YSO₄F·H₂O: A Deep-Ultraviolet Birefringent Rare-Earth Sulfate Fluoride with Enhanced Birefringence Induced by Fluorinated Y-Centered Polyhedra

Abstract

Birefringent crystals can modulate and detect the polarization of light and are important optical functional materials. The birefringence is positively correlated to the anisotropy of the structure. By partially substituting sulfate anion with large electronegative fluorine in the parent compound Y 2 (SO 4 ) 3 •8H 2 O, a new fluorinated rare-earth sulfate YSO 4 F•H 2 O with enhanced anisotropy was achieved. YSO 4 F•H 2 O features a dense 3D structure constructed by the polarizable [YOF] polyhedra and [SO 4 ]tetrahedra. The diffuse reflectance spectrum reveals that it has a short UV absorption edge of below 200 nm. The substitution of the F − ion enhances the optical anisotropy, making the material exhibit an enhanced birefringence (0.0357 at 546 nm), which is 5.1 times that of the parent compound and is also larger than most deep-UV birefringent sulfates. It is expected that this work may shed useful insights in the exploration of deep-UV birefringent materials with enhanced optical performances..

Centrosymmetric CaBaMF8 and Noncentrosymmetric Li2CaMF8 (M = Zr, Hf): Dimension Variation and Nonlinear Optical Activity Resulting from an Isovalent Cation Substitution-Oriented Design

“…Compounds with a short ultraviolet (UV) cutoff edge play an increasingly crucial role in scientific and technological applications for the capacity of providing short, strong, efficient, and stable laser sources. − To obtain NLO materials with short wavelengths, the selection of chemical elements is of great importance. Alkali/alkaline earth (A/AE) elements averting the d–d/f–f electron transition have long-term been recognized as powerful elements for a large band gap .…”

NaK5La2(SO4)6: Enhanced Birefringence of Multiple-Alkali Metal Sulfate Systems via Rare Earth Metal-Centered Polyhedra

“…In current research, various birefringent active functional groups have been discovered, including π-conjugated groups (NO 3 , CO 3 , B 3 O 6 , C 3 N 3 O 3 , and BO 3 ) − and non-π-conjugated groups [SO 4 ]. − Compared to π-conjugated basic building blocks, non-π-conjugated units (such as the [SO 4 ] unit) offer the advantage of a larger band gap, making sulfate an effective candidate for optical materials. Alkali metal sulfates are known for their excellent UV transparency, making them ideal candidates for deep UV transmission.…”

Thermochemistry, Structure, and Optical Properties of a New β-La2(SO4)3 Polymorphic Modification

“…The sulfates of rare earths are perhaps the most frequently studied group of inorganic complex compounds due to their wide range of applications [14][15][16][17][18][19][20][21]. The thermodynamic properties of these compounds occupy an important position in various hydrometallurgical processes for REE production [22].…”