BaSbBS: a record-high-performance birefringent crystal identified by a target-driven closed-loop strategy.

Exploring infrared (IR) birefringent materials with both large birefringence (Δ) and wide band gaps ( ) is urgently demanded for high-power optoelectronic applications and has long been a tough challenge due to the intrinsic contradictory relationship between the two metrics. Herein, we developed a target-driven closed-loop framework in coupling with functional motif and crystal structure screening, deep learning assisted high-throughput optical property computation, targeted experiment and mechanism investigation, enabling efficient discovery of potential birefringent materials. Utilizing it, a batch of superior IR birefringent crystals containing planar [BS] and/or stereochemically active lone pair (SCALP) groups ([SbS], [SnS], ) were identified: six with huge birefringence (Δ > 1.

(CNH)IOF and (CNH)(IOF): two new organic-inorganic hybrid fluoroiodate birefringent crystals.

Birefringent crystals are anisotropic materials commonly used in modern optical devices to obtain polarized light. The traditional commercial birefringent crystals, such as MgF and CaCO, have low birefringence and are not easy to grow. Herein, two organic-inorganic hybrid birefringent crystals composed of π-conjugated organic groups and lone pair-containing (IOF) anions, namely, (CNH)IOF and (CNH)(IOF), were successfully grown by a simple evaporation method.

LaZn(SeO): A UV Selenite Crystal with Second-Harmonic Generation and Large Birefringence.

Inorganic selenites are promising candidates for nonlinear optical and birefringent crystals. However, selenites that can effectively transmit in the UV region are still relatively scarce. In this study, we successfully synthesized the first Zn-based UV selenite with birefringent and nonlinear optical properties using a hydrothermal method by introducing Zn and La ions, which can cause a blue shift in the compound's bandgap, into the selenite system.

Na[BIO(OH)] and Na[BIO](IO): Explorations of Boroiodates with Strong Second Harmonic Generation Response and Large Birefringence.

In the exploration of nonlinear optical (NLO) materials, developing new functional groups for high performance is essential. Achieving a balance among band gap, second harmonic generation (SHG), and birefringence within a compound is quite challenging. By directly connecting iodates and borates by B-O-I bridges, two boroiodates with novel [BIO(OH)] and [BIO] anionic functional groups, namely, Na[BIO(OH)] () and Na[BIO](IO) (), were successfully synthesized for the first time through the boric acid melting method under different molar ratios of HBO/NaIO.

Potassium Tetraiodatoiodate(III) Iodate(V): A Nonlinear Optical Crystal with Exceptional Second-Harmonic Generation and Full-Wavelength Phase Matching.

The development of nonlinear optical materials with large nonlinear optical susceptibilities, wide transmission ranges, and comprehensive full-wavelength phase matching capabilities remains a significant challenge. In this study, we synthesized a novel potassium tetraiodatoiodate(III) iodate(V) via an in-situ reduction and complexation reaction. The resulting compound, K[I(IO)]IO, exhibits exceptional second-harmonic generation responses (21.

BaLa(SiS)(BS): Structurally Ordered Thioborate-Thiosilicate Obtained by Adjusting the Cationic Size.

Thioborates are of interest as nonlinear optical materials, birefringent materials, and solid-state electrolytes. Under the dilemma that all known thioborate-thiosilates are disordered structures with co-occupied atomic sites, the first structurally ordered thioborate-thiosilicate, BaLa(SiS)(BS), has been successfully obtained by adjusting the cationic size. It features a novel 3D tunnel network assembled by La-B-S chains and La-Si-S bilayers.

From Holodirected to Hemidirected Coordination Activated by Oxygenation Strategy: A Facile Route to Long Wave Infrared Birefringent Crystal.

Long wave infrared (LWIR) birefringent crystals are essential for infrared optical applications but such materials are rarely reported due to the requirements of large birefringence and wide infrared transmission range. This study proposes a facile route to create new LWIR birefringent crystal by oxygenation strategy in halides with cations containing lone pair electrons. Given the tendency of such cations to form holodirected geometry, a divalent oxygen was introduced to substitute the monovalent halogen to decrease the coordination number and activate the lone pair electrons.

A Wide Band Gap Germanate with the Largest Second Harmonic Generation Response Created by Hypoxic Strategy.

Nonlinear optical material is one of the core components for modern laser equipment. The second harmonic generation (SHG) intensity and optical band gap are two key indicators of such materials. Herein, a wide band gap germanate, Li(OH)PbGeO, with the largest SHG intensity has been created successfully by hypoxic strategy via traditional hydrothermal reactions.

BaPb(CO)F: Enhancing Birefringence by a Multiunit Synergy Effect.

