LnBSb₂O₈ (Ln = Sm, Eu, Gd, Tb): A Series of Lanthanide Boroantimonates with Unusual 3D Anionic Structures

A series of lanthanide boroantimonates, namely, LnBSb₂O₈ (Ln = Sm <b>1</b>, Eu <b>2</b>, Gd <b>3</b>, and Tb <b>4</b>) have been successfully synthesized by high temperature solid-state reactions for the first time. They are isostructural and feature novel three-dimensional (3D) frameworks composed of 2D [Sb₃O₁₂]^9– layers interconnected by 1D [SbBO₇]^6– chains with remaining BO₃ groups hanging on the walls of the 1D 6-membered-ring (MR) tunnels along the <i>a</i>-axis, and the lanthanide ions filled in the voids of the anionic structure. They exhibit high thermal stability (up to 900 °C). Luminescent studies suggest that compounds <b>1, 2,</b> and <b>4</b> have potential application as orange, red, and green light luminescent materials, respectively. Magnetic measurements reveal ferromagnetic coupling interactions in compound <b>3</b> and antiferromagnetic coupling interactions between magnetic centers in compounds <b>1</b>, <b>2</b>, and <b>4</b>

A Series of Mixed-Metal Germanium Iodates as Second-Order Nonlinear Optical Materials

A series of new compounds in the A/Ae-Ge⁴⁺-IO₃ system, namely, A₂Ge­(IO₃)₆ (A = Li, Na, Rb, or Cs) and BaGe­(IO₃)₆(H₂O), have been obtained by introducing GeO₆ octahedra into a ternary metal iodate system. The structures of all five new compounds feature a zero-dimensional [Ge­(IO₃)₆]^2– anion composed of a GeO₆ octahedron connecting with six IO₃ groups, the alkali or alkali-earth cations acting as spacers between these anions and maintaining charge balance. Interestingly, the isomeric Li₂Ge­(IO₃)₆ and Na₂Ge­(IO₃)₆ are noncentrosymmetric (NCS), whereas the isostructural Rb₂Ge­(IO₃)₆ and Cs₂Ge­(IO₃)₆ are centrosymmetric. BaGe­(IO₃)₆(H₂O) is the first NCS alkali-earth germanium iodate reported. Powder second-harmonic generation (SHG) measurements show that Li₂Ge­(IO₃)₆, Na₂Ge­(IO₃)₆, and BaGe­(IO₃)₆(H₂O) crystals are phase-matchable and display very large SHG signals that are approximately 32, 15, and 12 times that of KH₂PO₄, respectively, under 1064 nm radiation and 2, 0.8, and 0.8 times that of KTiOPO₄, respectively, under 2.05 mm laser radiation. The compounds show high thermal stability and a large laser damage threshold, indicating their potential applications as nonlinear optical (NLO) materials in visible and infrared spectral regions. Measurement of optical properties, thermal analysis, and theoretical calculations of the SHG origin have been performed. Our studies indicate that introducing non-second-order Jahn–Teller-distortive MO₆ octahedra into metal iodate systems can also lead to good mixed-metal iodate NLO materials

A Series of Mixed-Metal Germanium Iodates as Second-Order Nonlinear Optical Materials

A series of new compounds in the A/Ae-Ge⁴⁺-IO₃ system, namely, A₂Ge­(IO₃)₆ (A = Li, Na, Rb, or Cs) and BaGe­(IO₃)₆(H₂O), have been obtained by introducing GeO₆ octahedra into a ternary metal iodate system. The structures of all five new compounds feature a zero-dimensional [Ge­(IO₃)₆]^2– anion composed of a GeO₆ octahedron connecting with six IO₃ groups, the alkali or alkali-earth cations acting as spacers between these anions and maintaining charge balance. Interestingly, the isomeric Li₂Ge­(IO₃)₆ and Na₂Ge­(IO₃)₆ are noncentrosymmetric (NCS), whereas the isostructural Rb₂Ge­(IO₃)₆ and Cs₂Ge­(IO₃)₆ are centrosymmetric. BaGe­(IO₃)₆(H₂O) is the first NCS alkali-earth germanium iodate reported. Powder second-harmonic generation (SHG) measurements show that Li₂Ge­(IO₃)₆, Na₂Ge­(IO₃)₆, and BaGe­(IO₃)₆(H₂O) crystals are phase-matchable and display very large SHG signals that are approximately 32, 15, and 12 times that of KH₂PO₄, respectively, under 1064 nm radiation and 2, 0.8, and 0.8 times that of KTiOPO₄, respectively, under 2.05 mm laser radiation. The compounds show high thermal stability and a large laser damage threshold, indicating their potential applications as nonlinear optical (NLO) materials in visible and infrared spectral regions. Measurement of optical properties, thermal analysis, and theoretical calculations of the SHG origin have been performed. Our studies indicate that introducing non-second-order Jahn–Teller-distortive MO₆ octahedra into metal iodate systems can also lead to good mixed-metal iodate NLO materials

Acentric La₃(IO₃)₈(OH) and La(IO₃)₂(NO₃): Partial Substitution of Iodate Anions in La(IO₃)₃ by Hydroxide or Nitrate Anion

Partial substitution of iodate anions in La­(IO₃)₃ by OH^– or NO₃^– anion led to acentric La₃(IO₃)₈(OH) and chiral La­(IO₃)₂(NO₃). The structure of La₃(IO₃)₈(OH) can be seen as a complex three-dimensional (3D) network composed of two-dimensional [La₃(IO₃)₂(OH)]⁶⁺ cationic layers that are further bridged by remaining iodate anions, or alternatively as a 3D network composed of one-dimensional [La₃(IO₃)₆(OH)]²⁺ cationic columns being further interconnected by additional iodate anions, while the structure of La­(IO₃)₂(NO₃) can be seen as a novel 3D structure with planar NO₃ groups serving as linkage between the [La₃(IO₃)₆]³⁺ triple layers. Compared to La­(IO₃)₃, both compounds show considerably wide band gaps and enhanced thermal stability. La­(IO₃)₂(NO₃) shows a moderate second harmonic generation (SHG) response of ∼0.6 times that of KDP (KH₂PO₄), a wide band gap of 4.23 eV, and a high LDT value (22 × AgGaS₂). Optical property measurements, thermal analysis, as well as theoretical calculations on SHG origin, were performed. It can be deduced that partial substitution of iodate anions can be a facile route to design new noncentrosymmetric metal iodates with novel structure and potential application

Two Barium Gold Iodates: Syntheses, Structures, and Properties of Polar BaAu(IO₃)₅ and Nonpolar HBa₄Au(IO₃)₁₂ Materials

Two new barium gold iodates, namely, BaAu­(IO₃)₅ and HBa₄Au­(IO₃)₁₂, have been prepared. BaAu­(IO₃)₅ crystallizes in the polar space group <i>Pca</i>2₁, whereas HBa₄Au­(IO₃)₁₂ crystallizes in the centrosymmetric space group <i>P</i>2₁/<i>c</i>. BaAu­(IO₃)₅ consists of unique polar [Au­(IO₃)₄]⁻ anions whose four iodate groups are located at both sides of the AuO₄ plane and the polarity points in the [001̅] direction. BaAu­(IO₃)₅ displays strong second-harmonic-generation (SHG) effects about 0.6KTiOPO₄ (KTP) and is phase-matchable. Thermal properties, optical spectra analyses, and theoretical calculations are also reported