Metal Organic Frameworks (MOFs) are hybrid materials, usually crystalline, consisting of metallic... more Metal Organic Frameworks (MOFs) are hybrid materials, usually crystalline, consisting of metallic species or clusters, connected by polytopic organic ligands originating bi or tridimensional porous structures. In this work, Gd-1,4-BDC-MOFs doped with 5% mol Eu 3þ were synthesized via solvothermal method at 180 C. The effect of the synthesis time (3, 5 or 7 days) on the microstructure and photophysical properties of the obtained MOFs were evaluated. It was found that porous agglomerates were formed within three days, gradually changing their morphology to rod-like crystals within seven days. The photo-luminescence excitation and emission spectra revealed an efficient energy transfer from the ligand to the Eu 3þ levels (antenna effect), what is not expected for 1,4-BDC 2-in a Eu(III)-based MOFs. We concluded that the presence of highly paramagnetic Gd 3þ ions in the matrix enhanced the antenna effect, resulting in a strong red emission.
... respectivamente. 2. Através da micrografia do pó foi possível observar a formação de aglomera... more ... respectivamente. 2. Através da micrografia do pó foi possível observar a formação de aglomerados moles (constituídos por forças fracas de Van der Waals) de nanopartículas. ... Mater. 164 (1996) 255-260. 15. K. Suresh, NRS Kumar, KC Patil, Advan. Mater. Comm. 3 [3] (1991) ...
... 3. Para o sistema estudado, observou-se a formação de aglomerados moles (constituídos por for... more ... 3. Para o sistema estudado, observou-se a formação de aglomerados moles (constituídos por forças fracas de Van der Waals) de nanopartículas. ... 17. SURESH, K.; PATIL, KC Combustion synthesis and properties of fine particle Mg-Zn ferrites. ...
... formação de aglomerados moles de partículas finas, constituídos por ligações fracas deVan der... more ... formação de aglomerados moles de partículas finas, constituídos por ligações fracas deVan der Waals e de fácil desaglomeração. ... 16. SURESH, K.; KUMAR, NRS; PATIL, KC A novel combustion synthesis of spinel ferrites, orthoferrites and garnets. ...
Zinc aluminate (ZnAl 2 O 4) is a ceramic material with spinel structure and is used as catalysis ... more Zinc aluminate (ZnAl 2 O 4) is a ceramic material with spinel structure and is used as catalysis for reduction of NOx and SOx, and also as electronic ceramic. Zinc aluminate when doped with rare earth ions, such as Tb 3+ ion, the matrix of ZnAl 2 O 4 :Tb acquires luminescent properties. This material has been produced in laboratory scale by different methods of chemical synthesis, such as, spray pyrolysis, hydrothermal synthesis, co-precipitation and Pechini method. Among this method, the combustion reaction is an alternative, simple, fast and safe method, used to prepare ceramic powder with high purity, chemical homogeneity and nanosize particles. So, the aim of this work is to evaluate the influence of the Tb 3+ ion in the morphologic characteristics and luminescent properties of the zinc aluminate powder. The resulting powders from the combustion were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and excitation and emission spectroscopy. The XRD res...
The spinel constitute an important group of materials of common use in the it elaborates ceramic ... more The spinel constitute an important group of materials of common use in the it elaborates ceramic as pigments to color glass bases. These are described as colored inorganic substances, that to the they be dispersed in the ceramic enamel and roasted if they maintain stable front to the attack of the enamel, coloring it. The obtaining of ceramic materials through different synthesis methods for use as pigment has been told by several authors especially the ones that present high thermal stability. This work has as objective analyzes her it influences of the doped with different concentrations of the ions rare earths in the structure and thermal stability of the spinel Zn7Sb2O12, synthesized by road chemistry by the Pechini method and submitted to thermal treatment to 1000°C during 4 hours and rate of heating 10°C/min. These doped spinels were characterized physically by analysis termogravimetric and of X- ray diffraction. The results showed the obtaining of crystalline phase with high ...
This paper reports how zinc aluminate nanoparticles doped with Eu3+ ions were obtained by the met... more This paper reports how zinc aluminate nanoparticles doped with Eu3+ ions were obtained by the method of combustion reaction synthesis. Four samples were prepared with different amounts of dopant to evaluate the effect of the concentration of Eu3+ ions on the powders' luminescence. X-ray diffraction results confirmed the formation of the spinel phase, as well as secondary phases identified as EuAlO3 and ZnO, in amounts directly proportional to the content of dopant in the samples. An excitation wavelength of 265 nm was determined based on the excitation spectrum. This wavelength was used to obtain the emission spectrum, which revealed the presence of peaks characteristic of Eu3+ ions located at around 578, 591 613, 653 and 703 nm. SEM analysis indicated that the powder's morphology consisted of irregular plate-shaped agglomerates composed of nanoparticles with scattered points of secondary phase on their surface. These results indicate how the intensity of luminescence is dep...
