scholarly journals Study of structural, optical, and morphological characteristics of manganese titanate (MnTiO3) obtained by combustion reaction using microwave energy

Cerâmica ◽  
2021 ◽  
Vol 67 (381) ◽  
pp. 28-31
Author(s):  
R. C. V. Costa ◽  
G. N. Marques ◽  
T. P. Oliveira ◽  
M. M. Oliveira ◽  
J. H. G. Rangel
Keyword(s):  
Morphological Characteristics ◽  
Microwave Energy ◽  
Combustion Reaction

Synthesis of Ni-Zn Ferrite Catalysts by Combustion Reaction Using Different Fuels

2010 ◽  
Vol 660-661 ◽  
pp. 943-947 ◽  
Author(s):  
Normanda Lino de Freitas ◽  
Juliana Pimentel Coutinho ◽  
Mirele Costa Silva ◽  
Hélio Lucena Lira ◽  
Ruth Herta Goldsmith Aliaga Kiminami ◽  
...  
Keyword(s):  
Citric Acid ◽  
Stoichiometric Composition ◽  
Morphological Characteristics ◽  
Nitrogen Adsorption ◽  
Vitreous Silica ◽  
Textural Analysis ◽  
Combustion Reaction ◽  
Combustion Time ◽  
Synthesis Parameters ◽  
Zn Ferrite

The aim of this work is to evaluate the effect of different fuels in the preparation of Ni-Zn ferrites by combustion reaction. The catalysts were prepared according to the propellants chemistry, in stoichiometric composition, using a vitreous silica container. Carbohydrazine, monohydrated citric acid and glycine fuels were used. During the synthesis parameters as flame combustion time and temperature were measured. The structural and morphological characteristics of the powders were evaluated by XRD, textural analysis by nitrogen adsorption and SEM. The fuel monohydrated citric acid presented the greatest time and temperature of combustion reaction. The results show that the type of fuel changed the final characteristics of the powders. The XRD results showed the formation of Ni-Zn ferrite phase for all fuels used in this study. The powders prepared with carbohydrazine resulted in largest value of surface area. All powders showed morphology constituted by soft agglomerates of nanoparticles.

Influence of Fuel in the Synthesis of ZnAl2O4 Catalytic Supports by Combustion Reaction

2010 ◽  
Vol 660-661 ◽  
pp. 52-57 ◽  
Author(s):  
Kaline Melo de Souto Viana ◽  
Bruno Brito Dantas ◽  
N.A.S. Nogueira ◽  
J.M. Sasaki ◽  
Normanda Lino de Freitas ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Crystallite Size ◽  
Size Distribution ◽  
Spinel Structure ◽  
Morphological Characteristics ◽  
Combustion Reaction ◽  
Nanosized Particles ◽  
Catalytic Supports ◽  
Stoichiometric Proportion

The aim of this work is to evaluate the influence of fuel in the synthesis of ZnAl2O4 catalytic supports by combustion reaction. For this, it was used the fuels: urea, carbohidrazide, glycine and aniline. The total amount of reagents was calculated according to the theory of propellants and explosive using urea in the stoichiometric proportion (Φe = 1). The structural and morphological characteristics of the powders were evaluated by XRD, FTIR, TEM, SEM and particle size distribution. The results from XRD showed the formation of the normal cubic spinel structure. The powders presented nanosized particles with narrow agglomerates size distribution. The powders prepared with urea showed better value of surface area and smaller crystallite size.

USE OF NATURAL DOLOMITE AS A CHEAP FOAMING AGENT FOR PRODUCING GLASS FOAMS FROM GLASS WASTE IN THE MICROWAVE FIELD

2020 ◽  
Vol 26 (1) ◽  
pp. 57-64
Author(s):  
LUCIAN PAUNESCU ◽  
MARIUS FLORIN DRAGOESCU ◽  
SORIN MIRCEA AXINTE
Keyword(s):  
Thermal Conductivity ◽  
Microwave Field ◽  
Specific Energy Consumption ◽  
Morphological Characteristics ◽  
Microwave Energy ◽  
Glass Waste ◽  
Foaming Agent ◽  
Insulating Material ◽  
The World ◽  
Glass Foam

The paper presents experimental results obtained in the process of making glass foam from glass waste using a cheap foaming agent (natural dolomite). The originality of the work is the application of the microwave energy, unlike the conventional techniques commonly used in the world. The main advantage highlighted by the experiments is the very low specific energy consumption (below 1.5 kWh/kg), due to the peculiarities of the microwave heating technique. The foamed product has physical, mechanical and morphological characteristics (density between 0.30-0.32 g/cm3, thermal conductivity between 0.064-0.067 W/m·K, compressive strength in the range 2.2-2.6 MPa), which are similar to those of foams made by conventional methods and are suitable for its use as insulating material in construction.

