scholarly journals Investigation of the Heterovalent Substitution Cadmium for Lanthanum in Molybdate La2MoO6

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
K. A. Chebyshev ◽  
A. V. Ignatov ◽  
L. V. Pasechnik ◽  
N. I. Selikova ◽  
E. I. Get`man
Keyword(s):  
Solid State Reaction Method ◽  
Fluorite Phase ◽  
Cubic Phase ◽  
Cadmium Content ◽  
Heterovalent Substitution ◽  
Rietveld Refinements ◽  
X Ray ◽  
Refinement Method ◽  
Study Results ◽  
Lanthanum Molybdate

This paper presents the investigation of the heterovalent substitution of cadmium for lanthanum in the La2-xCdxMoO6-x/2 system. The samples were synthesized by the solid state reaction method at 1000°C. The samples were characterized by X-ray powder diffraction with Rietveld refinements, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy methods. The study results revealed that cadmium incorporation in the lanthanum molybdate leads to the transformation of the tetragonal structure of La2MoO6 to a cubic fluorite-like one. The content of the cubic phase reaches 94% in the Lа1.4Cd0.6MoO5.7 sample. The unit cell parameter of fluorite-like-phase decreases with cadmium content rising. The preferred location of cadmium ions in the cubic structure was established by the Rietveld refinement method. The heterovalent substitution cadmium for lanthanide in tetragonal La2MoO6 molybdate leads to the cubic fluorite phase stabilization in a similar way as it occurs in the process of reduction.

Structural analysis of Gd2Ce2O7

2015 ◽  
Vol 1743 ◽  
Author(s):  
Maulik K. Patel ◽  
Gianguido Baldinozzi ◽  
Jeffery A. Aguiar ◽  
James A. Valdez ◽  
Sven C. Vogel ◽  
...  
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Fluorite Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Broadening ◽  
Transmission Electron ◽  
Refinement Method ◽  
History Of ◽  
Miscibility Gaps

ABSTRACTA complex cerium bearing oxide, Gd2Ce2O7 was synthesized in order to simulate Pu in a fluorite derivative oxide. X-ray diffraction (XRD) data was collected using a lab diffractometer at room temperature and analyzed by Rietveld refinement method using the xnd program. The diffraction pattern obtained from the material could be indexed as a C-type cubic bixbyite crystal structure however several peaks showed peak broadening and could not be accounted for within the single-phase bixbyite model. A full pattern refinement, assuming a possible existence of short order disordered bixbyite regions within an average disordered fluorite phase gave a good fit with the experimental data, providing an estimate for correlation length of those bixbyite regions. Transmission electron microscopy confirms the existence of these correlated domains of disordered bixbyite type phase inside a defect fluorite lattice. Understanding the extent of these domains as a function of composition and the thermal history of the samples may have a profound effect on our understanding of miscibility gaps in Re2O3-CeO2 phase diagrams. These effects could be eventually exploited to design materials with increased radiation resistance, a desired feature for oxide matrices where actinides can be safely disposed.

scholarly journals Effect of Zr4+ Content on Crystal Structure, Micromorphology and Dielectric Properties of Ba(Zrx Ti1-X)O3 Ceramics

2019 ◽  
Vol 3 (1) ◽  
Keyword(s):  
Crystal Structure ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Great Influence ◽  
Secondary Phase ◽  
Solid State Reaction Method ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

Ba(Zrx Ti1-x)O3 ceramics (X=1.5, 2.0, 2.5, 3.0) were prepared by solid-state reaction method. Effect of controlling the ratio of Zr/Ti on the crystal structure, micromorphology and dielectric properties of BZT ceramics. Their crystal structures, morphologies, and electric properties were respectively characterized using X-ray diffraction, scanning electron microscope and impedance analyzer. The X-ray diffraction patterns show that the zirconium titanate ceramic samples behave cubic phase structure and no secondary phase. The ratio of Zr/Ti has a great influence on the crystal structure, microstructure and dielectric properties. As the Zr4+ content increases, the lattice constant increases and the grain size decreases. The dielectric constant is the largest when the Zr content is 15%. As the Zr4+ content increases, the dielectric constant decreases gradually, and the Curie temperature moves toward the low temperature region.

Powder X-ray diffraction data of new bismuth yttrium gadolinium oxides

2008 ◽  
Vol 23 (3) ◽  
pp. 255-258
Author(s):  
M. Alizadeh ◽  
K. Ahmadi ◽  
A. Maghsudipour ◽  
F. Moztarzadeh
Keyword(s):  
Diffraction Data ◽  
Solid State Reaction Method ◽  
Cubic Phase ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Good Agreement

X-ray powder diffraction data for five new bismuth yttrium gadolinium oxide compounds synthesized by solid state reaction method are reported. The unit cell dimensions were determined from X-ray diffraction methods, using CuKα radiation, and evaluated by indexing programs. The cubic phase was the sole crystalline phase detected by X-ray diffraction analysis in Bi0.88Y0.06Gd0.06O1.5, Bi0.88Y0.08Gd0.04O1.5, Bi0.82Y0.09Gd0.09O1.5, Bi0.82Y0.12Gd0.06O1.5, and Bi0.82Y0.06Gd0.12O1.5 samples with lattice constants of a=5.5371(1) Å, a=5.5368(1) Å, a=5.5303(2) Å, a=5.53487(8) Å, and a=5.5279(1) Å, respectively. The results are in good agreement with those reported for bismuth yttrium oxide (Bi0.75Y0.25)O1.5 (PDF 01-084-1450).

