Preparation and thermal behavior of mixture of basic carbonate and 4-dimethylaminocinnamylidenepyruvate with lanthanides (III) and yttrium (III) in the solid state

Solid Ln-OHCO3-DMCP compounds, where Ln represents lanthanides (III) and yttrium (III) ions and DMCP is the anion 4-dimethylaminocinnamylidenepyruvate, have been prepared. Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC), x-Ray diffraction powder patterns and elemental analysis have been used to characterize the compounds. The thermal stability as well as the thermal decomposition of these compounds were studied using an alumina crucible in an air atmosphere.

Thermal behaviour studies of solid state compounds of cinnamylidenepyruvate with trivalent lanthanides and yttrium (III) in an atmosphere of CO2

Solid state cinnamylidenepyruvate of trivalent lanthanides (except for promethium) and yttrium, were prepared. Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC), X-ray diffraction powder patterns and complexometry were used to characterize and to study the thermal behavior of these compounds in a dynamic CO2 atmosphere. The results obtained showed significative differences on the thermal stability and thermal decomposition of these compounds, with regard to the thermal behavior study in a dynamic air atmosphere.

Thermal decomposition of solid state compounds of lanthanide and yttrium benzoates in CO2 atmosphere

Solid-state Ln-Bz compounds, where Ln stands for trivalent lanthanides and Bz is benzoate have been synthesized. Simultaneous thermogravimetric and differential thermal analysis in a CO2 atmosphere were used to study the thermal decomposition of these compounds.

Partículas nanométricas de ferritas de ítrio

Nanoparticles of yttrium iron garnet (YIG) were obtained by coprecipitation. The particles were prepared by hydrolysis in acid medium with addition of ammonia or urea, for homogeneous nucleation, at 90ºC. Different compositions and spherical morphologies were achieved by changing reactants concentrations and precipitation agent. X-ray diffractometry, transmission electron microscopy, differential thermal analysis and electrophoretic mobility were carried out on these particles to investigate the obtained phase, phase transition temperature, morphology, particle size and zeta potential, respectively.

Óxido misto de ítrio-alumínio dopado com Eu(III)

In this work, we report the synthesis and the photoluminescence features of Eu(III)-doped yttrium-aluminium oxide obtained by non-hydrolytic sol-gel routes. After heating the powders above 600 ºC the XRD patterns show the presence of the Y4Al2O9 (YAM) and Y3Al5O12 (YAG) phases. At 800 and at 1500 ºC the PL spectra display the Eu(III) lines characteristic of the YAM monoclinic phase. The 5D0->7F2 transition is favored relatively to the 5D0->7F1 lines. However, at 1100 ºC the cubic YAG is the preferential phase and the 5D0->7F1 transition dominates the spectrum. The Eu(III) ions lie in a centrosymmetrical site. The different solvents used in the sol-gel synthesis also change the relative proportion between these two phases. This is monitored analyzing the modifications in the relative intensity between the 5D0->7F2 and the 5D0->7F1 transitions.

Determinação de arsênio em águas contaminadas usando fluorescência de raios-X por energia dispersiva

This work proposes a simple, fast and inexpensive method to determine As in natural waters, using X-ray fluorescence. 50 µL of each sample containing 100 mg L-1 of yttrium as internal standard were deposited over a 2.5 µm thickness MylarTM film. The samples were dried at 50 °C for 2 h. X-ray spectra were obtained using an EDXRF apparatus. The accuracy was determined by analyte addition/recovery and by comparison with Hydride Generation Atomic Absorption Spectrometry (HG AAS). A recovery of about 100% was obtained and the results were in good agreement with HG AAS. The method showed a relative standard deviation of 6.8% and a detection limit of 10.5 µg L-1 of As.