Small Changes, Big Impact: Tungsten Bronzes with Extremely Large Second Harmonic Generation Achieved by the Transition Metal Doping on the B‐Site

Abstract

Two novel transition metal-doped tungsten bronze oxides, Pb 2.15 Li 0.85 Nb 4.85 Ti 0.15 O 15 (PLNT) and Pb 2.15 Li 0.55 Nb 4.85 W 0.15 O 15 (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, Pmn2 1 (no. 31). As a class of tungsten bronze oxide, PLNT and PLNW retain a unique rigid framework composed of d 0 transition metal cation (Ti 4+ or W 6+ )-doped highly distorted NbO 6 octahedra along with the subsequently generated Pb/LiO 12 and PbO 15 polyhedra. Interestingly, the d 0 transition metal-doped tungsten bronzes, PLNT and PLNW, exhibit extremely large second-harmonic generation (SHG) responses of 56 and 67 × KH 2 PO 4 , respectively. The observed immeasurably strong SHG is mainly attributed to a net polarization originating from the alignment of highly distorted NbO 6 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.

MB3P2S10 (M = Rb, Cs): two new alkali metal thioboratephosphates with [B6P4S20] T3-supertetrahedra

“…To uncover their electronic structures and optical properties, DFT calculations were carried out. 73,74 As shown in Fig. 4c and d, the band structures indicate that the two compounds are direct band gap semiconductors with calculated GGA band gaps of 2.42 eV for RbB 3 P 2 S 10 and 2.38 eV for CsB 3 P 2 S 10 .…”

Role of Incommensurate Modulation in Ba4(Sm1–xLax)2Ti4Nb6O30 Tetragonal Tungsten Bronzes

“…As an important ferroelectric family next to perovskites, tetragonal tungsten bronzes (TTBs) have been attracting rising attention. Recently, a series of work has emerged on various applications of tungsten bronze ferroelectrics with remarkable performance, including enhancing energy storage properties, , giant piezoresponse, large second-harmonic generation responses, and even enhanced cycling stability, as anodes for ion batteries. , On the other hand, the unique ferroelectric behavior and polarization mechanism of tungsten bronze oxides have received sustained scientific attention, and a number of outstanding research works have been reported recently.…”

Breaking the bottleneck of simultaneously wide band gap and large nonlinear optical coefficient by a “pore reconstruction” strategy in a salt-inclusion chalcogenide

“…Such a significant NLO technology has been deployed skillfully in numerous cutting-edge fields. [1][2][3][4][5][6][7][8] For an optical application in the mid-far infrared (IR) transmission region, all the dominated NLO crystals, including AgGaS 2 (AGS), AgGaSe 2 (AGSe), and ZnGeP 2 , can have desirable second harmonic generation (SHG) responses. 9 Regrettably, the stubborn drawbacks of low laser-induced damage threshold (LIDT), narrow range of phase-matchable wavelength, and detrimental multiple-phonon absorption occur in the above-mentioned crystals, respectively, thereby hindering their high-power laser applications.…”