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VELOX-CI was launched on December 16, 2015 into the near-equatorial orbit. It is the second micro-satellite of Satellite Research Center (SaRC) in Nanyang Technological University in Singapore. VELOX-CI is designed to explore the potential of using the commercial-off-the-shelf (COTS) GPS receivers for RO mission for the first time. Three GPS antennas are located at the zenith, forward-velocity, and after-velocity directions. In total, VELOX-CI collected 240 radio occultation (RO) missions (570 h) from 2015 to 2018 with mission durations ranging from 0.5 to 16.7 h. The lowest penetration altitude from the COTS receivers reaches 6 km. In this paper, the RO performance of the VELOX-CI is evaluated and validated with both ground-based and space-based measurements. Tropospheric and ionospheric profiles obtained from VELOX-CI are also compared with assimilative atmospheric models and empirical ionospheric models, respectively. Results show that with proper sampling frequencies (5–20 Hz), the refractivity error estimated by VELOX-CI RO is below 5% at altitudes below 25 km compared to reanalysis model estimations and radiosonde measurements. The observed ionospheric peak density and height show reasonable ranges for both daytime and nighttime. This study demonstrates the capability of COTS receiver in observing atmospheric and ionospheric parameters. In the future, utilizing COTS receivers with lower-cost low Earth orbit (LEO) satellite missions can largely increase the data volume of RO and enhance our capability in monitoring the Earth's atmosphere. [ABSTRACT FROM AUTHOR]

Two new ternary rare earth chalcogenides, Dy3GaS6 (1) and Y3GaS6 (2), are reported here. They both crystallize in the orthorhombic space group Cmc21 (no. 36). Both are synthesized in pure phase and show phase-matchable second harmonic generation (SHG) of about 0.2 and 0.5 times, respectively for 1 and 2, as strong as that of KTiOPO4 (KTP) based on the powder SHG measurement at the wavelength of 1910 nm. They possess high powder laser induced damage thresholds (LIDTs), respectively, about 14 and 18 times that of AgGaS2 (AGS) based on the powder LIDT measurements under 1064 nm laser irradiation. They both exhibit wide transparency in the IR region (2.5–25 μm). It is believed that the title compounds are new candidates for nonlinear optical (NLO) materials in the IR region. To gain further insights into the NLO and LIDT properties of 1 and 2, the calculations of second-order NLO susceptibility and lattice energy density (LED) were also performed to explain their SHG efficiencies and high LIDTs. [ABSTRACT FROM AUTHOR]

A novel mixed-anion NLO crystal, namely, Bi4O(I3O10)(IO3)3(SeO4), containing a brand-new "pinwheel-like" I3O105− polyiodate anion group was constructed from the trimeric condensation of IO43− monomers. Bi4O(I3O10)(IO3)3(SeO4) exhibits a complex 3D topological structure and gives a moderate second harmonic generation (SHG) signal about 1.1 times that of KH2PO4 (KDP). [ABSTRACT FROM AUTHOR]

A large nonlinear optical (NLO) coefficient and a wide band gap are two crucial but contradictory parameters that are difficult to achieve simultaneously in a single infrared (IR) NLO compound. A salt‐inclusion chalcogenide (SIC), Li[LiCs2Cl][Ga3S6] (1), was prepared that presents a nanosized tunnel framework constructed from monotype chalcogenide tetrahedra. Highly oriented covalent GaS4 tetrahedra in the host lead to a moderate second harmonic generation response (0.7 AgGaS2), and ionic guests effectively broaden the band gap to the widest value (4.18 eV) among all IR NLO chalcogenides, thereby achieving a remarkable balance between NLO efficiency and band gap. [ABSTRACT FROM AUTHOR]

A large nonlinear optical (NLO) coefficient and a wide band gap are two crucial but contradictory parameters that are difficult to achieve simultaneously in a single infrared (IR) NLO compound. A salt‐inclusion chalcogenide (SIC), Li[LiCs2Cl][Ga3S6] (1), was prepared that presents a nanosized tunnel framework constructed from monotype chalcogenide tetrahedra. Highly oriented covalent GaS4 tetrahedra in the host lead to a moderate second harmonic generation response (0.7 AgGaS2), and ionic guests effectively broaden the band gap to the widest value (4.18 eV) among all IR NLO chalcogenides, thereby achieving a remarkable balance between NLO efficiency and band gap. [ABSTRACT FROM AUTHOR]

