A Facile Route to Nonlinear Optical Materials: Three‐Site Aliovalent Substitution Involving One Cation and Two Anions

Abstract

Tw om ixed-metal gallium iodate fluorides,n amely, a-and b-Ba 2 [GaF 4 (IO 3 ) 2 ](IO 3 )(1 and 2), have been designed by the aliovalent substitutions of a-a nd b-Ba 2 [VO 2 F 2 (IO 3 ) 2 ]-(IO 3 )( 3 and 4)i nvolving one cationic and two anionic sites. Both 1 and 2 display large second-harmonic generation responses ( % 6 KH 2 PO 4 (KDP)), large energy band gaps (4.61 and 4.35 eV), wide transmittance ranges ( % 0.27-12.5 mm), and high relevant laser-induced damage thresholds (29.7 and 28.3 AgGaS 2 ,r espectively), whichi ndicates that 1 and 2 are potential second-order nonlinear optical materials in the ultraviolet to mid-infrared. Our studies propose that three-site aliovalent substitution is af acile route for the discovery of good NLO materials.Noncentrosymmetric (NCS) oxide materials have extensively excited academic interest owing to their probable properties with applications in second-order nonlinear optics (NLO) as well as in pyroelectrics,f erroelectrics,a nd piezoelectrics. [1][2][3][4][5][6] To the best of our knowledge,a ne xcellent second-order NLO material should feature al arge second harmonic generation (SHG) coefficient, ahigh relevant laserinduced damage threshold (LDT), appropriate optical transmittance range,m oderate birefringence for achieving phase matching,and good thermal stability.Inaddition, it should be free of moisture and accessible by af acile synthetic method. [7][8][9] Metal iodates currently attract extensive research interest due to their potential outstanding SHG response. [10] Up to now,several effective synthetic routes have been reported for exploring the NCS metal iodates featuring novel crystal structures and remarkable SHG performance,s uch as condensing IO 3 À and IO 4 3À units to form polyiodates, [11][12][13] combining six-or five-coordinate d 0 transition metal (TM) cations (e.g.T i 4+ ,V 5+ ,M o 6+ ,a nd Nb 5+ ) [14][15][16][17][18][19][20][21][22] or metal cations (e.g. Bi 3+ and Pb 2+ ) [23][24][25][26] having as tereochemically active lone-pair (SCALP) with iodates,a nd introducing fluoride anions into iodates. [27][28][29][30][31][32] Anumber of excellent SHG materials have been discovered, for instance,NaI 3 O 8 , [11] Cs 2 I 4 O 11 , [13] Li 2 M(IO 3 ) 6 (M = Ti 4+ ,Sn 4+ ,Ge 4+ ), [33][34][35] A(VO) 2 O 2 (IO 3 ) 3 (A = K, Rb,C s, NH 4 ), [15,20] AMoO 3 IO 3 (A = Rb,C s), [14] BaNbO-(IO 3 ) 5 , [17] BiOIO 3 , [23] PbPt(IO 3 ) 6 , [25] Bi(IO 3 )F 2 , [28] and KBi 2 -(IO 3 ) 2 F 5 , [30] which can produce very strong SHG effects (> 10 KH 2 PO 4 (KDP)).Recently,anumber of new NCS crystals were obtained by the aliovalent substitution of known parent compounds to produce materials with strong SHG response. [36][37][38][39][40][41] For example,S e IV O 3 2À has typically been used as as urrogate for I V O 3 À ,w ith substitution of the oxo anion by ah alide anion (usually fluoride anion) to maintain charge balance.T he first bismuth selenite fluoride,B iFSeO 3 ,w ith the strongest SHG performance of all metal selenites,was designed by aliovalent substitution of laye...

CsVO2F(IO3): An Excellent SHG Material Featuring an Unprecedented 3D [VO2F(IO3)]− Anionic Framework

“…Laser‐induced‐damage‐threshold (LIDT) experiments showed that CsVO 2 F(IO 3 ) has a very large LIDT value of 107.9 MW cm −2 , which is about 50 times of that of AgGaS 2 (AGS; 2.22 MW cm −2 ). This value is also larger than that of α‐Ba 2 [GaF 4 (IO 3 ) 2 ](IO 3 ) (63.35 MW cm −2 ) . We suggest that the novel 3D anionic framework is favorable to enhance the LIDT value.…”

“…Under laser‐generating radiation at 2.05 μm (Figure ), CsVO 2 F(IO 3 ) exhibits a strong SHG signal 1.1 times as intense as KTP (particle size 150–210 μm), which is type‐I phase‐matchable. It is obviously larger than those of α‐ and β‐Ba 2 [VO 2 F 2 (IO 3 ) 2 ](IO 3 ) (0.7 times that of KTP) and α‐ and β‐Ba 2 [GaF 4 (IO 3 ) 2 ](IO 3 ) (0.4 times that of KTP) measured under the same experimental conditions; all of them contain the 0D Λ‐shaped cis ‐[MO x F y (IO 3 ) 2 ] n − building units.…”

“…Dipole‐moment calculations yielded values of 14.410 and 6.923 D for the IO 3 and VO 5 F groups, respectively (Table S4). The net local dipole moment of CsVO 2 F(IO 3 ) is 28.224 D, while the dipole moment per unit cell is 0.05 D Å −3 , which is larger than those of α‐ and β‐Ba 2 [VO 2 F 2 (IO 3 ) 2 ](IO 3 ) (0.03 D Å −3 ) and α‐ and β‐Ba 2 [GaF 4 (IO 3 ) 2 ](IO 3 ) (0.04 D Å −3 ) . Hence, it is necessary to investigate the inherent mechanism of the SHG difference from a theoretical perspective.…”

From Ag2Zr(IO3)6 to LaZr(IO3)5F2: A Case of Constructing Wide‐band‐gap Birefringent Materials through Chemical Cosubstitution

“…[14,18,[37][38] Another effective strategy that has been widely recognized to realize wide band gap is to introduce F À into iodates, which has led to a series of F À -containing iodates with large band gaps, such as Bi(IO 3 )F 2 (3.97 eV), and α-Ba 2 [GaF 4 (IO 3 ) 2 ]IO 3 (4.61 eV). [19,39] The existence of F À can shorten the optical cutoff edge and even alter the birefringence property of iodate compounds. 39 Therefore, investigation in the fifth periodic d 0 À TM (Zr 4 + , Nb 5 + )containing iodates system can be very meaningful in exploring iodate crystals with wide band gap; further introducing F À into MÀ d 0 À TM (Zr 4 + , Nb 5 + )À IO 3 is very likely to enlarge the band gap of the iodate compounds.…”

Five New Silver Rare‐Earth Iodates, AgLn(IO3)4 (Ln=Pr, Sm, Dy, Er and Tm): Synthesis, Structures and Properties

“…However, the reported materials in deep‐ultraviolet (DUV) and mid and far‐infrared (MFIR) regions are unable to meet market requirements. Even though a variety of NLO materials have been developed in this regard, exploring new suitable NLO materials with NCS structures in these spectrum regions remains a major challenge, and it is also a hot topic in the field of inorganic solid state chemistry.…”