Publicaciones: Nanocomposites Multifuncionales

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07

Dec 2018

Synthesis, crystal structure, characterizations and magnetic study of a novel two-dimensional iron fluoride

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A new hybrid compound formulated as [Fe3F8(H2O)2](Am2TAZ)2 (Am2TAZ= 3,5-diamino-1,2,4-triazole) was prepared under hydrothermal conditions. The crystal structure was solved by single-crystal X-ray diffraction and the bulk was characterized by thermal analyses (TG-MS), vibrational spectroscopy (FTIR, Raman), Ultraviolet-visible spectroscopy (UV–Vis), and scanning electron microscopy (SEM-EDX). It crystallizes in the triclinic system space group P with unit cell parameters a= 7.100(2) Å, b= 7.658(2) Å, c= 8.321(2) Å, α = 107.330(20)°, β = 111.842(18)°, γ = 93.049(17)°, Z = 1 and V= 394.01(17) Å3. The studied X-ray crystal structure shows the two oxidation states for iron atoms (Fe2+, Fe3+) and generates a 2D inorganic network, built up of inorganic layers constructed from infinite inorganic chains running along a axis. In fact, these chains are connected via (Fe3+(3)F6) octahedral. OW-H…F and N-H…F hydrogen bonds, making up the whole 3D network, are strongly linked in the layers. Magnetization measurements were performed, exhibiting the paramagnetic feature of the studied compound above 150 K.

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07

Dec 2018

Synthesis, crystal structure, thermal analysis, dielectric properties and electrical conduction mechanisms of the new mixed solid solution of thallium rubidium sulfate selenate tellurate

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The new mixed compound Tl1.90Rb0.10(SO4)0.92(SeO4)0.08Te(OH)6 (TlRbSSeTe) has been synthesized in order to determine the temperature transitions and to specify the electrical properties as well as the conduction mechanism. It is obtained by slow evaporation at room temperature and prove to crystallize in the monoclinic system with P21/c space group using X-ray diffractometer data. The basic property of these atomic arrangements is the coexistence of three different anions (, and groups) in the unit cell, related by O−H…O hydrogen bonds building up the crystal. Thermal analysis (DSC, DTA and TG) of the title compound confirms the presence of the phase transitions and the temperature of the decomposition of the studied salt. In order to characterize the phase transitions, Raman spectra have been recorded at various temperatures in the wavenumber range from 50–1200 cm−1. Detailed dielectric and electrical properties of the material have been analyzed as a function of frequency (100 Hz–10 MHz) and temperature (383–518 K). Besides, the analysis of Nyquist plots were well fitted to an equivalent circuit consisting of a series of combination of grains and grain boundary elements. The variation of the DC and AC conductivity confirms all the transitions of our sample. Furthermore, The frequency dependence of alternative current (AC) conductivity is interpreted in terms of Jonscher’s law (developed). The alternative current (AC) electrical conduction in TlRbSSeTe material is accounted for in terms of two processes that can be assigned to a hopping transport mechanism. These processes are the correlated barrier hopping (CBH) model in some regions, as well as the non-overlapping small polaron tunneling (NSPT) model in the other regions. The conduction mechanism for each phase is determined with the help of Elliot’s theory.

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04

Dec 2018

Structure characterization, photoluminescence and dielectric properties of a new hybrid compound containing chlorate anions of zincate (II)

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A new hybrid compound, bis (2-aminophenylenamonium) tetrachlorozincate (II), was synthesized and formulated as (C6H9N2)2ZnCl4. Its crystal structure was solved by single crystal X-ray diffraction reveling that compound crystallizes in the monoclinic system, space group C2/c (N: 15) with cell parameters a ¼ 7.4957(4) Å, b ¼ 25.6837(15) Å, c ¼ 9.4041(5) Å, b ¼ 94.35(0), V ¼ 1805.23(45) Å3 . Their atomic arrangement can be described as an alternation of inorganic and organic layers, [ZnCl4] 2- tetrahedral anions and 2-aminophenylenamonium cations. The cohesion of the atomic arrangement is ensured by hydrogen bonds (strong NeH/N and weak NeH/Cl) and p-p stacking interactions between identical antiparallel organic moieties. In optical transmission and photoluminescence measurements, this material exhibit two absorption bands (253 and 316 nm) and a strong emission line (390 nm), while the thermal analysis disclosed a phase transition at 420e445 K previously to the sample decomposition at 476 K. Finally, electrical measurements were performed to discuss the phase-transition mechanism.

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