Authors:Márcia Silva, Mary Alves, S. Lima, L. Soledade, Elaine Paris, E. Longo, A. Souza, and Iêda Santos
Sr(Ti,Nd)O3 was synthesized in order to evaluate the influence of the amount of neodymium on the thermal and structural properties of
SrTiO3. The synthesis was carried out using the polymeric precursor method. A small mass gain was observed for the SrTiO3 and SrTi0.98Nd0.02O3 samples accompanied by an exothermic peak in the DTA curves. Other steps at higher temperatures are assigned to the combustion
of the organic material and carbonate. Elimination of defects by previous calcination of the precursors is responsible by
the short and long range ordering of the perovskite. Cubic phase was obtained for undoped and doped SrTiO3.
Authors:Mary Alves, Soraia Souza, S. Lima, E. Longo, A. Souza, and Iêda Santos
CaSnO3 was synthesized by the polymeric precursor
method, using different precursor salts as (CH3COO)2CaH2O,
CaCl22H2O and CaCO3,
leading to different results. Powder precursor was characterized using thermal
analysis. Depending on the precursor different thermal behaviors were obtained.
Results also indicate the formation of carbonates, confirmed by IR spectra.
After calcination and characterization by XRD, the formation of perovskite
as single phase was only identified when calcium acetate was used as precursor.
For other precursors, tin oxide was observed as secondary phase.
Authors:Mary Alves, Soraia Souza, Márcia Silva, Elaine Paris, S. Lima, R. Gomes, E. Longo, A. de Souza, and Iêda Garcia dos Santos
SrSnO3 was synthesized by the polymeric precursor method with elimination of carbon in oxygen atmosphere at 250 °C for 24 h. The
powder precursors were characterized by TG/DTA and high temperature X-ray diffraction (HTXRD). After calcination at 500, 600
and 700 °C for 2 h, samples were evaluated by X-ray diffraction (XRD), infrared spectroscopy (IR) and Rietveld refinement
of the XRD patterns for samples calcined at 900, 1,000 and 1,100 °C. During thermal treatment of the powder precursor ester
combustion was followed by carbonate decomposition and perovskite crystallization. No phase transition was observed as usually
presented in literature for SrSnO3 that had only a rearrangement of SnO6 polyhedra.
Authors:Soraia de Souza, Mary Alves, A. de Oliveira, E. Longo, F. Ticiano Gomes Vieira, Rodinei Gomes, L. Soledade, A. de Souza, and Iêda Garcia dos Santos
In this work, the synthesis of Nd-doped SrSnO3 by the polymeric precursor method, with calcination between 250 and 700 °C is reported. The powder precursors were characterized
by TG/DTA and high temperature X-ray diffraction (HTXRD). After heat treatment, the material was characterized by XRD and
infrared spectroscopy. Ester and carbonate amounts were strictly related to Nd-doping. According to XRD patterns, the orthorhombic
perovskite was obtained at 700 °C for SrSnO3 and SrSn0.99Nd0.01O3. For Sr0.99Nd0.01SnO3, the kinetics displayed an important hole in the crystallization process, as no peak was observed in HTXRD up to 700 °C,
while a XRD patterns showed a crystalline material after calcination at 250 °C.