Tunable Optical Anisotropy in Rare‐Earth Borates with Flexible [BO₃] Clusters

Abstract

Borates have garnered a lot of attention in the realm of solid‐state chemistry due to their remarkable characteristics, in which the synthesis of borates with isolated [BO3] by adding rare‐earth elements is one of the main areas of structural design study. Five new mixed‐metal Y‐based rare‐earth borates, Ba2ZnY2(BO3)4, KNa2Y(BO3)2, Li2CsY4(BO3)5, LiRb2Y(BO3)2, and RbCaY(BO3)2, have been discovered using the high‐temperature solution approach. Isolated [BO3] clusters arranged in various configurations comprise their entire anionic framework, allowing for optical anisotropy tuning between 0.024 and 0.081 under 1064 nm. In this study, we characterize the relative placements of their [BO3] groups and examine how their structure affects their characteristics. The origin of their considerable optical anisotropy has been proven theoretically. This study unequivocally demonstrates that even a slight alteration to borates' anionic structure can result in a significant improvement in performance.

A Rare-Earth-Based Borate Optical Crystal with Enlarged Dihedral Angles of Distinct [BO3] Groups Exhibiting a Wide UV Transparent Range

“…14), different from that observed in KNa 2 YB 2 O 6 , which adopt the orthorhombic Pnma (no. 62) . The title compound features lattice parameters a = 6.8971(8) Å, b = 10.8814(10) Å, c = 8.7771(10) Å and Z = 4.…”

“…The valence electrons of the K 2 NaYB 2 O 6 compound, namely, K 3p 6 4s 1 , Na 2p 6 3s 1 , Y 4d 1 5s 2 , B 2s 2 2p 1 , and O 2s 2 2p 4 , were considered in the orbital electron analyses. An energy cutoff of 750 eV was implemented for the plane-wave calculations, while a Monkhorst–Pack point mesh of dimensions of 4 × 3 × 2 was utilized for a rigorous integration over the Brillouin zone . Additionally, the calculated electronic transitions were used to determine the theoretical refractive index of K 2 NaYB 2 O 6.…”