scholarly journals The interaction between cerium dioxide, lanthanum and europium oxides at 1500°C

2021 ◽  
Vol 15 (1) ◽  
pp. 32-39
Author(s):  
Olena Andrievskaya ◽  
Oksana Kornienko ◽  
Oleksandr Bykov ◽  
Olga Chudinovich ◽  
Larysa Spasonova
Keyword(s):  
Solid Solutions ◽  
Cerium Dioxide ◽  
Phase Relationship ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Wide Range ◽  
Phase Fields ◽  
Unit Cells ◽  
Fluorite Type

Materials based on CeO2-La2O3-Eu2O3 and La2O3-Eu2O3 systems are promising candidates for a wide range of applications, but the phase relationship has not been studied systematically previously. The phase relations in the CeO2-La2O3-Eu2O3 ternary system at 1500?C and binary La2O3-Eu2O3 system at 1600-1500?C were studied in air by X-ray diffraction (XRD) investigation in the overall concentration range. The isothermal section of the phase diagram for the CeO2-La2O3-Eu2O3 system has been constructed. It was established that in the ternary CeO2-La2O3-Eu2O3 system there exist fields of solid solutions based on hexagonal (A) modification of La2O3, cubic modification of CeO2 with fluorite-type structure (F), cubic (C) and monoclinic (B) modification Eu2O3. It was established that in the binary La2O3-Eu2O3 system there exist fields of solid solutions based on hexagonal (A) modification of La2O3 and monoclinic (B) modification Eu2O3. The phases were separated by two-phase fields (A+B). The refined lattice parameters of the unit cells for solid solutions and microstructures of the definite field of compositions for the systems were determined.

Effect of temperature on formation of murataite and murataite-pyrochlore ceramics

2002 ◽  
Vol 757 ◽  
Author(s):  
O. I. Kirjanova ◽  
S. V. Stefanovsky ◽  
S. V. Yudintsev
Keyword(s):  
Effect Of Temperature ◽  
Cold Crucible ◽  
Iron Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Solid Solution ◽  
Transmission Electron ◽  
Heat Treated ◽  
Unit Cells ◽  
Fluorite Type

ABSTRACTProcesses of phases formation in the ceramic mixtures with basic compositions (wt.%) 10 CaO, 10 MnO, 5 Al2O3, 5 Fe2O3, 55 TiO2, 5 ZrO2, 10 UO2 (M1) and 8 CaO, 8 MnO, 4 Al2O3, 4 Fe2O3, 20 Gd2O3, 44 TiO2, 4 ZrO2, 8 UO2 (M4) were studied using X-ray diffraction, scanning and transmission electron microscopy. The batches were milled, compacted in pellets at 200 MPa, and heat-treated in a resistive furnace at 1100 °C, 1300 °C, 1400 °C, and 1500 °C as well as melted in a cold crucible at ∼1600 °C. Reactions in the mixtures heat-treated at 1100 °C were not completed and samples contained significant amount of unreacted and intermediate (altered rutile, cubic oxide solid solution, perovskite) phases. Within the temperature range 1100–1300 °C reactions are mainly completed and ceramics sintered at 1300 °C are composed of major murataite and minor rutile (M1) or major murataite and pyrochlore and minor zirconolite and perovskite (M4). However full homogenization at 1300 °C has not been reached yet and to obtain the ceramics with uniform compositions of the phases sintering at 1400 °C or melting at 1500–1600 °C were required.In the ceramic sample M1 two murataite varieties with five- (murataite-5C) and eight-fold (mu-rataite-8C) fluorite-type unit cells were found. The sample M4 is composed of pyrochlore, murataite-8C and zirconolite-3O. In the sample M1 murataite-5C is enriched with U and Ca and depleted with iron group elements as compared to murataite-8C. Fraction of murataite-5C concentrates about 80% of total U and about 70% of Mn+Fe (corrosion products). Waste elements partitioning among the phases in the M4 sample depends significantly on temperature of heat-treatment.

scholarly journals Influence of mg doping on structural, optical and photocatalytic performances of ceria nanopowders

2017 ◽  
Vol 11 (4) ◽  
pp. 304-310
Author(s):  
Branko Matovic ◽  
Jelena Lukovic ◽  
Bojan Stojadinovic ◽  
Sonja Askrabic ◽  
Aleksandra Zarubica ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Oxygen Vacancies ◽  
Uv Light ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Fluorite Type ◽  
Photocatalytic Performances ◽  
Mg Doped

Nanosized Mg-doped ceria powders were obtained by self-propagating room temperature reaction without using surfactants or templates. X-ray diffraction analysis and field emission scanning microscopy results showed that the doped samples are solid solutions with fluorite-type structure and spherical morphology. Raman spectra revealed an increase in the amount of oxygen vacancies with the increase of Mg concentration. This increasing results in a narrowing of the bandgap of CeO2. The photocatalytic performances of the Mg-doped ceria solid solutions were evaluated by decomposing an organic dye, crystal violet under UV irradiation. The Mg-doped ceria solid solutions exhibit significantly better photocatalytic activity than the pure CeO2 and commercial TiO2. The higher first rate constant of the Mg-doped samples demonstrated that they are much more efficient than TiO2 and CeO2 under UV light. Mg2+ dopant ions and oxygen vacancies play a significant role in the enhancement of photocatalytic performances of the Mg-doped ceria.

