CoFe Prussian Blue Analogues under Variable Pressure. Evidence of Departure from Cubic Symmetry: X-ray Diffraction and Absorption Study

2008 ◽  
Vol 112 (45) ◽  
pp. 17709-17715 ◽  
Author(s):  
Anne Bleuzen ◽  
Jean-Daniel Cafun ◽  
Anne Bachschmidt ◽  
Michel Verdaguer ◽  
Pascal Münsch ◽  
...  
Keyword(s):  
Prussian Blue ◽  
Variable Pressure ◽  
Absorption Study ◽  
X Ray Diffraction ◽  
Cubic Symmetry ◽  
X Ray ◽  
Prussian Blue Analogues

scholarly journals Influence of the Presence of Different Alkali Cations and the Amount of Fe(CN)6 Vacancies on CO2 Adsorption on Copper Hexacyanoferrates

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3371 ◽  
Author(s):  
Svensson ◽  
Grins ◽  
Eklöf ◽  
Eriksson ◽  
Wardecki ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Prussian Blue ◽  
Co2 Adsorption ◽  
X Ray Diffraction ◽  
Alkali Cations ◽  
Prussian Blue Analogue ◽  
X Ray ◽  
Infra Red ◽  
Adsorption Desorption ◽  
Adsorption Capability

The CO2 adsorption on various Prussian blue analogue hexacyanoferrates was evaluated by thermogravimetric analysis. Compositions of prepared phases were verified by energy-dispersive X-ray spectroscopy, infra-red spectroscopy and powder X-ray diffraction. The influence of different alkali cations in the cubic Fm3m structures was investigated for nominal compositions A2/3Cu[Fe(CN)6]2/3 with A = vacant, Li, Na, K, Rb, Cs. The Rb and Cs compounds show the highest CO2 adsorption per unit cell, 3.3 molecules of CO2 at 20 C and 1 bar, while in terms of mmol/g the Na compound exhibits the highest adsorption capability, 3.8 mmol/g at 20 C and 1 bar. The fastest adsorption/desorption is exhibited by the A-cation free compound and the Li compound. The influence of the amount of Fe(CN)6 vacancies were assessed by determining the CO2 adsorption capabilities of Cu[Fe(CN)6]1/2 (Fm3m symmetry, nominally 50% vacancies), KCu[Fe(CN)6]3/4 (Fm3m symmetry, nominally 25% vacancies), and CsCu[Fe(CN)6] (I-4m2 symmetry, nominally 0% vacancies). Higher adsorption was, as expected, shown on compounds with higher vacancy concentrations.

Hydrothermal Treatment of Coprecipitated YSZ Powders

2010 ◽  
Vol 660-661 ◽  
pp. 983-988 ◽  
Author(s):  
Alexander Rodrigo Arakaki ◽  
Walter Kenji Yoshito ◽  
Valter Ussui ◽  
Dolores Ribeiro Ricci Lazar
Keyword(s):  
Surface Area ◽  
Hydrothermal Treatment ◽  
Gas Adsorption ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
Immersion Method ◽  
Cubic Symmetry ◽  
X Ray ◽  
Granulometric Analysis ◽  
Symmetry Surface

Zirconia stabilized with 8.5 mol% yttria (YSZ) were synthesized by coprecipitation and resulting gels were hydrothermallly treated at 200°C and 220 PSI for 4, 8 and 16 hours. Products were oven dried at 70°C for 24 hours, isostatically pressed as pellets and sintered at 1500 °C for 1 hour. Powders were characterized for surface area with N2 gas adsorption, X-ray diffraction, laser diffraction granulometric analysis and scanning and transmission electronic microscopy. Density of ceramics was measured by an immersion method based on the Archimedes principle. Results showed that powders dried at 70°C are amorphous and after treatment has tetragonal/cubic symmetry. Surface area of powders presented a significant reduction after hydrothermal treatment. Ceramics prepared from hydrothermally treated powders have higher green density but sintered pellets are less dense when compared to that made with powders calcined at 800°C for 1 hour due to the agglomerate state of powders. Solvothermal treatment is a promising procedure to enhance density.

