb have also been studied by Vienna ab initio simulation package calculations.

Growth and characterization of BaGa4Se7 crystal

“…However, AgGaQ 2 have low laser damage thresholds, whereas ZnGeP 2 exhibits strong two-photon absorption of conventional 1 mm laser (Nd:YAG), which severely limits their applications [4]. Extensive efforts have been made to find new IR NLO materials that could overcome the shortcomings of currently used materials [5][6][7][8][9][10][11][12][13][14][15][16].…”

Synthesis, Crystal and Electronic Structure, and Optical Property of the Quaternary Selenide: La3Sb0.33SiSe7

“…[5,[10][11][12] However, rare earth-antimony-chalcogenides are less studied, only several compounds are known, such as La 7 Sb 9 S 24 , [13] Pr 8 Sb 2 S 15 , [14] EuSbSe 3 , [15] K 2 RE 2-x Sb 4+x Se 12 (RE = La, Ce, Pr, Gd), [16] K 2 RE 2 Sb 2 Q 9 (RE = La, Q = S; RE = Gd, Q = Se), [17] Na 9 Gd 5 Sb 8 S 26 , [18] and Ba 4 LaGe 3 SbSe 13 . [19] Recently, many efforts in the quaternary RE/M/Sb/Q (RE = rare earth metal, M = main group or transition metal, Q = chalcogenides) system have yielded several compounds with structural diversity and technologically important properties, such as La 4 FeSb 2 S 10 , RE 2 Mn 3 Sb 4 S 12 (RE = Pr, Nd, Sm, Gd), [20] RE 4 GaSbS 9 (RE = Pr, Nd, Sm, Gd-Ho) [21] with strong SHG 1 hedra running parallel to the c direction surrounded by the discrete SiSe 4 tetrahedra and La cations. UV/Vis/NIR diffuse reflectance spectroscopy study shows its optical gap of around 1.75 eV.…”

Synthesis, Crystal Structure, and Optical Property of the Quaternary Semiconductor La4Cd4In2S13

“…In recent years, rare-earth chalcogenides in combination with a triel element have attracted a great deal of attention not only because they can form a large number of structure types but also because of their excellent IR NLO performance, [6][7][8] (RE = Pr, Nd, Sm, Gd -Ho) [6] and Ba 2 InYSe 5 [7] with strong SHG effects in the IR region and RE 4 InSbS 9 (RE = La, Pr, Nd) [8] exhibiting strong Kleinman forbidden NLO coefficients in type I phase-matchable behavior. On the other hand, binary CdS, CdSe, and CdTe are also interesting for their semiconducting, photoconducting, and light-emitting properties, which made them some of the most important members of the II-VI family of solids.…”