Abstract Sample of the quaternary phase CuAlGeSe4, a part of I-III-IV-⃞-VI4 semiconductor system, was synthesized by the melt and annealing technique and analyzed using X-ray powder diffraction data. The indexing and refinement of the pattern indicate that this compound crystallizes in the tetragonal system, space group I 4 - ( N 82 ) with unit cell parameters: α = 5.5646(3) Å, c = 10.682(2) Å, V = 330.77(5) Å3. The space group was established from a cationic and anionic distribution analysis in the tetragonal space groups: I 4 - 2 d (N◦ 122), I 4 - 2 2 m (N◦ 121), and I 4 - 2 (N◦ 82), for an ordered structure in this material. The Rietveld refinement, performed with the starting model: Cu 2c, Al 2b, Ge 2d, ⃞2a, and Se 8g, converged to R exp = 7.2%, R P = 7.4%, R wp = 9.6%, and χ 2 = 1.7.

ABSTRACT A novel coordination polymer was synthesized from strontium carbonate and benzylic acid in aqueous solution and is formulated as Sr[(C6H5)4(COCOO)2·2H2O]. This compound was characterized by FTIR spectroscopy and powder X-ray diffraction. The crystal structure was determined by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic P21/n space group, with unit cell parameters a = 15.0224(9) Å, b = 7.5038(6) Å, c = 25.000(2) Å, β = 94.764(2)°, V = 2808.4 Å3, Z = 4. In the structure, the metallic ion is coordinated to eight oxygen atoms, six from benzilate molecules, and two from water molecules, forming a distorted tetragonal antiprism. One of the benzilates is coordinated to the metal in a monodentate fashion (carboxylate only), while the other benzilate molecule does it in the bidentate from carboxylate and hydroxide. Strontium ions form infinite zig-zag chains along the [010] direction, which form a three-dimensional network via O--H···O hydrogen-bond interactions between the coordinated water molecules and the O atoms of the carboxylate groups. The intermolecular interactions were analyzed using Hirshfeld surface analysis.

Abstract Fe2SnSe4 belongs to the adamantine family of quaternary chalcogenides crystallizing in the olivine type structure, which can be described from a hexagonal close-packing of selenium anions with the octahedral and tetrahedral sites occupied by the iron and tin cations, respectively. The structural characterization of the sample, synthesized by the melt and annealing technique, was carried out by powder X-ray diffraction at room temperature. The XRD data analysis shows, that Fe2SnSe4 adopt the orthorhombic olivine type structure, space group Pnma, and unit cell parameters a = 13.2019(3) Å, b = 7.6746(1) Å, c = 6.3572(1) Å, V = 644.11(2) Å3 were derived.

ABSTRACT The title compound, C16H16N2O, a potential antiparasitic agent, crystallizes in the orthorhombic Pca21 space group with unit cell parameters a= 9.912(1) Å, b= 9.035(1) Å, c= 15.681(2) Å. The crystalline structure is stabilized by weak C---H⋯O and C--H⋯Cg(π) interactions among neighboring molecules producing an efficient packing with 66.0% of occupied space. The C--H⋯O hydrogen bond keeps the molecules linked into supramolecular chains propagating along the a axis direction with a graph-set notation C(4), which are reinforced by C--H⋯Cg(π) interactions. Hirshfeld surface analysis of the intermolecular contacts reveal that the most important contributions for the crystal packing are from H⋯H (55.2%) and H⋯C/C⋯H (27.1%) interactions. Energy framework calculations suggest that the contacts formed between molecules are slightly dispersive in nature.

Abstract The crystal structure of the quaternary compound CuVInSe 3, belonging to the system (CuInSe 2) 1 - x(VSe) x with x = 1 / 2, was analyzed using X-ray powder diffraction data. This material was synthesized by the melt and anneal method and crystallizes in the tetragonal space group P 4 ¯2c (N ∘ 112), with unit cell parameters a = 5.7909 ( 4 ) Å, c = 11.625 ( 1 ) Å, V = 389.84 ( 5 ) Å 3. The Rietveld refinement of 25 instrumental and structural variables led to R exp = 6.6%, R p = 8.7 %, R w p = 8.8 % and S = 1.3 for 4501 step intensities, and 153 independent reflections. This compound has a normal adamantane structure and is isostructural with CuFeInSe 3. The DTA indicates that this compound melts at 1332 K.