Two UV inorganic yttrium selenite optical materials, namely, Y(HSeO 3)(SeO 3)(H 2 O)·(H 2 O) (1) and Y 2 (SeO 3) 2 (SeO 4)(H 2 O) 2 ·(H 2 O) 0.75 (2), have been synthesized successfully by hydrothermal reactions. Of these, Y 2 (SeO 3) 2 (SeO 4)(H 2 O) 2 ·(H 2 O) 0.75 (2) is a new mixed valent selenium oxide containing Se(IV) and Se(VI) cations simultaneously. Y(HSeO 3)(SeO 3)(H 2 O)·(H 2 O) (1) shows a 3D structure composed of 2D yttrium selenite layers linked by O−H···O bonds. Y 2 (SeO 3) 2 (SeO 4)(H 2 O) 2 ·(H 2 O) 0.75 (2) exhibits a 3D structure composed of 2D yttrium selenite layers connected by SeO 4 tetrahedron. Y(HSeO 3)(SeO 3)(H 2 O)·(H 2 O) (1) crystallized in a chiral space group P 2 1 2 1 2 1 and could display a moderate SHG intensity about 0.7 times of the commercial KH 2 PO 4 (KDP). Its powder laser damage threshold quantity was estimated to be 120.2 MW/cm2, which is about 46.2 times that of AGS (2.6 MW/cm2). UV–vis–NIR spectra reflectance spectra showed that these solids are wide band gap compounds with Eg of 5.5 and 5.1 eV respectively. Theoretical calculations disclosed that Y(HSeO 3)(SeO 3)(H 2 O)·(H 2 O) (1) is an indirect band gap structures and its bandgaps is determined by O and Se atoms. [Display omitted] • Y(HSeO 3)(SeO 3)(H 2 O)•(H 2 O) is a UV NLO material in pure selenite compounds with balanced properties. • Y(HSeO 3)(SeO 3)(H 2 O)•(H 2 O) exhibits a moderate SHG intensity, wide band gap, large LIDT and moderate birefringence. • Y 2 (SeO 3) 2 (SeO 4)(H 2 O) 2 •(H 2 O) 0.75 is a new mixed valent selenium oxide containing Se(IV) and Se(VI) cations simultaneously. [ABSTRACT FROM AUTHOR]

The new compounds Ba3(BS3)1.5(MS3)0.5 (I) with M: Sb, Bi and Ba3(BQ3)(SbQ3) (II) with Q: S, Se are synthesized by solid state reaction of stoichiometric mixtures of the elements (graphite crucible in an evacuated silica tube, 820-920 °C). [ABSTRACT FROM AUTHOR]

New middle and far-infrared (MFIR) nonlinear optical (NLO) chalcogenides have been receiving increasing attention for their great importance in military and civil fields. In addition, the current challenge in the efforts for identifying a promising MFIR NLO material lies in achieving simultaneously large second-harmonic generation (SHG) intensity and high laser-induced damage threshold (LIDT) in the same material. In this study, two quaternary non-centrosymmetric (NCS) sulfides, BaAg2GeS4 (1) and BaAg2SnS4 (2), were synthesized from a high-temperature solid-state reaction using BaCl2 flux in evacuated closed silica tubes. Although 1 and 2 show identical stoichiometry, they crystallize in different NCS space groups, tetragonal I4̅2m (no. 121) and orthorhombic I222 (no. 23), respectively, based on the results of crystal structure solution. In their structures, highly distorted AgS4 tetrahedra interconnect together via corner-sharing to form two-dimensional (2D) layers, which are further bridged with isolated GeS4 or SnS4 units to produce a three-dimensional (3D) framework structure with Ba cations lying in the tunnels. Remarkably, they not only possess phase-matchable (PM) abilities but also exhibit a good balance between strong SHG responses (1.7× and 0.4× AgGaS2) and high LIDTs (3.2× and 1.5× AgGaS2). Moreover, theoretical calculations based on density functional theory (DFT) methods have aided the understanding of energy bands, electronic structures, and linear and NLO properties. [ABSTRACT FROM AUTHOR]

