Zur Oxydation intermetallischer Phasen: Die Oxoplumbate(II) K6[Pb2O5] [1] und K4[PbO3] [2]

On the Oxidation of Intermetallic Phases: The Oxoplumbates(II) K₆[Pb₂O₅] [1] and K₄[PbO₃] [2] Very pale yellow crystals of K₆[Pb₂O₅] were obtained by heating a wellground mixture of LiPb und K₂O₂ (K₂O₂: LiPb = 2.5:1) in Ag-tubes (550°C; 40 d). The crystal structure, triclinic, space group P1 , a = 1 326.7(6); b = 758.8(4); c = 637.0(3) pm; α = 92.17(3)°; β = 94.41(3)°; γ = 112.85(4)°; Z = 2 was determined (four-circle diffractometer data, Mo? K, 3 270 I_o(hkl), R = 8.0%, R_w = 3.5%, parameters see text). The pale yellow crystals of K₄[PbO3] were received by heating KPb and K₂O₂ (K₂O₂: KPb = 3.3:2) in Ni-tubes (450°C; 17 d). The crystal structure (orthorhombic, space group Pbca with a = 658.2(1); b = 1 131.8(4); c = 1 872.2(6) pm; Z = 8) was refined (four-circle diffractometer data, Mo? K, 2 003 I_o(hkl), R = 4.9%, R_w = 2.8%). The Madelung Part of Lattice Energy (MAPLE), Effective Coordination Numbers (ECoN), the Mean Fictive Ionic Radii (MEFIR) and the Charge Distribution (CHARDI) are being calculated for both oxides.     

Über Cs2Li2[GeO4]

About Cs₂Li₂[GeO₄] By heating of a well-ground mixture of the binary oxides CsO_0.55, Li₂O and GeO₂ (Cs:Li:Ge=2,6:2,2:1; Ni-tube; 600 °C; 49d) we got single crystals of Cs₂Li₂[GeO₄] for the first time. Cs₂Li₂[GeO₄] is isotypic to Rb₂Li₂[MO₄] [M = Si, Ti, Ge] [2] and Cs₂Li₂[MO₄] (M = Si, Ti) [3]: according to this Cs₂Li₂[GeO₄] crystallizes triclinic, in the spacegroup P1 with a = 968.7(4) pm, b = 586.0(2) pm, c = 571.4(2) pm, α = 92.71(4)°, β = 110.95(3)° and γ = 94.34(4)° (Guinier-Simon data), Z = 2. The structure was determined by four-circle diffractometer data (Ag? K_α ; 2381 I_o(hkl); R = 8,4%; R_w = 5.0%), parameters see text. Further the Madelung Part of Lattice Energy (MAPLE), Effective Coordination Numbers (ECoN) and the Mean Fictive Ionic Radii (MEFIR), have been calculated.     

Ein neuer Strukturtyp bei Oxoiridaten mit quadratisch-planaren [IrO4]4−-Gruppen: K2Na2[IrO4], ein Raumnetz [Na2IrO4] mit Kanälen. (Mit einer Anmerkung zu Rb2Na2[IrO4])

A New Type of Structure in Oxoiridates with Square-planar Groups [IrO₄]^4?: K₂Na₂[IrO₄], a Network [Na₂IrO₄] with Channels (With a Remark on Rb₂Na₂[IrO₄]) For the first time magnificent dark red cuboid single crystals of K₂Na₂[IrO₄] were prepared by annealing intimate mixtures of a) KO_0.51, Na₂O₂, IrO₂ and Ir-powder (molar proportions 3.02 : 1.40 : 1.00 : 1.00; Ag-bomb, 740°C, 54 d) and of b) KO_0.51, Na₂O and IrO₂ (molar proportions K : Na : Ir = 2.20 : 2.20 : 1.00; Ag-bomb, 760°C, 57 d) respectively. The oxide crystallizes mP36, space group P2₁/c with a = 600.35(6) pm, b = 1111.2(1) pm, c = 933.0(1) pm and β = 113.14(1)°. Structure determination via four-circle diffractometer data (Siemens AED 2, Mo-Kα-Radiation) for all 2347 unique reflexions (merged from 9397 I_o(hkl) gave R = 0.0357 and R_w = 0.0340. K₂Na₂[IrO₄] crystallizes in a new type of structure. The oxide is antiferromagnetic as magnetic measurements showed (T_N = 32 K, Θ = ?60.2 K (single crystals) and ?49.2 K (powder) respectively, μ = 3.06 μ_B (single crystals) and 2.93 μ_B (powder) respectively). Effective coordination numbers ECoN, mean fictive ionic radii MEFIR and the Madelung part lattice energy MAPLE as well as the charge distributions CHARDI and CHARDINO are calculated and discussed.     

Thermal properties of tetraethylammonium tetrachloro-, bromotrichloro-and tribromochloroferrates(III)

A new synthesized 4CN type azomonoether, exhibiting dying properties, crystalline nature and generating interest as a material for non-linear optical applications was investigated. Modern devices incorporating liquid crystals tend to use thin films of such materials because of their special characteristics. Thermal stability studies are indispensable before attempting any deposition experiment. We have investigated the thermal behaviour of 4-[(4-chlorobenzyl)oxy]-4′-cyano-azobenzene (TG, DTG, DTA and DSC) in inert flow atmosphere, under non-isothermal conditions. The phase transitions were studied by repeated heating-cooling regimes, with intercalated isothermal steps. The thin films were deposited on silicon and quartz substrates by matrix assisted pulsed laser evaporation (MAPLE) using a Nd:YAG laser working at 266 nm. FTIR spectroscopy of the obtained thin films confirmed the preservation of the compound’s structure.     