Carbonates are ideal birefringent materials because their π-conjugated [CO] groups are beneficial for large anisotropy. How to maximize the birefringence and maintain a wide transmittance simultaneously in carbonates is a great challenge. Adopting a multiple-functional group synergy strategy by combining alkaline-earth metal Ba with large ion radius, PbOF distorted hexagonal pyramid, and paralleled π-conjugated CO triangles together, we synthesized a new metal carbonate crystal, BaPb(CO)F.

Noncentrosymmetric tellurite halides created by a depolymerization strategy: toward strong SHG intensity and wide bandgap.

The design and synthesis of nonlinear optical (NLO) materials with a strong second harmonic generation (SHG) effect and wide band gap is a long-standing challenge because of their inverse relationship, especially for metal tellurites. We found that a lower degree of polymerization of tellurite groups corresponds to a higher proportion of non-centrosymmetric (NCS) structures formed. Based on Pauling's rule #4, introduction of cations (Al/Ga) with higher coordination numbers and lower valence states than Te into the reaction system decreases the connectivity among tellurite groups.

[CHN][BO(OH)] and [CHN][BO(OH)]: Two Melamine Borates with Large Birefringence.

The π-conjugated [CHN] ( = 0-3) cations are good functional groups, which are widely employed in the preparations of nonlinear optical (NLO) and birefringent materials due to their high hyperpolarizability and optical anisotropy. In this paper, the first melamine hydroxyborate [CHN][BO(OH)] () was synthesized by the boric acid melting method under the molar ratio of HBO:CHN = 1:1. (2/) exhibits a two-dimensional (2D) {[CHN][BO(OH)]} layer composed of [CHN] cations and [BO(OH)] anions interconnected via hydrogen bonds.

SbO(OH)(IO): The First Polar Sb-Iodate with a Strong Second-Harmonic Generation Response and a Wide Bandgap.

Widening the bandgaps while maintaining a strong second harmonic generation response has always been a research hotspot in the field of nonlinear optical iodate materials. A strategy involving covalent bonding is proposed that leverages the high valent later main group cation to construct iodates with predominantly covalent interactions. By using BiO(IO) as a template, the first Sb-containing polar iodate, SbO(OH)(IO) is successfully isolated.

Fully tricoordinated assembly unveils a pioneering nonlinear optical crystal (SbTeO)(NO).

Balancing the critical property requirements is key to surmounting the obstacles in the application of nonlinear optical (NLO) crystals. Tricoordinated units, characterized by nearly the lowest coordination number, are common in inorganic NLO-active oxides; however, crystals solely composed of such units are rare. Herein, by assembling three distinct tricoordinated units (SbO, TeO, and NO) into a single crystal, a pioneering fully tricoordinated NLO material, (SbTeO)(NO), was synthesized a facile volatilization method.

[(CHN)H](SbF): a polyfluoroantimonite with a strong second harmonic generation effect.

It is of great difficulty to create a new antimonite with second-harmonic-generation (SHG) intensity larger than 6 times that of KDP. In this study, a polyfluoroantimonite strategy has been proposed to explore fluoroantimonites with large nonlinear optical (NLO) coefficients. Under the cooperation of chemical (highly asymmetric π-conjugated organic amine) and physical (viscous reaction medium ethylene glycol) methods, two novel polyfluoroantimonites, namely, (3PC)(SbF) and (3AP)(SbF), have been achieved.

Pb(SeO)(SiF): the first selenite fluorosilicate with a wide bandgap and large birefringence achieved through perfluorinated group modification.

Birefringent crystals serve as the core elements of polarizing optical devices. However, the inherent challenge of balancing bandgap and birefringence poses a significant hurdle in designing crystals with excellent overall performance. In this study, we propose a novel approach, namely modification with perfluorinated groups, to achieve dual enhancement of the bandgap and birefringence of selenite materials.

UV-Transparent SHG Material Explored in an Alkali Metal Sulfate Selenite System.

The first examples of alkali metal selenite sulfates, namely, Na(SeO)(SO) (1), Na(HSeO)(SO) (2), and K(HSeO)(HSO)(SO) (3), were successfully synthesized by hydrothermal reactions. Their structures display three different zero-dimensional configurations composed of isolated sulfate tetrahedra and selenite groups separated by alkali metals. Na(SeO)(SO) (1) features a noncentrosymmetric structure, while Na(HSeO)(SO) (2) and K(HSeO)(HSO)(SO) (3) are centrosymmetric.

Hg(TeO)(SO): A Giant Birefringent Sulfate Crystal Triggered by a Highly Selective Cation.

Sulfate crystals are often criticized for their low birefringence. The small anisotropic SO group is becoming the biggest bottleneck hindering the application of sulfates in optical functional materials. In this study, we report a new method to significantly enhance the birefringence of sulfates.

