From β-KBOF to α-KBOF: Phase Transition-Directed Great Changes in Structure and Optical Anisotropy.

Herein, a new fluorooxoborate α-KBOF is synthesized successfully in a closed system. It crystallizes in the 2/ space group and features the rare one-dimensional (1D) zigzag [BOF] chains built by fundamental building blocks (FBBs) [BOF]. To the best of our knowledge, KBOF is a unique example of inorganic anhydrous borate whose two polymorphs show 1D B-O/F chains constructed by different FBBs but the same symmetry operation.

LiNaBSO: A Deep-UV Transparent Borosulfate with Moderate Birefringence Derived from the [BSO] Infinite Chain Designed by the High Boron-to-Sulfur Ratio Strategy.

The first mixed alkali metal borosulfate compound, LiNaBSO (LNBSO), which contains [BO] groups, was designed and synthesized by using a high boron-to-sulfur ratio strategy through the high temperature solution method. LNBSO exhibits a birefringence of 0.057@546.

(C(NH))(IOF)(IO)(HO) and C(NH)IOF: Two Guanidine Fluorooxoiodates with Wide Band Gap and Large Birefringence.

Enhancing anisotropy through an effective synergistic arrangement of anionic and cationic groups is crucial for improving the birefringence optical properties of materials. In this work, by transforming I-O into I-F through the fluorination strategy, two metal-free guanidine fluorooxoiodates (C(NH))(IOF)(IO)(HO) and C(NH)IOF and one guanidine iodate C(NH)IO were successfully synthesized using the hydrothermal method. An unprecedented dimer [IOF] formed by [IOF] and [IO] in (C(NH))(IOF)(IO)(HO) was found, which greatly enriches the structural diversity of fluorooxoiodates.

ZnIOF: Zinc Iodate Fluoride with Large Birefringence and Wide Band Gap.

The first zinc iodate fluoride, ZnIOF, was synthesized by the Zn cation, the IO group, and fluorine ion, where Zn is coordinated by O atoms from iodate and F atoms to form the ZnOF polyhedron. It has outstanding optical characteristics, including large birefringence (Δ = 0.219 at 546 nm), wide band gap ( = 4.

Ba(BOF(OH)) with well-ordered OH/F anions and a unique BOF(OH) dimer.

In minerals and artificial crystals, the OH and F groups often coexist and have a high probability of disordered structure. The OH/F position cannot be determined accurately in the crystal structure only by the direct X-ray diffraction method because of the poor contrast between O and F and the weak diffractivity of hydrogen atoms. In this work, a new fluorooxoborate Ba[B2OF3(OH)2]2, with a size of up to 12 × 4 × 3 mm3, has been synthesized successfully by a facile hydrothermal reaction.