Search

Nonlinear optical (NLO) materials are indispensable for laser frequency conversion, by which the output wavelength of laser can be greatly expanded. A prerequisite for the applications of NLO materials is that they must be optically transparent in the working spectral range. Although the widely used infrared (IR) NLO crystals such as AgGaS2, AgGaSe2, and ZnGeP2 have very broad mid‐IR (2–20 μm) transparency, they are all inherently suffered by low laser‐induced damage thresholds (LDTs). Oxide‐based materials usually possess desirably high LDTs, however, most of them have quite limited IR transparency, typically, within 6 μm. In this Minireview, we focus on new oxide‐based NLO materials showing exceptionally wide IR transparent ranges beyond 6 μm, in which significant developments have been achieved in recent years. Nine relevant NLO materials are investigated and analyzed from the aspects of design strategy, synthesis and large crystal growth, optical and NLO properties as well as composition‐structure‐property correlations. A brief perspective on the future research directions is also provided. [ABSTRACT FROM AUTHOR]

Two novel transition metal‐doped tungsten bronze oxides, Pb2.15Li0.85Nb4.85Ti0.15O15 (PLNT) and Pb2.15Li0.55Nb4.85W0.15O15 (PLNW), are synthesized by high‐temperature solid‐state reactions. The Rietveld method using the high‐resolution synchrotron radiation indicates that PLNT and PLNW crystallize in the orthorhombic polar noncentrosymmetric space group, Pmn21 (no. 31). As a class of tungsten bronze oxide, PLNT and PLNW retain a unique rigid framework composed of d0 transition metal cation (Ti4+ or W6+)‐doped highly distorted NbO6 octahedra along with the subsequently generated Pb/LiO12 and PbO15 polyhedra. Interestingly, the d0 transition metal‐doped tungsten bronzes, PLNT and PLNW, exhibit extremely large second‐harmonic generation (SHG) responses of 56 and 67 × KH2PO4, respectively. The observed immeasurably strong SHG is mainly attributed to a net polarization originating from the alignment of highly distorted NbO6 octahedra with doped transition metals in the frameworks. It is believed that doping transition metal cations at the B‐site of the tungsten bronze structures should be an innovative strategy to develop novel high‐performance nonlinear optical materials. [ABSTRACT FROM AUTHOR]

To develop high‐performance nonlinear optical (NLO) materials for infrared (IR) applications, we have applied a rational element‐composition design strategy and investigated the unexplored PbO–PbCl2–PbI2 system. By doing so, we discovered a new polar lead mixed oxyhalide, Pb18O8Cl15I5, the first synthetic metal oxyhalide combining both Cl− and I−. Pb18O8Cl15I5 reveals an unprecedented structural feature with two different dimensional types of oxocentered Pb–O units, namely, [O4Pb8]8+ clusters and [OPb2]2+ chains. Centimeter‐sized single crystals of Pb18O8Cl15I5 have been successfully grown under ambient conditions. Remarkably, Pb18O8Cl15I5 satisfies all fundamental yet rigorous criteria for high‐performance IR NLO materials, exhibiting the widest IR transparency (up to 16.0 μm) among oxide‐based crystals, strong second‐harmonic generation response (1.05×AgGaS2), superior birefringence (0.086 at 636 nm), and a high laser‐induced damage threshold (8.5×AgGaS2). [ABSTRACT FROM AUTHOR]

To develop high‐performance nonlinear optical (NLO) materials for infrared (IR) applications, we have applied a rational element‐composition design strategy and investigated the unexplored PbO–PbCl2–PbI2 system. By doing so, we discovered a new polar lead mixed oxyhalide, Pb18O8Cl15I5, the first synthetic metal oxyhalide combining both Cl− and I−. Pb18O8Cl15I5 reveals an unprecedented structural feature with two different dimensional types of oxocentered Pb–O units, namely, [O4Pb8]8+ clusters and [OPb2]2+ chains. Centimeter‐sized single crystals of Pb18O8Cl15I5 have been successfully grown under ambient conditions. Remarkably, Pb18O8Cl15I5 satisfies all fundamental yet rigorous criteria for high‐performance IR NLO materials, exhibiting the widest IR transparency (up to 16.0 μm) among oxide‐based crystals, strong second‐harmonic generation response (1.05×AgGaS2), superior birefringence (0.086 at 636 nm), and a high laser‐induced damage threshold (8.5×AgGaS2). [ABSTRACT FROM AUTHOR]

