Finding a Deep-UV Borate BaZnB4 O8 with Edge-sharing [BO4 ] Tetrahedra and Strong Optical Anisotropy

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

Achieving high luminescent quantum yield and thermal stability of phosphors simultaneously remains challenging, yet it is critical for facilitating high-power white light emitting diodes (WLEDs). Herein, we report the design and preparation of the layered structure BaZnB4O8:xEu3+ (0.10 ≤ x ≤ 0.60) red phosphors with high quantum yield (QY = 76.5%) and thermal stability (82.8%@150 °C) by the traditional solid-state reaction method. The results of XRD and Rietveld refinement show that the presence of Eu3+ ions at Ba2+ sites causes the formation of cation (Zn2+/Ba2+) vacancies in the lattice. The PL and PL decay results reveal that the quenching concentration of BZBO:xEu3+ phosphors is as high as 50%, and the lifetime remains unchanged with Eu3+ concentration due to the unique structure of the host and the cation vacancies generated by the heterovalent substitution. Furthermore, on a 395 nm near-UV chip, a pc-WLED device with exceptional optical performance (CCT = 4415 K, CRI = 92.1) was realized using the prepared BZBO:0.50Eu3+ as a red phosphor. Simple synthesis and excellent performance parameters suggest that the reported BaZnB4O8:xEu3+ phosphors have promising applications in high-power pc-WLEDs. At the same time, it also indicates that cationic vacancy engineering based on heterovalent ion substitution is a potential strategy for improving luminescence quantum yield and thermal quenching performance.

Recent Progress in Crystalline Borates with Edge-Sharing BO4 Tetrahedra

Crystalline borates have received great attention due to their various structures and wide applications. For a long time, the corner-sharing B-O unit is considered a basic rule in borate structural chemistry. The Dy₄B₆O₁₅ synthesized under high-pressure is the first oxoborate with edge-sharing [BO₄] tetrahedra, while the KZnB₃O₆ is the first ambient pressure borate with the edge-sharing [BO₄] tetrahedra. The edge-sharing connection modes greatly enrich the structural chemistry of borates and are expected to expand new applications in the future. In this review, we summarize the recent progress in crystalline borates with edge-sharing [BO₄] tetrahedra. We discuss the synthesis, fundamental building blocks, structural features, and possible applications of these edge-sharing borates. Finally, we also discuss the future perspectives in this field.

Discovery of SrZn2B6O12 with an unprecedented quadruple-layered configuration

A new borate, SrZn2B6O12, is found to show a quadruple-layered configuration. This rare quadruple-layer is stacked by two 2[Zn2B6O12]∞ double-layers that are constructed by two single-layers of 2[B4O7]∞ and 2[Zn2B2O4]∞.