Finding a Deep‐UV Borate BaZnB₄O₈ with Edge‐sharing [BO₄] Tetrahedra and Strong Optical Anisotropy

Abstract

The polarization modulation of deep‐UV light is an important process that incorporates functionality to selectively respond to light‐mater interaction. Typically, optical anisotropy is foremost to the use efficiency of deep‐UV birefringent crystals. Herein, a new congruently melting polyborate with extremely large birefringence (Δn(001)=0.14@589.3 nm) and band gap (6.89 eV) is discovered as a high performance birefringent crystal, which breaks the current deadlock of deep‐UV polyborates that usually show small birefringence. The rigid tetrahedra, including [ZnO4] and edge‐sharing [BO4] tetrahedra, make all the planar [BO3] triangles in the lattice adopt preferential arrangement and thereby lead to an extraordinary large birefringence that is larger than all the deep‐UV borates with experimentally measured values. Structural analyses with the additional theoretical calculations were used to study the origin of strong optical anisotropy in BaZnB4O8.

Cation vacancy-boosted BaZnB4O8:xEu3+ phosphors with high quantum yield and thermal stability for pc-WLEDs

“…The unit cell of BZBO (CCDC#2206525) is classified as the P 1̄ space group of the triclinic system and the structure is composed of a two-dimensional 2 [ZnB 4 O 8 ] ∞ double-layer configuration separated by Ba 2+ ions. 43 The BO 3 triangle and BO 4 tetrahedron serve as two coordination environments for B atoms in this structure. The BO 3 triangle and BO 4 tetrahedron form B 3 O 6 and B 6 O 12 clusters by sharing vertices or edges.…”

“…The pure BZBO host and BZBO: x Eu 3+ (0.10 ≤ x ≤ 0.60) phosphors were prepared by the solid-state reaction method reported in the literature. 43 In a typical preparation of the BZBO host, BaCO 3 (0.7894 g, 4 mmol), ZnO (0.3256 g, 4 mmol) and B 2 O 3 (0.5570 g, 8 mmol) were weighed and sufficiently ground to homogeneous samples in an agate mortar. And then they were pressed into cylindrical pieces and placed in covered ceramic crucibles.…”

“…BaZnB 4 O 8 consists of a two-dimensional 2 [ZnB 4 O 8 ] ∞ double-layer configuration separated by Ba 2+ ions and is classified as the P 1̄ space group of the triclinic system. 43 The Ba 2+ sites in the lattice provide suitable crystal substitution points for Eu 3+ ions and the photoluminescence properties of Eu 3+ in this crystal are still unknown.…”

Zn(C6H4NO2)2·4H2O: A Solar-Blind Birefringent Crystal

“…14 Similarly, Pan's group employed a strategy involving rigid tetrahedron-induced planar triangular anion prioritization to synthesize deep ultraviolet borate BaZnB 4 O 8 , achieving a breakthrough birefringence value of 0.14@589.3 nm within the same category. 15 Both studies underscore that the design of crystal structures holds promise as an effective approach for preparing large-scale birefringent crystals.…”

C10H6NO2Cd(NO3)·2H2O: a birefringent crystal with an enlarged band-gap derived from covalent edge-sharing connection

“…In addition, one team broke the ultraviolet cut-off limit of zinc-borate through the edge-sharing connection of the [BO 4 ] tetrahedron (6.89 eV). 18,19…”