scholarly journals Synthesis of barium-zinc-titanate ceramics

2012 ◽  
Vol 44 (1) ◽  
pp. 65-71 ◽  
Author(s):  
N. Obradovic ◽  
M.V. Nikolic ◽  
N. Nikolic ◽  
S. Filipovic ◽  
M. Mitric ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Zinc Titanate ◽  
X Ray ◽  
Microstructure Characteristics ◽  
Amplitude Spectra ◽  
Titanate Ceramics

Mixtures of BaCO3, ZnO and TiO2 powders, with molar ratio of 1:2:4, were mechanically activated for 20, 40 and minutes in a planetary ball mill. The resulting powders were compacted into pellets and isothermally sintered at 1250?C for 2h with a heating rate of 10?C/min. X-ray diffraction analysis of obtained powders and sintered samples was performed in order to investigate changes of the phase composition. The microstructure of sintered samples was examined by scanning electron microscopy. The photoacoustic phase and amplitude spectra of sintered samples were measured as a function of the laser beam modulating frequency using a transmission detection configuration. Fitting of experimental data enabled determination of photoacoustic properties including thermal diffusivity. Based on the results obtained correlation between thermal diffusivity and experimental conditions, as well the samples microstructure characteristics, was discussed.

scholarly journals Investigation of zinc stannate synthesis using photoacoustic spectroscopy

2007 ◽  
Vol 39 (2) ◽  
pp. 153-160 ◽  
Author(s):  
T. Ivetic ◽  
M.V. Nikolic ◽  
P.M. Nikolic ◽  
V. Blagojevic ◽  
S. Djuric ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Ball Mill ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Microstructure Characteristics ◽  
Amplitude Spectra ◽  
Scanning Electron

Mixtures of ZnO and SnO2 powders, with molar ratio of 2:1, were mechanically activated for 40, 80 and 160 minutes in a planetary ball mill. The resulting powders were compacted into pellets and non-isothermally sintered up to 1200?C with a heating rate of 5?C/min. X-ray diffraction analysis of obtained powders and sintered samples was performed in order to investigate changes of the phase composition. The microstructure of sintered samples was examined by scanning electron microscopy. The photoacoustic phase and amplitude spectra of sintered samples were measured as a function of the laser beam modulating frequency using a transmission detection configuration. Fitting of experimental data enabled determination of photoacoustic properties including thermal diffusivity. Based on the results obtained a correlation between thermal diffusivity and experimental conditions as well the samples microstructure characteristics was discussed. .

scholarly journals Dilatometer Investigations of Reactive Sintering of Zinc Titanate Ceramics

2005 ◽  
Vol 494 ◽  
pp. 411-416 ◽  
Author(s):  
N. Obradović ◽  
Nebojsa Labus ◽  
Tatjana Srećković ◽  
Momcilo M. Ristić
Keyword(s):  
Mechanical Activation ◽  
Solid State Reactions ◽  
Molar Ratio ◽  
Formation Processes ◽  
X Ray Diffraction ◽  
Time Intervals ◽  
Zinc Titanate ◽  
X Ray ◽  
Sintering Time ◽  
Titanate Ceramics

Starting powder mixtures of ZnO and TiO2, at the molar ratio that is in accordance with the stoichiometry of zinc titanate Zn2TiO4, were mechanically activated using a planetary ball mill in different time intervals from 0 to 90 minutes. X-ray diffraction analysis, scanning electron microscopy and non-isothermal dilatometric measurements were performed in order to investigate zinc titanate formation. Processes occurring during mechanical activation led to the formation of a specific structure of obtained powders that promoted and accelerated solid-state reactions and densification during sintering. The main conclusion based on analysis is that mechanical activation enables better compaction of activated powders, i.e. possibility of achieving higher densities of green bodies without binders, but first of all that Zn2TiO4 ceramics can be obtained by mechanical activation after a certain time with appropriate thermal treatment, i.e. heating rate and sintering time, at temperatures lower than those when non-activated mixtures were used.

Refined Determination of the Structure of Kerogen Etc. by Xrd and its Significance

1995 ◽  
Vol 39 ◽  
pp. 553-560
Author(s):  
Wei Mingxin ◽  
Liu Delian ◽  
Chen Deyu ◽  
Wang Guanxin
Keyword(s):  
Nearest Neighbors ◽  
Computer Programs ◽  
X Ray Diffraction ◽  
Empirical Coefficient ◽  
Experimental Conditions ◽  
X Ray ◽  
Peak Separation ◽  
Aromatic Clusters ◽  
Degree Of Order

The aromaticity fa, crystallite parameters dm, dy, La, Lc, Mc, and RDF parameters r1 and Ka have been determined for sedimentary organic matter, such as kerogens, coals, and bitumens. Here, the rt value is the interatomic distance between the nearest neighbors of carbon atoms, and Ka is an empirical coefficient as an indicator of the degree of order-stacking for aromatic clusters. The refined methods of X-ray diffraction include the improved experimental conditions and new computer programs. The computer programs are composed of four software: AMORPHOUS software; NORMALIZATION software; RDF (Radial Distribution Function) software; and MPS (Multiple Peak Separation) software.

