Direct Deep-UV Second-Harmonic Generation in Disordered Χ-Modulated Ferroelectric Crystals.

The generation of coherent deep-ultraviolet (DUV) radiation via nonlinear frequency conversion remains a major scientific and technological challenge in modern optics. To date, only a very limited number of nonlinear optical (NLO) crystals-such as KBBF, ABF, and quartz-have been experimentally demonstrated to support measurable direct second-harmonic generation (SHG) at wavelengths of 177 nm or shorter. There is a pressing need to develop alternative materials or strategies that enable efficient frequency conversion in the DUV region.

Enhancement of Low Temperature Superionic Conductivity by Suppression of Li Site Ordering in LiSiGeSI.

Ge substitution into the recently discovered superionic conductor LiSiSI is demonstrated by synthesis of LiSiGeSI, where x≤1.2. The anion packing and tetrahedral silicon location of LiSiSI are retained upon substitution.

Superionic lithium transport via multiple coordination environments defined by two-anion packing.

Fast cation transport in solids underpins energy storage. Materials design has focused on structures that can define transport pathways with minimal cation coordination change, restricting attention to a small part of chemical space. Motivated by the greater structural diversity of binary intermetallics than that of the metallic elements, we used two anions to build a pathway for three-dimensional superionic lithium ion conductivity that exploits multiple cation coordination environments.

Control of Ionic Conductivity by Lithium Distribution in Cubic Oxide Argyrodites LiPSiOCl.

Argyrodite is a key structure type for ion-transporting materials. Oxide argyrodites are largely unexplored despite sulfide argyrodites being a leading family of solid-state lithium-ion conductors, in which the control of lithium distribution over a wide range of available sites strongly influences the conductivity. We present a new cubic Li-rich (>6 Li per formula unit) oxide argyrodite LiSiOCl that crystallizes with an ordered cubic (23) structure at room temperature, undergoing a transition at 473 K to a Li site disordered 4̅3 structure, consistent with the symmetry adopted by superionic sulfide argyrodites.

Extended Condensed Ultraphosphate Frameworks with Monovalent Ions Combine Lithium Mobility with High Computed Electrochemical Stability.

Extended anionic frameworks based on condensation of polyhedral main group non-metal anions offer a wide range of structure types. Despite the widespread chemistry and earth abundance of phosphates and silicates, there are no reports of extended ultraphosphate anions with lithium. We describe the lithium ultraphosphates LiPO and LiPO based on extended layers and chains of phosphate, respectively.

Polymorph of LiAlPO: Combined Computational, Synthetic, Crystallographic, and Ionic Conductivity Study.

We report a new polymorph of lithium aluminum pyrophosphate, LiAlPO, discovered through a computationally guided synthetic exploration of the Li-Mg-Al-P-O phase field. The new polymorph formed at 973 K, and the crystal structure, solved by single-crystal X-ray diffraction, adopts the orthorhombic space group with = 5.1140(9) Å, = 8.

LiSiOCl: A Hexagonal Argyrodite Based on Antiperovskite Layer Stacking.

A hexagonal analogue, LiSiOCl, of the cubic lithium argyrodite family of solid electrolytes is isolated by a computation-experiment approach. We show that the argyrodite structure is equivalent to the cubic antiperovskite solid electrolyte structure through anion site and vacancy ordering within a cubic stacking of two close-packed layers. Construction of models that assemble these layers with the combination of hexagonal and cubic stacking motifs, both well known in the large family of perovskite structural variants, followed by energy minimization identifies LiSiOCl as a stable candidate composition.

A new barium fluorooxoborate BaBOF·xHO with large birefringence and a wide UV transparency window.

A new barium fluorooxoborate, BaB5O8F·xH2O (x ≈ 0.17), with two interesting independent three-dimensional B-O/F frameworks has been synthesized by a solid-state reaction in a closed system. Compared with the lead fluorooxoborate PbB5O8F, BaB5O8F·xH2O exhibits a comparable birefringence and a wider UV transparency window.

K[BO(OH)](CO)X·7HO (X = Cl, Br): Syntheses, Characterizations, and Theoretical Studies of Noncentrosymmetric Halogen Borate-Carbonates with Short UV Cutoff Edges.

Two mixed halogen borate-carbonates K[BO(OH)](CO)X·7HO (X = Cl, Br) have been successfully synthesized with the hydrothermal method. They crystallize in the space group P6̅2 c, and their structures feature 3D networks consisting of the KOCl polyhedra. The isolated [BO] groups and [BO] triangles are filled in the space of 3D networks.

Designing Three Fluorooxoborates with a Wide Transmittance Window by Anionic Group Substitution.

Three fluorooxoborates, KRbBOF and MBPOF (M = K, Cs), were designed and synthesized under the open system. One of the common features is that the title compounds consist of six-membered oxofluoride anions. The oxofluoride anions [BOF] and [BPOF] display structures similar to the boroxine [BO].

The first lithium difluorophosphate LiPOF with a neutral polytetrahedral microporous architecture.

Herein, we present the first lithium difluorophosphate LiPO2F2 exhibiting a unique polytetrahedral microporous architecture. The unique fluorine coordination environments and interlaced [LiO2]3- straight chains give rise to the neutral pore framework with a 10- membered ring channel along the crystallographic c axis. A variety of measurements have been adopted to systemically characterize LiPO2F2.

