Strontium titanate (SrTiO3 ) is a compound with perovskite structure, with a face-centred cubic symmetry [ 1 ] and stable over a wide temperature range between 104 and 2300 K [ 2 ]. Owing to its high dielectric
Authors:Márcia Silva, L. Soledade, S. Lima, E. Longo, A. Souza, and Iêda Santos
The present work investigates
the influence of milling and calcination atmosphere on the thermal decomposition
of SrTiO3 powder precursors. Both pure and neodymium-modified SrTiO3 samples
were studied. Milling did not significantly influence numerical mass loss
value, but reduced the number of decomposition steps, modifying the profiles
of the TG and DTA curves. On the other hand, milling increases the amount
of energy liberated by the system upon combustion of organic matter. It was
also observed that the milling process, associated to the calcination in an
oxygen atmosphere, considerably decreases the amount of organic matter and
increases the final mass loss temperature.
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.
Methods of DTA, TG, DSC, IR spectroscopy and X-ray phase analysis were used to study the thermal dehydration and decomposition
of Ca2+ and Sr2+ peroxotitanates to the corresponding metatitanates. The stages of the process and the intermediate phases were identified.
The information obtained was utilised to determine the optimum temperatures of heating of the initial peroxotitanates to yield
metatitanates with a fairly high degree of crystallinity (for CaTiO3 680C, and for SrTiO3 650C).
Authors:H. Ortiz-Oliveros, E. Ordoñez-Regil, and S. Fernández-Valverde
The sorption of uranium(VI) on the perovskite structure of strontium titanate in a 0.5M KNO3 solution is studied. SrTiO3 commercial material was characterized by XRD showing a tausonite face, with a specific area of 2.42 m2.g−1. The electrical surface characterization of the compound was performed by mass and potentiometric titrations. pHpzc in water was 8.5±0.3 and 9.1±0.2 in 0.5M KNO3 solution, showing a positively charged surface. FITEQL 4.0 program was used to calculate the sorption curves and the surface
acidity constants by the constant capacitance model obtaining: log K1 = 8.67 and log K2 = −9.43. The sorption edge was fitted with two different uranium(VI) species sorbed, corresponding to bidentate complexes
of UO22+ and UO2(OH)2H2O on the surface of strontium titanate.
Authors:T. Łada, K. Przybylski, A. Morawski, J. Prażuch, and T. Brylewski
The fabrication method of superconducting thin films of compositions HgBa2Ca2Cu3O8+δ (Hg-1223) and Tl2Ba2CuOy (2201) on single-crystalline SrTiO3 and LaAlO3 substrates is reported. The highest obtained Tc was 134 K and Jc over 106 A cm–2 at 77 K. High pressure DTA(HP-DTA) was applied to grow mercury- and thallium-based high-temperature superconducting crystals
and thin films, to identify melting points of particular phases within these oxide systems and determine suitable processing
conditions. The DTA system operates at the: maximum temperature of 1200C, volume up to 5 cm3, working pressure up to 1.5 GPa and at a working atmosphere — inert gas with up to 25% oxygen.
Perovskites belong to the great group of the inorganic pigments and thanks to their excellent properties they have been widely
used in an industry. CaTiO3, BaTiO3 and SrTiO3 with the perovskite structure were prepared in this work. These compounds were synthesized with using the solid state reaction
by calcination in temperature region 1000–1200°C. The thermal analysis was used for characterization of thermal behaviour
and formation of tested perovskites. The main aim of this work was studied the influence of calcination temperature on colour
properties of perovskites. Colour properties of powdered compounds and samples applied into ceramic transparent glaze P 07491
were also studied. The tested compounds can be described by different light colour hues and that depending on calcining temperature.
The structures of the powdered compounds were studied by X-ray diffraction analysis.