Chalcogenide alloys CuMnAlSe3, CuMnGaSe3 and CuMnInSe3, new members of the semiconductor system I-II-III-VI3, were synthetized and structurally characterized by the Rietveld method using X-ray powder diffraction data. All compounds crystallize in the tetragonal space group P4 2c (Nº 112) with a CuFeInSe3-type structure.

Se prepararon muestras policristalinas de CuCo2InTe4 and CuNi2InTe4 en su valor nominal por el método de fusión y recocido, y los productos fueron caracterizados por las técnicas de difracción de rayos X y SQUID. Se encontró que CuCo2InTe4 and CuNi2InTe4 cristalizan en una estructura tetragonal, grupo espacial (Nº 121), Z = 2, tipo estannita, con presencia de los binarios CoTe y NiTe como fases secundarias, respectivamente. El comportamiento magnético de CuCo2InTe4 es de tipo superparamagnético con una temperatura de irreversibilidad de ~450K y un campo coercitivo máximo de 35 Oe a 2K; mientras que CuNi2InTe4 presenta dos componentes magnéticas, una diamagnética y otra ferromagnética débil.

Polycrystalline samples of nominal CuCo2InTe4 and CuNi2InTe4 were prepared by the melt and anneal method and the products characterized by powder X-ray diffraction and SQUID techniques. It was found that CuCo2InTe4 and CuNi2InTe4 crystallize in the tetragonal space group (Nº 121), Z = 2, in a stannite-type structure, with the binaries CoTe and NiTe as secondary phases, respectively. The magnetic behavior of CuCo2InTe4 is that of a superparamagnetic state with an irreversibility temperature of ~450K and a maximum coercive field of 35 Oe at 2K; whereas CuNi2InTe4 shows two magnetic components, one diamagnetic an another weak ferromagnetic.

The crystal structure of the chalcogenide compounds CuCo2InTe4 and CuNi2InTe4, two new members of the I-II2-III-VI4 family, were characterized by Rietveld refinement using X-ray powder diffraction data. Both materials crystallize in the tetragonal space group I4 2m (No. 121), Z = 2, with a stannite-type structure, with the binaries CoTe and NiTe as secondary phases.

Los calcogenuros ternarios AgInSe2 y AgInTe2 se estudiaron mediante refinamiento Rietveld utilizando datos de difracción de rayos-X en muestras policristalinas. Ambos compuestos cristalizan con una estructura tipo calcopirita en el grupo espacial I <img border=0 width=9 height=15 src="http:/img/fbpe/rlmm/v35n1/art14raya4.gif">2d, (N° 122), Z = 4, y parámetros de celda unidad a = 6.0988(2) Å, c = 11.7086(6) Å, V = 435.51(3) ų para AgInSe2 y a = 6.4431(4) Å, c = 12.6362(9) Å, V = 524.57(6) ų para AgInTe2. Se reportan mejores datos de difracción de polvo con figuras de mérito M19 = 84.0, F19 = 40.7 (0.0071, 66) para AgInSe2, y M20 = 80.8, F23 = 39.0 (0.0075, 79) para AgInTe2.

The ternary chalcogenides AgInSe2 and AgInTe2 were studied by X-ray powder diffraction structure refinement using the Rietveld method. Both compounds crystallizes with a chalcopyrite structure in the space group I <img border=0 width=9 height=15 src="http:/img/fbpe/rlmm/v35n1/art14raya4.gif">2d (N° 122), Z = 4, and unit cell parameters a = 6.0988(2) Å, c = 11.7086(6) Å, V = 435.51(3) ų for AgInSe2 and a = 6.4431(4) Å, c = 12.6362(9) Å, V = 524.57(6) ų for AgInTe2. Improved X-ray powder diffraction data are reported with figures of merit M19 = 84.0, F19 = 40.7 (0.0071, 66) for AgInSe2, and M20 = 80.8, F23 = 39.0 (0.0075, 79) for AgInTe2.