Phase relations in the Ba–Sr–Co–Fe–O system at 1273 K in air

2009 ◽  
Vol 42 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Zhèn Yáng ◽  
Ashley S. Harvey ◽  
Anna Infortuna ◽  
Ludwig J. Gauckler
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Solid State Reaction Method ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray

Selected compositions of the Ba–Sr–Co–Fe–O system were synthesized from powders by the solid-state reaction method. Samples were equilibrated at 1273 K for 36 000 s in air. The resulting powders were characterized by X-ray diffraction (XRD) at room temperature and by high-temperaturein situXRD. The phases present in the BaxSr1−xCoyFe1−yO3−δsystem are outlined for 1273 K in air. For most of the quaternary compositions, the cubic perovskite is formed, except for the compositions withx= 1 (excludingy= 0.4),y= 1 andx,y= 0.8, where the phases mainly show hexagonal distortions, andx, y= 0, for which a predominant cubic phase is mixed with other phases.

Luminescence Properties of Eu2+ Doped Ba3La(PO4)3 Phosphor

2013 ◽  
Vol 815 ◽  
pp. 535-539
Author(s):  
Ji You Wang ◽  
Jian Bo Wang ◽  
Hong Mei Liu ◽  
Ping Duan
Keyword(s):  
Solid State ◽  
Solid State Reaction Method ◽  
Concentration Quenching ◽  
Maximum Intensity ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Major Mechanism ◽  
Uv Visible

Eu2+-doped Ba3La (PO4)3phosphors were synthesized by solid-state reaction method. The X-ray diffraction (XRD) results showed that the obtained phosphors were cubic phase. The structure of Ba3La (PO4)3doped slight Eu2+does not changed. Ba3La1-x(PO4)3:xEu2+phosphor can be excited by UV-visible light, which emits intensely blue light with broadband peaked at about 466 nm. The relative PL intensity increases with Eu2+-concentration increasing until a maximum intensity is reached, at about x=0.015mol. According to the Dexters theory, it was found that the major mechanism for concentration quenching as a result of dipole-dipole (d-d) interaction.

scholarly journals Electrical properties of KTa0.65Nb0.35O3 lead-free ceramics

2020 ◽  
Vol 14 (4) ◽  
pp. 372-377
Author(s):  
Felicia Gheorghiu ◽  
Mihai Asandulesa ◽  
Lavinia Curecheriu
Keyword(s):  
Solid State Reaction Method ◽  
Lead Free ◽  
Cubic Phase ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Suitable Candidate ◽  
X Ray ◽  
Tunable Capacitors ◽  
High Tunability ◽  
Lead Free Ceramics

In the present study, lead-free KTa0.65Nb0.35O3 ceramics were prepared by solid state reaction method using successive calcination steps in order to ensure the complete reaction of the system. The X-ray diffraction analyses of the prepared ceramics have shown the formation of a perovskite structure without any secondary phases. The increase of sintering temperature from 1150 to 1200?C leads to a better densification and decreasing of the Curie temperature (associated with tetragonal-cubic phase transition) closer to the room temperature, i.e. to 290K. The ceramics sintered at 1200?C exhibits a high tunability (n = 1.6) and a reduced hysteretic behaviour. Due to its moderate permittivity, low losses and field dependence permittivity, the KTa0.65Nb0.35O3 ceramics is suitable candidate for application as tunable capacitors.

scholarly journals Modeling of the Resonant X-ray Response of a Chiral Cubic Phase

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 214
Author(s):  
Timon Grabovac ◽  
Ewa Gorecka ◽  
Damian Pociecha ◽  
Nataša Vaupotič
Keyword(s):  
Absorption Edge ◽  
Unit Cell ◽  
Resonant Peak ◽  
Cubic Phase ◽  
Tensor Form ◽  
Resonant Enhancement ◽  
X Ray ◽  
X Ray Scattering ◽  
Thermotropic Liquid Crystals ◽  
Carbon Absorption

The structure of a continuous-grid chiral cubic phase made of achiral constituent molecules is a hot topic in the field of thermotropic liquid crystals. Several structural models have been proposed so far. Resonant X-ray scattering (RXS), which gives information on the molecular orientation in the unit cell, could be applied to select the most appropriate model. We modeled the RXS response for the recently proposed chiral cubic phase structure with an all-hexagon chiral continuous grid. A tensor form factor of a unit cell is constructed, which enables calculation of intensities of peaks for all Miller indices. We find that all the symmetry allowed peaks are resonantly enhanced, and their intensity is much stronger than the intensity of the symmetry forbidden (resonant) peaks. In particular, we predict that a strong resonant enhancement of the symmetry allowed peaks (011) and (002), not observed in a nonresonant scattering, could be observed by RXS at the carbon absorption edge. By RXS at the sulfur absorption edge, one might observe a resonant peak (113) and resonantly enhanced peak (233), and resonant enhancement of all the peaks that are observed in a nonresonant scattering, which probably hide the rest of the predicted resonant peaks.