Determination of the Relative Amounts of α-carbamazepine and β-carbamazepine in a Mixture by Powder X-Ray Diffractometry

1990 ◽  
Vol 5 (3) ◽  
pp. 155-159 ◽  
Author(s):  
Raj Suryanarayanan
Keyword(s):  
Weight Fraction ◽  
Preparation Technique ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Sample Preparation Technique ◽  
Integrated Intensity ◽  
Diffraction Patterns ◽  
Good Agreement

AbstractA powder X-ray diffraction technique has been developed to quantify the relative amounts of α-carbamazepine (A) and β-carbamazepine (B) when they occur as a mixture. The theoretical basis of this technique was developed in 1948 by Alexander and Klug (Anal. Chem., 20:886-889). The powder X-ray diffraction patterns of A and B revealed that the line with d-spacing of 10.1 Å was unique to A. The ratio of the integrated intensity of the 10.1 Å line in a mixture of A and B, to the intensity of the 10.1 Å line in a sample consisting of only A, was calculated as a function of weight fraction of A in the mixture. These ratios were also experimentally determined, and there was a good agreement between the theoretical and experimental intensity ratios. The particle size of the samples, the sample preparation technique and the experimental conditions were controlled so as to eliminate the major sources of error in powder X-ray diffractometry. In order to minimize preferred orientation of the particles, a sample holder was specially fabricated.

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

Effect of Hydrated Metal Salts on the Coordination Product of Cobalt(II) halide and PNP Type Ligand, 2,6-bis(di-tertbutylphosphinomethyl) pyridine

2018 ◽  
Author(s):  
Tasneem Siddiquee ◽  
Abdul Goni
Keyword(s):  
Metal Salts ◽  
Molar Ratio ◽  
Pincer Complexes ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Distorted Tetrahedral Geometry ◽  
Cobalt Center

Chemical treatment of CoX<sub>2</sub><b><sup>. </sup></b>6H<sub>2</sub>O (X = Cl, Br, I) with the potentially tridentate PNP pincer ligand 2,6-bis(di-<i>tert</i>-butylphosphinomethyl)pyridine in 1:1 molar ratio results in cobalt(II) halide-PNP pincer complexes. The effect of the hydrated metal source on molecular structure and geometry of the complexes was studied by single crystal X-ray diffraction analysis. The complexes are neutral and the cobalt center adopts a penta-coordinate system with potential atropisomerization. Within the unit cell there are two distinct molecules per asymmetric unit. One of the two phosphorus atoms in the PNP ligand was observed to be partially oxidized to phosphinoxide. Disorder in the structure reflects a mixture of square pyramidal and distorted tetrahedral geometry.

New Coordination Compounds of Fe(III) with Organic Ligands

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihaela Flondor ◽  
Ioan Rosca ◽  
Doina Sibiescu ◽  
Mihaela-Aurelia Vizitiu ◽  
Daniel-Mircea Sutiman ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Complex Compounds ◽  
Organic Ligands ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Chemical Analysis ◽  
Structural Formulae ◽  
Paramagnetic Properties

In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands derived from: 2-(4-chloro-phenylsulfanyl)-1-(2-hydroxy-3,5-diiodo-phenyl)-ethanone (HL1), 1-(3,5-dibromo-2-hydroxy-phenyl)-2-phenylsulfanyl-ethanone(HL2), and 2-(4-chloro-phenylsulfanyl)-1-(3,5-dibromo-2-hydroxy-phenyl)-ethanone (HL3) is presented. The characterization of these complexes is based on method as: the elemental chemical analysis, IR and ESR spectroscopy, M�ssbauer, the thermogravimetric analysis and X-ray diffraction. Study of the IR and chemical analysis has evidenced that the precipitates form are a complexes and the combination ratio of M:L is 1:2. The central atoms of Fe(III) presented paramagnetic properties and a octaedric hybridization. Starting from this precipitation reactions, a method for the gravimetric determination of Fe(III) with this organic ligands has been possible. Based on the experimental data on literature indications, the structural formulae of the complex compounds are assigned.

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