30 documents found, page 1 of 3
The affinity between dark night and church: for a sanjuanist contribution to co...
Dias, Anderson; Maçaneiro, MarcialThis paper establishes a dialog between systematic theology and mysticism, linking two themes: the Dark Night and the Church. Although this imagery is generally used to understand spiritual experience on a personal/individual level, here we question the possibilities of understanding and applying it from a collective/ecclesial perspective. In order to develop this inquiry, we carried out a bibliographical surve...
Micro far-infrared dielectric response of lanthanide orthotantalates for applic...
Dias, Anderson; Siqueira, Kisla Prislen Félix; Moreira, Roberto LuizLanthanide orthotantalates LnTaO4 (Ln ¼ La, Nd, Dy and Lu) were synthesized by solid-state reactions at 1300 C leading to well crystallized single-phase materials. XRD and infrared spectroscopic investigations showed that the samples exhibited three different monoclinic crystal structures depending on the lanthanide ion: P21/c (for La), I2/a (for Nd) and P2/a (for Dy and Lu). For LaTaO4, 21 polar modes could be...
High-temperature antiferroelectric and ferroelectric phase transitions in phase...
Abreu, Yuslín Gonzále; Siqueira, Kisla Prislen Félix; Matinaga, Franklin Massami; Moreira, Roberto Luiz; Dias, AndersonPhase-pure LaTaO4 ceramics was prepared by solid-state reaction. Dielectric spectroscopic data as well as differential scanning calorimetric experiments showed the existence of a sequence two high-temperature firstorder structural phase transitions. The first phase transition occurs above 160 °C (on heating), from the monoclinic P21/c space group at room temperature to the polar orthorhombic Cmc21 group, exhibi...
Structural and vibrational properties of phase - pure monoclinic NdLuO3 interla...
Soares, Júlia Cristina; Siqueira, Kisla Prislen Félix; Moreira, Roberto Luiz; Dias, AndersonPhase-pure monoclinic NdLuO3 interlanthanides were successfully synthesized from hydrothermalderived precursors. LuO(OH) and Nd(OH)3 materials were firstly obtained by hydrothermal synthesis at 250 _C, for 24 h. X-ray diffraction, micro-Raman spectroscopy, scanning and transmission electron microscopies were employed to investigate the thermal behavior of these precursors and NdLuO3 interlanthanide up to 1600 _...
Optical phonon features of triclinic montebrasite : dispersion analysis and non...
Almeida, Rafael Mendonça; Höfer, Sonja; Mayerhöfer, Thomas G.; Popp, Jürgen; Krambrock, Klaus Wilhelm Heinrich; Lobo, Ricardo P. S. M.; Dias, AndersonPolarized infrared and Raman spectra of triclinic LiAl(PO4)(OH) [montebrasite] single crystal were recorded for appropriate optical configurations. Dispersion analysis was applied on the infrared reflectivity spectra taken at low incidence angle (11 ) to determine the oscillator parameters and the dipole directions of the polar phonons. In particular, all the 27 polar phonons, predicted by group theory for tric...
Effect of the processing parameters on the crystalline structure of lanthanide ...
Siqueira, Kisla Prislen Félix; Dias, AndersonThe influence of the synthesis parameters on the crystalline structures of orthotantalate ceramics has been investigated. Powder materials were prepared by the solid-state reaction route. X-ray diffraction and Raman scattering measurements were employed to investigate the crystal structure of the produced materials. In this work, we analyzed three different examples in which the temperature and time were decisi...
Ce1−xSmxO1.9−δ nanoparticles obtained by microwave assisted hydrothermal proces...
Silva, Anderson Gabriel Marques da; Rodrigues, Thenner Silva; Dias, Anderson; Fajardo, Humberto Vieira; Gonçalves, Rosana de FátimaHeterogeneous catalysts based on Sm-doped ceria were employed for the first time in the liquid-phase oxidation of α-bisabolol. Nanometer-sized catalysts were obtained by microwave-hydrothermal synthesis and were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), Raman spectroscopy and N2-physisorption. The influence of Sm doping, temperature and the solvent used on the catalytic b...
Influence of crystalline structure on the luminescence properties of terbium or...
Siqueira, Kisla Prislen Félix; Carmo, Alexandre Peixoto do; Bell, Maria José Valenzuela; Dias, AndersonTerbium orthotantalate powders were produced with M-fergusonitetype (I2/a) and M0-fergusonite type (P2/a) structures.The samples were studied byX-ray diffraction, Ramans cattering, and photo luminescence measure ments (emission and decaycurves).The results showed that crystalline materials were obtained with all the 18Raman-active modes predicted by group theory alculations. Also, it was observed through photo ...
Catalytic carbon deposition-oxidation over Ni, Fe and Co catalysts : a new indi...
Oliveira, Patrícia E. F.; Ribeiro, Leandro Passos; Rosmaninho, Marcelo Gonçalves; Ardisson, José Domingos; Dias, AndersonIn this work, a new two-step route to store and transport associated natural gas, promoted by Ni, Fe and Co supported catalyst was presented. Initially, CH4 is converted into carbon deposits (M/C composite), being Fe catalyst the most active catalyst. In Step 2, M/C composite reacts with H2O producing H2, CO and CH4. TPO experiments showed that efficiency and selectivity of oxidation depends on the metal. Ni ca...
Crystal structure of fluorite-related Ln3SbO7 (Ln=La–Dy) ceramics studied by sy...
Siqueira, Kisla Prislen Félix; Borges, Raquel Moreira; Granado, Eduardo; Moreira, Leandro Malard; Paula, Ana Maria de; Moreira, Roberto LuizLn3SbO7 (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) ceramics were synthesized by solid-state reaction in optimized conditions of temperature and time to yield single-phase ceramics. The crystal structures of the obtained ceramics were investigated by synchrotron X-ray diffraction, second harmonic generation (SHG) and Raman scattering. All samples exhibited fluorite-type orthorhombic structures with different oxygen ...