BaB₂O₃F₂: A Barium Fluorooxoborate with a Unique [B₂O₃F]⁻ Layer and Short Cutoff Edge

Abstract

Substitution of oxygen by fluorine in the borate group offers am aterials platform from which intriguing structure and functionality may arise. Herein,w er eport a new fluorooxoborate, BaB 2 O 3 F 2 ,s ynthesized by introducing the Fa toms into the BaO-B 2 O 3 system.B aB 2 O 3 F 2 exhibits au nique oxyfluoride layer 2 1 [B 2 O 3 F] À and ad eep-ultraviolet cutoff edge below 180 nm. The effect of the introduction of Fatoms on the structure ando ptical property of the borateg roup has been investigated;t his should be useful to furthere xpand borate chemistry and materials.Borates have attracted extensive research interests due to their tremendousp erformances and practical applicationsi nm any fields. [1, 2] Generally,b oron can coordinate to three or four O atoms forming triangular[ BO 3 ] 3À and tetrahedral [BO 4 ] 5À units, respectively,a nd these units share commonc orners or edges formingv ariousf undamentalb uildingb locks (FBBs). [3] These FBBs can exist as isolated (0D) groups or connect with each other forming different kinds of 1D chains, 2D layers,o r3 D networks, which finally lead to the diverses tructures of more than 2000 borates. Owingt ot he excellent optical properties of metal borates, they are widely used as ultraviolet (UV) and deep-UVn onlinear optical (NLO) materials, as well as birefringent crystals. [4] Today,t he introductiono fFa toms into borates offers an ew materials platform from which intriguing structures and functionalities may arise. In fluorooxoborates, the F atoms are coordinated with the Ba toms, and the borate unit [BO 4 ] 5À is extended to the oxyfluoride units [BO 3 F] 4À ,[ BO 2 F 2 ] 3À , and [BOF 3 ] 2À ,w hich can generate even more unprecedented FBBs and novel structures. [5] Since the physicalp roperties were determined by structures, the effect of O/F substitution on the physicalp roperties of borate is also significant. Generally, the Oa tom can bond to 1-4 Ba toms, whereas the Fatom is at ypical terminal atom that can only bond to lessBa toms. [6] Therefore, the incorporationo fFin the borate could break down the 3D B-O frameworks and increase the probability of layer structures, which is beneficial to optical anisotropies [7] Thus fluorooxoborates are feasible candidates fort he exploration of birefringent materials. [8] Also, after partial O/Fs ubstitution, the symmetry of the [BO 4 ] 5À tetrahedron will be reduced leading to ag reater proportion of noncentrosymmetric (NCS) structures that are prerequisites for second-order NLOm aterials. In combination with the first principles analysis, in our previous work ad esign strategy for NLO materials by using oxyfluoride groups in borates has been proposed, and aseries of NCS fluorooxoborates with excellent NLO properties were synthesized. [9] However,f luorooxoboratesa re quite rare. Unlike borates, the structural chemistry of which has been well developed on the basis of the great abundance of borate compounds, fluorooxoborates are far from fully explored.It is noticed that the modification of the crystal st...

α-, β-Pb4B2O7 and α-, β-Pb4B6O13: Polymorphism drives changes in structure and performance

“…The IR spectra of α-Pb 4 B 2 O 7 and β-Pb 4 B 6 O 13 are shown in Fig. S4 ) were both observed [60,61]. This result also matches pretty well with the crystal structure analysis.…”

Ba3(BO3)(CO3)F: The First Borate Carbonate Fluoride Synthesized by the High‐Temperature Solution Method

“…In recent years, the structural chemistry of inorganic crystals has been significantly extended by the incorporation of more anion units, such as [BO 3 ] 3− , [BO 4 ] 5− , [CO 3 ] 2− , [PO 4 ] 3− , [NO 3 ] − , and [SiO 4 ] 4− , etc., which results in various kinds of mixed multiple‐anions compounds, like borate carbonate, borate phosphate, phosphate nitrate, and phosphate silicate, etc. In addition, chemists and material scientists found that the introduction of F atoms with large electronegativity into the crystals can harmonize the ratio of anions and cations to make the crystal structures more flexible and variable [23–25] . Up to now, a series of unique structures of F‐containing borates or carbonate have been reported, some of which have been reported exhibiting novel structure frameworks and excellent functional performances.…”

Prediction of Fluorooxoborates with Colossal Second Harmonic Generation (SHG) Coefficients and Extremely Wide Band Gaps: Towards Modulating Properties by Tuning the BO3/BO3F Ratio in Layers

“…[41] All of the predicted new structures possess very wide band gaps (8. One of the structures with the P2 1 space group (BaB 2 O 3 F 2 -I) has been experimentally synthesized very recently.…”

“…One of the structures with the P2 1 space group (BaB 2 O 3 F 2 -I) has been experimentally synthesized very recently. [41] All of the predicted new structures possess very wide band gaps 3 Fgroup and have colossal SHG coefficients (ca. 4 KDP) that give the direct evidence that the BO 3 F group could generate large SHG effect.…”

“…[29,30] What confirms the reliability of the method we used is that one of the predicted structure BaB 2 O 3 F 2 -I has recently been synthesized experimentally. [41] All of the predicted structures possess very wide band gaps (8.1-9.0 eV). BaB 2 O 3 F 2 (II-V) exhibit large SHG coefficients (> 3 KDP, d 36 = 0.39 pm V À1 ).…”