Influence of the External Heating Type in the Morphological and Structural Characteristics of Alumina Powder Prepared by Combustion Reaction

2010 ◽  
Vol 660-661 ◽  
pp. 58-62 ◽  
Author(s):  
V.V. Cordeiro ◽  
Normanda Lino de Freitas ◽  
Kaline Melo de Souto Viana ◽  
G. Dias ◽  
Ana Cristina Figueiredo de Melo Costa ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Structural Characteristics ◽  
Morphological Characteristics ◽  
Nitrogen Adsorption ◽  
Combustion Reaction ◽  
Alumina Powder ◽  
Ceramic Plate ◽  
External Heating ◽  
Plate Shape

The aim of this work is to evaluate the influence of the external heating in the morphological and structural characteristics of the alumina powder prepared by combustion reaction. It was evaluated different types of external heating: muffle oven, microwave oven and ceramic plate with electrical spiral resistance. The powders were prepared according to the propellants and explosives theory, using urea in the stoichiometric proportion (Φe = 1). During the synthesis parameters such as flame combustion time and temperature were measured. The structural and morphological characteristics of the powders were evaluate by XRD, particle size distribution, SEM and nitrogen adsorption (BET). The results showed the production of -alumina as unique phase and formed by agglomerates with irregular plate shape of thin particles for all studied conditions. The powders prepared by electrical oven presented small particle size, with narrow agglomerates size distribution.

Sintering of Ni-Zn Ferrite by Microwave Energy

2012 ◽  
Vol 727-728 ◽  
pp. 977-981
Author(s):  
Verônica C.S. Diniz ◽  
Débora A. Vieira ◽  
Ruth Herta Goldsmith Aliaga Kiminami ◽  
Daniel Cornejo ◽  
Ana Cristina Figueiredo de Melo Costa
Keyword(s):  
Magnetic Material ◽  
Magnetic Measurements ◽  
Morphological Characteristics ◽  
Secondary Phase ◽  
Microwave Energy ◽  
Microwave Oven ◽  
Soft Magnetic ◽  
Magnetic Devices ◽  
Magnetic Parameters ◽  
Zn Ferrite

This paper proposes to assess the sintering of Ni-Zn ferrites synthesized by combustion reaction in advance to procure materials for applications as soft magnetic devices. The samples used for sintering have different morphological characteristics and were previously synthesized by microwave energy. The samples were uniaxially pressed and sintered in a microwave oven at 1200°C/2h with a heating rate of 5°C/min, and characterized by XRD, SEM and magnetic measurements. The results show that for all samples have the formation of Ni-Zn phase and traces hematite as secondary phase. The resulting microstructure after sintering was different and was influenced by previous morphological characteristics of the synthesized samples. As for the magnetic parameters, all samples were characteristic of soft magnetic material with saturation magnetization between 57 and 62 emu.g-1, indicating are promising materials for the fabrication of soft magnetic devices.

Evaluation of Structural and Morphological Characteristics of the System Ni1-xZnxFe2O4 Obtained by Combustion Reaction

2014 ◽  
Vol 775-776 ◽  
pp. 678-681
Author(s):  
Aluska do Nascimento Simões Braga ◽  
Alberto Correia Gomes Filho ◽  
Laédna Souto Neiva ◽  
Tamiris Rodrigues Silva ◽  
João Bosco Lucena Oliveira ◽  
...  
Keyword(s):  
Spinel Phase ◽  
Low Cost ◽  
Synthesis Method ◽  
Morphological Characteristics ◽  
Zinc Content ◽  
Particle Morphology ◽  
Nitrogen Adsorption ◽  
Combustion Reaction ◽  
Nominal Composition ◽  
Direct Formation

The synthesis by combustion reaction stands as an alternative technique for preparing powders with high purity level, nanometric particle size and low cost. Therefore, this study had as objective the synthesis and characterization of ferrite powders with nominal composition NI1-xZnxFe2O4(x = 0.6, 0.7 and 0.8 mol) prepared by combustion reaction using urea as fuel. The influence of the quantity of zinc in the final characteristics of the powders was also investigated. The powders were characterized by X-ray diffraction (XRD), nitrogen adsorption (BET) and scanning electron microscopy (SEM). All compositions resulted in nanometric powders of Ni-Zn ferrites with direct formation of the inverse spinel phase, showing the effectiveness of the synthesis method applied. The increase of zinc's concentration caused an increase in surface area, ranging 4 m2g-1from 23 m2g-1. And the SEM micrographs show that the powders have thinner particle morphology with increasing zinc content.

scholarly journals USE OF NATURAL DOLOMITE AS A CHEAP FOAMING AGENT FOR PRODUCING GLASS FOAMS FROM GLASS WASTE IN THE MICROWAVE FIELD

2020 ◽  
Vol 26 (1) ◽  
Author(s):  
LUCIAN PAUNESCU ◽  
MARIUS FLORIN DRAGOESCU ◽  
SORIN MIRCEA AXINTE
Keyword(s):  
Thermal Conductivity ◽  
Microwave Field ◽  
Specific Energy Consumption ◽  
Morphological Characteristics ◽  
Microwave Energy ◽  
Glass Waste ◽  
Foaming Agent ◽  
Insulating Material ◽  
The World ◽  
Glass Foam