scholarly journals Pristine and Magnetic Kenaf Fiber Biochar for Cd2+ Adsorption from Aqueous Solution

2021 ◽  
Vol 18 (15) ◽  
pp. 7949
Author(s):  
Anwar Ameen Hezam Saeed ◽  
Noorfidza Yub Harun ◽  
Suriati Sufian ◽  
Muhammad Roil Bilad ◽  
Zaki Yamani Zakaria ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Photoelectron Spectroscopy ◽  
Textural Properties ◽  
Ion Concentration ◽  
Solution Temperature ◽  
Maximum Adsorption Capacity ◽  
Magnetic Biochar ◽  
X Ray ◽  
Study Results ◽  
Capacity Surface

Development of strategies for removing heavy metals from aquatic environments is in high demand. Cadmium is one of the most dangerous metals in the environment, even under extremely low quantities. In this study, kenaf and magnetic biochar composite were prepared for the adsorption of Cd2+. The synthesized biochar was characterized using (a vibrating-sample magnetometer VSM), Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption batch study was carried out to investigate the influence of pH, kinetics, isotherm, and thermodynamics on Cd2+ adsorption. The characterization results demonstrated that the biochar contained iron particles that help in improving the textural properties (i.e., surface area and pore volume), increasing the number of oxygen-containing groups, and forming inner-sphere complexes with oxygen-containing groups. The adsorption study results show that optimum adsorption was achieved under pH 5–6. An increase in initial ion concentration and solution temperature resulted in increased adsorption capacity. Surface modification of biochar using iron oxide for imposing magnetic property allowed for easy separation by external magnet and regeneration. The magnetic biochar composite also showed a higher affinity to Cd2+ than the pristine biochar. The adsorption data fit well with the pseudo-second-order and the Langmuir isotherm, with the maximum adsorption capacity of 47.90 mg/g.

scholarly journals Transport and Dielectric Properties of Mechanosynthesized La2/3Cu3Ti4O12 Ceramics

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 313
Author(s):  
Mohamad M. Ahmad ◽  
Hicham Mahfoz Kotb ◽  
Celin Joseph ◽  
Shalendra Kumar ◽  
Adil Alshoaibi
Keyword(s):  
Dielectric Constant ◽  
Sintering Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Boundary Conductivity ◽  
X Ray ◽  
Giant Dielectric ◽  
Mechanochemical Milling ◽  
Giant Dielectric Constant ◽  
Lower Temperature

La2/3Cu3Ti4O12 (LCTO) powder has been synthesized by the mechanochemical milling technique. The pelletized powder was conventionally sintered for 10 h at a temperature range of 975–1025 °C, which is a lower temperature process compared to the standard solid-state reaction. X-ray diffraction analysis revealed a cubic phase for the current LCTO ceramics. The grain size of the sintered ceramics was found to increase from 1.5 ± 0.5 to 2.3 ± 0.5 μm with an increase in sintering temperature from 975 to 1025 °C. The impedance results show that the grain conductivity is more than three orders of magnitude larger than the grain boundary conductivity for LCTO ceramics. All the samples showed a giant dielectric constant (1.7 × 103–3.4 × 103) and dielectric loss (0.09–0.17) at 300 K and 10 kHz. The giant dielectric constant of the current samples was attributed to the effect of internal barrier layer capacitances due to their electrically inhomogeneous structure.

scholarly journals Influence of Li2CO3 addition on electrical and magnetic properties of Ni0.6Mg0.4Fe2O4

2020 ◽  
Vol 10 (03) ◽  
pp. 2050003
Author(s):  
M. R. Hassan ◽  
M. T. Islam ◽  
M. N. I. Khan
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Low Frequency ◽  
Solid State Reaction Method ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Frequency Regime ◽  
Xrd Patterns

In this research, influence of adding Li2CO3 (at 0%, 2%, 4%, 6%) on electrical and magnetic properties of [Formula: see text][Formula: see text]Fe2O4 (with 60% Ni and 40% Mg) ferrite has been studied. The samples are prepared by solid state reaction method and sintered at 1300∘C for 6[Formula: see text]h. X-ray diffraction (XRD) patterns show the samples belong to single-phase cubic structure without any impurity phase. The magnetic properties (saturation magnetization and coercivity) of the samples have been investigated by VSM and found that the higher concentration of Li2CO3 reduces the hysteresis loss. DC resistivity increases with Li2CO3 contents whereas it decreases initially and then becomes constant at lower value with temperature which indicates that the studied samples are semiconductor. The dielectric dispersion occurs at a low-frequency regime and the loss peaks are formed in a higher frequency regime, which are due to the presence of resonance between applied frequency and hopping frequency of charge carriers. Notably, the loss peaks are shifted to the lower frequency with Li2CO3 additions.

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