Glass-ceramic materials were obtained by heat treatment (960 oC for 2, 4, and 6 hs) of glasses wi... more Glass-ceramic materials were obtained by heat treatment (960 oC for 2, 4, and 6 hs) of glasses with CaCO3 47.50 wt%-TiO2 23.75 wt%-SiO2 23.75-Al2O3 5.00 wt% formulation produced by the melt-quenching technique (melting at 1650 oC and subsequent annealing at 650 oC). The materials’ structural characterization and crystallization kinetics (Kissinger method) indicate the presence of CaTiO3, CaSiO3, and CaTiSiO5 crystalline phases with activation energies 217, 281, and 446 kJ/mol, respectively. The structure refinement (Rietveld method) suggests metastability for the CaSiO3 and CaTiSiO5 phases as a function of the heat treatment time. The increase in time favors CaTiO3 crystallization, from 62.97 wt%, in the 2 hs treated sample, to 79.21 wt%, in the 6 hs treated sample. EDS and microstructure analyses confirm the glass-ceramic production and indicate segregation of the CaTiO3 phase for longer heat treatment times.
... bricks and roof tiles is a viable practice, and could be of interest to ceramic manufacturers... more ... bricks and roof tiles is a viable practice, and could be of interest to ceramic manufacturers ([Andreoli, 2006], [El-Mahllawy and El-Sokkary, 2008], [Huang et al., 2001], [Huang et al., 2005] and [Jordan et al., 2005]; [Kayaci et al., 2010], [Li et al., 2005], [Li et al., 2006], [Menezes et al ...
ABSTRACT ABSTRACT: SrTiO3 crystalline nanoparticles were prepared using the microwave-assisted hy... more ABSTRACT ABSTRACT: SrTiO3 crystalline nanoparticles were prepared using the microwave-assisted hydrothermal method at 140 °C with synthesis times varying from 4 to 160 min. Sample characterization showed that the method is effective in obtaining nanoparticles in a relatively short time, which have the highest photoluminescence emission. The crystalline phase of perovskite-type SrTiO3 is not significantly influenced by synthesis time. However, the SrTiO3 phase is already obtained with a 4 min synthesis time. Also, all samples exhibited photoluminescence at room temperature in the blue-green region, where intensity decreased with increasing synthesis time and particle size. The samples synthesized with the shortest time showed higher photoluminescence emission and smaller particle sizes. The morphology obtained based on FESEM showed cubic nanoparticles with inhomogeneous grain growth at higher temperatures of synthesis in addition to the formation of new architectures.
Page 1. Morphological and Structural changes of CaxSr1ÀxTiO3 Powders Obtained by the Microwave-As... more Page 1. Morphological and Structural changes of CaxSr1ÀxTiO3 Powders Obtained by the Microwave-Assisted Hydrothermal Method Agda E. Souza,* Gleyson T. Almeida Santos, and Ranilson A. Silva Universidade Estadual ...
Sugarcane bagasse ash (SCBA) is a residue resulting from the burning of bagasse in boilers in the... more Sugarcane bagasse ash (SCBA) is a residue resulting from the burning of bagasse in boilers in the sugarcane/alcohol industry. SCBA has a very high silica concentration and contains aluminum, iron, alkalis and alkaline earth oxides in smaller amounts. In this work, the properties of sintered ceramic bodies were evaluated based on the concentration of SCBA, which replaced non-plastic material. The ash was mixed (up to 60 wt%) with a clayed raw material that is used to produce roof tiles. Prismatic probes were pressed and sintered at different temperatures (up to 1200 °C). Technological tests of ceramic probes showed that the addition of ash has little influence on the ceramic properties up to 1000 °C. X-ray diffraction and thermal analysis data showed that, above this temperature the ash participates in the sintering process and in the formation of new important phases. The results reported show that the reuse of SCBA in the ceramic industry is feasible.
Sugarcane bagasse ash (SCBA) is an industrial waste that contains silicon and aluminum oxides as ... more Sugarcane bagasse ash (SCBA) is an industrial waste that contains silicon and aluminum oxides as the major components and iron, calcium, magnesium, and potassium oxides as the main minor components. In this paper, SCBA from one Brazilian factory was characterized and tested ...
ABSTRACT a b s t r a c t Ba 1Àx Ca x TiO 3 (x = 0, 0.25, 0.50, 0.75, and 1.0) samples report the ... more ABSTRACT a b s t r a c t Ba 1Àx Ca x TiO 3 (x = 0, 0.25, 0.50, 0.75, and 1.0) samples report the association of three types of clusters syn-thesized by the microwave-assisted hydrothermal at 140 °C for 40 min. In order to evaluate influence of structural order–disorder degree among them, photoluminescence (PL) emission, X-ray diffraction, FT-Raman spectroscopy and Ultraviolet–Visible absorption were used. The PL emission of the crystalline phases grows up with the calcium concentration and reaches the highest PL emission to 0.75 Ca concen-tration, which is supported by the symmetry break caused by the phase transition. This PL emission is higher than that of the CaTiO 3 phase.
... Inter. 33 1105 [5] L Wang, H Kang, D Xue and C Liu 2009 J. Crys. Grow. 311 605 [6] VS Marques... more ... Inter. 33 1105 [5] L Wang, H Kang, D Xue and C Liu 2009 J. Crys. Grow. 311 605 [6] VS Marques, LS Cavalcante, JC Sczancoski, DP Volanti, JWM Espinosa, MR Joya,MRM C Santos, PS Pizani, JA Varela and E Longo 2008 Solid State Sci. ...
