UV Solar‐Blind‐Region Phase‐Matchable Optical Nonlinearity and Anisotropy in a π‐Conjugated Cation‐Containing Phosphate

Abstract

Wide ultraviolet (UV) transparency, strong second‐harmonic generation (SHG) response, and sufficient optical birefringence for phase‐matching (PM) at short SHG wavelengths are vital for practical UV nonlinear optical (NLO) materials. However, simultaneously optimizing these properties is a major challenge, particularly for metal phosphates. Herein, we report a non‐traditional π‐conjugated cation‐based UV NLO phosphate [C(NH2)3]6(PO4)2⋅3 H2O (GPO) with a short UV cutoff edge. GPO is SHG active at 1064 nm (3.8 × KH2PO4 @ 1064 nm) and 532 nm (0.3 × β‐BaB2O4 @ 532 nm) and also possesses a significant birefringence (0.078 @ 546 nm) with a band gap >6.0 eV. The PM SHG capability of GPO can extend to 250 nm, indicating GPO is a promising UV solar‐blind NLO material. Calculations and crystal structure analysis show that the rare coexistence of wide UV transparency, large SHG response, and optical anisotropy is due to the introduction of π‐conjugated cations [C(NH2)3]+ and their favorable arrangement with [PO4]3− anions.

[o‐C5H4NHOH]2[I7O18(OH)]⋅3 H2O: An Organic–Inorganic Hybrid SHG Material Featuring an [I7O18(OH)] Branched Polyiodate Chain

“…The organic–inorganic hybrid SHG materials can combine the excellent properties of inorganic groups and the structural diversities of organic groups [25] such as (C 5 H 6 ON) + (H 2 PO 4 ) − [26] and [C(NH 2 ) 3 ] 6 (PO 4 ) 2 ⋅3 H 2 O [27] reported recently. Up to now, there has been only one organic–inorganic hybrid SHG polyiodate, namely, (C 6 H 16 N 2 O 2 )(IO 3 )(I 2 O 5 OH), been reported [25] .…”

A Congruent‐Melting Mid‐Infrared Nonlinear Optical Vanadate Exhibiting Strong Second‐Harmonic Generation

“…[9] In comparison with non-oxides such as chalcogenides and pnictides, [10] traditional metal oxide NLO candidates (e.g. borates, [11] nitrates, [12] carbonates, [13] phosphates 14 )u sually exhibit wider optical band gaps,higher LIDTs,and increased ease of single crystal growth, but their IR absorption edges do not reach 5 mm. [15] An emerging effective approach for developing mid-IR NLO materials is to introduce relatively heavy elements [16] such as d 0 transition metal (d 0 -TM) cations (e.g.T i 4+ ,Z r 4+ , W 6+ ,M o 6+ ) [17] and stereochemically active lone-pair cations (e.g.…”

Unprecedented boat-shaped [Mo2O5(IO3)4]2− polyanions induced a strong second harmonic generation response

“…Recently, the introduction of organic cation groups with structural diversities into material systems with inorganic anion groups has produced many superior organic–inorganic hybrid NLO materials, such as C(NH 2 ) 3 ClO 4 (3 × KDP), 40 [C(NH 2 ) 3 ] 6 (PO 4 ) 2 ·3H 2 O (3.8 × KDP) 41 and (C 5 H 6 ON) + (H 2 PO 4 ) − (3 × KDP) etc. 42 To our knowledge, only one case of an organic–inorganic hybrid NLO iodate has been studied, that is [ o -C 5 H 4 NHOH] 2 [I 7 O 18 (OH)]·3H 2 O (8.5 × KDP).…”

“…The absorption bands and peaks appearing at wavenumbers of 3187–3144, 1674 and 1127 cm −1 can be assigned to the O–H, N–H and C–N, and the absorption peaks at 804–952 and 474–726 cm −1 are ascribed to the vibration of Mo–O and I–O, which are in accordance with other previously reported compounds. 19,41…”