scholarly journals INTERACTION OF LANTHANE AND LUTETIUM AT TEMPERATURE 1500–1600°C

2020 ◽  
Vol 86 (3) ◽  
pp. 19-25
Author(s):  
Olga Chudinovych ◽  
Nataliya Zhdanyuk
Keyword(s):  
Systematic Study ◽  
Composition Range ◽  
Phase Relationship ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Wide Range ◽  
Concentration Dependences ◽  
Perovskite Type ◽  
Perovskite Type Structure

Materials based on La2O3–Lu2O3 system are promising candidates for a wide range of applications, but the phase relationship has not been studied systematically previously. To address this challenge, the subsection of the phase diagram for 1500 and 1600 °C have been elucidated. The samples of different compositions have been prepared from nitrate acid solutions by evaporation, drying and heat treatment at 1100, 1500 and 1600 °C. The phase relations in the binary La2O3–Lu2O3 system at 1500 and 1600 °C were studied from the heat treated samples using X-ray diffraction analysis and scanning electron microscopy in the overall concentration range. The X–ray analysis of the samples was performed by powder method using DRON-3 at room temperature (CuKa radiation). It was established that in the binary La2O3–Lu2O3 system there exist fields of solid solutions based on hexagonal (A) modification of La2O3, cubic (C) modification of Lu2O3, and with perovskite–type structure of LaLuO3 (R) with rhombic distortions. The systematic study that covered whole composition range excluded formation of new phases. The systematic study that covered whole composition range excluded formation of new phases. The boundaries of mutual solubility and concentration dependences the lattice parameters for all phases have been determined. The solubility of Lu2O3 in the hexagonal А–lanthanum modification is ~ 9 mol. % at 1500 and 1600 °С. The solubility of La2O3 in the cubic C–Lu2O3 is ~ 4 mol. % at 1500 and 7 mol. % at 1600 °С.

scholarly journals Limits of Solid Solutions and Thermal Deformations in the L-Alanine–L-Serine Amino Acid System

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 618 ◽  
Author(s):  
Elena Kotelnikova ◽  
Roman Sadovnichii ◽  
Lyudmila Kryuchkova ◽  
Heike Lorenz
Keyword(s):  
Amino Acid ◽  
Solid Solutions ◽  
Elevated Temperatures ◽  
Deformation Tensor ◽  
Acid System ◽  
X Ray Diffraction ◽  
Active Components ◽  
Two Phase ◽  
X Ray ◽  
Thermal Deformations

The limits of solid solutions and thermal deformations in the L-alanine–L-serine (L-ala–L-ser) amino acid system have been determined. Thirteen amino acid mixtures with various proportions of the components L-ser/L-ala were studied using powder X-ray diffraction techniques. It was found that the regions of solid solutions in the system are rather limited and cover less than 10 mol. % from each component side. The thermal behavior of the components L-ser and L-ala and the composition L-ser/L-ala = 90/10 were studied by temperature-resolved powder X-ray diffraction. The heating of L-ser and L-ala only causes thermal deformations, while two-phase mixtures with the 90/10 L-ser/L-ala ratio form solid solutions at elevated temperatures. Additionally, the parameters of the thermal deformation tensor for L-ser and L-ala were calculated, and the figures of their thermal expansion coefficients were plotted and analyzed. The study conducted is of high applicability, since amino acids are active components of various biological, geological, and technological processes, including those at elevated temperatures, and have numerous applications in life-science industries.

X-ray diffraction studies of solid solutions of Cr-, Mn-, Fe-, Co-, and Ni-containing transition metal spinel oxides

1995 ◽  
Vol 10 (3) ◽  
pp. 214-220 ◽  
Author(s):  
G. C. Allen ◽  
K. R. Hallam ◽  
J. A. Jutson
Keyword(s):  
Transition Metal ◽  
Metal Oxide ◽  
Solid Solutions ◽  
Cell Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Spinel Oxides ◽  
Steel Surfaces ◽  
Diffraction Patterns

A wide range of transition metal oxide solid solutions have been prepared and characterised using powder X-ray diffraction (MnxCo1−xFe2O4, FexCo1−xFe2O4, NixCo1−xFe2O4, FeFexCr2−xO4, MnFexCr2−xO4, MnxFe1−xCr2O4, MnxFe1−xFe2O4, NixFe1−xFe2O4). Calibration curves have been obtained relating oxide composition to unit cell parameter or d spacing. From these curves it is possible to identify the composition of oxides formed on steel surfaces in varied industrial environments. Even when poor diffraction patterns are obtained and little sample is available, an estimate of composition can be made.

scholarly journals Phase Equilibrium in ZrO2-CeO2-Eu2O3 System at a Temperature of 1500 °C

