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Borates have emerged as a significant resource for exploring birefringent materials in the UV frequency region. The π‐conjugated planar anions, such as the [BO3], [B2O5], and [B3O6] units, exhibiting strong polarizability anisotropy, are traditionally good structural models. Both fluorination and hydroxylation have been proven effective strategies to modulate the optical properties of the planar anions. Controlling the ratio between F and OH is the key to realizing a balanced performance between birefringence and bandgap. Based on a fluorination mechanism proposed recently, a novel hydroxyfluorooxoborate (C3N2H5)B3O3F2(OH)2 with an optimal F/OH ratio of 1/1 is synthesized. During the synthesis, another strategy known as “cation activation” is also employed, which further increases birefringence by introducing active cation units. With its superior performance, this compound exhibits a short UV cutoff edge at 214 nm and a substantial birefringence of 0.205 at 546 nm, surpassing the commercial birefringent crystal α‐BBO (0.122@532 nm). The synergy between F/OH‐ratio optimization and cation activation offers a practical methodology for developing UV birefringent materials.

Abstract Chirality and polarity are the two most important and representative symmetry‐dependent properties. For polar structures, all the twofold axes perpendicular to the principal axis of symmetry should be removed. For chiral structures, all the mirror‐related symmetries and inversion axes should be removed. Especially for duality (polarity and chirality), all of the above symmetries should be broken and that also represents the highest‐level challenge. Herein, a new symmetry‐breaking strategy that employs heteroanionic groups to construct hourglass‐like [Sr3OGeS3]2+ and [Sr3SGeS3]2+ groups to design and synthesize a new oxychalcogenide Sr18Ge9O5S31 with chiral‐polar duality is proposed. The presence of two enantiomers of Sr18Ge9O5S31 is confirmed by the single‐crystal X‐ray diffraction. Its optical activity and ferroelectricity are also studied by solid‐state circular dichroism spectroscopy and piezoresponse force microscopy, respectively. Further property measurements show that Sr18Ge9O5S31 possesses excellent nonlinear optical properties, including the strong second harmonic generation efficiency (≈2.5 × AGS), large bandgap (3.61 eV), and wide mid‐infrared transparent region (≈15.3 µm). These indicate that the unique microstructure groups of heteroanionic materials are conducive to realizing symmetry‐breaking and are able to provide some inspiration for exploring the chiral‐polar duality materials.

The approach of synergistically combining mixed chromophores has garnered significant attention attributed to its ability to leverage the advantages of both groups and design novel nonlinear optical (NLO) materials. Herein, Sr(NO3)(NH2SO3)·H2O, a noncentrosymmetric compound, which represents the first reported nitrate sulfamate compound, is successfully designed and synthesized. The compound features zigzag [SrNO10(H2O)]∞ infinite layers, forming a honeycomb‐like graphene topology in its layered structure. The unique arrangement results in an excellent second harmonic generation response, 5.1 times that of KH2PO4, and an optimized birefringence of 0.06650 at 532 nm. In addition, the presence of interlayered covalent [NH2SO3] groups facilitates improved crystal growth habits, resulting in a large single crystal measuring 19.0 × 17.0 × 3.5 mm3. In this discovery, a new class of NLO materials is introduced and the scope of structural chemistry is significantly expanded.

Strontium titanate (STO) nanocuboids are a novel support for Pt nanoparticle catalysts (Pt/STO). The first of many steps in commercializing Pt/STO will be developing a scalable, environmentally sustainable, and cost‐effective STO nanocuboid synthesis. Herein, Sr–Ti–OH mixtures are synthesized from various Sr2+ and Ti4+ reagents and treated by convection‐ and microwave‐assisted heating to obtain STO nanoparticles. These experiments clarify how phase composition of the prehydrothermal Sr–Ti–OH mixture and choice of heating method affect final nanoparticle morphology. In Sr–Ti–OH mixtures synthesized with TiCl4, STO is the most stable phase and precipitates prior to heating, while titania sol–gels are the most stable phase when other Ti4+ sources are used. STO nanocrystals always form when Sr–Ti–OH mixtures are treated by convection heating, though nanocuboids are only observed if STO precipitates from the Sr–Ti–OH mixture. Microwave‐assisted hydrothermal treatment more rapidly heats the precursor solution, and thus, STO nanocuboids can form from a variety of Sr–Ti–OH mixtures regardless of mixture composition. Two microwave syntheses of STO nanocuboids are reported: one which uses TiCl4 as a Ti4+ source, and another that uses titanium(IV) bis(ammonium lactato) dihydroxide ([NH4CH3CH(O)CO2]2Ti(OH)2), a water‐stable Ti4+ complex.