KREP₂Se₆ (RE = Sm, Gd, Tb): The First Rare‐Earth Selenophosphates with Remarkable Nonlinear Optical Activities Realized by Synergistic Effect of RE‐ and P‐Based Motifs

Abstract

factor beneficial for increasing bandgap and LIDT usually tend to decrease the NLO coefficient. [5] MIR NLO crystals are important components for outputting MIR lasers. However, according to these requirements, AGS and ZGP cannot satisfy the increasing market's needs in view of their low LIDTs and harmful doublephoton absorption. [6] Therefore, how to maintain the balance between high LIDT and strong NLO response is the main concern for researchers in this field. After years of exploration, MIR NLO materials with superior comprehensive properties are still scarce. Therefore, the discovery of novel ones with balanced comprehensive properties is urgent while challenging.Hitherto, MIR NLO materials are mainly metal chalcogenides, and also several mixed-anionic materials, such as oxyhalides

Quaternary alkaline-earth metal thiophosphate SrAgPS4: syntheses, structures, and optical properties

“…22–25 Meanwhile, alkali metals are typically considered to be beneficial for enlarging the band gap due to their fully filled d or f orbitals, which prevent d–d or f–f electronic transitions. AHgPS 4 (A = Na, K), 26 KAg 2 PS 4 , 27 KREP 2 Se 6 (RE = Sm, Gd, Tb), 28 A 2 Zn 3 P 4 S 13 (A = Rb and Cs), 29 and other alkali metal thiophosphates were evaluated as outstanding IR NLO candidates. Alkaline-earth metals have similar characteristics to alkali metals and are often used in the design of wide-band gap NLO materials.…”

KNa2La2(BO3)3: a shortite-type lanthanide borate exhibiting strong nonlinear optical activity induced by isolated [BO3] triangles and distorted [LaO9] polyhedra

“…According to previous studies, the enriched structural chemistry of lanthanide metal ions enables them to produce local asymmetric coordination environments, similar to the second-order SOJT distortions. 19 In particular, some rare-earth metal ions with closed-shell electron systems, such as Y 3+ , Sc 3+ , La 3+ , and Lu 3+ , inhibit the intrinsic d-d or f-f electronic transitions and thus give sufficient optical transparency in the UV window, as seen in compounds like La 2 CaB 10 O 19 , 20 K 5 Mg 2 La 3 (BO 3 ) 6 , 21 and K 7 CdRE 2 B 15 O 30 (RE = Sc, Y, Gd, Lu). 22 Motivated by these, we focused special attention on the rare-earth metal-borate system in order to fabricate novel UV NLO crystals with improved optical properties.…”

An overview of Mg-based IR nonlinear optical materials

“…Among these, the most commonly used method for obtaining non-centrosymmetric structures is the introduction of various asymmetric building units (ABUs) into one structure. The common ABUs for IR-NLO materials are as follows: (i) distorted [MQ 4 ] tetrahedra (M = main-group elements; Q = chalcogen); 44–52 (ii) [MQ n ] polyhedra (M = transition-metal elements; n = 2, 3, and 4); 53–57 (iii) distorted [REQ n ] polyhedra (RE = rare-earth-metal elements); 58–61 (iv) lone-pair-cation-based [MQ n ] polyhedra (M = As( iii ), Sb( iii ), Bi( iii ), Pb( ii ), and Sn( ii )); 62–71 and (v) mixed-anion [MO x Q y ] polyhedra. 72–81…”

“…Among these, the most commonly used method for obtaining non-centrosymmetric structures is the introduction of various asymmetric building units (ABUs) into one structure. The common ABUs for IR-NLO materials are as follows: (i) distorted [MQ 4 ] tetrahedra (M = main-group elements; Q = chalcogen); [44][45][46][47][48][49][50][51][52] (ii) [MQ n ] polyhedra (M = transition-metal elements; n = 2, 3, and 4); [53][54][55][56][57] (iii) distorted [REQ n ] polyhedra (RE = rare-earth-metal elements); [58][59][60][61] (iv) lone-pair-cation-based [MQ n ] polyhedra (M = As(III), Sb(III), Bi (III), Pb(II), and Sn(II)); [62][63][64][65][66][67][68][69][70][71] and (v) mixed-anion [MO x Q y ] polyhedra. [72][73][74][75][76][77][78][79][80][81] Recently, the introduction of Mg-based ABUs into the noncentrosymmetric structures has attracted considerable interest due to the following reasons: (i) Mg possesses large electropositivity (χ = 1.31), has a high Z/R ratio of 2.8 (Z, cation charge; R, cation radius), has light atomic mass and is non-poisonous.…”