Screening of Metal-Organic Frameworks for Highly Effective Hydrogen Isotope Separation by Quantum Sieving.

Separation of hydrogen isotopes is of great importance to produce highly pure hydrogen isotopes for numerous applications, which is however very difficult because of their almost identical thermodynamic properties. Adsorptive separation is considered as a simple, highly efficient, and cost-effective technique compared to the traditional methods, where the key is the suitable adsorbent. Herein, SIFSIX-3-Zn was screened out from the reported metal-organic frameworks (MOFs), exhibiting high selectivities for a D/H mixture by quantum sieving effect.

Mo Cation Enrichment of the Structure Chemistry of Iodates: Syntheses, Structures, and Calculations of Ba(MoO)(IO)O, Ba[(MoO)(IO)O(OH)]·2HO, and Sr[(MoO)(IO)O]·HO.

The three metal iodates Ba(MoO)(IO)O (1), Ba[(MoO)(IO)O(OH)]·2HO (2), and Sr[(MoO)(IO)O]·HO (3) have been successfully synthesized by introducing second-order Jahn-Teller distorted Mo cations by a mild hydrothermal method. Single-crystal X-ray diffraction (XRD) was used to determine the structures of the three title compounds. In compound 1, the [MoO] dimers connect with the [IO] units by sharing oxygen atoms to form two-dimensional (2D) layers that are separated by the Ba cations.

Fluorooxoborates: Ushering in a New Era of Deep Ultraviolet Nonlinear Optical Materials.

Borates are one of the most important classes of functional materials, and several hundreds of artificial borates have been synthesized. The substitution of oxygen by fluorine leads to manifold classes of borates. Fluorooxoborates (also known as fluoroborates), in which the F atoms covalently connect with the B atoms, show additional compositional and structural diversity compared to classic borates.

KRbBO: a new triple-layered borate with an unprecedented [BO] fundamental building block.

A new mixed-alkali borate, K11RbB28O48, has been obtained using the high-temperature solution method. It features a new [B28O57] fundamental building block. Meanwhile, these units further polymerize to form unusual triple-layered anionic groups.

A Fluorooxosilicophosphate with an Unprecedented SiO F Species.

The large number and structural beauty of silicates are largely due to the variety of connection mode of SiO tetrahedra. SiO and SiF octahedra are also known and give rise for structural versatility of inorganic silicates. However, to date, the crystal structure of inorganic fluorooxosilicates with oxofluoride SiO F or SiO F species are unknown.

Synthesis of hierarchical-pore metal-organic framework on liter scale for large organic pollutants capture in wastewater.

Large organic pollutants in wastewater are harmful to human health and environmental ecosystem, and it is of great importance to remove them from waste water. In this report, hierarchical-pore metal-organic frameworks with different mesopore sizes (H-UiO-66-3.8 nm and H-UiO-66-17.

K B O F : A New Fluorooxoborate with Four Different Anionic Units.

K B O F , a first fluorooxoborate containing four different units, that is, [BO ] , [BO ] , [BO F] , and [BO F ] , has been designed and synthesized by two different routes. The unique anionic 2∞ [B O F ] layers avoid forming terminal oxygen atoms, which are beneficial to enlarge the band gap. The structure-properties relationship of the title compound is discussed.

Growth, Properties, and Theoretical Analysis of MLiVO (M = Rb, Cs) Crystals: Two Potential Mid-Infrared Nonlinear Optical Materials.

Mid-Infrared nonlinear optical (Mid-IR NLO) crystals with excellent performances play a particularly important role for applications in areas such as telecommunications, laser guidance, and explosives detection. However, the design and growth of high performance Mid-IR NLO crystals with large NLO efficiency and high laser-damage threshold (LDT) still face numerous fundamental challenge. In this study, two potential Mid-IR NLO materials, RbLiVO (RLVO) and CsLiVO (CLVO) with noncentrosymmetric structures (Orthorhombic, Cmc2) were synthesized by high-temperature solution method.

Role of the metal cation types around VO4 groups on the nonlinear optical behavior of materials: experimental and theoretical analysis.

In order to explore new NLO crystals with superior performances, it is greatly desirable to understand the intrinsic relationship between the macroscopic optical properties and microscopic structural features in crystals. A novel mechanism for nonlinear optical (NLO) effects of vanadate crystals, Li3VO4, KCd4(VO4)3 and Ca3(VO4)2 with distorted (VO4)(3-) groups, has been investigated. Experiments related to the synthesis and structures were determined.

Experimental and theoretical studies on the linear and nonlinear optical properties of lead phosphate crystals LiPbPO4.

Phosphates with noncentrosymmetric (NCS) structures usually display short ultraviolet (UV) cut-off edges, but often exhibit weak powder second harmonic generation (SHG) intensities. Here we synthesized a NCS-phosphate, LiPbPO4, that achieves a desired balance between UV transparency, a cut-off edge of about 232 nm, and large SHG activity (about 3 × KDP). The three dimensional (3D) framework of LiPbPO4 consists of PO4 and LiO4 tetrahedra that are corner-shared, forming wide channels where lead cations reside.