(NH4)3B11PO19F3: a deep-UV nonlinear optical crystal with unique [B5PO10F]∞ layers

Abstract

Deep-ultraviolet (DUV) nonlinear optical (NLO) crystals that can extend the output range of coherent light below 200 nm are pivotal materials for solid-state lasers. To date, KBe2BO3F2 (KBBF) is the only usable crystal that can generate DUV coherent light by the direct second harmonic generation (SHG), but the layered growth habit and toxic ingredients limit its application. Herein, we report a new fluoroborophosphate (NH4)3B11PO19F3 (ABPF) containing four different functional units-[BO3], [BO4], [BO3F] and [PO4]. ABPF exhibits a KBBF-like structure while eliminating the limitations of KBBF crystal. The unique [B5PO10F]∞ layers help ABPF exhibit excellent performances, such as a large SHG response (1.2 × KDP) and a sufficient birefringence (0.088 at 1064 nm) that enables the shortest phase-matching wavelength (190 nm) to the DUV region. Meanwhile, the introduction of strong B-O-P covalent bonds decreases the layered growth habit. These findings will enrich the structural chemistry of fluoroborophosphate and contribute to the discovery of more excellent DUV NLO crystals.

NaK5Zn2(B5O10)2 and β-K3ZnB5O10: Two Zincoborates with Deep-UV Cutoff Edge

“…The bond valence of O atoms is in the range of 1.5−2.0 e and it is greater than that of O atoms on the isolated [BO 3 ] unit based on the charge-transfer model and Mulliken analysis (Figure S4). 58,59 It confirms that the introduction of strong covalent [ZnO 4 ] units is beneficial to the elimination of dangling bond, 60,61 thus S9. About 90% of 39 borates containing [ZnO 4 ] units are isolated B−O clusters, which is significantly higher than the proportion of 0D borates (65.5%).…”

NaB3O4F(OH): A Hydroxyfluorooxoborate with One-Dimensional Chain Featuring Large Birefringence and Short Ultraviolet Cutoff Edge

“…A lot of fluorooxoborates with high performances were found in past years, including MB 4 O 6 F (M = NH 4 , Na, Rb, Cs), MB 5 O 7 F 3 (M = Mg, Ca, Sr), M 2 B 6 O 9 F 2 (M = Li, Na), PbB 5 O 8 F, RbB 3 O 4 F 2 , BaB 4 O 5 F 4 , MM’B 3 O 4 F 3 (M = Rb, K; M’ = Cs, K, Na), etc. Most of them are potential deep-ultraviolet (DUV) nonlinear optical (NLO) or birefringent crystals. , …”

Difluoro(oxalato)borates as Short-Wavelength Optical Crystals with Bifunctional [BF2C2O4] Units

“…40 Among them, especially, the introduction of π-conjugated units will bring gain to generalized birefringence and NLO coefficients, as evidenced by representative structures in optimal arrangement, 41,42 such as the discovery of (NH 4 ) 2 B 4 SO 10 and (NH 4 ) 3 B 11 PO 19 F 3 , in which the π-conjugated [BO 3 ] units push the phase-matching (PM) wavelengths of borosulfates and fluoroborophosphates to new heights. 33,35 In the above two multiple anion compounds, the bifunctional units [B 4 SO 12 O 4 ] units by sharing the edges. Thus, in the above two systems, the preliminary goal of introducing additional π-conjugated units in the B−O anionic skeleton is naturally achieved.…”

“…B–O units and P–O units share O atoms to form multiple B–P–O anions in borophosphates, whereas they arrange in the lattice separately from each other in the borate-phosphates. Nowadays, boron-based compounds with multiple anionic units have been found and reported in other systems, like borosilicates (B–O + Si–O), , borophosphates (B–O + P–O), , borosulfates (B–O + S–O), − and borogermanates (B–O + Ge–O), , etc., in which short-wavelength UV NLO and birefringent crystals have been screened out as future optical materials. In addition, design strategies represented by chemical substitution-oriented design accelerate the discovery of new UV optical materials .…”

“…In addition, design strategies represented by chemical substitution-oriented design accelerate the discovery of new UV optical materials . Among them, especially, the introduction of π-conjugated units will bring gain to generalized birefringence and NLO coefficients, as evidenced by representative structures in optimal arrangement, , such as the discovery of (NH 4 ) 2 B 4 SO 10 and (NH 4 ) 3 B 11 PO 19 F 3 , in which the π-conjugated [BO 3 ] units push the phase-matching (PM) wavelengths of borosulfates and fluoroborophosphates to new heights. , In the above two multiple anion compounds, the bifunctional units [B 4 SO 12 ] ([BO 4 ] + [SO 4 ] + [BO 3 ]) and [B 5 PO 14 F] ([BO 3 F] + [BO 4 ] + [PO 4 ] + [BO 3 ]) constructed by both π- and non-π-conjugated units are responsible for the balanced optical properties. Other π-conjugated units, such as [CO 3 ], [NO 3 ], and [H x C 3 N 3 O 3 ] ( x = 0–2) units, can also show identical positive roles on increasing the birefringence and/or NLO coefficients. − Unfortunately, the assembly of B–O units and π-conjugated [CO 3 ]/[NO 3 ] units can only lead to the formation of borate-carbonates and borate-nitrates. , That is to say, the incorporations of [CO 3 ]/[NO 3 ] units with B–O units fail to form B–C–O or B–N–O multiple anions via a O atom-sharing mode.…”