Trigonal planar units with large polarizability anisotropy and high physicochemical stability are ideal structural units for exploring nonlinear optical (NLO) materials. Integrating the merits of two types of triangular‐like moieties, a family of second‐order NLO‐active hybrid halides, MATX (X = Cl (1), Br (2), and I (3)), are achieved. MATX crystallizes in a nonpolar space group of P6¯$P\overline 6 $2c but exhibits the optimal spatial arrangement and superior NLO performance. The low coordination planar trigonal AgX3 units enable segregation in layers of the three‐winged propeller‐like Me3TPA units. All of the layers are packed in a perfect parallel fashion, making the functional materials exhibit superior NLO performances, including the phase matchable behavior with strong SHG responses (6.2/1, 6.5/2, and 7.6/3 times that of potassium dihydrogen phosphate), large birefringence (0.232/1, 0.252/2 and 0.260/3 at 1064 nm), high laser damage threshold, wide transparent window, and easiness of crystal growth. The first‐principles calculations reveal that the coexistence of strong linear and nonlinear optical properties are ascribed to the synergistic effect of the trigonal moieties. This study points out a useful path for the rational design of excellent NLO materials. [ABSTRACT FROM AUTHOR]

Trigonal planar units with large polarizability anisotropy and high physicochemical stability are ideal structural units for exploring nonlinear optical (NLO) materials. Integrating the merits of two types of triangular‐like moieties, a family of second‐order NLO‐active hybrid halides, MATX (X = Cl (1), Br (2), and I (3)), are achieved. MATX crystallizes in a nonpolar space group of P6¯$P\overline 6 $2c but exhibits the optimal spatial arrangement and superior NLO performance. The low coordination planar trigonal AgX3 units enable segregation in layers of the three‐winged propeller‐like Me3TPA units. All of the layers are packed in a perfect parallel fashion, making the functional materials exhibit superior NLO performances, including the phase matchable behavior with strong SHG responses (6.2/1, 6.5/2, and 7.6/3 times that of potassium dihydrogen phosphate), large birefringence (0.232/1, 0.252/2 and 0.260/3 at 1064 nm), high laser damage threshold, wide transparent window, and easiness of crystal growth. The first‐principles calculations reveal that the coexistence of strong linear and nonlinear optical properties are ascribed to the synergistic effect of the trigonal moieties. This study points out a useful path for the rational design of excellent NLO materials. [ABSTRACT FROM AUTHOR]

Two new polar potassium gold iodates, namely, K2Au(IO3)5 ( Cmc21) and β-KAu(IO3)4 ( C2), have been synthesized and structurally characterized. Both compounds feature zero-dimensional polar [Au(IO3)4]− units composed of an AuO4 square-planar unit coordinated by four IO3− ions in a monodentate fashion. In β-KAu(IO3)4, isolated [Au(IO3)4]− ions are separated by K+ ions, whereas in K2Au(IO3)5, isolated [Au(IO3)4]− ions and non-coordinated IO3− units are separated by K+ ions. Both compounds are thermally stable up to 400 °C and exhibit high transmittance in the NIR region ( λ=800-2500 nm) with measured optical band gaps of 2.65 eV for K2Au(IO3)5 and 2.75 eV for β-KAu(IO3)4. Powder second-harmonic generation measurements by using λ=2.05 μm laser radiation indicate that K2Au(IO3)5 and β-KAu(IO3)4 are both phase-matchable materials with strong SHG responses of approximately 1.0 and 1.3 times that of KTiOPO4, respectively. Theoretical calculations based on DFT methods confirm that such strong SHG responses originate from a synergistic effect of the AuO4 and IO3 units. [ABSTRACT FROM AUTHOR]

The first NLO-active metal iodate-phosphates, namely, Cd2(IO3)(PO4) and Cd1.62Mg0.38(IO3)(PO4) (1 and 2), with three types of NLO groups, have been reported. 1 and 2 are isostructural and the structure of 1 features a 3D network formed by the Cd4(IO3)8/4(PO4)6/3 groups. 1 and 2 with strong SHG signals of 4 × and 3.5 × KH2PO4 are promising SHG materials in the visible region. [ABSTRACT FROM AUTHOR]

Three nonlinear optical materials Cd4REO(BO3)3 (RE = Sm, Eu, Tb) have been synthesized through high-temperature solid-state reactions. In their crystal structures, Cd(1)O8 and Cd(2)O6 polyhedra are interconnected via sharing edges and corners into a 3D anion framework with two types of tunnels based on 4- and 7-membered rings; the BO3 groups are grafted into the above-mentioned types, creating new tunnels based on Cd4B3 seven-membered rings, which are filled by RE3+ cations. Powder SHG measurements revealed that the Cd4REO(BO3)3 (RE = Sm, Eu, Tb) samples display SHG signals that are approximately 1.2, 5.6 and 1.5 times that of the KDP sample. In addition, Cd4EuO(BO3)3 and Cd4TbO(BO3)3 emit red and green light, respectively. The lifetime of the Eu(5D0) state for λex,em = 464, 610 nm in Cd4EuO(BO3)3 is measured to be about 1.43 ms whereas the lifetime of the Tb(5D4) state for λex,em = 376, 543 nm in Cd4TbO(BO3)3 is measured to be about 1.01 ms. [ABSTRACT FROM AUTHOR]