HgSe(SeO)(SO): A Mixed-Valent Selenium Compound with Mid-Infrared Transmittance Obtained by In Situ Reaction.

Exploring new material systems is a highly significant task in the field of inorganic chemistry. A new mixed-valent selenium compound, HgSe(SeO)(SO), was successfully synthesized through in situ reactions. This compound exhibits a novel three-dimensional structure composed of HgSe(SO) layers bridged by SeO trigonal pyramids.

A UV non-hydrogen pure selenite nonlinear optical material for achieving balanced properties through framework-optimized structural transformation.

For non-centrosymmetric (NCS) oxides intended for ultraviolet (UV) nonlinear optical (NLO) applications, achieving a wide band gap, large second harmonic generation (SHG) intensity, and sufficient birefringence to satisfy phase matching is a significant challenge due to their inherent incompatibility. To address this issue, this study proposes a strategy called framework-optimized structural transformation. Building upon centrosymmetric (CS) NaGa(SeO) as a foundation, an original UV selenite NLO material, NaLu(SeO), was successfully synthesized.

(CHNCl)(IOCl): a birefringent crystal featuring unprecedented (IOCl) anions and π-conjugated organic cations.

Birefringent crystals can manipulate the polarization state of lasers and have vital application in polarizers, optical isolators, phase compensators, The design and synthesis of crystals with large birefringence remains a challenging task. To design crystals with large birefringence, we combine an unprecedented chloroiodate(v) group (IOCl) featuring large polarizability anisotropy and a strong stereochemically active lone pair (SCALP) with the π-conjugated 2-amino-5-chloropyridine group. The superior synergy effect of (IOCl) and 2-amino-5-chloropyridine groups produces a new birefringent crystal, namely (CHNCl)(IOCl).

BaBO: A Deep Ultraviolet Transparent Nonlinear Optical Crystal with Strong Second Harmonic Generation Response Achieved by a Boron-Rich Closed-Loop Strategy.

Discovering new deep ultraviolet (DUV) nonlinear optical (NLO) materials is the current research hotspot. However, how to perfectly integrate several stringent performances into a crystal is a great challenge because of the natural incompatibility among them, particularly wide band gap and large NLO coefficient. To tackle the challenge, a boron-rich closed-loop strategy is supposed, based on which a new barium borate, BaBO, is designed and synthesized successfully via the high-temperature solid-state melting method.

Highly Birefringent d Transition Metal Fluoroantimonite in the Mid Infrared Band: Order-Disorder Regulation by Cationic Size.

An unusual O/F ordered d transition metal fluoroantimonite, namely, KSbMoOF, has been created by the cationic size effect of alkali metals. It features the largest birefringence of 0.220@550 nm among inorganic antimonites with a halogen element, which is an order of magnitude larger than the disordered ASbMoOF (A = Rb, Cs).

Ln F (OH )(MoO ) (SeO ) : Promising Multifunctional Nonlinear Optical Materials Created by Partial Fluorination Strategy under Corrosion Resistant Supercritical Reactions.

It has historically been exceedingly challenging to create physically and chemically stable lanthanide compounds with strong second harmonic generation (SHG) due to their strong preference to central symmetry. In this work, five new non-centrosymmetric lanthanide selenites, namely, Ln F (OH )(MoO ) (SeO ) (Ln = Sm, Eu, Gd, Tb and Dy), are achieved by partial fluorination of the lanthanide oxygen polyhedron. An HF corrosion resistant supercritical hydrothermal method is developed, which is a facile and universal method for HF corrosion and high-temperature high-pressure environment.

Ca Ln(BS )(SiS ) (Ln = La, Ce, and Gd): Mixed Metal Thioborate-Thiosilicates as Well-Performed Infrared Nonlinear Optical Materials.

The first examples of thioborate-thiosilicates, namely Ca Ln(BS )(SiS ) (Ln = La, Ce, and Gd), are synthesized by rationally designed high-temperature solid-state reactions. They crystalize in the polar space group P6 mc and feature a novel three-dimensional crystal structure in which the discrete [BS ] and [SiS ] anionic groups are linked by Ca and Ln cations occupying the same atomic site. Remarkably, all three compounds show comprehensive properties required as promising infrared nonlinear optical materials, including phase-matchable strong second harmonic generation (SHG) responses at 2.

Ce(IO)F and Ce(IO)(NO): Two Mixed-Anion Cerium Iodates with Good Nonlinear Optical and Birefringent Properties.

Two new mixed-anion cerium iodates, namely, Ce(IO)F and Ce(IO)(NO), have been rationally designed through the integration of hybrid anionic functional building blocks (FBBs). The structure of Ce(IO)F features a novel [Ce(IO)F] bilayer, and the material exhibits large birefringence (0.225 @546 nm).