Designing a Deep-UV Nonlinear Optical Fluorooxosilicophosphate

Abstract

Structures composed of SiO x F6–x (x = 1, 2, 3, 4, 5) or SiO x F4–x (x = 1, 2, 3) species have thus far been observed in only a few compounds, and their functional properties are completely unknown in silicate chemistry. By introducing the least electronegative element, cesium, and the most electronegative element, fluorine, into the silicophosphate system, we successfully designed the first noncentrosymmetric fluorooxosilicophosphate with Si–F bonds, CsSiP2O7F, whose structure consists of an unprecedented SiP2O10F moiety containing hexacoordinate SiO5F species. The experimental results highlight CsSiP2O7F as the first fluorooxosilicophosphate deep-UV nonlinear optical (NLO) material. The first-principles calculations reveal that the SiP2O10F moiety is a new type of NLO-active unit and that both cesium and fluorine increase the deep-UV transparency of CsSiP2O7F. This work provides a new source of deep-UV NLO materials and insights into obtaining noncentrosymmetric structures that are indispensable to functional materials in nonlinear optics, piezoelectricity, ferroelectric, pyroelectricity, etc.

To improve the key properties of nonlinear optical crystals assembled with tetrahedral functional building units

“…Notably, this value is also comparable to those of several newly discovered bismuth- and/or lead-based NLO phosphates, namely, A 3 BBi(P 2 O 7 ) 3 (A = Rb, Cs; B = Pb, Ba) (Δ n = 0.025–0.03 at 1064 nm) which encompass highly distorted Bi–O and/or Pb–O polyhedra which easily induce an enhanced birefringence. 41 …”

“…Notably, this value is also comparable to those of several newly discovered bismuth-and/or lead-based NLO phosphates, namely, A 3 BBi(P 2 O 7 ) 3 (A ¼ Rb, Cs; B ¼ Pb, Ba) (Dn ¼ 0.025-0.03 at 1064 nm) which encompass highly distorted Bi-O and/or Pb-O polyhedra which easily induce an enhanced birefringence. 41 It seems necessary to discuss the possible mechanism of birefringence enhancement observed in ABAF and we inferred that [BO 3 F] tetrahedra are mainly responsible for this. As shown in Table 1 and Fig.…”

M(NH2SO3)2 (M=Sr, Ba): Two Deep‐Ultraviolet Transparent Sulfamates Exhibiting Strong Second Harmonic Generation Responses and Moderate Birefringence

“…As shown in Figure 4 c and d, both of them are phase‐matchable at 1064 and 532 nm based on the rule proposed by Kurtz and Perry [39] . The SHG responses of SNSO and BNSO are about 1.2 and 2.7 times that of the KDP, and about 0.32 and 0.73 times that of β‐BBO with the particle size of 150–212 μm, respectively, and are larger than most of DUV NLO phosphates and sulfates, such as KLa(PO 3 ) 4 (0.7 × KDP), [36] CsLa(PO 3 ) 4 (0.5 × KDP), [37] (NH 4 ) 2 PO 3 F (0.9 × KDP), [30] [C(NH 2 ) 3 ] 2 PO 3 F (1.0 × KDP), [30] Rb 2 Ba 3 (P 2 O 7 ) 2 (0.3 × KDP), [20] CsSiP 2 O 7 F (0.7 × KDP), [40] K 2 SrP 4 O 12 (0.5 × KDP), [38] (NH4) 2 Na 3 Li 9 (SO 4 ) 7 (0.5 × KDP) [25] and Li 8 NaRb 3 (SO 4 ) 6 ⋅2 H 2 O (0.5 × KDP) [41] . It is worth noting that the SHG response of BNSO is the largest among all of known DUV NLO sulfates and sulfamates, and is even comparable to the DUV NLO crystals containing π‐conjugated groups including M 2 B 10 O 14 F 6 (M=Ca, Sr) (2.3 and 2.5 × KDP), [42] γ‐Be 2 BO 3 F (2.3 × KDP) [43] and CsB 4 O 6 F (1.9 × KDP) [44] …”

Nonpolar Na 10 Cd(NO 3 ) 4 (SO 3 S) 4 Exhibits a Large Second-Harmonic Generation

“…19,20 Elemental substitution is a common but effective strategy to design novel NLO-active anionic groups and new NLO materials with enhanced SHG responses. For example, the substitution of oxygen by the much more electronegative fluorine gives rise to novel oxyfluoride NLO-active units, such as BO 3 F, [21][22][23] BO 2 F 2 , 24 PO 3 F, 25,26 as well as the emerging SO 3 F, 27 and SiO 5 F, 28 resulting in polar NLO materials, such as NH 4 B 4 O 6 F, 23 MB 5 O 7 F 3 (M = Ca and Sr), 21,22 (NH 4 ) 2 PO 3 F, 25,26 C(NH 2 ) 3 SO 3 F, 27 and CsSiP 2 O 7 F. 28 Recently, the substitution of oxygen by the less electronegative sulfur also led to several polar NLO materials, such as CaCoSO, 29 SrZn 2 S 2 O, 30 and Sr 6 Cd 2 Sb 6 O 7 S 10 . 31 In particular, Sr 6 Cd 2 Sb 6 O 7 S 10 exhibits a strong SHG response owing to the highly polarizable Sb/O/S groups.…”