Tunable Optical Anisotropy in Rare-Earth Borates with Flexible [BO 3 ] Clusters.

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 [BO 3 ] by adding rare-earth elements is one of the main areas of structural design study. Five new mixed-metal Y-based rare-earth borates, Ba 2 ZnY 2 (BO 3 ) 4 , KNa 2 Y(BO 3 ) 2 , Li 2 CsY 4 (BO 3 ) 5 , LiRb 2 Y(BO 3 ) 2 , and RbCaY(BO 3 ) 2 , have been discovered using the high-temperature solution approach. Isolated [BO 3 ] 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 [BO 3 ] 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.