<p>The paper presents experimental results obtained in the process of making glass foam from glass waste using a cheap foaming agent (natural dolomite). The originality of the work is the application of the microwave energy, unlike the conventional techniques commonly used in the world. The main advantage highlighted by the experiments is the very low specific energy consumption (below 1.5 kWh/kg), due to the peculiarities of the microwave heating technique. The foamed product has physical, mechanical and morphological characteristics (density between 0.30-0.32 g/cm<sup>3</sup>, thermal conductivity between 0.064-0.067 W/m·K, compressive strength in the range 2.2-2.6 MPa), which are similar to those of foams made by conventional methods and are suitable for its use as insulating material in construction.</p>

Synthesis of ZnAl2O4 Catalytic Support by Combustion Reaction Using Different Fuels

2012 ◽  
Vol 727-728 ◽  
pp. 1260-1265 ◽  
Author(s):  
Elvia Leal ◽  
Bruno Brito Dantas ◽  
Laédna Souto Neiva ◽  
Ruth Herta Goldsmith Aliaga Kiminami ◽  
Ana Cristina Figueiredo de Melo Costa
Keyword(s):  
Particle Size ◽  
Morphological Characteristics ◽  
Nitrogen Adsorption ◽  
Vitreous Silica ◽  
Combustion Reaction ◽  
Muffle Furnace ◽  
Heating Source ◽  
Catalytic Support ◽  
Higher Temperature ◽  
Adsorption Desorption

This work shows the influence of the fuels aniline, carbohydrazide and glycine on structural and morphological characteristics of ZnAl2O4synthesized by combustion reaction. Samples were prepared according to the propellants and explosives theory using a vitreous silica crucible and a muffle furnace as heating source. During the synthesis was measured the time and temperature of the reaction. After The samples were structurally and morphologically characterized by the following techniques: XRD, nitrogen adsorption / desorption (BET / BJH), and SEM. The higher temperature was achieved by the synthesis using aniline, whose value was of 876°C. XRD results showed that all the samples presented the ZnAl2O4spinel as majority phase and, ZnO and Al2O3as segregated phases. The samples also showed low surface area, varying of 23.6 to 28.7 m2/g, and particle size of 45 to 55 nm, besides mesoporous characteristic and irregular agglomerates formation.

Cell Wall Ultrastructure in Three Strains of a Cariogenic Streptococcus

1971 ◽  
Vol 29 ◽  
pp. 338-339
Author(s):  
M. J. Kramer ◽  
Alan L. Coykendall
Keyword(s):  
Cell Wall ◽  
Dental Caries ◽  
Streptococcus Mutans ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Genetic Heterogeneity ◽  
Morphological Characteristics ◽  
Electron Microscopic ◽  
Dna Reassociation ◽  
Wall Ultrastructure

During the almost 50 years since Streptococcus mutans was first suggested as a factor in the etiology of dental caries, a multitude of studies have confirmed the cariogenic potential of this organism. Streptococci have been isolated from human and animal caries on numerous occasions and, with few exceptions, they are not typable by the Lancefield technique but are relatively homogeneous in their biochemical reactions. An analysis of the guanine-cytosine (G-C) composition of the DNA from strains K-1-R, NCTC 10449, and FA-1 by one of us (ALC) revealed significant differences and DNA-DNA reassociation experiments indicated that genetic heterogeneity existed among the three strains. The present electron microscopic study had as its objective the elucidation of any distinguishing morphological characteristics which might further characterize the respective strains.

Aberrant Type C Virus Production in a Cell Line Derived from Balb/3T3

1972 ◽  
Vol 30 ◽  
pp. 286-287
Author(s):  
N. Savage ◽  
A. Hackett
Keyword(s):  
Electron Microscopy ◽  
Cell Line ◽  
Leukemia Virus ◽  
Morphological Characteristics ◽  
Virus Production ◽  
Oncogenic Viruses ◽  
Endogenous Virus ◽  
Virus Particles ◽  
Moloney Leukemia Virus ◽  
A Cell

A cell line, UC1-B, which was derived from Balb/3T3 cells, maintains the same morphological characteristics of the non-transformed parental culture, and shows no evidence of spontaneous virus production. Survey by electron microscopy shows that the cell line consists of spindle-shaped cells with no unusual features and no endogenous virus particles.UC1-B cells respond to Moloney leukemia virus (MLV) infection by a change in morphology and growth pattern which is typical of cells transformed by sarcoma virus. Electron microscopy shows that the cells are now variable in shape (rounded, rhomboid, and spindle), and each cell type has some microvilli. Virtually all (90%) of the cells show virus particles developing at the cell surface and within the cytoplasm. Maturing viruses, typical of the oncogenic viruses, are found along with atypical tubular forms in the same cell.

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