Aracely Hernandez

Preparation of ternary compound Ba3Li2Ti8O20 by the sol–gel process

Abstract In this work, we have synthesized the compound Ba 3 Li 2 Ti 8 O 20 by the sol–gel method using titanium isopropoxide, barium isopropoxide and lithium acetate salt as precursors reactants. Ethanol was used as solvent and the reaction was carried out at pH 3 using glacial acetic acid as catalyst. The synthesized products were thermally treated at different temperatures and characterized by infrared (IR) spectroscopy, X-ray diffraction and thermal analysis. The crystalline phase Ba 3 Li 2 Ti 8 O 20 was achieved by heating the obtained gel at 800°C for 6 h, which represents a lower temperature and smaller reaction time than reported through the solid-state reaction method, which use temperatures of 1150–1200°C for 2–10 days.

Conductivity and viscosity behavior of asymmetric phosphonium iodides.

In this work, we report the physicochemical properties of a variety of aliphatic phosphonium iodide (API) salts, including thermal degradation. Also, we compared the conductivity, viscosity, and fragility behavior of APIs to similar molten systems and related these properties to their structure. Our investigation has found that APIs have an intermediate fragility behavior. We plotted the conductivity and viscosity data of APIs according to Waldens rule and found that they can be classified as an associated ionic liquid (AIL), an intermediate between a true ionic liquid and a molecular species. Lastly, we correlated the structure and behavior of APIs and similar polarizable anions, such as the diacetamide anion.

Synthesis of Ba3Li2Ti8O20 sol–gel at basic conditions

Abstract The compound Ba 3 Li 2 Ti 8 O 20 was synthesized by the sol–gel method in the presence of ammonium hydroxide as hydrolysis catalyst. The precursors used were titanium isopropoxide, barium sopropoxide and lithium acetate salt. Portions of the gel obtained were annealed at different temperatures. The samples were characterized by IR spectroscopy, X-ray diffraction and thermal analysis. The hydrolysis process depends on the pH. The gel prepared at basic pH is formed in shorter time and it is less hydroxylated than at acidic conditions. The samples were probed as catalysts on the isopropanol decomposition, yielding propylene and acetone which is indicative of acidic and basic sites in the solid.

Photocatalytic properties of Ba3Li2Ti8O20 sol–gel

Samples of Ba3Li2Ti8O20 were prepared by the sol–gel method at pH 3 and 9 using acetic acid and ammonia hydroxide respectively as hydrolysis catalysts. The band gap (Eg) of the solids prepared was calculated from the UV-Vis absorption spectra of samples thermally treated at different temperatures, the values obtained ranging from 3.37 to 3.09 eV. The Eg values of the powders synthesized at pH 9 were higher than those of samples prepared at pH 3. Surface characterization of the solids was carried out from adsorption isotherms and FTIR studies, and their photocatalytic activities on 2,4-dinitroaniline degradation were also measured. The decomposition rate followed Langmuir–Hinshelwood kinetics. According to the calculated kinetic parameters, better results were obtained once the crystalline structure of Ba3Li2Ti8O20 had formed.

Ceramic Compounds M2TinO2n+1 (M=Li,Na,K and n=2), Synthesis and Photocatalytic Properties

Ceramic compounds M2TinO2n+1 (M= Li, Na, K y n=2) were prepared by sol-gel method and Solid state reaction. The obtained samples were characterized by X-ray diffraction (XRD), Thermal analysis (DTA, TGA) and Infrared spectroscopy (FTIR). The specific surface area was calculated by BET method from Nitrogen adsorption isotherms. The synthesis of each compound is favored when the sol-gel method is used, achieving the structure formation at lower temperatures and shorter reaction times than the solid state method. Lithium hexatitanate was only obtained by sol-gel technique. The materials prepared were tested as a photocatalysts on the 2,4-dinitroaniline decomposition reaction.

Effect of the Sol-Gel Synthesis Parameters on the Incorporation of an Anti-inflammatory Drug in a Ceramic Material

In the present work, sol-gel method was used to incorporate in a ceramic material a non steroidal anti-inflammatory drug (piroxicam) as model drug. The incorporation of the drug in the SiO 2 network was carried out at different sol-gel synthesis parameters, such as pH (3 and 5) and the alkoxide/water ratio (1:6 and 1:8). The biomaterial obtained was analyzed by thermal analysis TGA-DTA, infrared spectroscopy (FTIR), Scanning Electronic Microscopy (SEM) and X-ray diffraction (XRD); specific surface area and porosity were analyzed from nitrogen adsorption isotherm. Better drug incorporation into the material was achieved at the synthesis conditions of pH 5 and 1:6 alkoxide/water molar ratio.