K5B19O31: A Deep‐Ultraviolet Congruent Melting Compound

Abstract

A potassium borate, K 5 B 19 O 31 , has been obtained via the hightemperature solid-state reaction. The single crystal for K 5 B 19 O 31 with dimensions up to 4 mm × 2 mm × 1 mm was grown by the top-seeded solution growth method. The crystal structure of K 5 B 19 O 31 shows a complex three-dimensional (3D) frame filled by three different types of K-based polyhedra. Optical properties and thermal behavior of K 5 B 19 O 31 were carried out. The transmission spectrum of K 5 B 19 O 31 shows that it possesses a UV optical cut-off edge lower than 180 nm. The birefringence was calculated to be about 0.05 at 1064 nm. Structure-property relationships were further illuminated via the first-principles calculation methods.

Characteristic, electrical and optical properties of potassium borate (KB5O8·4H2O) hydrothermally synthesized from different boron sources

“…This result causes However, properties such as crystal structure and crystalline size have a significant effect on the band gap. The amount of metal cations in the borate structure causes UV shift of the absorption edge, and the amount of O atoms in the B-O unit is also known to improve the use of the material for UV region applications [23].…”

Topological Features of A+B2+[B5O9] Layered Pentaborates: Structural Changes in NaSr[B5O9] at High Temperatures or Why KCa[B5O9] Is Unstable?

“…The topological features of the borate layer in type I structures have been previously determined using the Top-osPro software. 32 Previously, using the cluster simplification where all [B 5 O 11 ] groups were regarded as a 4c or 5c node, the Schlafi symbol of the resulting 2D net was determined as 4 4 6 2 . 15 Here we use the standard simplification 33 for the description in which only the centers of the primary building units (PBUs) represented by boron atoms in triangular and tetrahedral environments are retained in the underlying net, while all other 2-connected atoms (oxygen ligands) and BO 3 groups are pulled into edges, acting as bridges between the PBUs.…”

“…., r n are the relative numbers of the corresponding rings in a graph of the net 34 ), which can be simplified as 3 1 7 1 to obtain a (3,4)connected 2D cationic net (Figure 5). An analysis of the geometrical characteristics of these (3,4)-connected nets shows that they are characterized by the individual topological features (different vertex symbols and symmetry) and represent different topological types. The borate layers in the crystal structures of NaCa, 7 NaSr, 8−10 NaPb, 11 NaBa, 12 and KBa-I 15 are unique and are characterized by the plane group p1 and layer group p1m1 (Figure 5a).…”

“…The monovalent metal borates exhibit the most diverse crystal chemistry among borates since most oxygen atoms in their structures are bridging . Such structures often show extremely complex boron–oxygen groups and interpenetrating frameworks. − The A + B 2+ [B 5 O 9 ] family of compounds (where A = Na, K; B = Ca, Sr, Ba, and Pb) are based on the corrugated layers 5: ∞ 2 [(5:3Δ + 2T)] with the pentaborate groups (fundamental building units, FBUs) with the following scheme: 5B:3Δ2□:<2Δ□>−<Δ2□>. This family includes seven borates, NaCa­[B 5 O 9 ], NaSr­[B 5 O 9 ], − NaPb­[B 5 O 9 ], NaBa­[B 5 O 9 ], KSr­[B 5 O 9 ], KPb­[B 5 O 9 ], and KBa­[B 5 O 9 ]. , Among them the NaSr­[B 5 O 9 ] matrix doped with REE 3+ ions has been studied in connection with the luminescent properties: NaSr­[B 5 O 9 ]:Dy 3+ , , NaSr­[B 5 O 9 ]:Tb 3+ , , NaSr­[B 5 O 9 ]:Sm 3+ , and NaSr­[B 5 O 9 ]:Eu 3+ .…”

Bi2[B2(SeO3)6]: A Metal Boroselenite with a Unique Zero-Dimensional [B2(SeO3)6]6– Anionic Group and Large Birefringence

“…On the basis of the basic anionic building blocks (BO 3 3– , BO 4 5– , etc. ), many borate compounds with diverse anionic skeletons have been developed including Eu 9 MgS 2 B 20 O 41 , β-CsB 9 O 14 , Li 4 Na 2 CsB 7 O 14 , and K 5 B 19 O 31 . − In recent years, in order to widen the band gap and obtain new kinds of borates, introducing the largest-electronegativity F atoms is a fruitful method, which was proven by AB 4 O 6 F (A = NH 4 , Na, Rb, and Cs), BaB 8 O 12 F 2 , PbB 5 O 8 F, MB 5 O 7 F 3 (M = Ca and Sr), KBe 2 BO 3 F 2 (KBBF), and crystals in the KBBF family. − …”