Glass-ceramic materials were obtained by heat treatment (960 oC for 2, 4, and 6 hs) of glasses wi... more Glass-ceramic materials were obtained by heat treatment (960 oC for 2, 4, and 6 hs) of glasses with CaCO3 47.50 wt%-TiO2 23.75 wt%-SiO2 23.75-Al2O3 5.00 wt% formulation produced by the melt-quenching technique (melting at 1650 oC and subsequent annealing at 650 oC). The materials’ structural characterization and crystallization kinetics (Kissinger method) indicate the presence of CaTiO3, CaSiO3, and CaTiSiO5 crystalline phases with activation energies 217, 281, and 446 kJ/mol, respectively. The structure refinement (Rietveld method) suggests metastability for the CaSiO3 and CaTiSiO5 phases as a function of the heat treatment time. The increase in time favors CaTiO3 crystallization, from 62.97 wt%, in the 2 hs treated sample, to 79.21 wt%, in the 6 hs treated sample. EDS and microstructure analyses confirm the glass-ceramic production and indicate segregation of the CaTiO3 phase for longer heat treatment times.
... bricks and roof tiles is a viable practice, and could be of interest to ceramic manufacturers... more ... bricks and roof tiles is a viable practice, and could be of interest to ceramic manufacturers ([Andreoli, 2006], [El-Mahllawy and El-Sokkary, 2008], [Huang et al., 2001], [Huang et al., 2005] and [Jordan et al., 2005]; [Kayaci et al., 2010], [Li et al., 2005], [Li et al., 2006], [Menezes et al ...
ABSTRACT ABSTRACT: SrTiO3 crystalline nanoparticles were prepared using the microwave-assisted hy... more ABSTRACT ABSTRACT: SrTiO3 crystalline nanoparticles were prepared using the microwave-assisted hydrothermal method at 140 °C with synthesis times varying from 4 to 160 min. Sample characterization showed that the method is effective in obtaining nanoparticles in a relatively short time, which have the highest photoluminescence emission. The crystalline phase of perovskite-type SrTiO3 is not significantly influenced by synthesis time. However, the SrTiO3 phase is already obtained with a 4 min synthesis time. Also, all samples exhibited photoluminescence at room temperature in the blue-green region, where intensity decreased with increasing synthesis time and particle size. The samples synthesized with the shortest time showed higher photoluminescence emission and smaller particle sizes. The morphology obtained based on FESEM showed cubic nanoparticles with inhomogeneous grain growth at higher temperatures of synthesis in addition to the formation of new architectures.
Page 1. Morphological and Structural changes of CaxSr1ÀxTiO3 Powders Obtained by the Microwave-As... more Page 1. Morphological and Structural changes of CaxSr1ÀxTiO3 Powders Obtained by the Microwave-Assisted Hydrothermal Method Agda E. Souza,* Gleyson T. Almeida Santos, and Ranilson A. Silva Universidade Estadual ...
Sugarcane bagasse ash (SCBA) is a residue resulting from the burning of bagasse in boilers in the... more Sugarcane bagasse ash (SCBA) is a residue resulting from the burning of bagasse in boilers in the sugarcane/alcohol industry. SCBA has a very high silica concentration and contains aluminum, iron, alkalis and alkaline earth oxides in smaller amounts. In this work, the properties of sintered ceramic bodies were evaluated based on the concentration of SCBA, which replaced non-plastic material. The ash was mixed (up to 60 wt%) with a clayed raw material that is used to produce roof tiles. Prismatic probes were pressed and sintered at different temperatures (up to 1200 °C). Technological tests of ceramic probes showed that the addition of ash has little influence on the ceramic properties up to 1000 °C. X-ray diffraction and thermal analysis data showed that, above this temperature the ash participates in the sintering process and in the formation of new important phases. The results reported show that the reuse of SCBA in the ceramic industry is feasible.
Sugarcane bagasse ash (SCBA) is an industrial waste that contains silicon and aluminum oxides as ... more Sugarcane bagasse ash (SCBA) is an industrial waste that contains silicon and aluminum oxides as the major components and iron, calcium, magnesium, and potassium oxides as the main minor components. In this paper, SCBA from one Brazilian factory was characterized and tested ...
ABSTRACT a b s t r a c t Ba 1Àx Ca x TiO 3 (x = 0, 0.25, 0.50, 0.75, and 1.0) samples report the ... more ABSTRACT a b s t r a c t Ba 1Àx Ca x TiO 3 (x = 0, 0.25, 0.50, 0.75, and 1.0) samples report the association of three types of clusters syn-thesized by the microwave-assisted hydrothermal at 140 °C for 40 min. In order to evaluate influence of structural order–disorder degree among them, photoluminescence (PL) emission, X-ray diffraction, FT-Raman spectroscopy and Ultraviolet–Visible absorption were used. The PL emission of the crystalline phases grows up with the calcium concentration and reaches the highest PL emission to 0.75 Ca concen-tration, which is supported by the symmetry break caused by the phase transition. This PL emission is higher than that of the CaTiO 3 phase.
... Inter. 33 1105 [5] L Wang, H Kang, D Xue and C Liu 2009 J. Crys. Grow. 311 605 [6] VS Marques... more ... Inter. 33 1105 [5] L Wang, H Kang, D Xue and C Liu 2009 J. Crys. Grow. 311 605 [6] VS Marques, LS Cavalcante, JC Sczancoski, DP Volanti, JWM Espinosa, MR Joya,MRM C Santos, PS Pizani, JA Varela and E Longo 2008 Solid State Sci. ...
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