2021 ◽  
Vol 03 (03) ◽  
pp. 1-1
Author(s):  
Oksana Kornienko ◽  
◽  
Anatoliy Sameljuk ◽  
Olena Andrievskaya ◽  
Serhii Yushkevych ◽  
...  
Keyword(s):  
Isothermal Section ◽  
Phase Equilibria ◽  
Solid Solutions ◽  
Intermediate Phase ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Three Phase ◽  
Unit Cells ◽  
Fluorite Type ◽  
Pyrochlore Type

The phase equilibria and structural transformations in the ternary ZrO2-CeO2-Eu2O3 system at 1500 °C were studied by X-ray diffraction and scanning electron microscopy in the overall concentration range. The system was found to constitute fields of solid solutions based on the tetragonal (Т) modification of ZrО2, cubic (С) and monoclinic (B) modifications of Eu2O3, cubic with a fluorite-type structure (F) modifications of СеО2 (ZrО2), and ordered intermediate phase with a pyrochlore-type structure of Eu2Zr2O7 (Py). The refined lattice parameters of the unit cells corresponding to the solid solutions and microstructures of the definite field of compositions for the systems were determined. The peculiarity of the isothermal section of the phase diagram in the ZrO2-СеO2-Eu2O3 system at 1500 °С is the formation of phase equilibria on the basis of the fluorite solid solutions of ZrO2(CeO2) along with other components. There are at least three homogeneous fields of cubic phases. The isothermal section of the ZrO2-CeO2-Eu2O3 system at 1500 °С was constituted of four three-phase regions (C-Eu2O3 + F-CeO2+Py, C-Eu2O3 + F-ZrO2+Py, Py + F-ZrO2 + T-ZrO2, Py + F-CeO2 + T-ZrO2).

scholarly journals Multidimensional Ln-Aminophthalate Photoluminescent Coordination Polymers

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1786
Author(s):  
Carla Queirós ◽  
Chen Sun ◽  
Ana M. G. Silva ◽  
Baltazar de Castro ◽  
Juan Cabanillas-Gonzalez ◽  
...  
Keyword(s):  
Water Content ◽  
Coordination Polymers ◽  
Metal Ion ◽  
Low Cost ◽  
Microwave Assisted Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

The development of straightforward reproducible methods for the preparation of new photoluminescent coordination polymers (CPs) is an important goal in luminescence and chemical sensing fields. Isophthalic acid derivatives have been reported for a wide range of applications, and in addition to their relatively low cost, have encouraged its use in the preparation of novel lanthanide-based coordination polymers (LnCPs). Considering that the photoluminescent properties of these CPs are highly dependent on the existence of water molecules in the crystal structure, our research efforts are now focused on the preparation of CP with the lowest water content possible, while considering a green chemistry approach. One- and two-dimensional (1D and 2D) LnCPs were prepared from 5-aminoisophthalic acid and Sm3+/Tb3+ using hydrothermal and/or microwave-assisted synthesis. The unprecedented LnCPs were characterized by single-crystal X-ray diffraction (SCRXD), powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM), and their photoluminescence (PL) properties were studied in the solid state, at room temperature, using the CPs as powders and encapsulated in poly(methyl methacrylate (PMMA) films, envisaging the potential preparation of devices for sensing. The materials revealed interesting PL properties that depend on the dimensionality, metal ion, co-ligand used and water content.

scholarly journals Synthesis of Ce1−xPdxO2−δ Solid Solution in Molten Nitrate

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 640
Author(s):  
Hideaki Sasaki ◽  
Keisuke Sakamoto ◽  
Masami Mori ◽  
Tatsuaki Sakamoto
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Ionic States

CeO2-based solid solutions in which Pd partially substitutes for Ce attract considerable attention, owing to their high catalytic performances. In this study, the solid solution (Ce1−xPdxO2−δ) with a high Pd content (x ~ 0.2) was synthesized through co-precipitation under oxidative conditions using molten nitrate, and its structure and thermal decomposition were examined. The characteristics of the solid solution, such as the change in a lattice constant, inhibition of sintering, and ionic states, were examined using X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), transmission electron microscopy (TEM)−EDS, and X-ray photoelectron spectroscopy (XPS). The synthesis method proposed in this study appears suitable for the easy preparation of CeO2 solid solutions with a high Pd content.

Nanostructured TiO2-Based Composites for Light Absorption

2014 ◽  
Vol 975 ◽  
pp. 207-212
Author(s):  
Dayse I. dos Santos ◽  
Olayr Modesto Jr. ◽  
Luis Vicente A. Scalvi ◽  
Americo S. Tabata
Keyword(s):  
Metal Oxide ◽  
Light Absorption ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Oxide Powders

Metal oxide nanocomposites were prepared by two different routes: polyol and sol-gel. Characterization by X ray diffraction showed that the first process produces directly a two-phase material, while the sol-gel powder never showed second phase below 600°C. Light spectroscopy of the treated powders indicated similarities for the processed materials. Although the overall material compositions are about the same, different structural characteristics are found for each processing. With the exception of Ti-Zn materials, all the double metal oxide powders showed higher absorbance than either TiO2 powder.

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