计算幂和多项式的矩阵方法

利用矩阵给出了计算幂和多项式的统一方法.     

Thin films of Cu(II)-o,o′-dihydroxy azobenzene nanoparticle-embedded polyacrylic acid (PAA) for nonlinear optical applications developed by matrix assisted pulsed laser evaporation (MAPLE)

Thin films based on two different metal-organic systems are developed by MAPLE and their nonlinear optical applications are explored. A complex of o,o′-dihydroxy azobenzene with Cu²⁺ cation is found to organize as a non-central symmetric crystallite. A simple protocol is developed for the in situ fabrication of highly monodisperse copper-complex nanoparticles in a polymer film matrix of polyacrylic acid. The thin films were deposited on quartz substrates by MAPLE (matrix assisted pulsed laser evaporation) using a Nd:YAG laser working at 355 nm. Atomic force microscopy (AFM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and optical second harmonic generation (SHG) were performed on the samples. The optical limiting capability of the nanoparticle-embedded polymer film is investigated.     

High fluence deposition of polyethylene glycol films at 1064 nm by matrix assisted pulsed laser evaporation (MAPLE)

Matrix assisted pulsed laser evaporation (MAPLE) has been applied for deposition of thin polyethylene glycol (PEG) films with infrared laser light at 1064 nm. We have irradiated frozen targets (of 1 wt.% PEG dissolved in water) and measured the deposition rate in situ with a quartz crystal microbalance. The laser fluence needed to produce PEG films turned out to be unexpectedly high with a threshold of 9 J/cm², and the deposition rate was much lower than that with laser light at 355 nm. Results from matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis demonstrate that the chemistry, molecular weight and polydispersity of the PEG films were identical to the starting material. Studies of the film surface with scanning electron microscopy (SEM) indicate that the Si-substrate is covered by a relatively homogenous PEG film with few bare spots.     

Matrix completion problems of block type

The solvability, either unconditional or under certain conditions, is proved for three matrix completion problems of block type. Being a problem of block type means that a matrixA must be constructed with a prescribed characteristic polynomial and one or several blocks in a 2 × 2 partition also prescribed. For the problems under analysis, one prescribes, respectively, (a) the blockA ₁₂; (b) the blockA ₁₁; (c) the blocksA ₁₁ andA ₁₂. We discuss our experience in implementing the algorithms that solve the problems above as procedures in the symbolic computation system MAPLE. Translated fromMatematicheskie Zametki, Vol. 67, No. 6, pp. 863–873, June, 2000. The first author was supported by the Russian Foundation for Basic Research under grant No. 97-01-00927.     

Oxydation intermetallischer Phasen: K4{Na2[Tl2O6]} aus NaTl und K2O2

Oxidation of Intermetallic Phases: K₄{Na₂[Tl₂O₆]} from NaTl and K₂O₂ The hitherto unknown K₄{Na₂[Tl₂O₆]} was prepared in form of transparent, yellow single crystals from NaTl and KO_1,08 (molar ratio 1:1.3; sealed Ag-cylinder; 450°C, 30 d). The structure determination (four-circle diffractometer, MoKα, 1 280 out of 1 523 I_o(hkl), R = 5.75%, R_w = 4.58%) confirms the space group P2₁/c with a = 641.3 pm, b = 691.1 pm, c = 1188.5 pm, β = 95.69° and Z = 2. As characteristic building units of the structure there are doubles of tetrahedra of [Tl₂O₆] and [Na₂O₆]. The compound is isotypic with Cs₆[In₂O₆] and Rb₆[Tl₂O₆]. The Madelung Part of Lattice Energy, MAPLE, the Mean Fictive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN, and Charge Distribution, CHARDI, are calculated.     

Das erste gemischt-valente Oxocobaltat(I,II): Rb5Co2O4 [1]

A New Mixed-Valent Oxide of Cobalt(I, II): Rb₅Co₂O₄ For the first time we obtained a new mixed-valent oxide of mono- and divalent Cobalt. Black-red single-crystals of Rb₅Co₂O₄ were prepared by heating powders of “Rb₆CdO₄” in closed Co-cylinders at 500° during 48 days. Structure solution and refinement are covered by two measurements with four-circle diffractometers. MoKα : 2 145 I_o(hkl), out of 2 818 I_o(hkl), R = 9.85%, R_w = 5.93% AgKα : 1 813 I_o(hkl) out of 4 007 I_o(hkl), R = 9.46%, R_w = 6.51%) and confirm the space-group P1 . The lattice constants are a = 696.4(1) pm, b = 922.2(3) pm, c = 958.9(3) pm , α = 117.99(2)°, β = 89.96(2)°, γ h= 108.12(2)°, Z = 2 According to its composition Rb₁₀[OCoO]₂[OCoO₂CoO] the structure is built up by two Co atoms of chemically and crystallographically different nature. We find isolated dumb-bell-like anions [O? Co? O]^3? being already known with monovalent Co (e. g. K₃CoO₂) together with units [OCoO₂CoO]^4? of two connected triangles CoO₃ being well-known from K₂BeO₂ ? K₄[Be₂O₄]. ECoN/mEFIR calculations are made starting with values obtained by a new procedure called “MEFIR-FIT”.