Crystal structure and microstructure of synthetic hexagonal magnesium–cobalt cordierite solid solutions (Mg2−2xCo2xAl4Si5O18)

Author(s):  
Francisco Javier Serrano ◽  
Noemí Montoya ◽  
José Luis Pizarro ◽  
María Mercedes Reventós ◽  
Marek Andrzej Kojdecki ◽  
...  

Co2+-containing cordierite glasses, of nominal compositions (Mg1−xCox)2Al4Si5O18(withx= 0, 0.2, 0.4, 0.6, 0.8 and 1), were prepared by melting colloidal gel precursors. After isothermal heating at 1273 K for around 28 h, a single-phase α-cordierite (high-temperature hexagonal polymorph) was synthesized. All materials were investigated using X-ray powder diffraction and field-emission scanning electron microscopy. The crystal structure and microstructure were determined from X-ray diffraction patterns. Rietveld refinement confirmed the formation of magnesium–cobalt cordierite solid solutions. The unit-cell volume increased with the increase of cobalt content in the starting glass. The crystalline microstructure of the cordierites was interpreted using a mathematical model of a polycrystalline material and characterized by prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice-strain distribution. Hexagonal prismatic was the prevalent shape of α-cordierite crystallites. Bimodality in the size distribution was observed and interpreted as a consequence of two paths of the crystallization: the nucleation from glass of μ-cordierite, which transformed into α-cordierite with annealing, or the nucleation of α-cordierite directly from glass at high temperatures. Scanning electron microscopy images agreed well with crystalline microstructure characteristics determined from the X-ray diffraction line-profile analysis.

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Tatiana M. Savankova ◽  
Lev G. Akselrud ◽  
Lyudmyla I. Ardanova ◽  
Alexey V. Ignatov ◽  
Eugeni I. Get’man ◽  
...  

Solid solutions of Pb(8−x)Na2Smx(VO4)6O(x/2)were studied using X-ray diffraction analysis including Rietveld refinement and scanning electron microscopy and by measuring their electrical conductivity. Crystal structure of the solid solutions was refined and the solubility region0≤x≤0.2was determined for samarium substitution for lead under the scheme2Pb2++□→2Sm3++O2-. The influence of degree of substitution on the electrical conductivity of solid solutions was established.


2017 ◽  
Vol 23 (S1) ◽  
pp. 934-935
Author(s):  
R. Rodriguez-Mijangos ◽  
O. Hernández-Negrete ◽  
R. C. Carrillo-Torres ◽  
F. J. Carrillo-Pesqueira ◽  
M. E. Alvarez-Ramos ◽  
...  

2014 ◽  
Vol 602-603 ◽  
pp. 947-950
Author(s):  
Zhen Wang ◽  
Hai Yan Chen ◽  
Lin Qiang Gao ◽  
Xin Zou

BiFeO3 nanoparticles were successfully synthesized by a hydrothermal method by a mineralizer (KNO3). Structural characterization was performed by thermal analysis, powder X-ray diffraction (XRD) and scanning electron microscopy (TEM).The results showed that the products were perovskite structure BiFeO3 powders. Optimal conditions for the synthesis of single-phase BiFeO3 ceramics were obtained.


2017 ◽  
Vol 891 ◽  
pp. 473-477
Author(s):  
Renáta Verbová ◽  
Viktor Kavečanský ◽  
Pavel Diko ◽  
Samuel Piovarči

Crystalline barium cerate was synthesized by oxalate coprecipitation from nitrates of barium and cerium [1]. The oxalate precursor prepared by chemical methods was calcined at different temperatures up to 950°C. The barium cerate was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). X-ray diffraction investigation enables the determination of the phases that originate at different stages of synthesis and the crystal structure of final barium cerate, as well. From XRD patterns the average size of coherent regions was estimated by using Halder-Wagner method [2]. Both size and shape of crystallites were also studied by scanning electron microscopy. It was found that crystallites of barium cerate arise within the initial particles of the oxalate precursor.


2015 ◽  
Vol 71 (2) ◽  
pp. 89-92
Author(s):  
Ali Hejrani-Dalir ◽  
Masumeh Tabatabaee ◽  
Ali Sheibani

2-Amino-3-hydroxypyridinium dioxido(pyridine-2,6-dicarboxylato-κ3O2,N,O6)vanadate(V), (C5H7N2O)[V(C7H3NO4)O2] or [H(amino-3-OH-py)][VO2(dipic)], (I), was prepared by the reaction of VCl3with dipicolinic acid (dipicH2) and 2-amino-3-hydroxypyridine (amino-3-OH-py) in water. The compound was characterized by elemental analysis, IR spectroscopy and X-ray structure analysis, and consists of an anionic [VO2(dipic)]−complex and an H(amino-3-OH-py)+counter-cation. The VVion is five-coordinated by oneO,N,O′-tridentate dipic dianionic ligand and by two oxide ligands. Thermal decomposition of (I) in the presence of polyethylene glycol led to the formation of nanoparticles of V2O5. Powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of the synthesized powder.


2013 ◽  
Vol 785-786 ◽  
pp. 697-700
Author(s):  
Mei Mei Wu ◽  
Wei Wang ◽  
Zi Jun Wang ◽  
Rong Deng Liu

Bi0.9Pr0.1Fe1-xTixO3 ceramics were prepared by a rapid liquid sintering method. The structure of samples was confirmed by X-ray diffraction and scanning electron microscopy. Ti substitution leads to some changes in the crystal structure of Bi0.9Pr0.1FeO3, which also significantly affects the dielectric constant and loss.


2014 ◽  
Vol 936 ◽  
pp. 452-458
Author(s):  
Di Huo

The surface morphology and structure of the cubic stoichiometric spinel LiMn2O4powder prepared by microwave heating were examined using X-ray diffraction, scanning electron microscopy and transmittance electron microcopy. It is shown that the surface morphology of LiMn2O4particle changed with increasing preparing temperature, while the crystal structure kept unchanged. Novel nanostructured morphologies including nanorods and nanowhiskers were formed under appropriate synthesis conditions. The growth mechanism of the nanostructured morphology of spinel LiMn2O4was discussed in accordance with period bonding chains (PBCs) theory.


2019 ◽  
Author(s):  
Merry Thressia ◽  
Dwi Puryanti ◽  
Sri Handani

The synthesis process of Ni1-xZnxFe2O4 nanoparticles from iron sand originating from Surian Village, Muaro Labuh Regency has been done by coprecipitation method. The extracted iron sand is then dissolved in HCl. The results of the solution obtained were mixed with NiCl2, ZnCl2 and NH4OH. The value of x at Ni1-xZnxFe2O4 varies with x = 0; 0.5 and 1. Characterization using X-ray diffraction in samples without PEG-1000 and samples with PEG-1000 templates showing the crystal structure of a cubic spinel. Morphological studies using Scanning Electron Microscopy (SEM) in samples with PEG-1000 templates show that sfera-shaped samples.


2019 ◽  
Vol 89 (8) ◽  
pp. 1229
Author(s):  
С.В. Ягупов ◽  
Н.И. Снегирёв ◽  
К.А. Селезнева ◽  
Е.Т. Милюкова ◽  
Ю.А. Могиленец ◽  
...  

Surface morphology and crystal structure of iron borate, FeBO3, annealed at different temperatures, have been studied by scanning electron microscopy and X-ray diffraction analysis. The temperature range of structurally stability of iron borate has been determined. It has been established that in the range of temperatures 800–900°C recrystallization in the iron orthoborate Fe3BO6 phase, and more than 900°C − in α-Fe2O3 phase, occurs.


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