Introducing a New d⁰ Sc³⁺ Asymmetric Ion for Functional Materials: Large Birefringence Enhancement by ScO₆ in Ba₃Sc₂(BO₃)₄

Abstract

Transition metal ions with d 0 electronic states (Ti 4 + , Zr 4 + , Nb 5 + and Ta 5 + ) are widely investigated as functional materials. This work first illustrates that Sc 3 + ion, long-time ignored, displays a second-order Jahn-Teller (SOJT) effect similar to asymmetric oxide-coordinated transition metal ions, thus providing a new ground to seek for asymmetric functional materials with enhanced performances. In Ba 3 Sc 2 (BO 3 ) 4 , BO 3 groups are parallelly arranged, satisfying the ideal arrangement to produce large birefringence. Importantly, distorted octahedral ScO 6 with Sc 3 + ion in its d 0 electronic state enlarges birefringence unexpectedly up to 0.149 @ 550 nm, which is larger than previously reported borates containing solely BO 3 , even to B 3 O 6 units. Subsequently, the SOJT influence of distorted ScO 6 octahedra on birefringence is verified by a comparison between experimental data and theoretical calculations. In addition, Ba 3 Sc 2 (BO 3 ) 4 also displays a high transmittance in the range of 230 nm-3.5 μm with a UV cut-off wavelength at 198 nm and a large laser induced damage threshold (2.7 GW/cm 2 ), comparable to α-BaB 2 O 4 . Above characteristics imply that the title compound may be a promising birefringent material.

Atomic Substitution to Tune ScO6 Distortion in Ba2MSc2(BO3)4 (M = Na, K, Ba) to Acquire a Large Birefringence

“…All values for bond distances and bond angles are consistent with the previously reported values (Tables S3–6), and the calculated bond valence sums for Ba, Sc, B, and O atoms also match well with their typical oxidation states (Tables S9 and 10). Nevertheless, the BVS values of Na and K atoms in Ba 2 K 1.6 Na 0.4 Sc 2 (BO 3 ) 4 and Ba1 in α-Ba 3 Sc 2 (BO 3 ) 4 show the deviations from their ideal values, which are similar to those for the previously reported compounds, Ba 3 Y­(BO 3 ) 3 and β-Ba 3 Sc 2 (BO 3 ) 4 . , …”

“…Nevertheless, the BVS values of Na and K atoms in Ba 2 K 1.6 Na 0.4 Sc 2 (BO 3 ) 4 and Ba1 in α-Ba 3 Sc 2 (BO 3 ) 4 show the deviations from their ideal values, which are similar to those for the previously reported compounds, Ba 3 Y(BO 3 ) 3 and β-Ba 3 Sc 2 (BO 3 ) 4 . 43,57 As seen in Figure 2, the structures of both compounds can be considered as stacking of [Sc(BO 3 ) 2 ] ∞ layers constructed by planar π-conjugated BO 3 units and ScO 6 octahedra along the c direction, whereas cations (Na + , K + , Ba 2+ ) reside in the interlayer. The BO 3 groups exhibit C 3v high symmetry with equal B−O bonds and angles, and, thus, BO 3 groups are almost 2b).…”

“…In ASc­(SeO 3 ) 2 (A = Na, K, Rb, and Cs), the magnitudes of ScO 6 distortion (Δ d ) are 0.08, 0.19, 0.06, and 0.18, respectively . In 2022, our group discovered a preferred-oriented layered β-Ba 3 Sc 2 (BO 3 ) 4 crystal (low-temperature phase) with severely distorted ScO 6 octahedra (Sc–O bond: 2.008(4)–2.201(3) Å) . The contribution to the birefringence (about 0.05), originating from distorted ScO 6 octahedra, provides a promising idea to build the bridge between ScO 6 octahedra and local asymmetric functional units.…”

Co-substitution design: a new glaserite-type rare-earth phosphate K2RbSc(PO4)2 with high structural tolerance

“…The peaks located at 637 and 600 cm −1 can be attributed to P–O asymmetric bending vibrations [ v 4 (F2)]. 65–67 The peaks at 758 and 696 cm −1 can be characterized as the Sc–O stretching mode. 68 Moreover, there are obvious absorption peaks in the range of 2361–1651 cm −1 in the IR spectra, which can be interpreted as O–H vibrations from H 2 O.…”

Thermodynamic parameters of phenylglycine interaction with UO22+, La3+ and Zr4+

“…As a result, the large value of La3 + 's radius in compared to the other investigated metal ions is responsible for its less stable complexes than those of the other transition metals [ 24 , 25 ]. The greater ratio of (valence/radius) and the Jahn–Teller effect lead to the conclusion that Zr 4+ complexes are more reliable than those for other metal ions complexes [ 26 – 28 ].…”