scholarly journals Piezoelectricity in perovskite-type pseudo-cubic ferroelectrics by partial ordering of off-centered cations

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Yoshihiro Kuroiwa ◽  
Sangwook Kim ◽  
Ichiro Fujii ◽  
Shintaro Ueno ◽  
Yuki Nakahira ◽  
...  
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Partial Ordering ◽  
Ferroelectric Ceramics ◽  
Piezoelectric Response ◽  
X Ray Diffraction ◽  
Cubic Symmetry ◽  
X Ray ◽  
Domain Structures ◽  
Perovskite Type

Abstract A large piezoelectric response in ferroelectric ceramics is typically associated with extrinsic contributions from ferroelectric domain structures. However, such domain structures cannot be expected in systems with pseudo-cubic symmetry. In this study, we determine the mechanism of significant piezoelectricity and ferroelectricity in 0.3BaTiO3–0.1Bi(Mg1/2Ti1/2)O3–0.6BiFeO3 ceramic with a perovskite-type pseudo-cubic symmetry. Synchrotron radiation X-ray diffraction reveals that the Bi ions in this ceramic essentially prefer to be off-centered at six sites by approximately 0.4 Å, in the cubic <100> directions. A phase transition occurs at TC ~725 K. However, the crystal seems to present a cubic symmetry even at room temperature. The large piezoelectric response is caused by the combinational partial ordering of the off-centered Bi ions, adapted to any direction of the applied electric field to the ceramic grains. The proposed mechanism for the emergence of a high polarization in the above system will enable designing novel Pb-free ceramics by controlling the fluctuated and off-centered ions under an applied electric field.

scholarly journals Neutron and X-ray powder diffraction study of skutterudite thermoelectrics

2016 ◽  
Vol 31 (1) ◽  
pp. 16-22
Author(s):  
H. Wang ◽  
M. J. Kirkham ◽  
T. R. Watkins ◽  
E. A. Payzant ◽  
J. R. Salvador ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Melt Spinning ◽  
Lattice Parameter ◽  
Type Material ◽  
General Motors ◽  
X Ray Diffraction ◽  
Filling Fraction ◽  
Cubic Symmetry ◽  
X Ray ◽  
P Type

N- and p-type filled-skutterudite materials prepared for thermoelectric power generation modules were analyzed by neutron diffraction at the POWGEN beam line of the Spallation Neutron Source (SNS) and X-ray diffraction (XRD). The skutterudite powders were processed by melt spinning, followed by ball milling and annealing. The n-type material consists of Ba–Yb–Co–Sb and the p-type material consists of Di–Fe–Ni–Sb or Di–Fe–Co–Sb (Di = didymium, an alloy of Pr and Nd). Powders for prototype module fabrication from General Motors and Marlow Industries were analyzed in this study. XRD and neutron diffraction studies confirm that both the n- and p-type materials have cubic symmetry. Structural Rietveld refinements determined the lattice parameters and atomic parameters of the framework and filler atoms. The cage filling fraction was found to depend linearly on the lattice parameter, which in turn depends on the average framework atom size. This knowledge may allow the filling fraction of these skutterudite materials to be purposefully adjusted, thereby tuning the thermoelectric properties.

In situ XRF analysis of Cs adsorption by the precipitation bands of Prussian blue analogues formed in agarose gels

2019 ◽  
Vol 34 (5) ◽  
pp. 979-985 ◽  
Author(s):  
Hisashi Hayashi ◽  
Yui Sato ◽  
Saya Aoki ◽  
Mao Takaishi
Keyword(s):  
Prussian Blue ◽  
Agarose Gel ◽  
X Ray ◽  
Agarose Gels ◽  
Xrf Analysis ◽  
Prussian Blue Analogues ◽  
Xrf Spectroscopy

The measurement of Cs adsorption by the precipitation bands of Mn-based Prussian blue analogues (PBAs), Co-based PBAs, and Prussian blue (PB), which were spontaneously formed in agarose gel, was carried out using in situ X-ray fluorescence (XRF) spectroscopy.

