Influence of Oxidizing Atmosphere on Crystalline Phase Formation and Microstructural Properties of Mixed Cerium-Zinc Oxides Obtained by Polymeric Precursor Method

This paper presents the synthesis, characterization and influence of oxidizing atmosphere in the calcinations and sintering processes on microstructural properties of mixed oxides of Cerium and Zinc, obtained by the polymeric precursor method, aiming at a subsequent catalytic application. The material was submitted to calcinations and sintering at 900 and 1050 °C. The samples were characterized by XRD analysis techniques, surface area by BET method and refined by the Rietveld method. The results of X-ray diffraction showed that interest phase was formed, indicating that the method for obtaining the phase is effective. The results of surface area for the system calcined in air were 85 m2/g and 65 m2/g for the system subjected to oxidizing atmosphere both at 900°C, in the same temperature. It was observed that the temperature increase leads to an increase in crystallite size. This fact is in line with other studies in the literature.

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Physical Characterization of K-Doped 0.9PMN-0.1PT Synthesized by an Association of the Columbite Route and the Polymeric Precursor Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.498-499.669 ◽

2005 ◽

Vol 498-499 ◽

pp. 669-675

Author(s):

A.A. Cavalheiro ◽

Juliana C. Bruno ◽

M.A. Zaghete ◽

José Arana Varela

Keyword(s):

Grain Size ◽

Perovskite Phase ◽

Rietveld Method ◽

Size Control ◽

Xrd Analysis ◽

Polymeric Precursor Method ◽

Polymeric Precursor ◽

Structural Refinement ◽

Precursor Method ◽

Columbite Precursor

The solid solution 0.9PbMg1/3Nb2/3O3-0.1PbTiO3 is one of the most widely investigated relaxor ceramic, because of its high dielectric constant and low sintering temperatures. PMN-PT powders containing single perovskite phase were prepared by using a Ti-modified columbite precursor obtained by the polymeric precursor method. Such precursor reacts directly with stoichiometric amount of PbO to obtain pyrochlore-free PMNPT powders. The structural effects of K additive included in the columbite precursor and 0.9PMN-0.1PT powders were also studied. The phase formation at each processing step was verified by XRD analysis, being these results used for the structural refinement by the Rietveld method. It was verified the addition of K in the columbite precursor promotes a slight increasing in the powder crystallinity. There was not a decrease in the amount of perovskite phase PMN-PT for 1mol% of K, and the particle and grain size were reduced, making this additive a powerful tool for grain size control.

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Layered niobate KNb 3 O 8 synthesized by thepolymeric precursor method

Cerâmica ◽

10.1590/0366-69132018643692269 ◽

2018 ◽

Vol 64 (369) ◽

pp. 104-108 ◽

Cited By ~ 2

Author(s):

J. K. D. de Souza ◽

L. M. C. Honório ◽

J. M. Ferreira ◽

S. M. Torres ◽

I. M. G. Santos ◽

...

Keyword(s):

Solid State ◽

Surface Area ◽

Pore Volume ◽

Synthesis Method ◽

Total Pore Volume ◽

Polymeric Precursor Method ◽

Polymeric Precursor ◽

Precursor Method ◽

Solid State Method ◽

State Method

Abstract The polymeric precursor method was used for the synthesis of KNb3O8 and compared to the solid-state method. The materials were characterized by X-ray diffraction (XRD), infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and determination of surface area and total pore volume by nitrogen isotherms at 77 K. The material prepared by the polymeric precursor method was single-phase while K2Nb4O11 was obtained as secondary phase when the solid-state method was used, as evidenced by the XRD patterns and the Raman spectra. The morphology of the materials was significantly altered by the synthesis method, as the KNb3O8 prepared by the polymeric precursor method presented a more porous morphology leading to a higher surface area and pore volume.

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XRD Analysis and Morphological Studies of Spin Coated LiNbO3 Nano Photonic Crystal Prepared for Optical Waveguide Application

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1133.457 ◽

2016 ◽

Vol 1133 ◽

pp. 457-461 ◽

Cited By ~ 16

Author(s):

Makram A. Fakhri ◽

Y. Al-Douri ◽

Uda Hashim ◽

Evan T. Salim

Keyword(s):

Spin Coating ◽

Xrd Analysis ◽

Polymeric Precursor Method ◽

Polymeric Precursor ◽

X Ray Diffraction ◽

Precursor Method ◽

X Ray ◽

Si Substrates ◽

Morphological Studies ◽

Pechini Process

Lithium niobate nanostructured thin films were deposited on (100) N-type Si substrates. Spin coating technique was used employed the polymeric precursor method (Pechini process) . The prepared films were Annealing in static air and oxygen atmosphere was performed at 500 _C for 2 h. X-ray diffraction analysis and SEM properties was carried out for films prepared at different mol concentration (0.25,0.50,0.75,1.00) Mol%. The results show a good enhancement in both structural and surface morphology of the films with increasing the concentration

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Influence of Polyester Chain Type in the Morphology of Silica-Carbon Composites Obtained by the Polymeric Precursor Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.881.289 ◽

2016 ◽

Vol 881 ◽

pp. 289-294

Author(s):

Tiziana Azario de Medeiros ◽

Eliane Kujat Fischer ◽

Igor Silva de Sá ◽

Graciele Vieira Barbosa ◽

Margarete Soares da Silva ◽

...

Keyword(s):

Surface Area ◽

Pore Volume ◽

Molecular Sieves ◽

Particulate Composite ◽

Metallic Phase ◽

Carbon Composites ◽

Polymeric Precursor Method ◽

Polymeric Precursor ◽

Carbon Phase ◽

Precursor Method

Particulate composite materials containing metallic phase in ceramic matrices may be obtained by direct routes with the advantage of avoiding the partial collapse of the composite structure when a subsequent step for metal insertion is carried out. The non-metallic silica-carbon matrix combines high values of pore volume and surface area with chemical refractivity and may be applied as molecular sieves, adsorbents, filters and catalyst support. The Polymeric Precursor Method is a versatile method to obtain this composite type as the metal precursor can be reduced to metallic phase by pyrolysis of organic matter. In this work, it was used three different diol chain sizes obtaining silica-carbon composites through the pyrolysis of polyester precursor at 600°C for 3 hours in closed tubular oven. It was observed a direct dependence between the amorphous carbon phase amount and the polyester chain size. All of the composite samples presented dual distribution for mesopore size, situated at 3.8 and 11 nm in diameter. However, the pore volume and surface area significantly lowers for larger polyester chain sizes.

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