Through systematic experiments, two novel mercury iodate sulfates, namely, Hg2(IO3)2(SO4)(H2O) and Hg2(IO3)2(SO4) were obtained. They crystallize in monoclinic space group C2 and C2/c, respectively. Hg2(IO3)2(SO4)(H2O) exhibits the [Hg(IO3)]+ polar cationic layer inherited from Hg(IO3)2 and the three‐dimensional (3D) framework inherited from HgSO4. This enables Hg2(IO3)2(SO4)(H2O) to generate a strong second harmonic generation (SHG) response of 6 times that of KH2PO4 (KDP). The structure of Hg2(IO3)2(SO4) is very similar to that of Hg2(IO3)2(SO4)(H2O), and they can be transformed into each other. Hg2(IO3)2(SO4)(H2O) shows a large optical band gap of 3.98 eV and a high dehydration temperature of 250 °C. This study indicates that by reasonable design, the introduction of multiple functional groups into a compound may combine their advantages to achieve good overall optical performance. [ABSTRACT FROM AUTHOR]

An organic–inorganic hybrid polyiodate, namely, [o‐C5H4NHOH]2[I7O18(OH)]⋅3 H2O (I), featuring a novel branched polyiodate chain has been obtained by evaporation method. [o‐C5H4NHOH]2[I7O18(OH)]⋅3 H2O (I) crystalizes in the polar space group Ia and features an [I7O18(OH)]∞2- branched polyiodate chain in which [I3O9]3− trimers are grafted on the same side of the one‐dimensional (1D) chain based on [I4O11(OH)]3− tetramers. The asymmetric organic amine groups are beneficial to the polymerization of iodate groups and inducing the formation of the non‐centrosymmetric (NCS) structure. Compound I exhibits a rather large Second‐Harmonic‐ Generation (SHG) signal of 8.5×KH2PO4 (KDP) upon 1064 nm laser radiation, a moderate band gap of 3.90 eV and a high laser‐induced‐damage‐threshold (LIDT) of 182.34 MW cm−2, hence it is a promising new SHG material. The relationship between the structures of the organic amine groups and the overall structures has been also analyzed. [ABSTRACT FROM AUTHOR]

An organic–inorganic hybrid polyiodate, namely, [o‐C5H4NHOH]2[I7O18(OH)]⋅3 H2O (I), featuring a novel branched polyiodate chain has been obtained by evaporation method. [o‐C5H4NHOH]2[I7O18(OH)]⋅3 H2O (I) crystalizes in the polar space group Ia and features an [I7O18(OH)]∞2- branched polyiodate chain in which [I3O9]3− trimers are grafted on the same side of the one‐dimensional (1D) chain based on [I4O11(OH)]3− tetramers. The asymmetric organic amine groups are beneficial to the polymerization of iodate groups and inducing the formation of the non‐centrosymmetric (NCS) structure. Compound I exhibits a rather large Second‐Harmonic‐ Generation (SHG) signal of 8.5×KH2PO4 (KDP) upon 1064 nm laser radiation, a moderate band gap of 3.90 eV and a high laser‐induced‐damage‐threshold (LIDT) of 182.34 MW cm−2, hence it is a promising new SHG material. The relationship between the structures of the organic amine groups and the overall structures has been also analyzed. [ABSTRACT FROM AUTHOR]

Titelbild: Li[LiCs2Cl][Ga3S6]: A Nanoporous Framework of GaS4 Tetrahedra with Excellent Nonlinear Optical Performance (Angew. In ihrem Forschungsartikel auf S. 4700 beschreiben S. Zhu et al. die De-novo-Synthese von hydroxyliertem Benzofuran und die Realisierung einer kollektiven Totalsynthese von hydroxylierten benzofuranhaltigen Naturstoffen. In der Zuschrift auf S. 4860 beschreiben J. H. van Esch et al. die Herstellung biomimetischer, unter Spannung erstarrender Hydrogele durch die Selbstassemblierung molekularer Gelbildner. [Extracted from the article]