To design high‐performance mid‐infrared (mid‐IR) nonlinear optical (NLO) materials, we have focused on the combination of a heavy metal lone pair cation, Pb2+ and mixed oxyhalides. A systematic investigation in PbO‐PbCl2‐PbBr2 system led us to discover the first examples of NLO lead mixed oxyhalides, namely, Pb13O6Cl4Br10, Pb13O6Cl7Br7, and Pb13O6Cl9Br5. All the reported materials have remarkably comprehensive properties including broad IR transparency (up to 14.0 μm), qualified second harmonic generation (SHG) responses (0.6–0.9×AgGaS2), wide band gaps (3.05–3.21 eV), and ease of crystal growth. Interestingly, a centimeter‐sized single crystal (2.9×1.3×0.5 cm3) of Pb13O6Cl9Br5 revealing a wide transparent range (0.384–14.0 μm) and high laser damage threshold (LDT) (14.6×AgGaS2) has been successfully grown in an open system. The study suggests that all the reported mixed oxyhalides are outstanding candidates for mid‐IR NLO materials. [ABSTRACT FROM AUTHOR]

To design high‐performance mid‐infrared (mid‐IR) nonlinear optical (NLO) materials, we have focused on the combination of a heavy metal lone pair cation, Pb2+ and mixed oxyhalides. A systematic investigation in PbO‐PbCl2‐PbBr2 system led us to discover the first examples of NLO lead mixed oxyhalides, namely, Pb13O6Cl4Br10, Pb13O6Cl7Br7, and Pb13O6Cl9Br5. All the reported materials have remarkably comprehensive properties including broad IR transparency (up to 14.0 μm), qualified second harmonic generation (SHG) responses (0.6–0.9×AgGaS2), wide band gaps (3.05–3.21 eV), and ease of crystal growth. Interestingly, a centimeter‐sized single crystal (2.9×1.3×0.5 cm3) of Pb13O6Cl9Br5 revealing a wide transparent range (0.384–14.0 μm) and high laser damage threshold (LDT) (14.6×AgGaS2) has been successfully grown in an open system. The study suggests that all the reported mixed oxyhalides are outstanding candidates for mid‐IR NLO materials. [ABSTRACT FROM AUTHOR]

A series of silicate materials with noncentrosymmetric structures, namely, Na3ScSi3O9 (NSSO), NSSO:Ce3+, NSSO:Eu2+, and NSSO:Tb3+, have been successfully synthesized by a microwave‐assisted solid‐state reaction. The materials reveal interesting second‐ and third‐harmonic generation and two‐photon absorption (2PA) properties attributable to the unusual connectivity and unique coordination environments around the cations, as evidenced by detailed structural analysis and maximum entropy method calculations. Upon irradiation with 980 nm laser light, the activator‐doped NSSO materials show an unusual upconversion emission property without using Yb3+ sensitizer ions, because of nonlinear absorption processes, as evidenced from 2PA spectroscopy results. The materials also show good chemical stability compared to NaYF4:Er3+, Yb3+. The findings of this work can stimulate the creation of a new scientific field devoted to upconversion luminescence in solid‐state materials. [ABSTRACT FROM AUTHOR]

Discovering new functional genes, designing perfect crystal structures, and developing high‐performance materials are the goals being pursued by scientists. Herein, the first antimony pyrophosphate, K2Sb(P2O7)F, possessing an optimal layered structure, is reported, where the perfect structural arrangement induces excellent optical properties. K2Sb(P2O7)F not only displays a sharply enhanced birefringence (0.157@546 nm) compared to the existing phosphate optical materials, but also exhibits a strong second‐harmonic generation response (4.0×KDP). Remarkably, a new bifunctional gene, the square‐pyramidal SbO4F group, was discovered, and a unique two‐dimensional arrangement of Cairo pentagonal tiling units was observed in inorganic compounds for the first time. [ABSTRACT FROM AUTHOR]

Discovering new functional genes, designing perfect crystal structures, and developing high‐performance materials are the goals being pursued by scientists. Herein, the first antimony pyrophosphate, K2Sb(P2O7)F, possessing an optimal layered structure, is reported, where the perfect structural arrangement induces excellent optical properties. K2Sb(P2O7)F not only displays a sharply enhanced birefringence (0.157@546 nm) compared to the existing phosphate optical materials, but also exhibits a strong second‐harmonic generation response (4.0×KDP). Remarkably, a new bifunctional gene, the square‐pyramidal SbO4F group, was discovered, and a unique two‐dimensional arrangement of Cairo pentagonal tiling units was observed in inorganic compounds for the first time. [ABSTRACT FROM AUTHOR]

Discovering new functional genes, designing perfect crystal structures, and developing high‐performance materials are the goals being pursued by scientists. Herein, the first antimony pyrophosphate, K2Sb(P2O7)F, possessing an optimal layered structure, is reported, where the perfect structural arrangement induces excellent optical properties. K2Sb(P2O7)F not only displays a sharply enhanced birefringence (0.157@546 nm) compared to the existing phosphate optical materials, but also exhibits a strong second‐harmonic generation response (4.0×KDP). Remarkably, a new bifunctional gene, the square‐pyramidal SbO4F group, was discovered, and a unique two‐dimensional arrangement of Cairo pentagonal tiling units was observed in inorganic compounds for the first time. [ABSTRACT FROM AUTHOR]