El compuesto semiconductor ternario Cu2GeSe4 ha sido caracterizado mediante difracción de rayos-X en muestras policristalinas y refinado por el método Rietveld. Este compuesto cristaliza en el sistema cúbico, grupo espacial F <img border=0 width=9 height=15 src="http:/img/fbpe/rlmm/v35n1/art05raya4.gif">3m (N° 216), Z = 1, con parámetros de celda unidad a = 5.5815(3) Å y V = 173.88 (3) ų. El refinamiento de 10 parámetros instrumentales y estructurales convergió a las figuras de mérito Rp= 4.4%, Rwp= 6.8%, Rexp= 5.5%, R B= 6.0% y S= 1.2 para 4001 intensidades y 28 reflexiones independientes. La estructura del Cu2GeSe4 pude ser descrita como derivada de la blenda de zinc donde los átomos de Zn están reemplazados por átomos de Cu y Ge, y por vacancias catiónicas.

The ternary semiconductor compound Cu2GeSe4 has been characterized by means of X-ray powder diffraction and refined by the Rietveld method. This compound crystallizes in the cubic system, space group F <img border=0 width=9 height=15 src="http:/img/fbpe/rlmm/v35n1/art05raya4.gif">3m (Nº 216), Z = 1, with unit cell parameters a = 5.5815(3) Å and V = 173.88 (3) ų. The refinement of 10 instrumental and structural parameters converged to the figures of merit Rp= 4.4%, Rwp= 6.8%, Rexp= 5.5%, R B= 6.0% and S= 1.2 for 4001 step intensities and 28 independent reflections. The Cu2GeSe4 structure can be described as derivative of the zincblende where Zn atoms are replaced by Cu and Ge atoms, and cationic vacancies.

Se sintetizaron nanopartículas de ferritas de cobalto (CoFe2O4) usando polietilenglicol como surfactante en un sistema de reflujo simple y posteriormente se trataron térmicamente desde 200°C hasta 800°C en atmosfera de N2. Las muestras se caracterizaron utilizando: Difracción de rayos X, Espectroscopia Infrarroja con Transformada de Fourier, Microscopía Electrónica de Barrido, Microscopía Electrónica de Transmisión, Termogravimetría, Calorimetría Diferencial de Barrido, Área superficial y Magnetometría de Muestra Vibrante. Se obtuvieron nanopartículas que cristalizan con una estructura cúbica tipo espinela, un tamaño promedio entre 9 y 102 nm y un área superficial entre 77.6 y 14.9 m²/g. Las medidas de magnetización en función del campo aplicado verificaron la marcada influencia de las condiciones de síntesis sobre el tamaño de la partícula y por lo tanto sobre las propiedades magnéticas. La magnetización a campo máximo M(H) muestra curvas de histéresis que no saturan al máximo campo utilizado, alcanzando una magnetización máxima de 44,62 emu/g.

Cobalt ferrite (CoFe2O4) nanoparticles were synthesized using polyethyleneglycol as surfactant in a simple reflux system and subsequently heat treated from 200°C to 800°C in N2 atmosphere. The samples were characterized using: X-ray diffraction, Infrared spectroscopy, Scanning electron microscopy, Transmission electron microscopy, Thermogravimetry, Differential scanning calorimetry, surface area and Vibrating sample magnetometry. Nanoparticles obtained crystallize with a spinel type cubic structure and an average size between 9 and 102 nm and a surface area between 77.6 and 14.9 m²/g. Magnetization measurements versus applied field verified the strong influence of synthesis conditions on the particle size and therefore on the magnetic properties. The maximum field magnetization M(H) shows hysteresis loops that not saturate at the maximum field applied, reaching a maximum magnetization of 44.62 emu/g.