The systematic modification of the molecular structure of nonlinear optical (NLO)-active materials is a very attractive approach to the improvement of NLO performance. In this study, one lutetium selenite compound Lu(SeO3)(HSeO3)(H2O)•(H2O) (1) was synthesized by hydrothermal means, while a further two lutetium selenites Lu3F(SeO3)4 (2) and Lu(SeO3)(NO3)(H2O) (3) were successfully synthesized by anion partial substitution (APS) of the parent structure 1 under hydrothermal conditions. Specifically, substitution of the [HSeO3] − anions in the noncentrosymmetric 1 by F − or [NO3] − anions with differing denticity leads to the formation of polar 2 and centrosymmetric 3. Our study reveals that the denticity of the secondary functional anions has a significant influence on the coordination environments of the rare-earth metal cation Lu 3+ and consequently the molecular configuration and NLO performance of the resultant multidimensional selenites. In contrast to 1, which displays a weak second-harmonic generation (SHG) response (0.1 × KH2PO4 (KDP)), 2 exhibits a greatly improved NLO performance, including a strong SHG signal (2.5 × KDP, the highest value among rare-earth-metal-based NLO selenites), a wide band gap (3.57 eV) and optical transparency window (0.35−10.3 μm), high thermal stability (~550 °C), and a large laser damage threshold (36 × AgGaS2). These results suggest that 2, as the first example of a fluorinated lutetium selenite, is a strong NLO candidate crystal spanning a region from the near-ultraviolet to the mid-infrared. These APS studies highlight a new feasible approach towards highperformance NLO crystals.

Study of mid-infrared (mid-IR) nonlinear optical (NLO) materials is hindered by the competing requirements of optimizeds econd-harmonic generation (SHG) coefficient d ij and laser-induced damage threshold (LIDT) as well as the harsh synthetic conditions.H erein, we report facile hydrothermal synthesis of ap olar NLO vanadate Cs 4 V 8 O 22 (CVO) featuring aq uasi-rigid honeycomb-layered structure with [VO 4 ]a nd [VO 5 ]p olyhedra aligned parallel. CVOp ossesses aw ide IR-transparent window,h igh LIDT,a nd congruentmelting behavior.I th as very strong phase-matchable SHG intensities in metal vanadate family (12.0 KDP @1 064 nm and 2.2 AGS@2100 nm). First-principles calculations suggest that the exceptional SHG responses of CVOl argely originate from virtual electronic transitions within [V 4 O 11 ] 1 layer;t he excellent optical transmittance of CVOa rises from the special characteristics of vibrational phonons resulting from the layered structure.

A new alkali metal-rare earth metal sulfate with the formula NaY(SO4)2.H2O has been synthesized using a mild hydrothermal method. It crystallizes in the noncentrosymmetric trigonal space group P3121 (No. 152)...

Introduction of rare-earth cations with moderate electropositivity into the iodate system afford three noncentrosymmetric rare-earth iodates REn(IO3)3n(H2O) with optimized balance between SHG efficiency and optical band gaps.

A rare-earth metal nitrate–selenite nonlinear optical crystal Gd(NO3)(Se2O5)·3H2O with a short ultraviolet cutoff edge was synthesized by a hydrothermal method.

Birefringence is a fundamental optical property for linear and nonlinear optical (NLO) materials. Thus far, it has proved to be very difficult to engineer large birefringence in optical crystals functioning in the UV region. Herein, we report the first 2D rare‐earth iodate–nitrate crystal Sc(IO3)2(NO3) (SINO), which is shown to exhibit giant optical anisotropy. Air‐stable SINO possesses a short UV absorption edge (298 nm), a strong NLO response (4.0 times that of benchmark KH2PO4) for the nitrate family, and the largest birefringence (Δn=0.348 at 546 nm) of inorganic oxide optical crystals. The unusually large birefringence and NLO response can be attributed to an optimized 2D layered structure, combined with highly polarizable and anisotropic building units [IO3]− and [NO3]−. These findings will facilitate the development of UV linear and NLO materials with giant optical anisotropy and promote their potential application in optoelectronic devices.

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The exploration of noncentrosymmetric chalcogenides is important for discovering second-oeder nonlinear optical (NLO) materials. We herein report two new gallium thioantimonates, (NH4)2.7Cs1.3Ga4SbS9S0.3O0.7H (GaSbS-I) and Cs4Ga4SbS9S0.3O0.7H (GaSbS-II), which have been successfully synthesized by facile solvothermal methods. GaSbS-I and GaSbS-II are isostructural, and they exhibit a three-dimensional open framework constructed by [Ga4S9Q] units and [SbS3] units. Both two compounds are second harmonic generation (SHG) active with powder SHG efficiencies of 1.2 and 1.4 times that of the benchmark KH2PO4 (KDP) in a non-phase-matching behavior at 1064 nm. The calculated band gaps for GaSbS-I and GaSbS-II are 2.08 and 2.36 eV, respectively, consistent with the experimental values of 2.60 and 2.95 eV. The crystal structures and their optical performance relationship have been clarified by theoretical investigations based on the DFT method.