Innentitelbild: Lead Mixed Oxyhalides Satisfying All Fundamental Requirements for High-Performance Mid-Infrared Nonlinear Optical Materials (Angew. Keywords: crystal growth; metal mixed oxyhalides; mid-IR NLO materials; nonlinear optics EN crystal growth metal mixed oxyhalides mid-IR NLO materials nonlinear optics 7342 7342 1 04/24/20 20200504 NES 200504 B Die gemischten Bleioxyhalogenide b Pb SB 13 sb O SB 6 sb Cl SB 4 sb Br SB 10 sb , Pb SB 13 sb O SB 6 sb Cl SB 7 sb Br SB 7 sb und Pb SB 13 sb O SB 6 sb Cl SB 9 sb Br SB 5 sb , die passende Bandlücken ( I E i SB I g i sb ) und NLO-Koeffizienten ( I d i SB I ij i sb ) aufweisen, erfüllen alle fundamentalen Anforderungen an hochleistungsfähige nichtlineare mid-IR-Materialien. Crystal growth, metal mixed oxyhalides, mid-IR NLO materials, nonlinear optics. [Extracted from the article]

Abstract: A nonlinear optical (NLO) carbonatoperoxovanadate, Rb3VO(O2)2CO3, was synthesized through a simple solution‐evaporation method in phase‐pure form. Single‐crystal X‐ray diffraction revealed that the structure of Rb3VO(O2)2CO3 consists of important noncentrosymmetric (NCS) chromophores, that is, π‐delocalized (CO3)2− groups, a second‐order Jahn–Teller (SOJT) distortive V5+ cation, and π‐localized distorted O22− groups, as well as charge‐balancing polarizable Rb+ ions. The powder second‐harmonic generation (SHG) measurements indicated that Rb3VO(O2)2CO3 is phase‐matchable (Type I) and exhibits a remarkably strong SHG response circa 21.0 times that of potassium dihydrogen phosphate (KDP), which is the largest efficiency observed among carbonate NLO materials. First‐principles calculation analysis suggests that the extremely large SHG response of Rb3VO(O2)2CO3 is attributed to the synergistic effect of the cooperation of all the constituting NCS chromophores. [ABSTRACT FROM AUTHOR]

Abstract: A nonlinear optical (NLO) carbonatoperoxovanadate, Rb3VO(O2)2CO3, was synthesized through a simple solution‐evaporation method in phase‐pure form. Single‐crystal X‐ray diffraction revealed that the structure of Rb3VO(O2)2CO3 consists of important noncentrosymmetric (NCS) chromophores, that is, π‐delocalized (CO3)2− groups, a second‐order Jahn–Teller (SOJT) distortive V5+ cation, and π‐localized distorted O22− groups, as well as charge‐balancing polarizable Rb+ ions. The powder second‐harmonic generation (SHG) measurements indicated that Rb3VO(O2)2CO3 is phase‐matchable (Type I) and exhibits a remarkably strong SHG response circa 21.0 times that of potassium dihydrogen phosphate (KDP), which is the largest efficiency observed among carbonate NLO materials. First‐principles calculation analysis suggests that the extremely large SHG response of Rb3VO(O2)2CO3 is attributed to the synergistic effect of the cooperation of all the constituting NCS chromophores. [ABSTRACT FROM AUTHOR]

In their Correspondence, Sergey V. Krivovichev and Luca Bindi argue that the novel excellent nonlinear optical material antimony pyrophosphate, K2Sb(P2O7)F, reported in our Research Article published in this journal belongs to the fresnoite Ba2[TiO(Si2O7)] group and its structure is not novel in terms of either topology or local coordination geometry around Sb3+ cations. We clarify that the statements regarding structural features of our original paper are valid in context. In reply to Krivovichev and Bindi, Deng et al. state that the structural features of their original paper are valid in context. They emphasize that this is the first time the SbO4F group has been used as a new bifunctional group to design nonlinear optical materials, and not as a structural group, and that this is the first example of a nonlinear material with a Cairo pentagonal tiling layered structure. [ABSTRACT FROM AUTHOR]

In their Correspondence, Sergey V. Krivovichev and Luca Bindi argue that the novel excellent nonlinear optical material antimony pyrophosphate, K2Sb(P2O7)F, reported in our Research Article published in this journal belongs to the fresnoite Ba2[TiO(Si2O7)] group and its structure is not novel in terms of either topology or local coordination geometry around Sb3+ cations. We clarify that the statements regarding structural features of our original paper are valid in context. [ABSTRACT FROM AUTHOR]