The first alkali‐metal vanadium iodate fluoride, CsVO2F(IO3), with a novel 3D anionic framework, has been rationally designed and hydrothermally synthesized. The 3D [VO2F(IO3)]− framework in CsVO2F(IO3) is built from 0D Λ‐shaped cis‐[VO3F(IO3)2]4− polyanions via corner‐sharing of oxo anions and bridging of the iodate groups. CsVO2F(IO3) displays both a strong second‐harmonic generation (SHG) 1.1 times as strong as KTiOPO4 (KTP) under 2.05 μm laser radiation and high laser‐induced damage threshold (LIDT) of 107.9 MW cm−2. This work provides a new route to design SHG crystals with stable 3D anionic structures from low‐dimensional structural building units. [ABSTRACT FROM AUTHOR]

The first alkali‐metal vanadium iodate fluoride, CsVO2F(IO3), with a novel 3D anionic framework, has been rationally designed and hydrothermally synthesized. The 3D [VO2F(IO3)]− framework in CsVO2F(IO3) is built from 0D Λ‐shaped cis‐[VO3F(IO3)2]4− polyanions via corner‐sharing of oxo anions and bridging of the iodate groups. CsVO2F(IO3) displays both a strong second‐harmonic generation (SHG) 1.1 times as strong as KTiOPO4 (KTP) under 2.05 μm laser radiation and high laser‐induced damage threshold (LIDT) of 107.9 MW cm−2. This work provides a new route to design SHG crystals with stable 3D anionic structures from low‐dimensional structural building units. [ABSTRACT FROM AUTHOR]

To develop new mid-infrared (MIR) nonlinear optical (NLO) materials, which can overcome the low laser damage threshold (LDT) of the commercial MIR-NLO crystals (AgGaS2, AgGaSe2 and ZnGeP2) and simultaneously keep the large NLO susceptibility, is necessary for high-power MIR laser frequency conversion technology. To improve the LDT, a new strategy of increasing lattice stability was adopted. Here, the strongly covalent structural unit of the PS4 tetrahedron was introduced into AgGaS2 (AGS), and that led to the isolation of the first compound in AgI-GaIII-PV-S system, namely, AgGa2PS6 ( Cc). It retains a large SHG efficiency (1.0×AGS) with phase-matchable ability, and also exhibits an improved LDT (5.1×AGS), indicating AgGa2PS6 is a new promising MIR-NLO crystal. Moreover, a novel 3D framework of [Ga2PS6]−, with triangular-shaped channels, as well as interesting single triangular geometry of AgS3-both of which are very rare in reported sulfides-was discovered in AgGa2PS6. Furthermore, theoretical calculations, and lattice energy and thermal expansions analyses suggest that the PS4 group makes a large contribution to the large SHG efficiency and high LDT. [ABSTRACT FROM AUTHOR]

The new polar compounds (IV) and (V) are characterized by single crystal XRD, IR, UV/VIS/NIR diffuse reflectance spectroscopy, and DFT electronic band structure calculations. [ABSTRACT FROM AUTHOR]

• NaMoO 3 (IO 3) is the first example of molybdenum(VI) iodate with 1D chain-like structure featuring a large birefringence (0.208@1064 nm). • Both 1D [MoO 3 (IO 3)]- anionic chain in NaMoO 3 (IO 3) and 3D [MoO 3 (IO 3)]- anionic framework in γ-KMoO 3 (IO 3) are assembled from 0D Λ-shaped cis -MoO 4 (IO 3) 2 units. • The polar 3D γ-KMoO 3 (IO 3) exhibits the largest SHG response (12 × KDP) among AMoO 3 (IO 3) family as well as a high LIDT value (52 × AGS). [Display omitted] Herein, we reported two alkali metal molybdenum(VI) iodates, namely, NaMoO 3 (IO 3) and γ-KMoO 3 (IO 3) with 1D and 3D [MoO 3 (IO 3)]− anionic architectures, respectively. The novel 1D chain in NaMoO 3 (IO 3) and the 3D network in γ-KMoO 3 (IO 3) are constructed by the 0D Λ-shaped cis -[MoO 4 (IO 3) 2 ]4− building units interconnected by bridging IO 3 − anions as well as the corner-sharing of oxo anions. Importantly, the polar γ-KMoO 3 (IO 3) exhibits a very large second-harmonic generation (SHG) effect of 12 × KH 2 PO 4 (KDP) under 1064 nm laser radiation, a high laser-Induced damage threshold value (52 × AgGaS 2), and a moderate birefringence of 0.087@1064 nm, whereas the centrosymmetric NaMoO 3 (IO 3) has a large birefringence of 0.208@1064 nm. This study further proves the useful route of exploring promising optical materials via assembling the 0D basic building units into higher dimensional anionic architectures. [ABSTRACT FROM AUTHOR]