Cation Ordering in Substituted LiMn2O4 Spinels

2002 ◽  
Vol 756 ◽  
Author(s):  
P. Strobel ◽  
A. Ibarra-Palos ◽  
C. Poinsignon
Keyword(s):  
Ir Spectroscopy ◽  
Lithium Batteries ◽  
Driving Force ◽  
Cation Ordering ◽  
X Ray Diffraction ◽  
Capacity Fading ◽  
Cubic Symmetry ◽  
X Ray ◽  
The Poor ◽  
Octahedral Cation

ABSTRACTIn order to overcome the capacity fading of LiMn2O4 in lithium batteries, various substitutions for Mn have been proposed. The structural implications of substitution in LiMn2-xMxO4 with x = 0.5, i.e. with exactly 1/4 octahedral (16d-site) cations replaced, are investigated here. For this stoichiometry, cationic ordering was known previously for M = Mg and Zn, resulting in a superstructure with primitive cubic symmetry. Given the poor chemical contrast of X-ray diffraction between Mn and Co, Ni or Cu, LiMn1.5M0.5O4 samples were studied by neutron diffraction and IR spectroscopy. Both techniques show the occurence of cationic ordering for M = Ni and Cu, but not for Co or Ga. In the case of M = Zn, further complication due Li/Zn ordering on the tetrahedral (8a) site is well resolved by FTIR. This investigation shows that the main driving force for octahedral cation ordering is the charge difference between Mn and M atoms.

Mössbauer study of 50MeV Li3+ ion irradiated Mg0.9Mn 0.1InxFe2-xO4 ferrite

2003 ◽  
Vol 792 ◽  
Author(s):  
M. Singh ◽  
Anjana Dogra ◽  
Ravi Kumar
Keyword(s):  
Isomer Shift ◽  
Quadrupole Splitting ◽  
Lattice Strain ◽  
Electronic Configuration ◽  
X Ray Diffraction ◽  
Mössbauer Study ◽  
Cubic Symmetry ◽  
X Ray ◽  
Anomalous Character ◽  
Super Exchange Interaction

ABSTRACTA series of samples of Mg0.9Mn0.1InxFe2-xO4 for x=0, 0.3, 0.5 were prepared by conventional solid-state technique. The spinel structure of this ferrite was confirmed by X-ray diffraction technique. The samples were irradiated with 50 MeV Li3+ ions with fluence 5×1013 ions/cm2. The Mössbauer studies were performed on unirradiated as well as on irradiated samples. Mössbauer study for unirradiated samples show insignificant variation of isomer shifts at both the tetrahedral and octahedral sites. On irradiation isomer shift changes from negative to positive values. This anomalous character of isomer shift after irradiation is due to a change in the electronic configuration of Fe3+ ions. The quadrupole splitting of unirradiated samples are negligibly small, indicates the presence of cubic symmetry at both the sites. On irradiation appreciable changes are observed in quadrupole splitting due to the presence of lattice strain. On irradiation super-exchange interaction energy is weakened which decrease the hyperfine field. PACS: 61.80, 76.80, 61.72

Formation and Characteristics of Thin Films of ZrO2-8 mol % Y2O3 Solid Electrolytes

2004 ◽  
Vol 97-98 ◽  
pp. 153-158 ◽  
Author(s):  
Darius Milčius ◽  
L.L. Pranevičius ◽  
V. Širvinskaitė ◽  
T. Šalkus ◽  
A. Kežionis ◽  
...  
Keyword(s):  
Thin Films ◽  
Solid Electrolytes ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Cubic Symmetry ◽  
X Ray ◽  
Pulsed Dc ◽  
Pulsed Dc Magnetron Sputtering ◽  
Diffraction Patterns

Thin films of ZrO2-8mol%Y2O3 have been deposed by pulsed DC magnetron sputtering method. The substrates of Ni-cermet and alloy-600 for the films were used. The results of the investigation of the X-ray diffraction patterns and SEM showed that the films are nanocrystalline and belong to cubic symmetry. The relaxation process is related to the ion transport in thin films. The results of the investigation of the temperature dependencies of thin films ionic conductivity (σ) showed that the dependence σ(T) is caused by the temperature dependence of oxygen vacancy mobility, while the number of charge carriers remains constant with temperature.

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