(NH₄)Bi₂(IO₃)₂F₅: An Unusual Ammonium‐Containing Metal Iodate Fluoride Showing Strong Second Harmonic Generation Response and Thermochromic Behavior

Abstract

An ammonium‐containing metal iodate fluoride compound, (NH4)Bi2(IO3)2F5, featuring a two‐dimensional double‐layered framework constructed by [BiO2F5]6− and [BiO4F4]9− polyhedra, as well as [IO3]− groups, was successfully synthesized. The well‐ordered alignment of these SHG‐active units leads to an extraordinary strong SHG response of 9.2 times that of KDP. Moreover, this compound possesses a large birefringence (Δn=0.0690 at 589.3 nm), a wide energy band gap (Eg=3.88 eV), and a high laser damage threshold (LDT; 40.2×AgGaS2). In particular, thermochromic behavior was observed for the first time in this type of compound. Such multifunctional crystals will expand the application of nonlinear optical materials.

[GaF(H2O)][IO3F]: a promising NLO material obtained by anisotropic polycation substitution

“…[1][2][3][4][5][6][7][8][9][10] Because of the absence of the lasers emitting mid-infrared (IR) (3-12 mm) light that has great advantages in the elds of spectroscopy analysis, laser surgery, laser communications, etc., NLO materials used for mid-IR generation are increasingly attractive. [11][12][13] However, currently commercialized mid-IR NLO crystals, such as AgGaS 2 (AGS), AgGaSe 2 and ZnGeP 2 , [14][15][16] have been heavily restricted by their relatively smaller band gaps which can always result in harmful two-photon absorptions and lower laser-induced damage thresholds (LDTs). 6,[17][18][19][20] Consequently, it is still urgent to explore mid-IR NLO material with improved band gap (or LDT) and great comprehensive properties.…”

“…, NLO materials used for mid-IR generation are increasingly attractive. 11–13 However, currently commercialized mid-IR NLO crystals, such as AgGaS 2 (AGS), AgGaSe 2 and ZnGeP 2 , 14–16 have been heavily restricted by their relatively smaller band gaps which can always result in harmful two-photon absorptions and lower laser-induced damage thresholds (LDTs). 6,17–20 Consequently, it is still urgent to explore mid-IR NLO material with improved band gap (or LDT) and great comprehensive properties.…”

KCs2[Pb2Br5(HCOO)2]: A Polar 3D Lead‐Bromide Framework Exhibiting Strong Second‐Harmonic Generation Response

“…KCs 2 [Pb 2 Br 5 (HCOO) 2 ] has an indirect band gap with valence band maximum (VBM) located at the Y point (−0.5 0 0) and conductive band minimum (CBM) located at the point (−0.4 0.5 0) between S and X point (Figure S11). The calculated band gap of KCs 2 [Pb 2 Br 5 (HCOO) 2 ] is 2.95 eV, which is slightly smaller than the experimental value (3.23 eV) due to the discontinuity of the PBE exchange‐correlation energy [21] . It is well known that optical properties mainly come from the electron transition between the top of the valence bands (VBs) and the bottom of the conduction bands (CBs).…”

“…The calculated band gap of KCs 2 [Pb 2 Br 5 (HCOO) 2 ] is 2.95 eV, which is slightly smaller than the experimental value (3.23 eV) due to the discontinuity of the PBE exchangecorrelation energy. [21] It is well known that optical properties mainly come from the electron transition between the top of the valence bands (VBs) and the bottom of the conduction bands (CBs). Therefore, the total density of states (TDOS) and the partial density of states (PDOS) of KCs 2 [Pb 2 Br 5 (HCOO) 2 ] in these regions are analyzed.…”

Helix-constructed polar rare-earth iodate fluoride as a laser nonlinear optical multifunctional material

“…In recent years, metal iodate fluorides have become a research hotspot. Several metal iodate fluoride NLO crystals have been reported, mainly including Bi(IO 3 )F 2 , 5 Bi 3 OF 3 (IO 3 ) 4 , 6 ABi 2 (IO 3 ) 2 F 5 (A = K, Rb, Cs, NH 4 ), 7 β-Ba[VFO 2 (IO 3 ) 2 ], 8 α/β-Ba 2 [VO 2 F 2 (IO 3 ) 2 ]IO 3 , 8 α/β-Ba 2 [GaF 4 (IO 3 ) 2 ](IO 3 ), 9 K 5 (W 3 O 9 F 4 )(IO 3 ), 10 CsVO 2 F(IO 3 ), 11 Ce(IO 3 ) 2 F 2 ·H 2 O, 12 Sn(IO 3 ) 2 F 2 , 13 etc. These metal iodate fluoride NLO crystals generally exhibit a wide transparent range covering the visible to mid-IR region, large SHG effects, and a high laser damage threshold (LDT).…”