Influence of the Cation Size on the Framework Structures and Space Group Centricities in AMo(2)O(5)(SeO3)(2) (A = Sr, Pb, and Ba)

Department of Chemistry, Chung-Ang University, 221 Heukseok-dong, Dongjak-gu, Seoul 156-756, Republic of Korea.
Inorganic Chemistry (Impact Factor: 4.76). 04/2012; 51(9):5393-9. DOI: 10.1021/ic3003564
Source: PubMed


Two new quaternary mixed-metal selenites, SrMo(2)O(5)(SeO(3))(2) and PbMo(2)O(5)(SeO(3))(2), have been synthesized as crystals and pure polycrystalline phases by standard solid-state reactions using SrMoO(4), PbO, MoO(3), and SeO(2) as reagents. The crystal structures of the reported materials have been determined by single-crystal X-ray diffraction. SrMo(2)O(5)(SeO(3))(2) and PbMo(2)O(5)(SeO(3))(2) are isostructural and crystallized in the triclinic centrosymmetric space group P1̅ (No. 2). The reported materials exhibit chain structures consisting of MoO(6) octahedra and asymmetric SeO(3) polyhedra. Complete characterizations including IR spectroscopy and thermal analyses for the compounds are also presented, as are dipole moment calculations. In addition, the powder second-harmonic-generating (SHG) properties of noncentrosymmetric polar BaMo(2)O(5)(SeO(3))(2) have been measured using 1064 nm radiation. Through powder SHG measurement, we are able to determine that BaMo(2)O(5)(SeO(3))(2) has a SHG efficiency of approximately 80 times that of α-SiO(2). Additional SHG measurements reveal that the material is phase-matchable (type 1). A detailed cation size effect on the symmetry and framework structure is discussed.

8 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new family of quaternary alkali-metal indium selenites, AIn(SeO(3))(2) (A = Na, K, Rb, and Cs) have been synthesized, as crystals and pure polycrystalline phases through standard solid-state and hydrothermal reactions. The structures of the reported materials have been determined by single-crystal X-ray diffraction. While AIn(SeO(3))(2) (A = Na, K, and Rb) crystallize in the orthorhombic space group, Pnma, with three-dimensional framework structures, CsIn(SeO(3))(2) crystallizes in the trigonal space group, R3m, with a two-dimensional structure. All of the reported materials, however, share a common structural motif, a network of corner-shared InO(6) octahedra and SeO(3) groups. Interestingly, the size of the alkali-metal cations profoundly influences the bonding nature of the SeO(3) group to the InO(6) octahedra. Complete characterizations including infrared spectroscopy, elemental analyses, and thermal analyses for the compounds are also presented, as are dipole moment calculations. A detailed cation size effect on the framework structure is discussed.
    Inorganic Chemistry 07/2012; 51(15):8530-7. DOI:10.1021/ic301316r · 4.76 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: New quaternary lithium-d(0) cation-lone-pair oxides, Li(6)(Mo(2)O(5))(3)(SeO(3))(6) (Pmn2(1)) and Li(2)(MO(3))(TeO(3)) (P2(1)/n) (M = Mo(6+) or W(6+)), have been synthesized and characterized. The former is noncentrosymmetric and polar, whereas the latter is centrosymmetric. Their crystal structures exhibit zigzag anionic layers composed of distorted MO(6) and asymmetric AO(3) (A = Se(4+) or Te(4+)) polyhedra. The anionic layers stack along a 2-fold screw axis and are separated by Li(+) cations. Powder SHG measurements on Li(6)(Mo(2)O(5))(3)(SeO(3))(6) using 1064 nm radiation reveal a SHG efficiency of approximately 170 × α-SiO(2). Particle size vs SHG efficiency measurements indicate Li(6)(Mo(2)O(5))(3)(SeO(3))(6) is type 1 nonphase-matchable. Converse piezoelectric measurements result in a d(33) value of ∼28 pm/V and pyroelectric measurements reveal a pyroelectric coefficient of -0.43 μC/m(2)K at 50 °C for Li(6)(Mo(2)O(5))(3)(SeO(3))(6). Frequency-dependent polarization measurements confirm that Li(6)(Mo(2)O(5))(3)(SeO(3))(6) is nonferroelectric, i.e., the macroscopic polarization is not reversible, or 'switchable'. Infrared, UV-vis, thermogravimetric, and differential thermal analysis measurements and electron localization function calculations were also done for all materials.
    Inorganic Chemistry 08/2012; 51(17):9529-38. DOI:10.1021/ic301334c · 4.76 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A transparent ZnTeMoO6 crystal with dimensions of ~12 × 10 × 1 mm3 has been successfully grown using the flux method. Single-crystal X-ray diffraction analysis reveals that ZnTeMoO6 features a neutral layered structure consisting of three types of asymmetric building units, i.e. TeO4 polyhedra with stereoactive lone pair, MoO4 tetrahedra and ZnO6 octahedra with large polar displacement. The ZnTeMoO6 crystal is non-hygroscopic, and resistant to diluted HNO3 aqua-solution. It is also thermally stable up to 669 ℃ and thereafter melts incongruently. Transmittance spectra of ZnTeMoO6 show a broad transparent window in the range of 350 nm–5.4 µm. On the basis of the powder second-harmonic generation (SHG) measurements, ZnTeMoO6 is type-Ι phase-matchable with a very strong SHG efficiency of ~10.5 × KDP. Furthermore, calculations on the dipole moments indicate that the strong SHG response may be arising from the three types of asymmetric building units.
    RSC Advances 05/2013; 3(33):-. DOI:10.1039/C3RA40247A · 3.84 Impact Factor
Show more