LaAlO3:Eu3+ and LaAlO3:Tb3+ phosphors were prepared by microwave-induced combustion reaction. X-r... more LaAlO3:Eu3+ and LaAlO3:Tb3+ phosphors were prepared by microwave-induced combustion reaction. X-ray diffraction (XRD), scanning electron microscopy (SEN) and photoluminescence spectroscopy (PL) were used to characterize the produced powders. X-ray diffraction patterns confirmed the formation of nanocrystalline LaAlO3 oxide. Traces of secondary phase, La(OH)3, were observed in the pattern of the sample doped with terbium. Under UV excitation, Eu3+ and Tb3+-doped LaAlO3 phosphors show red and blue/green photoluminescence, respectively. These systems are potential candidates for use as luminescent materials.
The study of the strontium-doped lanthanum manganites in the form of films covers a large area of... more The study of the strontium-doped lanthanum manganites in the form of films covers a large area of technological applications, such as ceramics semiconductors and solid oxide fuel cell cathode. Strontium-doped lanthanum manganite and samarium-doped ceria has been used as composite cathode of solid oxide fuel cells (SOFCs) because of its excellent performance in electronic and ionic conductivity. In this work, we produced films of the cathode LSM / SDC on yttria stabilized zirconia (YSZ) electrolytes. La0.8Sr0.2MnO3 (LSM) and Ce0.8Sm0.2O1.9 (SDC) powders were synthesized by a synthesis route similar to the Pechini method, in which the gelatin replaced the ethylene glycol as polymerizing agent. Precursor powders of LSM and SDC phases were calcined at 900 ºC. In the step of films production were prepared suspensions of the LSM and SDC powders with addition of ethyl cellulose as a pore-forming agent. The ceramic suspensions were deposited on YSZ electrolyte using the spin coating method....
Metal Organic Frameworks (MOFs) are hybrid materials, usually crystalline, consisting of metallic... more Metal Organic Frameworks (MOFs) are hybrid materials, usually crystalline, consisting of metallic species or clusters, connected by polytopic organic ligands originating bi or tridimensional porous structures. In this work, Gd-1,4-BDC-MOFs doped with 5% mol Eu 3þ were synthesized via solvothermal method at 180 C. The effect of the synthesis time (3, 5 or 7 days) on the microstructure and photophysical properties of the obtained MOFs were evaluated. It was found that porous agglomerates were formed within three days, gradually changing their morphology to rod-like crystals within seven days. The photo-luminescence excitation and emission spectra revealed an efficient energy transfer from the ligand to the Eu 3þ levels (antenna effect), what is not expected for 1,4-BDC 2-in a Eu(III)-based MOFs. We concluded that the presence of highly paramagnetic Gd 3þ ions in the matrix enhanced the antenna effect, resulting in a strong red emission.
... respectivamente. 2. Através da micrografia do pó foi possível observar a formação de aglomera... more ... respectivamente. 2. Através da micrografia do pó foi possível observar a formação de aglomerados moles (constituídos por forças fracas de Van der Waals) de nanopartículas. ... Mater. 164 (1996) 255-260. 15. K. Suresh, NRS Kumar, KC Patil, Advan. Mater. Comm. 3 [3] (1991) ...
... 3. Para o sistema estudado, observou-se a formação de aglomerados moles (constituídos por for... more ... 3. Para o sistema estudado, observou-se a formação de aglomerados moles (constituídos por forças fracas de Van der Waals) de nanopartículas. ... 17. SURESH, K.; PATIL, KC Combustion synthesis and properties of fine particle Mg-Zn ferrites. ...
... formação de aglomerados moles de partículas finas, constituídos por ligações fracas deVan der... more ... formação de aglomerados moles de partículas finas, constituídos por ligações fracas deVan der Waals e de fácil desaglomeração. ... 16. SURESH, K.; KUMAR, NRS; PATIL, KC A novel combustion synthesis of spinel ferrites, orthoferrites and garnets. ...
Zinc aluminate (ZnAl 2 O 4) is a ceramic material with spinel structure and is used as catalysis ... more Zinc aluminate (ZnAl 2 O 4) is a ceramic material with spinel structure and is used as catalysis for reduction of NOx and SOx, and also as electronic ceramic. Zinc aluminate when doped with rare earth ions, such as Tb 3+ ion, the matrix of ZnAl 2 O 4 :Tb acquires luminescent properties. This material has been produced in laboratory scale by different methods of chemical synthesis, such as, spray pyrolysis, hydrothermal synthesis, co-precipitation and Pechini method. Among this method, the combustion reaction is an alternative, simple, fast and safe method, used to prepare ceramic powder with high purity, chemical homogeneity and nanosize particles. So, the aim of this work is to evaluate the influence of the Tb 3+ ion in the morphologic characteristics and luminescent properties of the zinc aluminate powder. The resulting powders from the combustion were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and excitation and emission spectroscopy. The XRD res...
The spinel constitute an important group of materials of common use in the it elaborates ceramic ... more The spinel constitute an important group of materials of common use in the it elaborates ceramic as pigments to color glass bases. These are described as colored inorganic substances, that to the they be dispersed in the ceramic enamel and roasted if they maintain stable front to the attack of the enamel, coloring it. The obtaining of ceramic materials through different synthesis methods for use as pigment has been told by several authors especially the ones that present high thermal stability. This work has as objective analyzes her it influences of the doped with different concentrations of the ions rare earths in the structure and thermal stability of the spinel Zn7Sb2O12, synthesized by road chemistry by the Pechini method and submitted to thermal treatment to 1000°C during 4 hours and rate of heating 10°C/min. These doped spinels were characterized physically by analysis termogravimetric and of X- ray diffraction. The results showed the obtaining of crystalline phase with high ...
This paper reports how zinc aluminate nanoparticles doped with Eu3+ ions were obtained by the met... more This paper reports how zinc aluminate nanoparticles doped with Eu3+ ions were obtained by the method of combustion reaction synthesis. Four samples were prepared with different amounts of dopant to evaluate the effect of the concentration of Eu3+ ions on the powders' luminescence. X-ray diffraction results confirmed the formation of the spinel phase, as well as secondary phases identified as EuAlO3 and ZnO, in amounts directly proportional to the content of dopant in the samples. An excitation wavelength of 265 nm was determined based on the excitation spectrum. This wavelength was used to obtain the emission spectrum, which revealed the presence of peaks characteristic of Eu3+ ions located at around 578, 591 613, 653 and 703 nm. SEM analysis indicated that the powder's morphology consisted of irregular plate-shaped agglomerates composed of nanoparticles with scattered points of secondary phase on their surface. These results indicate how the intensity of luminescence is dep...
LaAlO3:Eu3+ and LaAlO3:Tb3+ phosphors were prepared by microwave-induced combustion reaction. X-r... more LaAlO3:Eu3+ and LaAlO3:Tb3+ phosphors were prepared by microwave-induced combustion reaction. X-ray diffraction (XRD), scanning electron microscopy (SEN) and photoluminescence spectroscopy (PL) were used to characterize the produced powders. X-ray diffraction patterns confirmed the formation of nanocrystalline LaAlO3 oxide. Traces of secondary phase, La(OH)3, were observed in the pattern of the sample doped with terbium. Under UV excitation, Eu3+ and Tb3+-doped LaAlO3 phosphors show red and blue/green photoluminescence, respectively. These systems are potential candidates for use as luminescent materials.
The study of the strontium-doped lanthanum manganites in the form of films covers a large area of... more The study of the strontium-doped lanthanum manganites in the form of films covers a large area of technological applications, such as ceramics semiconductors and solid oxide fuel cell cathode. Strontium-doped lanthanum manganite and samarium-doped ceria has been used as composite cathode of solid oxide fuel cells (SOFCs) because of its excellent performance in electronic and ionic conductivity. In this work, we produced films of the cathode LSM / SDC on yttria stabilized zirconia (YSZ) electrolytes. La0.8Sr0.2MnO3 (LSM) and Ce0.8Sm0.2O1.9 (SDC) powders were synthesized by a synthesis route similar to the Pechini method, in which the gelatin replaced the ethylene glycol as polymerizing agent. Precursor powders of LSM and SDC phases were calcined at 900 ºC. In the step of films production were prepared suspensions of the LSM and SDC powders with addition of ethyl cellulose as a pore-forming agent. The ceramic suspensions were deposited on YSZ electrolyte using the spin coating method....
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